FOUNDRY PRACTICE
GIFA 2003
hall 12, stand
12 A 05
16-21 JUNE 2003
Düsseldorf
Germany
IMPROVING FOUNDRY PROFITABILITY THROUGH THE
USE OF RHEOTEC*
XL COATINGS
THE APPLICATION OF KALPUR*
DIRECT POUR
TECHNOLOGY IN THE PRODUCTION OF SAFETY
CRITICAL STEEL CONSTRUCTION CASTINGS
DEVELOPMENTS IN DIE COATING TECHNOLOGY
FILTERCALC* FOR STEEL –
A WINDOWSTM
BASED PROGRAMME FOR SIZING FOAM FILTERS
FOR STEEL
LOW
DENSITY INSULATED LADLE LININGS AT
SINCLAIR WORKS
ISSUE
240
page
Contents
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IMPROVING FOUNDRY PROFITABILITY
THROUGH THE USE OF RHEOTEC* XL
FOUNDRY
PRACTICE
1
ISSUE 240
June 2003
COATINGS
BY NICK HODGKINSON
FOSECO METALLURGICAL, INC.; USA
&
TIM BIRCH
FOSECO FOUNDRY EUROPE
UNITED KINGDOM
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6
THE APPLICATION OF KALPUR* DIRECT POUR
TECHNOLOGY IN THE PRODUCTION OF SAFETY
CRITICAL STEEL CONSTRUCTION CASTINGS
BY GERD STOTTMEISTER
FOSECO GMBH
GERMANY
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DEVELOPMENTS IN DIE COATING TECHNOLOGY
Front cover: Moulding plant - pouring
line, Friedrich Wilhelm Hütte GIII,
Mühlheim, Germany
All rights reserved. No part of this
publication may be reproduced, stored in a
retrieval system of any nature or transmitted
in any form or by any means, including
photocopying and recording, without the
written permission of the copyright holder.
All statements, information and data
contained herein are published as a guide
and although believed to be accurate and
reliable (having regard to the manufacturer’s
practical experience) neither the
manufacturer, licensor, seller nor publisher
represents or warrants, expressly or
impliedly:
BY WOLFGANG HOPS
13
ROGER KENDRICK FOSECO
FOUNDRY EUROPE UNITED
KINGDOM
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FILTERCALC* FOR STEEL – A WINDOWS
17
(1) their accuracy/reliability
(2) that the use of the product(s) will not
infringe third party rights
(3) that no further safety measures are
required to meet local legislation
The seller is not authorised to make
representations nor contract on behalf of
the manufacturer/licensor. All sales by the
manufacturer/seller are based on their
respective conditions of sale available on
request.
FOSECO the logo, CERAMOL, DYCOTE,
FERRUX, FILTERCALC, KALMINEX, KALPUR,
KALTEK, MOLCO, RHEOTECand STELEX are
Trade Marks of the Foseco Group of
Companies used under licence.
© Foseco International Ltd. 2003
FOSECO GMBH
GERMANY
&
BASED PROGRAMME FOR SIZING
FOAM FILTERS FOR STEEL
BY TONY MIDEA & JOHN OUTTEN
FOSECO METALLURGICAL, INC.;
USA
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LOW DENSITY INSULATED LADLE LININGS AT
SINCLAIR WORKS
23
BY NICK CHILD FOSECO
FOUNDRY EUROPE, UNITED
KINGDOM
&
SAM APSLEY, ENERGY CONSULTANT,
UK ACTION ENERGY PROGRAMME
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Background
High production iron foundries everywhere are
facing enormous pressures to produce increasingly
complex, high performance automotive and other
castings, to ever-increasing quality specifications while attempting all the time to reduce casting
production costs.
Refractory core coatings are fundamental to
obtaining satisfactory casting surface quality and are
used extensively on resin-bonded cores and core
packages in production iron foundries. As the need
for more complex, critical castings and higher
quality standards grows, the function and
performance of the core coating utilized in the
process becomes critical.
The impact of a high performance core coating on
the overall production cost of a typical grey iron
casting can be significant. Fettling, cleaning, and
casting inspection operations can often contribute
as much as 20 - 25% of the total production cost
of an iron casting. While some of this time and cost
is associated with the removal of gating systems
and "flash", time-consuming repair of surface
defects and the removal of adhered sand / coating
residue from internal cavities are major cost
components which can be directly affected by the
core coating performance and application.
As with the proven standard RHEOTEC products,
RHEOTEC XL coatings are formulated and
manufactured under tight quality control process
conditions to provide excellent application behaviour
and stability and consistency in use. Specially
selected surfactants ensure controlled substrate
wetting with no foaming tendency, for defect free
core and casting surfaces and less remedial work on
coated cores. Levelling of the coating layer is
excellent, resulting in a consistent film thickness and
a uniform layer that is free from runs, drips and
curtain defects, even on complex core assemblies.
The engineered RHEOTEC XL coating refractory
system provides superior as-cast surface finish
quality in the most critical applications - in particular
the coating technology has been optimized to
eliminate or dramatically reduce veining defects.
Veining (or finning) defects (figure 1) occur when
metal enters cracks in the core surface which result
from thermal stresses generated by the expansion of
silica sand during casting. In severe cases, the metal
can actually penetrate the core completely causing a
total blockage of an internal cavity, rather than
simply causing a surface vein or fin defect.
The material cost of coating is typically a fraction of
the total manufacturing costs and usually would be
less than 1% of total production costs.
The experience of production iron foundries in
using the RHEOTEC XL range of premium core
coatings in the past 3-4 years has been extremely
positive. This paper provides an overview of the
technology and provides examples of how
RHEOTEC XL coatings have improved the
profitability of foundries in many different markets
and in different casting applications.
How RHEOTEC XL coatings function
RHEOTEC XL coatings are water-based slurries
containing a special blend of refractory fillers that
have been engineered specifically to meet the
most stringent demands of grey and ductile iron
casting producers.
Figure 1: Veining in a sectioned diesel cylinder head casting
Veining severity varies significantly, depending on
core type, sand quality and type, casting
configuration, and metal composition.
The superior anti-veining and overall casting quality
provided by RHEOTEC XL coatings is a direct result
of the optimized application behaviour and the
engineered refractory system which ensures that the
thermal shock experienced by the core during
casting is substantially delayed and diminished.
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.
Improving foundry profitability
through the use of
RHEOTEC* XL Coatings
The effect of RHEOTEC* XL coating chemistry on the
temperature profile of a standard AFS compression
core during pouring was studied through the use of
thermocouples embedded in the core (figure 2).
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Controlled penetration of refractory fillers into the
core substrate produces a high insulation value and
a coating layer with an enhanced "hot strength"
that inhibits the formation of core surface cracks at
casting temperatures.
Value to the User
In most cases, the use of RHEOTEC XL coatings will
totally eliminate moderate veining, as well as
adhesion of sand and core particulate matter
(figure 4).
Figure 4. Penetration defect in 1.8ltr engine block oil
gallery (left-hand section) eliminated through the
use of RHEOTEC XL coating ( right-hand section )
Figure 2: Coated test piece cores
The highly insulating nature of RHEOTEC XL
coatings is illustrated in Figure 3. The chart shows a
comparison of core temperature vs. time after
pouring, for a RHEOTEC XL coated core and a core
coated with conventional aluminosilicate coating.
The temperature increase at a 3 mm distance below
the core surface was measured for a period of time
after the test block had been poured.
The performance characteristics of RHEOTEC XL
core coatings provide significant casting quality and
operational benefits for production iron foundries,
both in the core room and in the casting finishing
area. Some of the benefits reported by RHEOTEC XL
users include :Quality Improvements:
❑ Superior as-cast surface finish
❑ Reduced retention of sand and coating material
particles
❑ Cleaner overall internal casting passageways.
