Do you require quick, economic plastic prototypes with production-like material properties? Vacuum casting in silicone molds is the method that you need. Due to the low die costs, vacuum casting is particularly attractive as an economical secondary procedure for the reproduction of models in small batches.
Vacuum casting process
The original model for vacuum casting is generally created using the stereolithography method. From this model, a primary mold of silicone is created and filled in the vacuum chamber with liquid polyurethane casting resin (PUR). The vacuum prevents bubbles and shrink holes even in complex molded parts. After hardening, the service of the casting is finished. Given the numerous available polyurethanes and ureols (PU hard foam), many conventional production plastics (injection molding) can be simulated.
Whether rubber-soft, last, semi-rigid or ABS rigid, there are vacuum casting resins for a very wide range of material requirements and priorities. Two component parts (hard/soft) or inserts are also possible. The dimensional precision of molded parts in vacuum casting is ± 0.1 mm or 0.2%. In vacuum casting, the maximum yield from one silicone mold is approximately 20 molded parts. There are no demolding chamfers and added material to compensate for shrinkage in vacuum casting.
Advantages of vacuum casting:
- Production-like plastic prototypes and small batches of 5-200 units (20-40 units are typical)
- A high level of dimensional accuracy and surface quality
- Complex geometries (undercuts) and integrated functions are possible
- Favorable simulation of production-like plastics (rubber, PE, PP, HDPE, POM, PA, PA-GF, PC, PMMA, ABS)
- Hardnesses of 35-100 Shore A (elastomers) and 45–85 Shore D (similar to thermoplastics)
- The molded parts can be highly transparent, translucent or colored according to RAL
- Polishing, painting, chrome plating, printing, laser engraving
- Smooth surfaces or with an eroded structure according to VDI 3400
- UV-resistant, flame retardant and temperature resistant casting resins up to approximately 140°C
- Two-component parts and inserts are feasible
- Economical mold production
- Maximum component size 850 x 550 x 600 mm
- Maximum molded part weight 5,000 g
- Minimum wall thickness: 0.5-1 mm
Whether function prototypes, models for testing market acceptance, quick measurement models, pilot series or exclusive small batches, vacuum casting is an attractive alternative to injection molding due to low mold costs and the range of material properties when small batch sizes prohibit other alternatives.