34th INTERNATIONAL CONFERENCE ON
PRODUCTION ENGINEERING
28. - 30. September 2011, Niš, Serbia
University of Niš, Faculty of Mechanical Engineering
CONTRIBUTIONS TO MANAGEMENT SWARF HIGH-SPEED MACHINE TOOLS
Baila Diana
University Politehnica of Bucarest, Splaiul Independentei 313, Bucharest, Romania
baila_d@yahoo.com
Abstract: The transition from traditional manufacturing with machine tools and CNC machine tools at
high speeds requires modification on the technological concept of steel, machinery, tools and cutting
regimes. This paper aims to draw attention to changes in management and management swarf. It also
presents some additional tests designed to increase the life of tools used at high speeds.
Key words: traditional machine tools, CNC machine tools and high speed, conical swarf, semi swarf, SIM
analysis.
1. INTRODUCTION
Development of manufacturing with high-speed
machine tools previously claimed, the development of
techno-economic study further the research and
management chip.
In general, chip generation and management
problems have made practical activities in workshops,
which resulted in finding technical solutions and safety,
as correct.
In this respect, with the evolution of machine
tools have diversified and expanded research objectives,
as follows:
-the traditional machine tools (lathes, milling machines)
with cutting speeds of 35-70 m/min was used Merchant
model to calculate the optimum cutting conditions and
chip evacuation recommendations were included in the
STAS:
-chip-shape and characteristics;
-how to remove the chip from the workpiece;
-compression chip-evacuation and transportation
are provided by the factory.
-the NC machine tools and CNC machining centers at
speeds of 60-120 m / min was used Oxley model [7], [10]
to calculate the optimum cutting conditions and chip
evacuation is included in STAS.
-the high-speed machine tools 150-480 m /min, is used at
present, the american way [1] to calculate rough cutting
regimes. Household chips are discharged inside the car
and involves the following elements:
-detached from the workpiece chips should have
taper type IIIB;
-to remove chips from the workpiece is
recommended to use 4 way chip clearance with turning
chips into each cup to get seated properly so called
conical fragment (fig. 1) and compression chip is inside
the machine frame.
Chip not detached from the workpiece, due to high speeds
necessary to make three additional tests, namely:
-determination of thickness of the resistance of semichips;
-analysis of the microstructure of white strip in the middle
section cutting;
-finding the diffusion of metallic elements (Cr, Mo, V, Ti)
on the lower surface of the chip.
Fig.1. Conical swarf
2. RESEARCH ON THE PROCESSING OF
LOW ALLOY STEELS TEMPERED
Programme of work uses a test bench from ENI Tarbes
laboratories where they planned the following actions:
2.1. Choice of workpiece material
In the last decade, most research contracts aimed at
economic reasons, the use of tempered low alloy steels,
which in case of high speed machine tools, provides:
-obtain workpiece with high strength and toughness;
-processing of these components is done with some hard
cutting
regimes
provides
hard-schemes:
-workpieces with fine-structure (give up to
rectification);
-in the case of precision parts after cutting take
electroerosion apply to Ra = 0.2 m.
Consequently, taking into account the provisions of the
agreement, a group of steels commonly used in cars with
high speeds (table 1), choose low-alloy steel 32CrMoV13
quality and delivered in the form of bar.
Table 1. Tempered low alloy steels
Metallurgical
state
Symbol
Steel grade
15CrMoV6
mechanical and
structural steel
heat treatment
annealed
32CrMoV13
nitrided steel used
in aerospace
hardened and
tempered
15CrNiTi1703
ferritic stainless
steel
hardened and
tempered
16NiCrMo13
hardening steel
bearings and
shafts
hardened and
tempered
Fig.4. General appearance of the CNC lathe
Preparing the way for chip evacuation is taking these
measures IIIB in the workspace:
Since adopting the ISO chip clearance mode 4:
-for outside the sample pot;
-advance movement in the opposite direction (fig.5).
By positioning curled cup ensure proper reception cone
chips IIIB as shown in fig.6.
Fig.2. General appearance of the CNC lathe
Researching test equipment (fig.2.) is provided as
follows:
-normally a lathe's wondering where the gearbox was
adapted to achieve cutting speeds between 60-480 m/min;
-were chosen ceramic plates mineral ceramics type TP200-TNM-160412-M5;
-cooling-medium: air stationary.
-pot type samples (fig. 3) are obtained from steel bar 32Cr
MoV13 delivered at dimensions of 100x150mm.
-it uses front turning scheme (fig.4)
-hard cutting regimes are scheduled:
-cutting speed v = 100 m/min;
-cutting thickness t1 = 0.1, 0.2, 0.3 mm;
-cutting width w = 7 mm;
-rake angle =0.
Fig.5. Working in the opposite direction of advance
movement
Fig.6. Working cup
Results of tests on three samples pot are shown in
Table 2 .
Fig.3. Pot workpieces
-chip-thickness resistance is on the lower t2 chips and
are measured directly, knowing the scale of magnification
photomicrography (fig. 9).
Table 2.
chip features
No
v
[m/min]
1
2
3
100
t1
t2
t2
h2
h1
Cr
0.1
0.58
12
26
22
18.2
0.2
0.7
18
30
27
11.1
0.3
1
26
46
43
7
2.2. Processing results
Fig.9. Photomicrography
When processing the results through two objectives:
-processing results in photomicrography;
-processing of the results obtained with a complex
apparatus.