Operational Benefits:
❑ Elimination of costly anti-veining sand additives
❑ Elimination of double coating practices
❑ Reduced core dressing (remedial work) operations
❑ Simplified core room process control
❑ Reduced core room labour costs
❑ Lower casting scrap levels (due to reduced
veining / metal penetration severity)
Figure 3: Comparison of thermal behaviour of a RHEOTEC XL coated core vs
conventional coated core
The time required for the core surface to reach the
temperature at which sand expansion occurs (alphabeta phase change), is delayed by a short but
significant period. This, combined with the high
coating hot strength, significantly reduces the
tendency for core surface cracking and subsequent
vein formation.
2
❑ Reduced shot-blasting costs (labour, equipment,
energy, materials)
❑ Reduced fettling and grinding costs (labour,
equipment, energy, materials)
❑ Reduced inspection costs
❑ Faster casting throughput - improved foundry
productivity & capacity
RHEOTEC XL coatings are most suited to critical
applications where dimensional accuracy and
exceptional surface characteristics are required,
where retained sand and coating particulate matter
in internal passageways is a critical issue, and where
veining is experienced. Typical casting applications
include cylinder heads, engine blocks (water jacket,
oil gallery), hydraulic castings, housings (differential,
pump, etc.) and brake disc rotors.
RHEOTEC XL coatings are most effective and
provide the greatest benefit on phenolic-urethane
cores. Phenolic-urethane cold-box cores are more
prone to veining defects than other systems (hotbox, shell, etc.) because of the inherent lower hot
strength of the binder system. However production
tests have also confirmed that RHEOTEC XL
coatings are effective when used on other binder
systems such as SO2-epoxy, PF Hot-Box and Shell
bonded cores.
Production experience with
RHEOTEC* XL coatings
The following case-studies highlight the benefits of
RHEOTEC XL coatings when targeted at the
elimination of sand expansion defects such as
veining and improving "strip and peel", to ensure a
defect free surface without coating adherence and
retained particulate. In all cases the benefits to the
foundry are to be found in reduced overall cost per
component. The cost savings are achieved through
lower scrap and defect levels resulting in reduced
processing times, both in the coreshop and the
finishing shop. The overall effect is improved
productivity and the elimination of production
bottlenecks, with reduced labour requirements and
no need for further capital investment in the
finishing shop.
Case Study 1. Grey iron diesel engine 6cylinder head
The case-study is based on the experiences of a
high production cylinder block and head foundry
located in Brazil, whose main customers include
Cummins, General Motors, Peugeot, Daimler
Chrysler and Mack Truck. The foundry has an
output of approximately 300,000 tonnes of finished
castings per annum, with between 50 and 60
percent of these being for direct export.
Details of the cylinder head casting and its
manufacturing parameters are as follows :❑ Weight
:
91.2 Kg
❑ Castings per mold
:
2
❑ Pouring temperature :
1400-1420ºC
❑ Castings per year
:
144,000
❑ Core Package
:
Phenolic-Urethane
Cold Box
Significant veining defects were typically encountered
within the internal channels of the casting (figure 6)
which required excessive cleaning times to eliminate,
resulting in a production bottleneck within the
finishing department of the foundry.
Figure 6: Extensive veining prior to use of RHEOTEC XL
coating
The objectives of the customer were to remove this
bottleneck by improving the as-cast quality of the
internal channels by preventing the vein formation.
This would reduce significantly the subsequent
fettling and cleaning times and avoid further
capital expenditure aimed at increasing the capacity
of the finishing shop to accommodate the
moulding line capacity.
Coating Application
The RHEOTEC XL coating was trialled against the
current coating practice, as outlined in the table
below. It should be noted that the RHEOTEC XL
coating was applied as one layer by using an
automated dipping machine, and that the layer buildup was equivalent to that achieved by a double
dipping operation with the traditional coating.
"Old" Practice
RHEOTEC XL Practice
Coating
Core Sand
Coating Method
Graphite-based
Silica 50/55
Water-Jacket manually
pre-coated prior to auto
dipping of core assembly
RHEOTEC XL
No Change
Single coat only of core
assembly
Baumé
Coating Thickness
Drying Conditions
33
0.22 - 0.24 mm
Gas Convection – 180ºC
for 40 mins.
34
No Change
No Change
RHEOTEC XL coating performance
The internal channels were observed to be free
from any veining defects, and there was also a
reduction in the amount of retained particulate
after the shot blasting operation (see figure 7). The
total benefits to the foundry in using RHEOTEC XL
coating are summarised below :❑ Improved coreshop productivity through the
elimination of the double dipping operation
❑ Elimination of the operator applying the
"pre-coat"
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Main Applications
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Reduced cleaning requirements would eliminate the
production bottleneck within the finishing shop,
allowing higher productivity and reducing overall
production costs per unit.
Figure 7: Defect free internal channels when using a single
coating application of RHEOTEC XL
❑ Reduced cleaning room labour – from 12 to 4
operators
❑ Increased cylinder head output – from 30 to 60
heads per hour
Coating Application
A coating from the RHEOTEC XL range was
compared directly with the established coating
practice as outlined in the table below. Again it
should be noted that the superior rheological
properties of the RHEOTEC XL coating allowed for
a one dip application.
"Old" Practice
RHEOTEC XL Practice
Coating
Talc / Aluminosilicate product
Sand Additive
Coating Method
3% anti-veining sand additive
PF Hot-Box water-jacket core
manually dipped, dried,
assembled with slab core and
re-dipped
RHEOTEC XL-C coating
supplied RFU at 34 Baumé
No Change
Single coat of RHEOTEC XL-C
coating to water-jacket/slab
core assembly
❑ Lower overall cylinder head production costs
❑ Zero expenditure on increasing cleaning shop
capacity
Case Study 2. Grey Iron 2.0 Litre Petrol
Engine Block
This case study is based on the development work
that took place between FOSECO and a high
production automotive foundry located in Australia.
The foundry is producing approximately 63,000
tonnes per annum of finished castings and supplies
customers such as General Motors, Daewoo, Isuzu
and Opel throughout Australia and Europe.
Baumé
Coating Thickness
Drying Parameters
28 - 32
0.45 - 0.65 mm (wet)
Gas Convection – 250ºC
RHEOTEC XL coating performance
The single layer of RHEOTEC XL coating produced a
clean, defect free internal water-jacket area with
significantly less retained particulate (figure 9).
The problematic casting is shown sectioned in
Figure 8, and highlights typical levels of both
veining and retained particulate experienced when
using the previous coating practice.
❑ Weight
: 23 kg (2 per mold)
❑ Pouring temperature : 1420ºC
❑ Castings per year
: 600,000
❑ Core Package
: PF Hot-Box Water-Jacket
The objectives of the customer were to improve the
internal finish of the water-jacket area, through
eliminating the formation of veining defects and
reducing the amount of retained particulate.
Figure 9: RHEOTEC XL coated water-jacket core and resulting defect free internal finish
The customer benefits resulting from this
performance are summarised below :
❑ Less retained particulate and zero veining in the
water-jacket area
❑ Reduced casting scrap – 35% reduction in
water-jacket related defects
❑ Overall 15 – 20% productivity increase
4
Figure 8: Veining and retained particulate levels prior to use
of RHEOTEC XL coatings
32 - 35
Same
Same (with no pre-coat cycle)
❑ Reduced labour in casting inspection and
finishing
❑ Finishing area bottleneck eliminated
❑ Lower drying oven energy costs, due to single
dip operation
Conclusion
To maintain a competitive edge within the foundry
market, production iron foundries need to produce
increasingly complex, higher quality castings, at
increased production levels and with lower overall
costs. A key factor in achieving this goal is the
reduction of costly cleaning and finishing operations
that can also be a major process bottle-neck.
This competitive edge can be achieved by using
RHEOTEC XL coating to optimise casting surface
integrity in a cost effective manner, and to help
ensure the consistency and quality of the
components being cast.
