The highest quality material in lost foam casting -EPMMA
In lost foam casting, the foam pattern material directly determines the quality of the casting. The solid residue after the pattern decomposes is the source of carbon residue defects — the most difficult defects to fix, and also the limit that many high-end products cannot exceed if the wrong material is chosen.
Ultra-low carbon residue
EPMMA(Expandable Polymethyl Methacrylate) is a polymer plastic made entirely from methyl methacrylate monomer — without styrene. With a carbon content of only 45% (compared to 63% for STMMA Copolymer, 82% for STMMA-FD, 92% for EPS), EPMMA decomposes extremely completely at high temperatures, has a very high degree of gasification, and almost no solid residue. This is currently the ideal pattern material.
4 FACTORSEPMMAHELPS IMPROVE PRODUCT QUALITY
Surface carbon <0.015%
Produces less carbon residue, so with high-quality steel and ductile iron, it does not increase surface carbon. For products that require strict surface carbon specifications, EPMMA is the only choice for the burning model casting method with high-quality products.
Zero defects
No solid residue → Products achieve a rate of over 98% under standard process conditions. Reduces casting defects, with reasonable technical design, it is possible to have no defective products at all.
Uniform mechanical properties
Does not increase carbon in the material. With fully spheroidized ductile iron, steel does not form abnormal carbides.
Rapid gasification
Rapid gasification, easy evaporation, allows suction systems to quickly remove it from the mold without affecting the material.
Note: the phenomenon of excessive gas production when using EPMMA
Due to EPMMA decomposes extremely quickly in a chain (zipper decomposition) and generates more gas than STMMA, the gas pressure in the mold will push back the flow of molten metal if not released in time. To thoroughly address this, the foundry needs to implement two approaches simultaneously:
High gas production is an inherent characteristic of this EPMMA product; good gas release is important during use.
1. Increase gas escape efficiency
- Pump:Increase vacuum suction capacity, maintain high and stable negative pressure.
- Coating:Use ultra-high-permeability paint to reduce resistance.
- Mold design:Increase the diameter and density of air vent holes, do not use overly fine sand mesh.
2. Reduce the amount of gas generated
- Drying time:Dry EPMMA samplesfor over 30 daysto eliminate volatiles, helping to reduce the total amount of gas released during pouring.
When to use EPMMA
Low carbon steel material (<0.3%), Steel 20, 25, Grade B
Preserve low C content, do not mislabel the steel.
Stainless steel
Steel sensitive to C increase >0.03% loses corrosion resistance.
High-grade ductile iron
Ensure perfect spheroidal graphite, with no areas of anomalous carbon.
