A brief presentation based on my experience with Lost Foam Casting Process Implementation

1. Lost Foam Casting
Implementation Challenges
Sunil Mohite, Jayshree Machines & Tools, www.foamcast.in
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2. Variants of the Lost Foam Process
• Vacuum Lost Foam Casting (V-LFC)
• Lost Foam Sintered Shell Process (LFS2/foamcast®/Replicast®)
• Full Mold Casting Process (FMC)
• foamcast® is the registered of Jayshree Machines & Tools, India
• Replicast® is the registered of Castings Technology International, UK
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3. Brief Process Steps
V-LFC | LFS2/foamcast | FMC
Process Comparison between all variants of LFC
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4. Vacuum Lost Foam Casting (V-LFC)
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5. Lost Foam Sintered Shell Process(LFS2/foamcast)
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6. Full Mold Casting Process (FMC)
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7. Process Comparison
Vacuum Lost Foam
Casting (V-LFC)
Lost Foam Sintered Shell
Process (LFS2/foamcast®)
Full Mold Casting
Process (FMC)
Pattern Media EPS/STMMA Foam EPS Foam EPS Foam
Pattern Mfg. Process Foam Injection Mold Foam Injection Mold Fabrication of Foam
Foam Pattern Density 18-20.0 Kgs/m3 45.0 Kgs/m3 18-20.0 Kgs/m3
Foam Pattern Coating Single Coat Multiple Coats + Stuccoing Single Coat
Shell Sintering Not Required Firing in furnace @ 1000o C Not Required
Silica Sand Free Flow 30 AFS Free Flow 45 AFS Free Flow 45 AFS
Sand Compaction Required Required Required
Vacuum Required Required Required
Suitable for Metals that allow
Carbon, CI, DI, GI &
Aluminium
Stainless Steels, Carbon
Sensitive Alloys, All Ferrous
& Non-Ferrous
CI, DI, GI &
Aluminium
Typical Castings Auto parts, Pumps,
Valves & Pipe Fittings
Aerospace, Propulsion,
Flow Control, Pumps &
Valves
Automobile Press
Dies, Machine Tools
Casting Weight Range 5 to 250 kg. net wt./piece 40 to 2,500 kg. net wt./piece ≥ 100 kg. net wt./piece
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8. Questions that every
foundry asks
Which castings should be produced using LFC?
Why LFC has not replaced traditional processes?*
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9. Which castings should be produced using LFC?
• Castings produced using the lost foam process should ideally be sold as machined
castings regardless of alloy
I. Due to process advantages lost foam castings are lighter in weight as compared to
other casting process. Features like casting with holes, without draft angles,
reduced machining allowance, etc. reduce the weight of the casting
II. Therefore if you are selling castings by weight you are not able to unlock the true
value of the casting which machining can. Furthermore due to lesser machining
allowances, machining time is saved which in turn reduces tool wear out
• Stainless Steels or some carbon sensitive alloys are materials which generally are a
challenge to pour in most foundry processes. However in LFS2 it is not as challenging
• Parts with a high core to metal ratio are suitable however not all. Classic example is
Brake Disc, it has high core to metal ration but still it is viable in DISA line not LFC
• Valve Bodies, Pump Casings and Impellors are ideal castings for LFS2 process
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10. Why LFC has not replaced traditional processes?*
• It is not cost effective to cast all castings in LFC
• There many castings that are viable specific to process like:
I. Crankshaft or brake disc the most economical method is using
green sand in a DISA line
II. For a simple Hub, Green Sand molding in a normal horizontally
parted molding line is economical
III. Likewise for forklift counter weight casting VPC is suitable
• Even in China there are large foundries still using operating using
the sand casting process
*Siamak Khalichi
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11. Commercial Challenges
Investment in Foam Pattern Molding Setup
Lost Foam Pattern Mold Cost
Difficult to arranging Lost Foam Foundry Visit
Lost Foam Pattern Mold Cost
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12. Investment in Foam Pattern Molding Setup
• To begin with foam pattern molding has to be a in-house process you
cannot outsource foam patterns
• It is the most critical process of Lost Foam process and is a multistage
process where the bead is pre-expanded first and then injected in mold
• Lost foam pattern molding is not like Thermocole packaging molding.
The process is similar but for foam pattern molding there a many
parameter that need strict control which are insignificant for
Thermocole packaging molding.
• One of the most critical parameter that requires critical machinery and
process control is the foam bead pre-expansion process which
determines the density of the foam pattern
• Without precise and consistent density control there can be many
casting defects in the foam pattern
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13. Difficult to arrange Lost Foam Foundry Visit
• Seeing is believing, most foundry owners prefer to see the process
live in the flesh, which is not possible
• Lost Foam foundry owners are worried that the visiting foundry
owners focus is not limited to the lost foam process and they are
worried that their productions process & methods are at risk
• It is a general perception in casting buyers mind that lost foam
castings are cheaper to produce and expect foundry to pass entire
cost saving benefit to them.
• Therefore many foundries using lost foam do not publicize their lost
foam casting capability. They do not sell their casting as “lost foam
casting” so that the buyer does not further negotiate pricing this is
common with investment casting foundries having lost foam process
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14. Lost Foam Pattern Mold Cost
• The die/tool/mold used for molding the foam pattern is made from
aluminum and is similar to investment casting tool. However the lost foam
tool is hollow to pass steam and the investment casting tool is solid to
transfer heat.
• Although the Lost Foam Process is coreless the aluminum tools that mold
the foam pattern have cores.