5
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❑ Reduced labour in coreshop
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The application of KALPUR*
direct pour technology in the
production of safety critical
steel construction castings
Introduction
The Olympic Stadium in Berlin is being renovated in
readiness for the Football World Championships in
2006. Its design will be in keeping with that of a
cultural monument yet at the same time cater for
all the demands placed on a modern stadium.
After completion, the stadium will have 76,000
covered seats. Until now the stadium has had a
capacity of 75,000 seats but only 27,000 of these
are covered by a roof (figure 1).
❑ Steel casting components can be optimised in
their shape and wall thickness in accordance
with load bearing requirements.
❑ Sharp corners and edges and variation in wall
thicknesses can be virtually eliminated, thereby
reducing stress concentration to the lowest
levels. This is a decisive advantage for
construction components subject to material
fatigue.
For these reasons, steel casting construction
components are normally used for cable net
structures, roof supports, pedestrian bridges, road
and railway bridges as well as stadia such as the
Berlin Olympic Stadium as described above.
Figure 1: Model of the Berlin Olympic Stadium after
reconstruction
The new roof has been intentionally designed to
have a different tone to the existing architecture of
the historic stadium; and will consist of a filigree
steel construction with a roof membrane over it.
Only the roof over the Marathon Gate remains
open so as not to obstruct the view of the bell
tower.
The main supports of this steel construction are
steel casting clusters welded together with either
pipes or solid material.
The key advantages of steel castings over welded
and screw-fixed components for construction are:
❑ The accurate production of even the most
complicated geometrical cluster shapes is
possible
6
Steel castings were originally used in the roof of this
stadium for the Olympic Games of 1972. The
castings for the new roof are being manufactured
by the Friedrich Wilhelms-Hütte (FWH) steel foundry
in Mülheim, Germany, who have been
manufacturing castings for bridge, hangar and roof
constructions for many years.
FWH produced the first casting clusters for railway
bridges in 1998/99 for the Humbold-Harbour Bridge
in Berlin. Further major projects are the Lerther
Railway Station in Berlin, the Nesenbachtal Bridge in
Stuttgart, the Traunstein Bridge and hangars at the
airports of Stuttgart and Leipzig.
Roof construction
The Berlin Stadium project comprises the supply of
254 different casting configurations with up to nine
different exits and up to three additional connecting
latches. The alloys used for the castings are
G20Mn5V and G18NiMoCr3.6V (figure 2).
Alloy G18NiMoCr3.6V with a wall thickness of 290
or 350 mm was chosen for the casting clusters of
the uprights and the connecting exits of the cluster
numbers 1 and 2. All other exits have a wall
thickness between 14 and 45 mm (figure 3).
The following case study concerns a cluster with 6 exits – 3 latches and a wall
thickness of 14 – 45 mm.
Pattern and Casting Data – Conventional Casting System
Several parts had already been produced with a conventional feeding and running
system.
General Data:
Part description:
Alloy:
Dimensions
Nett weight: Poured
weight: Running/Feeding
system: Moulding
system:
Cores:
Node
G 20Mn5V
(mm) 1100 x 800 x 685
792
(kg)
1298
(kg)
(kg)
506
Furan resin (quartz/chromite sand)
Coating: MOLCO* 246FA4 – CERAMOL* 58
alkali phenolic resin (quartz/chromite sand)
Coating: MOLCO 246FA4 – CERAMOL 58
Figure 3: Casting cluster with cross-struts
Gating and Feeding Data:
Downsprue:
1x dia 80mm
Runner:
1x dia 80mm
Ingates:
2x dia 60mm
Filters:
none
Feeders:
KALMINEX* X 12 - 500mm high (Modulus = 9.4)
sleeves
Casting Data
Casting temperature:
Casting time:
Casting vessel:
Melting furnace:
1610ºC
24-25 seconds
4t and 6t bottom pouring ladle – nozzle diameter 70mm
Arc furnace followed by VARP converter
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.
Figure 2: Initial roof construction. Architects: von Gerken, Mang and Partner. Photo: Heiner Leiska
A computer simulation of solidification was carried
out before production, which resulted in the
feeding method described above (figure 4).
Bridging
Pattern
Alternatives to the Conventional
Casting System:
KALPUR* Direct Pour Technology
Centering
Support
It was suggested to cast the aforementioned cluster
with the FOSECO patented KALPUR direct pour
technique. The following is the technical data of the
KALPUR direct pour casting product incorporating a
STELEX* PrO filter.
Application of KALPUR direct pour units:
The FOSECO KALPUR product combines the use of
feeders and filters and can replace the entire
conventional casting runner system, as the mould is
filled directly via the feeder. Because ingates are not
necessary and filling is carried out into a suitable
section of the casting, a directional or controlled
solidification of the casting is achieved or improved.
KALPUR direct pour units can either be positioned
on top of the casting or used as a side feeder head.
Figure 5: Ram-up style with a fixed centering peg and a
loose dummy reaching up to the cope
suitable for larger castings produced with the
KALPUR direct pour units (figure 5).
2. Automatic moulding line with horizontal
and vertical parting
Use of the insert sleeve method enables highlyautomated repetition foundries to take advantage
of KALPUR direct pour unit technology but will not
be described here.
1. Hand moulding and simple moulding machines
STELEX PrO Steel Filter
8
Open, neck-down shaped KALPUR direct pour units
are used for this purpose and have a supporting
surface on which the filter is located. They are
either placed on the pattern or inserted later into
the cavity created by an insert dummy. KALMINEX
2000 exothermic-insulating feeders are used for
iron and steel castings up to a modulus of 4.3 cm.
The neck-down KALMINEX TA feeding range is
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 4: Computer simulation of solidification
STELEX PrO is a new generation of ceramic foam
foundry filters which have been developed
especially for the filtration of carbon and low-alloy
steels. Even materials such as manganese steel can
be cast without problems. However, it is not
recommended for steels with a carbon content
below 0.15% or for high alloy stainless steels
(figure 6).
Some of the advantages of the STELEX PrO filters
include:
❑ Consistent "Priming" even when pouring
temperatures are low such that pouring
temperatures normal for conventional gating
systems are possible.
❑ Reduction of temperature related inclusions.
❑ Higher filtration capacity
Clusters cast with KALPUR
Direct Pour method
Because of the positive experiences with the KALPUR
direct pouring unit, the suggestion to try to produce
the cluster using this method was accepted.
The first step was to create a computer simulation
of the mould-filling and solidification in order to
ascertain its feasibility. The simulation results
indicated a successful result and casting trial was
planned (figure 7).
❑ Excellent flow rate characteristics compared to
zircon ceramics
❑ Flexible filter positioning - the filter can be
placed horizontally and vertically and is ideally
placed at the ingate
❑ The use of finer porosity filters is possible.
❑ When used in the KALPUR direct pour system
the filter will easily float to the feeder surface
after pouring, reducing the risk of secondary
shrinkage and maximising feeding efficiency
❑ No difficulties during remelting of returns
containing STELEX PrO filter material
❑ Lower energy costs
❑ Lower refractory materials costs
Figure 7: Computer simulation for solidification
9
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.
Figure 6: The STELEX PrO filter
The neck aperture of the feeder sleeve posed the risk
of the filter being washed into the mould by the high
ferrostatic pressure. To prevent this a shell sand core
was used to provide a defined base for the filter.
Feeder
Core
Filter
The filled feeder, open at the top, was covered with
FERRUX* 707G – an exothermic, expanding powder.
Covering the feeder with a suitable material is of
prime importance for the KALPUR direct pouring
system. Using FERRUX exothermic expanding
powder, the dual effect of heating and insulation of
the feeder surface facilitates the longest effect of
the atmospheric pressure on the molten feeder
metal. This leads to optimum use of the feeder,
improvement of the later interdendritic feeding and
consequently to a reduction of secondary shrinkage.
After removal, shotblasting and fettling of the
cluster, a cost comparison – conventional casting
method vs. direct pour method – was carried out.
