Flexible mould-making silicones for automotive castings

Developed for applications including automotive casting, aviation and consumer electronics; these silicones offer excellent transfer of pattern detail, long mould life and extremely high temperature resistance.

Flexible moulding is a popular system across many industries when faced with a part reproduction application. It is more cost effective than 3D Printing for small runs and a great alternative to solid mould processes such a liquid injection moulding or resin transfer moulding.

The Rapid Prototyping Industry has adopted flexible moulding for a wide range of applications including automotive casting, aviation and consumer electronics. This process is also making an impact with large-volume production tasks, architectural element production, and composite manufacturing and even with art reproduction and restoration projects.

Momentive Performance Materials has a large range of 21 addition and eight condensation cure mould-making silicones for prototyping applications and making moulds for complex precision parts.

Techsil, the authorised distributor for Momentive in the UK, has launched three new grades developed for use in flexible moulding applications. These new products will join the already very popular RTV664, an addition cure silicone system that can be used in compliance with US FDA food grade regulations.

TSE3478T

TSE3478T is a two-part addition cure silicone; this oil bleed system is easy to degas, has a handy 10:1 mix ratio and works to standard cure conditions. The product cures to a translucent rubber with a tensile strength of 6.0MPa, hardness of 40 (Type A), 380 per cent elongation and extremely low shrinkage.

TSE3480T

TSE3480T is a two-part addition cure silicone; a non-oil bleed system that offers improved mould life. This system has a handy 10:1 mix ratio and works to standard cure conditions. The product cures to a translucent rubber with a tensile strength of 6.0MPa, hardness of 37 (Type A), 380 per cent elongation and extremely low shrinkage.

RTV664RTV664 (available online)

RTV664 is a two-part addition cure silicone; it is a non-oil bleed system with a high cured shore hardness and can be used in compliance with US FDA regulations. This product has a shorter work life and demould time at room temperature than the new materials, but which cannot be further shortened with the addition of heat. RTV664 cures to a 62 Shore A, light blue rubber with very good tensile strength (6.4 MPa), 245% elongation and very low linear shrinkage.

RTV7888-20

RTV7888-20 is a two-part condensation cure silicone; this non-oil bleed system is best suited for soft mould making. Again, it has a handy 10:1 mix ratio and works to standard cure conditions; however unlike TSE3478T & TSE3480T, RTV7888-20’s work life and demould time cannot be shortened with heat. The product cures to a soft 20 Shore A light pink rubber with a tensile strength of 3.4MPa, 350 per cent elongation and low shrinkage.

During controlled testing, the above Momentive flexible mould-making silicones excelled in performance compared to other silicone offerings, providing a greater number of releases and showing better mould life. Momentive flexible moulding silicones offer excellent transfer of pattern detail, a moderate to long mould life and extremely high casting temperature restrictions. These are features and benefits that are not typically seen in other flexible mould materials such as latex, polysulfide, and PVC – which generally do not tolerate exotherms higher than 65°C and have very short mould life.

Although the relative material cost of silicone for flexible mould making is high compared to latex and PVC, the increased economic costs of silicone can be offset by its performance attributes required for fine detail castings and productivity.

Momentive provides 21 addition and eight condensation cure mould-making silicones for prototyping applications and making moulds for complex precision parts.