Metal tapping with vehicles as a part of
lean production approach
Presented at Aluminium Middle East
2013
The Market Situation
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Primary production over-capacity
Provision of Recycled metal
Estimated 10Mt of aluminium in warehouses
Stringent environmental standards
Need for restructuring/optimisation
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Stringent challenges for primary
producers
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Cost of energy
Cost of primary materials and manpower
Impact on the environment
Fair employment and safety in the workplace
Shareholders’ satisfaction
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Returning money back to shareholders
• The key point is how to return money back to
shareholders.
The only way is a rational
approach to production of
aluminium
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Improving overall plant efficiency
Tendencies of technology
• Higher amperages
• Higher current density
• Sophisticated controls to manage the pot
(magnetic field, heat balance, cathode effect
and so on)
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Tendencies of technology
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Material flow and processes
• The generalised side-by-side lay-out of
reduction cells imposes the use of cranes for
most pot-tending operations (anode changing,
anode covering and crust breaking)
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Material flow and processes
• Many tasks are still performed only with
vehicles: it is important to establish a correct
definition for plant logistics and vehicles traffic
in order to stabilise processes, reduce the cost
of potroom equipment, secure a high level of
safety and control of emissions.
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Analysis of the processes optimisation
• While computerised simulations of material
flows in the potroom can be a good way of
assessing the number of resources necessary
to accomplish a task a strict and perfect
control or an optimization of processes made
by machines and software is rigid and difficult,
at least with today’s technology.
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Anode changing and metal transporting
• In newer side-by-side smelter layouts – where
there is no room for the vehicles – the job of
anode changing went back to the cranes
• The crane has become an integrated pottending machine (PTM) capable of handling
anode changing, crust breaking and anode
covering.
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Anode changing and metal transporting
• But there are still some tasks where vehicles
are required, such as the removal of spent
anodes from the potroom and the installation
of new ones
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Metal tapping and transporting with
vehicles
• Metal tapping operations can be performed
with overhead cranes in conjunction with
transportation vehicles or with special metal
tapping vehicles (MTVs).
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The Lean production philosophy
• This approach aims to reduce waste (muda),
excess (muri) and irregularities (mura) on
production processes
• Combined with a systematic implementation of
Just in Time effort, a lean production approach
exposes quality problems that are otherwise
hidden by buffer stocks.
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The Lean production philosophy
• Forcing smooth flow of only value-adding
steps uncovers problems, which must be dealt
with explicitly.
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The Lean production philosophy
• Lean production is indeed, for a large amount,
an approach devised for the “human beings
hands, attention and skills”
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A complete closed Tapping System
Hot Crucible Cleaner
Tube cleaner, Inside
Siphon Tube Preheater
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HMR Hydeq
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Metal Tapping with Vehicles
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Metal Tapping with Vehicles
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Comparing different approaches
• METAL TAPPING WITH
VEHICLES (MTV)
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• METAL TAPPING WITH CRANE
+VEHICLES
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METAL TAPPING WITH
VEHICLES (MTV)
METAL TAPPING WITH CRANE
+VEHICLES
Detaching metal tapping from
crane operations reduces time
losses and waste due to the ‘over
dimensioning’ of the crane (load
capacity and number of cranes). It
reduces the movements of vehicles
and hence efficiency.
A pot tending crane is used to
bring the crucible to the pot to be
tapped. When full, the crucible is
loaded on a truck.
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METAL TAPPING WITH
VEHICLES (MTV)
METAL TAPPING WITH CRANE
+VEHICLES
The metal is delivered to the cast
house by MTVs Just in Time. Cast
house calls for metal and
information on the amount to be
delivered and cells to be tapped
are directly broadcasted to the MTV
driver. The process is clean and
clear as it is controlled only by the
MTV driver.
A pot tending crane is used to
bring the crucible to the pot to be
tapped. When full, the crucible is
loaded on a truck.
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METAL TAPPING WITH
VEHICLES (MTV)
METAL TAPPING WITH CRANE
+VEHICLES
Crucibles are taken to the cleaning
station and directly cleaned Just in
Time by the driver. No local storage
of crucibles is created. Possible
problems on cleaning have to be
solved immediately in order to
respect the scheduling.
Crucibles are usually not cleaned
Just in Time. A stock of several
crucibles waiting for cleaning is
easily produced.
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METAL TAPPING WITH
VEHICLES (MTV)
METAL TAPPING WITH CRANE
+VEHICLES
MTV driver performs tapping
according to cast house requests.
No other floor personnel are
required.
A crew attends the tapping
operations by the crane. Additional
manning for trucks.
Maintenance and substitution of
tapping and discharge tubes are
performed by MTV driver.
A separate shop is usually
dedicated to the cleaning of tubes.
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METAL TAPPING WITH
VEHICLES (MTV)
METAL TAPPING WITH CRANE
+VEHICLES
No need for a tilter in the cast
house as the MTV discharges the
metal by itself. No additional
equipment required. Active
suspension tilts vehicle to optimise
discharging efficiency.
A tilter (or emptying system) with
crew is necessary in the cast
house.
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METAL TAPPING WITH
VEHICLES (MTV)
METAL TAPPING WITH CRANE
+VEHICLES
The crucible stays on board the
MTV at all times. It is released only
for cleaning and maintenance,
when it is picked up by the vehicle
without the use of additional
equipment or manning.
The crucible is transferred from the
crane to the truck, then to the
casthouse tilter (or emptying
system). A lifting device is
necessary to unload the crucible
from the truck and vice versa at
the cleaning station.
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Considerations
• Metal tapping with vehicles requires disciplined
and skilled drivers. A continuous training
programme should be established and
monitored in order to check and improve the
ability of drivers.
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Considerations
• As for all vehicles and equipment a robust
program of training on daily routine checks
made by drivers should be established, run
and monitored. Reports coming from drivers
should integrate preventive maintenance
programmes.
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Considerations
• Focus should be put on all processes involved
in the use of vehicles: spare parts purchasing,
maintenance, operator training with
continuous reporting, review and improvement
in order to reduce problems and costs and
increase efficiency.
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Considerations
• The equipment supplier should be treated as a
resource. Two-way communication and
feedback on the product may improve and
reduce operation costs.
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Summary
• The only mandatory way of securing long-term
smelter profitability is to improve overall plant
efficiency. HMR believes that the lean
production approach is the best way to
improve a process.
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Summary
• Where lean production is concerned, it
appears evident that metal tapping with
vehicles is preferable as it results in a
smoother process with fewer risk zones. It
also exposes problems and calls for systematic
solutions instead of buffer stocks.
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