Costs
Casting Data KALPUR- Direct Pour Method
Casting temperature
Casting time: Casting
vessel: Moulding/Core
practice
10
1612ºC
23-24 seconds
6 tonne bottom pouring ladle 70mm nozzle diameter
no change
Conventional
Method
KALPU
R
Method
87.4%
Molten material
100.0%
Core-shop
100.0%
100.0%
Moulding
100.0%
97.3%
Pre-fettling/
sandblasting
100.0%
80.1%
Manual cutting
100.0%
65.1%
Arc Air
100.0%
88.1%
Initial grinding
100.0%
81.1%
Final fettling
100.0%
94.7%
Tolerance grinding
100.0%
100.0%
Heat treatment
100.0%
100.0%
Finishing
100.0%
29.6%
Production costs of
raw casting
100.0%
82.9%
Figure 8: CAD illustration of casting method
The pattern was specially designed for use with the
KALMINEX TA 11 feeder sleeve. This sleeve has the
advantage of a base area four times less than the
KALMINEX X 12 feeder sleeve – this also means
that cutting and fettling costs are significantly
reduced (figure 8).
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
KALMINEX TA 11 feeder sleeves were chosen as the
feeder, but since the height of feeder was not
sufficient a KALMINEX X 12 feeder sleeve was
placed on top of it. A STELEX PrO 200 dia x 40mm
/10ppi filter was used.
The filter floated upwards immediately after casting
and could be removed. Figure 9 shows the upper
side of the filter after casting.
Figures 10 and 11 show the cluster after
sandblasting, fettling and heat treatment.
Figure 9: Filter after casting
Figure 10
❑ direct pouring of the casting
❑ complete elimination of conventional running
systems
❑ directional solidification is improved or achieved
❑ increased yield
❑ reduction of fettling and grinding costs
❑ reduction of casting temperatures
❑ removal of fine inclusions
References:
Herion Mang Stahlbaukalender, Guß im Bauwesen
S. 641 / Ausgabe 2001
Figure 11
The finished casting passed the customary ultrasonic
inspection tests.
Conclusions
The example described above illustrates a significant
reduction in production costs, most noticeably in
the fettling shop.
Karl-Josef Müller, The stadium roof for the football
World Cup consists of 254 cast nodes.
Glück auf – Internal magazine of the
Georgsmarienhütte Group; Edition: April 2002,
page 20
STELEX PrO brochure, June 2003
Furthermore a significantly better casting surface
can be achieved compared with conventional
casting methods, especially where the new
STELEX PrO ceramic foam filter is used.
KALPUR Direct Pour brochure, May 1999
Depending on the geometry of the casting and the
arrangement of the patterns in the mould, not all
castings are suitable for the KALPUR direct pour
technique, and a feasibility study should be carried
out beforehand.
The ability to manufacture high-quality castings
whilst paying attention to economic and
environmental pressures is a pre-requisite for a
successful position in the market for many
manufacturers. Demands are placed, especially in
industrial Europe, for continuous improvement in
productivity and the development of new and
innovative production processes.
11
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.
The KALPUR direct pouring technique is just such an
innovative production process, offering the foundry
industry the following advantages:
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Background
Something in the region of 40% of aluminium
castings produced globally are made via the gravity
diecasting ( permanent mould ) and low pressure
diecasting processes. It has always been accepted
that a major contributor to the successful
manufacture of quality parts is the coating which is
applied to the die surface. FOSECO has had for
many years a comprehensive range of coatings
which give:
down- time while cleaning and recoating is a major cost
and inconvenience to the foundry so improvements in
DYCOTE life will offer significant benefits.
This has given FOSECO the opportunity to reassess
its strategy towards the DYCOTE product range.
Traditional DYCOTE die coating range
The DYCOTE die coating range can be separated
into three distinct product types:
❑ Insulation control
❑ Insulating coatings
❑ Release from the die
❑ Heat conductive coatings
❑ Encouragement to fill thin sections fully
❑ Lubricating coatings
❑ Control of surface finish
The insulating coating range is the largest of the
three groups. These coatings help maintain metal
temperature and therefore metal fluidity during the
filling of the mould. The insulating characteristics of
the coating will come partly from the constituents
and partly from the surface roughness of the
coating. The surface roughness is generated by the
particle size of the refractory fillers and varies
between 10 and 100 microns. In general the
coarser the coating the higher the insulation effect.
When selecting a die coating for each specific
application there is always a compromise between
surface finish of the casting and the filling of the
mould cavities.
❑ Soundness (feedability)
The use of DYCOTE die coatings has been
widespread in the foundry industry for more than 60
years with the traditional product range modified to
satisfy specific customer requirements. The products
have also evolved to reflect the change in casting
requirements, however, no major developments
have been made for some considerable period.
Over the past 5 years the market demands
regarding die coatings has been changing with
productivity and plant utilisation becoming more
important within the foundry industry. Any
interruption in production and subsequent
Type of Coating
Typical Grain Size
µm
Listed below are some typical coatings taken from
the FOSECO Insulating coating range.
Thinning
Ratio
Application,
Description
Base Coat
DYCOTE D R 87
18
1:1 - 1:3
Primer, increases adhesion and thereby
lifetime of the top coating
Insulating Coatings
DYCOTE D R 787
10
1:3 - 1:5
Can be applied at higher temperature
than standard coatings
DYCOTE D 39
DYCOTE D BN 120
15
35
1:3 - 1:5
1:10 - 1:20
Where excellent surface finish is essential
Coating containing boron nitride for
smooth surfaces, although the coating itself
has a rough surface, and long holding times
DYCOTE D 140
35
1:3 - 1:5
DYCOTE D 7039
78
1:3 - 1:5
DYCOTE D BN 7039
78
1:3
DYCOTE D 34
80
1:3 - 1:5
DYCOTE D 6 ESS
85
1:3 - 1:5
Mid range coating for
standard applications.
Coarse coatings often used for
thin walled automotive castings.
13
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.
Developments in die coating
Technology
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
In certain applications it is necessary to apply conductive coatings to increase heat transfer and encourage
rapid cooling. These coatings are all graphite based and can also be used for lubrication.
Below is a list of typical coatings from this range:
Heat Conductive
and Lubricating
Coatings
Typical Grain Size
µm
DYCOTE D 40
Thinning
Ratio
Application,
Description
Diluted with
mineral oil
Graphite/oil ingot coating
DYCOTE D 38
5
1:10
Colloidal graphite, lubricating coating for
low tapers, without binder
DYCOTE D 11
10
1:10
Semi colloidal graphite, for parts with
low tapers, chill coating, without binder
As DYCOTE D 11, however,
with additional binder
All the above listed coatings are delivered in a concentrated form and have to be diluted with water, except
for DYCOTE D 40, which has to be diluted with mineral oil.
DYCOTE D 36
35
1:3 - 1:5
Selection of die coatings
A number of factors must be taken into consideration
when selecting a die coating. Firstly the section
thickness of the casting. One of the main properties
of a coating is its ability to aid the filling of the die.
When the casting concerned has a thin section then a
DYCOTE die coating with high insulation properties
should be considered. Secondly there is the surface
finish requirement of a casting. This is very important,
however, coatings which give very good surface finish
do not also give good insulation. The balance of
surface finish and insulation will therefore always be a
compromise. Another important factor is the
geometry of the casting which can also be critical for
efficient feeding. If a casting has isolated thick
sections then a specific coating may be required to
help directional solidification. Where a casting has
small draft angles, then a coating with excellent
release may be required. Finally the casting process
may also influence DYCOTE die coating selection.
For example low-pressure castings can be made with
coatings which have different characteristics from
gravity castings. By carefully selecting the DYCOTE die
coating with the required features, then optimum
performance can be achieved.