2.2.1. Processing results in photomicrography
To process the results using an optical microscope to Carl
Zeiss Jena type MM3 and 38 mm respectively three
cylindrical samples, from which:
-fragment is positioned for measurements (fig. 7);
Basically, the objective of the consultation paper aimed at
three photomicrography made for t1 = 0.1, 0.2, 0.3 mm
and obtaining t2 values in table 2 (fig.10. a, b, c). With
these results demonstrate that there is a linear dependence
between the advance work using (t1) and the resistance of
the chip thickness (t2). The degree of segmentation of
chips (Gs) is measured on a peak period T by identifying
deep hole h1 and h2. It uses the formula:
GS 
h2  h1
h2
Fig.7. Positioned fragment for measurements
-symbolizes the chip with a plastic paste;
-leave a hole in the center centering cylindrical sample
and measurement system.
Microphotographs obtained by consulting with hard
cutting regimes in table 2, we can determine the
characteristics of the chips from chip geometry of fig. 8,
namely:
Fig.8.Geometry chip
-t2-chip thickness is calculated using the formula:
t2 
1
t 21max  t 22 max
2
(1)
Fig.10.Microstructure with different chip advances
Baila Diana, Contributions to management swarf high-speed machine tools, UPB, baila_d@yahoo.com.
(2)
Finally, the characteristic features of the chips allow us to
note the following:
-thickness of chip resistance (t2) should represent an
indication that detached fragment of the piece is right in
the cup reception coils (fig. 6). Any fragment breaks
minimum thickness t2 = 12 m to stop driving the car,
which must be kept fully closed during operation;
-chip-level segmentation (Gs) highlights the instability of
the operating regimes of cutting hard and is an indicator
for evaluating the workability of the steel cutting study.
2.2.2.Processing of the results obtained with complex
equipment
The management can be demanding two more additional
analysis:
1-white middle-width strip characterization chips conical
IIIB;
2-identification of metal-broadcast on the lower surface of
the chip.
Characterization of white middle band width chips:
-Chips in the middle white band width corresponds to the
secondary shear zone at the interface tool-fragment. In
this area the large amount of heat determines the chip
surface
but
also
deep
changes
in
phase
austenite/martensite.
-Interferometer is used to analyze Cr anticathode each
other as positioned. To see in depth the structure, the
lower surface of the chip is polished electrochemically, as
follows: Cr-anticathode initially be scheduled for a depth
of
6
where
noted:
m
-Fe austenite existing in the 111 plane angle of 65
-Fe martensite present in the 110 plane at the angle of
68.
-At depths greater austenite disappears almost completely
highlighting excessive hardness of the strip of white
conical
fragment
IIIB.
Given the dependence between hardness and strength,
hardness white band offers safe technology that will not
break chip cone, even if chip thickness t2 resistance is
small.
2.2.3.Identifying running on the lower surface of the
metal chips
It’s used semi chips obtained by cutting a tough regime: v
= 100 m /min, t1 = 0.2mm and pleasant mineral ceramics
TNM-TP-200-160412-M5.
After crossing the interface tool-fragment in the presence
of oxygen in the air, freshly detached fragment is finding
an oxide layer of Fe, Cr, Mo, V, Ti.
SIMS depth analysis on chips made using reverse
mechanism, the underlying oxidation process, as follows:
To interface of chip at a distance of 0.1 mm from the edge
tool, breathe a jet of oxygen, under certain conditions:
-adjustable pressure-controlled;
-pressure-stabilized;
-at certain times-blasting.
This near-interface layers of oxygen, metal ions cause
excitement Fe+, Cr+, Mo+, V+, Ti+, and excitation of ions
in the form of oscillations is recorded on a diagram
(fig.11)
Processing the results show the following:
elements of the charge-steel (Cr, V, Mo) is in large
quantities on the surface of the tool-fragment interface
and decrease with depth;
Ti-derived chemical element of the tool material and
decreases in concentration, with depth.
Basically, the elements Cr, Mo, V, Ti strongly
emphasizes the tool wear in particular crater on the
surface of the recess.
Finally, knowledge of the elements Cr, Mo, V, Ti allows
taking measures that:
-use another type of plate cutting;
correcting the chemical composition of the cast-steel 32
Cr MoV13.
Fig.11. Depth profile SIMS realized in fragment
3. CONCLUSION
The traditional machine tools with NC machine tools,
management of special chips not allowing it to raise a lot
of types of chips, according to STAS.
In contrast, the high-speed machine tools, the problems
are complicated because:
-the frame is required in the management of the car chip;
-tough regime to accommodate the claims cutting
conditions for obtaining a cone chips IIIB;
-during processing, workspace is locked and an accidental
breaking of the chip would interfere with proper operation
of the machine;
-further analysis shows that it can take steps to increase
the lifetime of the tool, even with some tough cutting
conditions.
REFERENCES
[1] ALTINTAS
Y:
Manufacturing
automation,
Cambridge University Press, 2000;
[2] LE CALVEZ C: Etude des aspects thermiques et
métallurgiques de la coupe orthogonale d’un acier au
carbone. Thèse. Centre de Paris, 1995.