Lost Foam Casting (LFC)

Vacuum Assisted

Lost Foam Casting v-LFC

Process

-: by GDM Technics

Courtesy: LFC Casting Art by Ju Ming Museum Taiwan

Preface

Much research and practical experiences have been gained since Mr H.F. Shroyer patented the process cavity-less method in 1958 using a polystyrene foam pattern imbedded in traditional green sand.Infinite possibilities with foam has been tapped to cast Engineering Products and Sculptures of any profile no restrain. Innovations, and variants have made possible to cast many types of metals and alloys with LFC process today.The possibilities and need to adopt this modern green molding method has risen more due to pollution concern all over the world. This molding technology is faster to adopt and economically very attractive compared to conventional molding method.

Lost Foam Casting (LFC) – An Introduction

Lost Foam Molding Line Most Cost efficient Foundry Process Today.

The beautiful castings with excellent surface finish you get requires almost nil knockout and fettling activities with almost nil machining. The core work is nil so cost comes down and you work on almost zero rejections.

1. You basically reduce 98% cost of sand and its chemicals and thus become environment-friendly.

2. Most Economical Moulding Process today

3. Any size any shape and weight possible.

Lost Foam Casting (LFC) – An Introduction

4. Intricate parts can be cast

5. No Core, so no Core cost; No Rejections due to Core Shifting

6. No Fins so almost nil fettling hence Faster Delivery, Satisfied Customers, More Orders

7. Casting weight reduced

8. Very good Surface Finish

9. Machining work minimized

10. Sand reused with almost nil wastage

11. Environmentally friendly

12. Steel, SG Iron & Grey Iron & non-ferrous castings all can be cast very successfully.

Various variants of LFC Process

Investment Casting

Lost Wax Casting

The Science & Art of Evaporative Mold Casting (LFC)

Make EPS/

STMMA Molds by Mouldin

g Machine

or CNC/hand Cutting

EPS Blocks

Choose Proper Coating

material. Apply

Refractory Paint on the

mold less than 1 mm for Vacuum Assisted

Lost Foam

Casting or 2-3 mm

Vacuum assisted Replicast or 5 -12 mm for

Replicast.

Dry paint or Build

Paint Shell by

re-coating

for vacuum assisted Replicast. Develop

Shell with

layers of coating

in Replicast without vacuum

Place the Coated Mold in Vacuum

Flask with Dry

sand support

and apply

vacuum before

pouring.Place the

Thin Shell in Vacuum

Flask with Dry

sand support

and burn the foam

with flame or pre-burn the foam

in an oven in Vacuum Assisted ReplicastBurn the Shell in a Oven to get Dry Heated

Shell ready for pouring

in Replicast

.

Pour

Metal

Globe Casting by LFC an Art

The Globe by LFC at National Science Museum of Japan

The Owl by LFC

Globe - Solid casting sculpture?

The creation of a real Artwork by Kimura Castings Japan – The Green Earth bubble appearance. The Foam surface of the Earth covered by five continents and four oceans manifested carefully. Observed: the appearance of a layered CNC machined several pieces of foam, using the modern CAD / CAM technology. The appearance of the whole works with fine and complex cavity, it is amazing. The whole earth and the base with solid casting made the whole casting, reflecting the Japanese LFC technology level. After casting was made by cast iron and painted green, as a work of art permanently placed in the door of the National Science Museum of Japan.

Professor Ye Sheng Ping HUST University

Infinite

Possibilities of

Foam Model for

Lost Foam

Casting

Tractor Parts Castings by LFC

Tractor Parts Castings by LFC

Length 2.66 m , 2.16 tons

Casting an Art with no limits when you adopt LFC

Aluminum alloy Lost Foam Casting Process

LFC possibilities for Magnesium CastingsThere are many advantages to using magnesium and its alloys. With the lowest density of all commercial casting alloys, magnesium is 33 percent lighter than aluminum and 75 percent lighter than steel. Magnesium and its alloys also have a high vibration damping capacity making them an ideal material choice for many high speed applications. Electromagnetic interference reduction is another desirable quality that magnesium can offer as an engineering material.