Figure 1: DYCOTE die coating management station
Process control
In order to achieve the optimum performance from a
particular coating it is now accepted that the mixing
and application of the coating is critical. To this end
FOSECO have developed a DYCOTE die coating
Management Station. This enables the foundry to mix
the coating in ideal conditions by accurately measuring
the water addition and also gives the option of
pre-programmed dilution to eliminate operator error.
The use of the FOSECO Carry&Mix mixer also ensures
the coating is not only mixed well but is held in
suspension during the working period. Cleaning of the
Carry&Mix is simple and must be carried out
thoroughly to avoid possible contamination with old
coating. By creating a central, controlled mixing area
then the preparation of the DYCOTE die coating will
be given the level of importance and control which it
deserves (figures 1 and 2).
14
Figure 2: FOSECO Carry&Mix mixer
A key feature in the improved performance of these products has been the final curing of the coating.
The finished die is soaked for 60 minutes at 450ºC to drive off any chemically combined moisture, reducing
the tendency to pick up moisture during storage. This also hardens the surface thus increasing the coating
life in service.
European Experience
When the first trials were made in Europe, using the Japanese developed products, it soon became clear that
these very fine coatings were not suitable for European casting techniques. Problems with mould filling were
experienced and it was found that a coarser range of Long Life DYCOTES die coating were required for the
European market. The European product range to date includes;
DYCOTE
Description
DYCOTE 1450
General purpose coating.
DYCOTE 2040
Coarser version of DYCOTE 2050 - for thinner walled gravity die applications such
as cylinder heads.
DYCOTE 2050
Successful for automotive castings.
DYCOTE 3950
DYCOTE 3975
Excellent for low pressure wheel production
Good surface finish, excellent release.
Application
❑ Best results are achieved with dilution rates of around 1 : 3
❑ Spray on to the die at 200 - 250ºC
❑ To achieve the optimum life time of the Long Life DYCOTE the die has to be cured at 450ºC for just
over one hour
Advantages of Long Life DYCOTE die coatings
❑ Improved Productivity - Dies run for longer and so the frequency of stopping production to change to a
newly coated die is reduced.
❑ A reduction in scrap on start up of a newly coated die. It is common when a newly coated die is first cast
that the temperature profile may not be correct. Shrinkage or mis-running sometimes results. Again the
less frequently a newly coated die is introduced, the fewer problems are created.
❑ Reduction in frequency of coating leads to a reduction in labour required in die preparation.
❑ As the Long Life DYCOTE die coating is tougher and more wear resistant then the die will run longer at the
optimum thickness and condition of the coating, resulting in better quality castings.
❑ With the special composition of Long Life DYCOTE die coatings there is less likelihood of settling and
segregation during mixing.
❑ Reduction in frequency of die cleaning will result in less die wear, improved die life and consistent
casting definition.
❑ A lower frequency of die cleaning means a reduction in cleaning consumables and less DYCOTE die
coating being consumed.
❑ Foundries will traditionally touch up the coating on the die to extend the coating life, without removing
and recoating. Again the amount of touching up required will be far lower with Long Life DYCOTE die coating.
15
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.
New Developments
As productivity in foundries became ever more important over the years FOSECO were continually asked to
develop new ranges of coatings which would improve die life. The original development work was carried out
by FOSECO Japan. It was soon evident that by moving to a different binder and more carefully graded fillers
then significant improvements could be made in die coating performance. By making these changes a range
of coatings were developed equating to the current range, and sold in Japan.
Europe
In the following table a selection of castings
produced throughout Europe using various DYCOTE
die coating products are shown.
Casting
LLDYCOTE
Dilution
Spray temp
Curing
Performance
Suspension arm
DYCOTE 2050
1:3
200ºC
400ºC
12 shifts
Cylinder head
DYCOTE 2040
1:3
200ºC
300ºC for
3 hours
3 days
Wheel Customer A
DYCOTE 3950
1:5
300ºC
None
10 shifts
Wheel Customer B
DYCOTE 3950
1:5
300ºC
None
4 shifts
Wheel Customer C
DYCOTE 3950
1:5
300ºC
None
Double l4fe.
Housing
DYCOTE 1450
1:3
225ºC
None
5 shifts
Conclusion
The developments in DYCOTE die coatings have
now given diecasting foundries a wider and more
sophisticated range of products from which to
choose. The products need to be able to perform
such that they satisfy the requirements placed on
the industry by casting designers and buyers.
By careful product selection, preparation and
application better performance can be achieved
with subsequent improvements in casting quality,
consistency, finish and productivity.
16
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Case Studies
TM
Abstract
The widely accepted benefits of ceramic foam filters
for steel casting include removal of non-metallic
inclusions, reduction of turbulence to minimize
reoxidation and simplified gating (1,2). However,
the filter must be properly sized and applied for
maximum effectiveness and cost efficiency.
Filter selection historically has been based on tables
of flow rate and filtration capacity ranges derived
from foundry experience under general melting,
pouring and moulding conditions. This has often
required interpolation and extended foundry trials to
determine proper selections for specific applications.
Elaborate methods already exist to design successful
filter gating systems, but they are not widely used
due to economic and/or time constraints.
A new computer programme simplifies and
increases the accuracy of filter selection. It uses
physical principles herein described governing
fluid flow and empirical data from extensive water
modelling studies to determine the pressure drop
effects of introducing ceramic foam filters into the
molten metal stream.
Introduction
A properly sized filter for a casting meets a
maximum mould pouring time requirement while
adhering to a filter capacity limitation, which is
defined as the amount of metal that will pass
through prior to blockage.
The pouring time is influenced by the geometry of
the casting and mould, alloy type, mould and core
materials, pouring temperature, and pressure drop
as flow passes through the filter. Filtration capacity
is influenced by alloy composition, deoxidation
practice, metallostatic pressure, pouring
temperature and the filter porosity and frontal area.
Besides removing inclusions from steel through
filtration, filters modify metal flow and reduce
turbulence. The flow modification produced is a
function of the filter material, thickness, pore size
and inlet flow velocity.
The maximum flow rate of the system is determined
by the system choke. For direct pouring systems, the
choke is always the exit area of the direct pour unit
(KALPUR“ unit). For in-line gating, determining the
location of the choke is more complex, and could be
affected by the exit area of the sprue, the filter print,
the filter flow characteristics and the foundry process
conditions. Depending on the above constraints, the
in-line system choke will either be located at the
sprue exit or at the filter print exit.
Ideally, choking before the filter should be avoided
due to the increased potential for turbulence and
mould erosion.
Current Filter Selection Methods
Existing filter sizing methods utilize tabular data
from general foundry experience. Ranges, rather
than specific flow rates and filtration capacities, are
normally given for each filter size. It is difficult to
adjust these values to account for variations in alloy
type, metal cleanliness, moulding conditions and
pouring practices found at an individual foundry.
Using current methods, once a filter size is selected,
the sprue is simply sized by using a recommended
sprue-to-filter-area ratio. However, this technique is
approximate because clogging of the filter is
proportional to the quantity of metal passed
through the filter, not the sprue-to-filter-area ratio.
Filtration capacity is based on several considerations.
Major limiting factors include clogging at which filter
flow rate is significantly affected, or failure of the
filter structure due to exceeding the filter capacity.
Current filter selection methods are severely limited
and generally result in over sizing and higher
filtration costs. This could conceivably prohibit the
use of filtration on a particular casting.
To simplify and improve ceramic foam filter sizing
accuracy, a unique computer programme has been
developed. It is an advanced application tool that
considers filter behaviour within, and as part of, the
specific gating system to be used.
17
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.
FILTERCALC* for steel –
a Windows based programme for
sizing foam filters for steel
Applied physics can significantly improve filter sizing
accuracy. Several methods exist to physically model
the flow through a filter. The most accurate and
complex require iterative solution of the NavierStokes equations. They employ sophisticated
software, are computationally intensive, and
generally require user expertise. They are not simple
application tools.
