When we are doing a small batches of rapid prototypes, around 20-30, we generally use silicone rubber mold and reactive polyurethane materials. Silicone mold can be used for quick, easy and inexpensive low volume production of various plastic parts and paraffin models under negative pressure pouring in room temperature, especially in aerospace, automotive, home appliances, toys prototypes and medical equipment and other fields.
Silicone rubber mould is a relatively popular rapid tooling manufacturing process and is widely used in the rapid manufacturing industry due to its good toughness to make prototypes with complicated structure, fine pattern, no mold inclination and even pouring angle. It has the following advantages:
Easy to demould
In conventional metal molding, it is usually necessary to set the draft angle so that the part can be smoothly removed after forming, especially for parts with deep grooves. In silicone rubber moulding, due to its good flexibility and elasticity, work pieces with complex structure, fine pattern, no draft angle and even deep groove, can be demoulded directly after the casting without additional draft angle, which simplifies mold design as much as possible.
Short production cycle
It only takes a few days or so to do the silicone rubber moulding as requested if the 3D CAD files for the parts are provides, thus use silicone rubber mold to pour out polyurethane plastic prototypes. It saves you 90% of time if compared with the steel moulding for injection prototyping, which takes around 30 to 90 days.
Room temperature vulcanized silicone rubber has excellent simulation and very low shrinkage and can be a good reproduction of the prototype parts on the fine features, and will almost not lose the dimensional accuracy of parts, thus is an excellent mold material.