Magnesium benefits:1. The lightest of all structural metals2. Excellent stiffness and strength-to-

weight ratio3. High conductivity, electrical, and

thermal4. Withstands high operating

temperatures5. Cost-effective to many engineered

thermoplastic materials

6. High dimensional accuracy and stability

7. Exceptional thin wall capability8. Good environmental corrosion

resistance9. Good finishing characteristics10.Full recyclability

LFC possibilities for Magnesium Castings

Equipment arrangement for casting AZ91 & AJ62 series of Mg Alloys Castings as used in Automotive castings.


• Alloy AZ91D is the most widely used magnesium alloy and has an excellent combination of mechanical properties, corrosion resistance, and castability.


The profile of the casting of Fiat cover pump shown is very complicated. But, it could be cast without problem using the low-pressure lost foam process in Mg alloy. The set parameters were: Casting temperature of 840 °C, pressure holding time 90 s. and pressure rise time 8 s.

The component on right side was cast using the low-pressure lost foam process and mold filling control at a pressure of 0.23 bar and a casting temperature of 810 °C as well as a pressure rise time of 5 s.

Environmental Protection by adopting LFC Green Foundry Process and future options

Sl. No Conventional Foundry Vacuum assisted Lost Foam Casting (v-LFC) Foundry

1

Sand Preparation- Sand making for MOULD with Organic/Inorganic Binders Organic Binders generate Hydrocarbons, Aldehydes, Ketons Inorganic Binders generate CO2 and SO2

No Sand preparation by Binders for MOULDS, so no reaction of binders for Mould formation nor burning of binders, while metal pouring. Sand is bonded by vacuum



2

Sand Preparation- Sand making for CORE with Organic/Inorganic Binders Organic Binders generate Hydrocarbons, Aldehydes, Ketons Inorganic Binders generate CO2 and SO2

CORE not required



3Pattern Making- Pattern is made generally by wood and high density EPS and sometimes by metal also. Wood is expensive and teak wood is a natural resource.

Pattern Making- made by EPS [(C8H8)n-(C8H8O2))n] /STMMA [(C8H8O2)n] in a die by steaming. This burns off and sucked by the vacuum system releasing CO2 an H2O through a Catalytic Convertor while pouring with no exposer to workers. Generally 1 g of EPS/STMMA would produce 300-350 grams of Grey Iron/Ductile Iron casting.



4 Mould & Core Coating- Water/Spirit based coating on mould and core

Pattern Coating- Water based coating and dried in in hot air drying room

5

Mould Sand & Core Sand reclamation- The sand lumps after knock-out is fed into reclamation unit which crushes sand lumps back to sand-grains and in secondary attrition the sand is scrubbed to remove the binder coating on it, this generate SiO2 fractured grains also, a measure reason of Silicosis, 100% removal of this dust is needed.

No Sand Reclamation needed. Only sand is cooled and used again.



6

Pouring - When hot metal is poured, the gas being generated from the mould and the cores needs to be burnt by flaming. The flames extinguish after sometime and the gas keeps on being generated from the mould for another about 4 hrs. This is quite hazardous for the workers around, though modern binders make such binders that least poisonous gas get generated.

Pouring- When hot metal is poured in vacuum condition, the EPS/STMMA gets burnt instantly and the gas generated is sucked by the vacuum system. There is no gas generation from the sand.



7Knock Out - Manual and Mechanical hitting of the mould required for removal of casting from the bonded sand, which also becomes strong after heat absorption

Knock Out - Very Simple Just tumble the Mould Box in a hopper, you get your casting, as the sand is free flowing and unbound.

8Fettling & Finishing- The runner riser and ingate are to be cut. The parting line is to be grinded along with all other area where ever sand sticking or pin holes etc. seen to get a acceptable casting surface.

Fettling & Finishing - The runner and in-gates need to be cut and grinded. No parting line. No sand sticking etc., minimal time and effort for finishing

Energy Savings in LFC/EPC Process and most Economical Casting Process today

1. Sand reclamation, the primary attrition and the secondary attrition to achieve 75% reclamation level and the thermal attrition to achieve total 95% reclamation level needs lots electrical and gas; which in Lost Foam Technology only needs to be sand cooling and recirculation.

2. Because the LFC process sand does not stick to the casting surface, no energy by way of hammering, grinding and chipping is needed for knockout and fettling of castings. Save time too.

3. Less machining allowances so less machining needed save Energy and Time.4. The overall weight of the casting is reduced needing less molten metal, so

Energy is saved.

Video Showing Engine Block

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Lost Foam Casting (LFC)