A less rigorous method is to apply the Conservation
of Energy (Bernoulli) (3) equation to solve for fluid
flow characteristics. Simply stated, Bernoulli’s
equation defines the relationship between pressure,
head height and velocity of a fluid in a system. For
simple gating systems, this method is adequate and
significantly better than previous filter sizing
methods. Complex gating systems require more
complete flow analyses.
In all cases, physics-based models of filter flow
require empirical data describing pressure drop
characteristics of the filter as a function of filter
inlet velocity. Pressure drop data describes the
restrictiveness of the filter and can be measured
using water modelling. A detailed report on the
development and validation of water modelling
data for steel filtration devices can be found in the
literature (4,5).
The head height, system losses, pouring temperature,
alloy density and viscosity, filter type, exit area and
thickness all play a role in determining the velocity at
the exit of the filter. System losses include not only
pressure drop, but also flow losses from turning and
contraction/expansion of the gating system.
Figure 1: Filter design screen
FP1
FP6
Figure 2: Steel filter print designs
TM
The FILTERCALC
for Steel Programme
Inputs
To use the programme, the user simply inputs
already known or easily calculated information in
the windows provided on the Filter Design screen
(figure 1).
Filtration Method can be chosen as In-line or
Direct pour.
If the In-line method is chosen, there are several filter
print types to choose from, as shown in Figure 2.
18
FP3
FP4
By balancing head height and system losses against
one another, the velocity at the exit of the filter can
be determined. The flow rate of the system can
then be calculated using the filter exit velocity,
metal density and filter exit area.
While filtration capacity for a given filter is still
determined from empirical tables based on alloy
type, metal cleanliness and pouring conditions, this
more precise calculation of flow rate significantly
improves filter selection accuracy.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Physics of Flow
FP7
For the Direct pour method, there are several sleeve component shapes to choose
from in the drop down menu, including Tube, Insert and Round Neckdown
(RND).
The entire mould cavity Pour Weight is input, even if there is more than one casting
per mould. The number of filters is asked for later, thus allowing the programme to
establish the requirements for capacity and flow rate per filter. Note: The programme
will assume that the same amount of metal is required to go through each filter.
The Maximum Pour Time can be input, or by using the Calculate button, can be
determined using the equations from the 1958 US Naval Research Report, "Pouring
Times for Steel Castings" (6).
The Delay Time input accounts for foundry-specific pouring behaviour. At the start
of pouring, the initial flow rate is generally low and increases to steady state flow
until the end of pouring. Using an average flow rate to calculate pour time could
undersize the filter. Therefore, proper filter sizing requires that the maximum flow
requirement be considered.
The pouring time for sizing is the input Maximum
Pouring Time minus the Delay Time. Then, the
required mass flow rate is calculated as the metal
weight per filter divided by the pouring time for sizing.
The Pour Temperature is input, or can be
calculated from metal chemistry inputs (using the
Calculate button).
For the Effective Head Height of the system, a
known value can be input or the user can select
Calculate to determine it, as shown in Figure 3.
The Alloy Type can be chosen from several alloys.
Within the programme, each alloy has its own
thermophysical data as a function of temperature,
and this information is used to calculate the flow rate.
Finally, the Ladle Type (Lip or Bottom pour) and
the metal Deoxidation Practice (CaSi/Al or Zr/Ti)
are input. These values affect the Maximum
Capacity of the Standard Filter Recommendation.
Filter Recommendations
Once the inputs are entered, the recommended filter
appears in the Standard Filter Recommendation
panel of the screen.
The default filter recommendation is 10ppi STELEX‚
ZR. Alternate filter types can be chosen from the
drop-down menu, and the resulting size
recommendation is given. (Note: The filter size is
given for in-line applications, and the KALPUR unit
size is given for direct pour applications). The
Maximum Capacity and Maximum Flow Rate of
the filter are shown, and the programme identifies
whether the filter (or unit) was Sized By filter flow
rate, filter capacity constraints, or sprue exit area
(in-line applications only).
The Predicted Pour Time is calculated using the
maximum flow rate for the recommended filter and
the delay time. This value will always be lower than
Maximum Pour Time plus the Delay Time.
The Critical Choke Area and Diameter
dimensions identify the minimum Sprue Exit Area
that can be used before the sprue becomes the
choke of the system and reduces the flow rate (inline applications).
Figure 3: Calculating effective head height
This input is very important to determining the
metal flow rate, so care should be taken to input
correct values. Increasing the head height will result
in higher flow rates, and potentially smaller filter
size recommendations. See the Direct Pour
discussion below.
Figure 4: Filter size options
The optional Sprue Diameter and Sprue Exit Area
inputs only apply to in-line systems. The user may
choose to allow the programme to calculate these
dimensions as described in the Filter Sizing Logic
section below.
The Capacity Factor input is applied to the
Maximum Capacity shown for the Standard Filter
Recommendation. It enables the user to adjust the
capacity based upon metal cleanliness and foundry
experience.
If the recommended in-line filter or direct pour unit
was Sized By filter flow rate, it may be possible to
evaluate smaller filter/unit options that still satisfy
the filtration capacity requirements. However, these
options will result in lower Maximum Flow Rates
and higher Predicted Pour Times. Options (figure
4) can be evaluated by selecting the Size Options
button, next to the Filter recommendation.
In this figure, two additional filters are shown that
can also satisfy the filtration capacity requirements
if the Max. Pour Time constraints can be relaxed.
19
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.
The Delay Time is the variable time occurring
before and after the steady state flow, resulting
from filter priming and human variations in pouring.
If a foundry pours hard, or uses automated pouring,
this input can be ignored or set to zero. This is the
default setting. The Delay Time input is subjective,
and is most critical for small castings.
However, if a slightly longer pour time is acceptable,
a 100 x 100 x 25 mm filter could be used, with a
total pour time of 11.18 seconds (9.18 + 2).
A 75 x 75 x 25 mm filter could be used as well, but
the predicted pour time would increase to 18.47
seconds (16.47 + 2).
when the sprue has become the system choke
(Sized By). Caution should be exercised whenever
the Sprue Exit input constrains the flow rate. A
better approach is to leave the Sprue Exit input
blank, and allow the programme to output the
sprue exit dimensions. If Sprue Exit Area or Sprue
Diameter inputs have been entered, check to
ensure that the Predicted Pour Time does not
exceed the Max. Pour Time.
First, the programme sizes the filter to satisfy the
Max. Pour Time requirements (maximum flow
rate); then it considers filtration capacity.
It should also be noted that actual pouring times
could be longer than predicted pour times when an
adequate pouring rate cannot be maintained. For
example, pour rates in excess of 16 kg/s (35 lb/s)
are generally difficult to achieve with a lip or teapot
ladle, and thus would be difficult to model using
this programme.
Direct Pour
Filter Prints
For direct pour configurations, the exit area of the
KALPUR unit is the choke. First, the smallest
KALPUR unit in the database is chosen. The
programme calculates the exit velocity as described
above; then it calculates the required flow rate,
using the KALPUR unit exit area. If the calculated
flow rate does not meet or exceed the required
flow rate, the programme chooses the next largest
size KALPUR unit and recalculates. This continues
until a KALPUR unit that meets the flow rate (Max.
Pour Time) constraint is found.
The programme allows the user to view the various
filter print designs. Examples are shown in Figure 2.
Filter Sizing Logic
Once a filter has been recommended, the user can
view the filter print drawing and print out its
dimensions (figure 5).
Care must be exercised in determining the effective
head height for a KALPUR unit. When pouring rapidly
from a lip pour or tea pot ladle with a large diameter
metal stream, the effective head height may be closer
to the pouring height of the ladle than any liquid level
in the direct pouring unit. In pouring where a smaller
metal stream is dissipated into a built-up reservoir of
metal above the filter, the metal height in the
KALPUR unit would be the effective head height.
If the KALPUR unit also meets the filtration capacity
requirements, then the programme is done. If not,
the programme recalculates, using the next largest
KALPUR unit, until the filtration capacity
requirement is met.
