Lost foam

Ceramic Filter. The ceramic filter collects, volatilizes, and destroys particulates and condensible organics emitted from industrial process streams, such as paint spray, lost foam casting, condensible organics, tenter frames, and cured rubber... 

Boston, Ma., 7th-llth May 1995, p.2178-82. 012 PHYSICOCHEMICAL ANALYSIS OF POLYMERS USED IN THE LOST FOAM CASTING PROCESS Shivkumar S Y Celotto M A Worcester,Polytechnic Institute (SPE)... 

A study was made of the thermal degradation behaviour of PS foams used as patterns in the lost foam process for metal casting. The data indicated that the thermal degradation of the pattern had a strong effect on mould filling and casting quality. The use of other types of foam such as PE, PP, PMMA and styrene-methyl methacrylate copolymers to overcome problems encountered with PS foam patterns is discussed. 7 refs. 

Lost-foam sand casting Sand (expendable but recyclable) pattern is consumed Ferrous and nonferrous As above plus no need for parting line better surface finish than conventional sand casting increased dimensional accuracy Increased cost, added process steps As above... 

This process, commonly called "Lost Foam casting , was developed 30 years ago and its commercial growth was initially rather slow. However, during the last 10 to 15 years, it is has become used more often, primarily for the mass production of automotive parts or similar products, in spite of significant set-up difficulties. 

The Lost Foam process (Figure 2.36) starts with the 3D-CAD design and production of a precision moulded foam pattern, made from expanded polystyrene (EPS) or PMMA, produced by automated injection moulding machines. These patterns can be made from one piece or by assembling a number of parts by adhesives. Here usually, a number of patterns, dependent on size, are fixed to a runner-down gating system, made from the same material as the pattern, thereby generating a cluster. 

Figure 2.37 Expendable polystyrene pattern (r.) for the Lost Foam process and an example of a casting produced by the Lost Foam method (1.)...

The Lost Foam process with chemically-bonded sand, in this case also called the full mould process , is mostly used for producing middle or large sized castings, in single production or in small batch series. 

Despite the fact that the Lost Foam and full mould techniques have been known for a long time, they are not widely applied in Europe. This is primarily because their optimisation requires a lot of research and development. The main difficulties are ... 

Expendable pattern casting (Lost Foam/full mould casting) 3.9.6.1 Unbonded sand - Lost Foam... 

Table 3.43 shows a comparative analysis of a green sand and a Lost Foam aluminium foundry, both producing 5490 tonnes of good castings per year. It should be noted that the values do not take into account the internal regeneration. In practice, both types of foundry will apply regeneration, thus reducing the amount of residue effectively left for disposal. 

Residue type Lost Foam foundry Green sand foundry... 

Table 3.43 Comparative data for residue production from Lost Foam and green sand aluminium casting...

Table 3.44 Stack emission data for Lost Foam and green sand aluminium foundries [96, Spillner, 1997]...

Alternative moulding/core-making methods Lost Foam casting... 

The general principles of Lost Foam casting have been described in Section 2.5.7.1. Due to the absence of binders, the technique produces a reduced amount of solid waste and emissions compared to sand casting methods. 

Lost foam foundries include a foam workshop, a melting shop and a casting shop. They do not have an extensive core-making shop and finishing shop. The foam shop involves foaming machines, steam generators and coolers and ambient air dryers. 

The Lost Foam models are made of polystyrene (EPS) or PMMA, with small amoimts of pentane, glue and a mineral coating. Since both EPS and pentane are pure hydrocarbons, organic carbons are formed upon pyrolysis of the model. In order to minimise emissions of the organic decomposition products of EPS, post combustion of the off-gases is performed. 

LCA analysis has confirmed that the environmental benefit as stated above, can be extended to an overall better environmental performance of the Lost Foam process over sand casting, in as far as the casting of core-intensive castings are concerned. For simple castings (e.g. lids), the life cycle approach shows that there is no overall better performing process. 

An LCA-based assessment of the Lost Foam process (also taking into account processes outside the foundry borders) shows a lower overall environmental impact for the production of core-intensive castings. 

Input material Green sand Chemically-bonded sand Lost Foam... 

Eeonomie data for an aluminium Lost Foam installation are given in Table 4.27. Investment costs include equipment, installation, start-up and training. 

Spillner, A. (1997). "Vermeidung von Kemsanden und Aminabfallen durch den Einsatz des Lost-foam-Verfahrens im Leichtmetall-SerienguB", Abfallberatungsagentur (ABAC). 

US Dept, of Energy (1998). "Advanced Lost Foam Casting", Office of Industrial Technologies, http //www.oit.doe.gov/factsheets/metalcast/pdfs/lostfoam.pdf... 

Lost Foam process moulding technique using foam models in unbonded sand, in which the model is lost upon pouring of the metal, used for series production... 

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