• The tool development cost is approx. 15-20% more than an aluminum
pattern with core box which is used in the sand casting process
• Aluminum tools are required for each casting like-wise in any foundry
process you require wood/aluminum patterns in any process
• Even though the development cost is high the tool life too is infinite (subject
to proper preventive maintenance) unlike wood/aluminum patterns which
require replacement due to wear out caused by the sand
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15. Technical Challenges
Critical Castings in VLFC require STMMA
Lost Foam Process Cost
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16. Critical Castings in VLFC require STMMA
• The pattern raw material used is all lost foam processes is EPS –
Expandable Polystyrene which is a petroleum product high in carbon
• A novel material STMMA – Styrene Methyl Methacrylate which is a
co-polymer and has very low carbon content is now available to
foundries for molding foam patterns
• Prevention is better than cure. Particularly the VLFC & FMC process
requires lot of process controls to tackle the issue of carbon generated
by EPS during the pouring stage. These can be easily negotiated if
STMMA is used instead of EPS.
• However the cost of STMMA is over four times higher than EPS and
the material has to be imported from Japan/Europe
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17. Lost Foam Process Cost
• Process cost of VLFC including the cost of STMMA at 75% yield is
approx. Rs. 20.0/Kg of finished casting
• Process cost of LFS2/foamcast® at 60% yield is Rs. 40.0/Kg of
finished casting
• Above costs do not include metal melting and fettling/finishing cost
• Important to note here that the salvage cost of the castings is
negligible as compared to other foundry processes
• It is very unfair that many foundries do not count casting salvage cost
which the foundry has to spend in the form of welding and chemical
impregnation to make the casting saleable
• If you sell machined castings the incremental process cost can easily
be absorbed by the savings achieved in the machining process
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18. Current Status of Lost Foam
Process in India
Lost Foam Foundries in India
Failed Attempts at setting up LFC plants
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19. Lost Foam Foundries in India
• It is still believed that Lost Foam is a new process to India but it is not
• We ourselves have installed 12 plants in India with first one being PTC
Industries, Lucknow in 2002
• Some of the foundries like Kirsloskar Brother Ltd., Kirloskarwadi and
SAM Turbo Pumps P Ltd., Coimbatore are captive foundries
• Foundries having investment casting process have added lost foam
process like Castech Foundries P Ltd., Junagadh, Sri Alka Industries,
Ahmedabad and Amruta Industries, Kolhapur
• Sand casting foundries have also added lost foam process like Sueera
Global Alloys P Ltd., Coimbatore and Gujrat Metal Casting Industries
Ltd., Vadodara
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20. Failed Attempts at setting up LFC plants
• The first failed attempt at LFC was by Alexcon Foamcast Ltd.,
Khopoli. The equipment was imported for Vulcan Engineering, US.
• The foundry was way ahead of its time and stopped operations in
1997-98 due to financial difficulties and NOT PROCESS FAILURE
• Some foundries and Pune, Kolhapur & Raipur regions imported
Chinese equipment from different manufacturers after doing
some online research/visit to China. The equipment manufactures
chosen were not able to support the buyers technically due to
lack of knowledge of the process and language difficulties.
• A foundry in Karnataka tried to setup a lost foam foundry by
importing the foam patterns, which was not viable
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21. How to implement the Lost
Foam Process?
Selection of correct variant of lost foam
Selecting a suitable part & sizing of plant capacity
Investing in the right machinery
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22. Selection of correct variant of lost foam
• The three variants of lost foam are V-LFC, LFS2/foamcast & FMC
• V-LFC & LFS2/foamcast are the only two suitable for mass production of
castings
• V-LFC is suitable for metals that allow Carbon, CI, DI, GI & Aluminium
• However it is advisable to use STMMA instead of EPS to reduce the number
of parameters required for process control
• If availability/cost of STTMMA is a concern EPS can be used however you
will have to select the castings accordingly.
• If EPS is used there is failure in thin wall (≤ 6mm)/critical V-LFC casting
• LFS2/foamcast is suitable for all metals especially Stainless Steels
• Exothermic sleeves can be used for pouring in LFS2/foamcast
• Methoding/gating is similar to sand casting in LFS2/foamcast and can be
further optimized using software to improve yields
• All raw materials required for LFS2/foamcast are abundantly available in
India
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23. Selecting a suitable part & sizing of plant capacity
• Part that is in production in foundry should be selected for migration to LFC
• The advantage of selecting proven part is you need not experiment with the
methoding of the casting
• Ideally part in the weight range of 10-100kgs. is suitable for trial
• Implementing of LFC becomes faster & easier if trial time is short
• Ideally to start with a plant capacity of 100MT/Month is sufficient to
produce desired casting quality and prove productivity of part
• Plant capacity can be designed for scaling up within short time
• Green field stand alone lost foam casting projects should be avoided
• It is better to implement lost foam process in existing foundry parallel with
running process to reduce cost of initial investment
• After success of Lost Foam Process suitable castings can be selected from
existing process for migration to LFC
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24. Investing in the right machinery
• Machinery selection is critical and key to success of LFC, especially
foam processing and molding equipment
• Equipment used for molding packaging material is not suitable for LFC
• Pre-Expansion machines should be able consistently produce desired
density of expanded bead
• Foam Molding machine should be able to handle multiple cores in
aluminum tool to keep gluing of pattern to minimum requirement
• Vacuum Flask/Molding Boxes should be designed for hassle free
maintenance since sand is prone to clogging in vacuum chamber
• Vibrating station should be programmable so that cycles can be set
and saved based on casting types to avoid damage to patterns
• Proper sand handling equipment should be designed to maintain sand
temperature, remove lumps & dust
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25. Thank You!
Sunil Mohite
Jayshree Machines & Tools
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