Figure 5: Filter print design drawing
In-Line
Validation
The in-line case is more difficult because it requires
determination of whether the system choke is the
filter or the sprue.
If the filter is the choke, the calculations are
identical to the direct pour situation. However, if
the sprue exit area is the choke, the system is
constrained by the sprue, and not the filter. Here,
the recommended filter is sized according to the
flow rate constraint determined by the sprue exit
area.
The filtration capacity calculations are then done, as
described above. The programme will tell the user
20
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The Standard Filter Recommendation is for a
STELEX ZR 125 x 125 x 30 mm filter, which would
result in a predicted pour time of 8.02 seconds
(6.02 actual + 2.0 delay).
The FILTERCALC for Steel programme results
compare very well with those obtained using
published datasheet information. However, because
the programme allows for significant adjustment of
input variables, recommendations are more
accurate than would have been possible using
datasheet information.
Two production casting examples were analyzed to
see if the programme could accurately predict filter
sizes and pouring times recorded during actual
production. For in-line filtration, a 2-up oil tool
casting was selected. For direct pour, a 2-up valve
body was selected.
Figure 7 shows the inputs and recommendation.
The programme recommends a 100 x 100 x 25mm
filter for the FP1 filter print. The filter has a Maximum
Capacity of 225.8 kg and Maximum Flow Rate of
16.03 kg/s. (A 224.5 mm head height is input,
calculated from the gating system dimensions.) This
configuration is Sized By filter flow rate, thus the filter
print exit area is the choke of the system.
In actual practice, a 100 x 100 x 25 mm filter is
used with an FP1 filter print. The actual casting
configuration is poured in an average of 8.85
seconds, with a standard deviation of 1 second.
This agrees well with the Predicted Pour Time of
8.83 seconds, well within the standard deviation of
1 second.
In addition, the measured flow rate of 16.25 kg/s
agrees well with the predicted Maximum Flow
Rate of 16.03 kg/s, well within the standard
deviation of 2 kg/s.
Direct-pour
Figure 8 shows the cope and drag patterns for the
2-up valve body casting.
Figure 6: Cope and Drag patterns for 2-up oil tool casting
The actual poured weight of the mould is 141.5 kg
and the net weight of each casting is 45 kg, for a
net yield of 64%. The pouring temperature of the
carbon steel is 1602ºC. The chemistry is:
(0.16% C, 0.56% Si, 0.96% Mn, 0.038% Al,
0.07% Cr, 0.08% Ni, 0.02% Mo, 0.019% P and
0.014% S). Electric arc melting is employed.
A teapot ladle is used; the desired maximum fill time
for this unpressurized runner system is 14 seconds.
Figure 8: Cope and Drag patterns for 2-up valve body casting
The actual poured weight of the mould is 169 kg.
The net weight of each casting is 40 kg, for a net
yield of 48%. The pouring temperature of the
carbon steel is 1606ºC. The chemistry is:
(0.26% C, 0.38% Si, 0.79% Mn, 0.058% Al,
0.16% Cr, 0.06% Ni, 0.05% Mo, 0.015% P and
0.008% S). Electric arc melting is employed.
Figure 7: Filtercalc for Steel inputs and recommendation for oil tool casting
A tea pot ladle is used; the maximum pour time for
this unpressurized runner system is 20 seconds.
21
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.
In-line
Figure 6 shows the cope and drag patterns for the
2-up oil tool casting. Note that the FP1 filter print
design is used.
Figure 9 shows the inputs and recommendation.
The programme recommends a 4 x 6 direct pour
unit (with 100mm STELEX ZR filter). The filter has a
Maximum Filtration Capacity of 177.3 kg and
Maximum Flow Rate capability of 12.74 kg/s.
(This is based on a 117.8 mm head height,
assuming the KALPUR unit is 3/4 full, standard
practice at this foundry.) This configuration is Sized
By filter flow capacity.
In actual practice, a 4 x 6, 100 mm direct pour unit
is used. The actual casting pouring time averages
14.5 seconds. This agrees well with the predicted fill
time of 13.28 seconds. In addition, the actual
measured flow rate of 11.65 kg/s agrees well with
the predicted Maximum Flow Rate of 12.74 kg/s.
The predicted flow rate results are within 8% of
actual practice for this direct pour configuration.
These results are consistent with other in-line and
direct pour configurations that have been
evaluated.
Summary and Conclusions
To reduce the complexity of sizing filters for steel
castings, a unique, advanced filter application tool
has been developed. This computer programme
generates more-accurate recommendations because
filter behaviour is considered within, and as part of,
the gating system; because it is based on physical
principles governing fluid flow; and because it
utilizes foundry-specific inputs.
The result is less-conservative recommendations
than those derived from flow and capacity ranges
traditionally found in datasheets. This offers the
potential for more-cost-effective filtration solutions.
22
References
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 9: FILTERCALC for Steel inputs and recommendation for valve body castings
1. J. Svoboda, "Filtration of Liquid Steel", Steel
Founder’s Society of America Research Report No. 98,
May 1986.
2. "Development of Casting Technology to Allow
Direct Use of Steel Castings in High Speed
Machining Lines", Steel Founder’s Society of
America Report, May 1987.
3. D.R. Poirier, G.H. Geiger, "Transport Phenomena
in Materials Processing", TMS, USA, (1994),
pp. 79-82 and 119-124.
4. T. Midea, B. Alquist, C. Blackburn, "Increasing
the Accuracy of Metal Flow Results in Steel
Castings", Steel Founder’s Society of America
Technical and Operating Conference, Chicago, IL,
November 2001.
5. T. Midea, "Increasing the Accuracy of Metal Flow
Results", Foundry Management and Technology,
August 2001.
6. E.A. Lange, A.T. Bukowski, "Pouring Times for
Steel Castings", U.S. Naval Research Report,
Washington, D.C., 1958.
Introduction
The Sinclair Works of St. Gobain Pipelines produces drainage castings in both grey
and ductile iron. There are three foundries on site, one producing larger fittings using
an airset system, one making rainwater products in metal moulds and the third using
a Disamatic machine to make smaller fittings. Metal is melted in coreless induction
furnaces in the rainwater and Disamatic shops, whilst the airset foundry receives its
metal by transfer ladle from the rainwater foundry. Typical Products are shown in
Figure 1.
Clearly, the operations involved vary slightly
depending upon the size, variety and performance
required of the ladle, but a typical sequence is:
❑ Clean the ladle shell of all lining material
❑ Pour about 75 mm of KALTEK* ISO powder
onto the base
❑ Coat the internal former with release agent
❑ Set the former in place (it is fitted with lugs
which engage with sockets on the shell)
❑ Feed the powder from its 25 kg bags directly
into the gap between former and shell (figure 2)
Figure 2: KALTEK ISO powder being applied
Figure 1: Typical products of Sinclair Works
❑ Fill the gap to the desired level
Staff and operators are well aware of the importance of controlling the temperature
and cleanliness of the iron poured into moulds and ladle linings play a vital part in
maintaining this control.
❑ Apply a gas torch to the inside of the former for
1 to 2 minutes to initiate the exothermic
reaction (figure 3)
KALTEK* ISO is a lightweight, highly insulating and easy-to-use lining material. It was
first introduced into the airset and rainwater foundries, and advantages identified
there have led to its being used also in the Disamatic foundry. The material is now
employed for all pouring ladles throughout the works. These ladles range in capacity
from 250 kg to 450 kg of iron.
The advantages will apply to many other iron foundries and the prime purpose of this
Case Study is to explain what the system is, how it is used and the benefits that can
be expected from it.
Lining a ladle with KALTEK ISO
The lining process consists essentially of pouring KALTEK ISO, a dry powder, around a
former suitably located within the ladle shell, igniting the powder, allowing the resulting
flame to spread throughout the mixture, and removing the former a few minutes later
from the hardened body of refractory.
Figure 3: The KALTEK ISO reaction being initiated with a
gas burner
23
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.
Low density insulated ladle
linings at Sinclair Works
❑ Excellent heat retention
❑ Reduction in energy consumption
❑Remove the former (figure 5)
❑Top off the lining and make up the spout with
rammable material
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
❑Remove the gas torch and allow the reaction to
go to completion (15-20minutes) (figure 4)
Reduced labour
Lining a ladle with the KALTEK* ISO lining is far simpler and quicker than using
conventional casting/ramming techniques. For example, a 330 kg ladle used on the
Disamatic line at Sinclair works requires some 85 minutes total labour time to remove
a used KALTEK* ISO lining and replace it completely. This compares with a labour
time of 175 minutes using a rammed refractory.
In each case, approximately half the labour time is needed to remove the old lining, a
task which involves the use of a pneumatic chisel. The reduction in time for which
the chisel has to be used is of considerable benefit in reducing the risk of Vibration
White Finger.
Rapid replacement of ladles
In many foundries, ladles lined with "conventional" materials are frequently kept in
use despite the lining being in a poor state and almost certainly resulting in "dirty
metal", simply because of the length of time required to replace the lining or effect
major repairs. The speed with which a ladle can be lined with KALTEK* ISO and
brought back into use contributes to increased productivity and improved quality.
Figure 4: The KALTEK ISO reacting
Reduced overall costs
Although the KALTEK* ISO lining material price per kilogram is higher than that of a
rammable refractory, the fact that ladles can be kept in use for far longer without
replacement or major repairs means that lining costs are lower, as seen from the
table below. This is based on the ladles in use in the Disamatic foundry.
Comparative costs of lining individual ladles at Sinclair Works
250 kg capacity
Figure 5: The finished KALTEK ISO lining
The ladle in use
Before being put into use, the ladle is usually preheated for an hour. The ladle then undergoes no
further heating during the shift unless there has
been an unusually prolonged stoppage. Lining life
varies with the duty, but, for example, on the
Disamatic line at Sinclair works, which works a 3shift day, it averages 5 shifts (This compares with 3
shifts on ladles lined with castable material). It is
noteworthy that the useful life when working on
ductile iron is about two-thirds that achieved on
grey iron, because of build-up on the lining.
Nevertheless, the life achieved is greater than that
of linings made of castable refractory.
The benefits
Use of the system has many benefits, including:
❑ Reduction in overall costs
❑ Rapid replacement of linings
24
❑ Consistent ladle capacity
330 kg capacity
KALTEK* ISO
Rammed
KALTEK* ISO
Rammed
_
_
_
_
Material
163.05
82.65
181.50
99.15
Labour
12.37
36.00
25.20
52.65
Heating
0.45
2.70
0.45
2.70
175.87
121.35
207.15
154.50
Total
Ladle lining costs over 3 shifts
KALTEK* ISO
Rammed
_
_
250 kg ladle
105.52
121.35
330 kg ladle
124.29
154.50
Note: KALTEK* ISO lined ladles average 5 shifts before replacement
Conventionally lined ladles average three shifts before replacement or
major refurbishment.
Consistent ladle capacity
The fact that ladles stay clean for a longer time when lined with the new material is an
additional benefit. The foundry produces SG iron by a process in which a measured
amount of a proprietary treatment alloy, based on the nominal capacity of the ladle, is
added to the metal stream as it passes through a refractory-lined vessel. Metal is
tapped from the electric furnace until the ladle is filled. Variations in ladle capacity
can result in the fixed quantity of alloy treating different amounts of metal. Since ladle
capacity does not vary to the same extent as with previously-used refractories, greater
metallurgical consistency is achieved in the SG iron.
Observations to date, however, indicate that the temperature loss rate of the ladle lined
with KALTEK* ISO is about one-third that of the alternative, typically 5ºC per minute
compared to 15ºC.
A model of the comparative metal temperature losses of a KALTEK* lined and
cement lined ladle is shown in Figure 6. The prediction was made using a "Ladle
Transient Temperature Calculation Program" based on the following assumptions:
❑ 350 kg capacity ladle
❑ 40mm lining thickness
The Manager’s view
" I am a firm believer in the use of KALTEK* ISO
lined ladles. It enables us to bring ladles into
service more quickly, reduces temperature loss
rates, reduces energy consumption and
contributes to the reductions in foundry scrap
levels we have achieved in recent months. It also
has several less obvious advantages. For example,
the consistent ladle capacity has simplified the
control of metal treatment, whilst the easier
removal of linings at the end of their life helps
significantly to reduce the hand-arm vibration
problem which can arise in carrying out this task".
Steve O’Brien
Plant Manager.
❑ The ladle is in use, the lining is therefore at
high temperature
❑ The ladle is not covered
Opportunities for other foundries
❑ 350kg of grey iron is tapped into the ladle at 1400ºC
Figure 6: A model of heat loss from molten iron contained in a KALTEK ISO lined ladle compared
with a refractory cement lined ladle
Metal quality
Good ladle practice is an important feature of practical metal control. The KALTEK*
ISO lining system now in use contributes to the reduction in levels of foundry scrap,
thanks to cleaner linings, better control of ferro-alloy addition levels and reduced
temperature losses during pouring.
Reduced energy
With the need for foundries to meet their obligations under the Climate Change Levy
Agreement, any reduction in the use of energy is welcome. Whilst a gas torch is used
to ignite the refractory powder, to dry any topping refractory and to pre -heat the
KALTEK* ISO lined ladle for up to one hour before initial use, the amount of gas
used in more conventional systems, where the ladle is likely to be under a pre-heater
for 5 to 6 hours , is far greater.
The excellent results obtained at Sinclair Works have
already been confirmed at a number of other plants
throughout Europe and should encourage many iron
foundries to examine their present ladle lining
practice and experiment with this simple and
effective system. The benefits they obtain will
inevitably vary. Some will gain from reductions in the
number of defective castings produced – e.g. misruns
and inclusions are likely to be fewer – others will find
the saving in labour very valuable and a few may
even discover that the lower weight of refractory will
enable them to use larger ladles on existing runways.
The energy savings possible are another important
feature, since lower heat losses and better yield lead
to energy savings in melting. Many foundries use
considerable (but unmetered!) quantities of gas to
cure and preheat ladle linings and should consider the
new material as an opportunity to reduce this cost.
The knocking out of conventional linings can be a
dirty and strenuous activity and has serious
Health and Safety implications. The ease of
removal of the KALTEK* ISO linings is therefore
an important benefit.
In carrying out trials, it should be remembered that
the very property which makes removal of the lining
so easy also makes it more prone to mechanical
damage than a rammed or cast lining of denser
refractory. It is for this reason that the tops and lips
of the ladles, which need frequent cleaning of buildup, are occasionally made of a denser refractory.
Acknowledgement
It is also worth noting that improved ladle practice helps to improve overall yield of good
castings, thereby reducing the amount of metal which has to be melted to produce a
given output of good castings and resulting in a lower electricity consumption.
The authors would like to acknowledge the assistance
provided by the employees of Sinclair Works St
Goban Pipelines in the preparation of this paper.
COMMENT
Editorial policy is to highlight the latest Foseco products and technical developments.
However, because of their newness, some developments may not be immediately available in your area.
Your local Foseco company or agent will be pleased to advise.
25
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.
Heat retention
The rate of loss of heat from a pouring ladle depends upon a number of factors,
hence it would not be possible without a prolonged and detailed study to make
precise comparisons of the difference between the rate of temperature loss from a
KALTEK* ISO lined ladle and that from a ladle lined with an alternative material.
GIFA 2003
Foseco International Limited
P.O. Box 5516
Tamworth
Staffordshire
England B78 3XQ
Registered in England No. 468147
ISSN 0266 9994
Printed in England
40006355
Design & Production: Warwicks UK Limited, Coventry, England.
hall 12, stand
12 A 05