RAPID PROTOTYPING - SILICONE RUBBER MOLD (SRM)

Silicone Rubber Molding  is a simple, accurate and forgiving process of making prototype parts. SRM is also the cheapest and fastest process to produce relatively small volume parts. The process start with a "Master Part" preparation. This part can be encapsulated with molding material and then many parts can be made from the resulting negative. This master can be encapsulated by supporting it on spacers and enclosing it in a retaining frame. The master part can be done using Fused Depositon Modeling (FDM) machine.

For an example,Trim Rear Pillar for a New Persona Car. The material to be used to do the master part is either PC or ABS. For my project, the material used to do the master part is ABS because PC material has been used up for other parts.  First of all, we do the parts at the Rapid Prototype by ourself because the vendor that has been appointed by us cannot do the parts. Time taken to finish the master part is approximately 131 hours or 6 days.

After the master part has been produced and taken out from FDM machine, it will come to the next process which is silicone rubber mold. An adjustable mold is placed around the master part and it should be no closer than 1 inch, so that the silicone rubber mold would be thick enough. The silicone rubber materials is mixed very well before pour it to make sure that air is not introduced into the material. When ready, pour the silicone rubber materials slowly to make sure no air pockets are left around the wall. Once the mold arrangement is filled, let it cure for 1 day before tear it apart.

Once the cure is finished, re-mold the arrangement. Since we made it one piece mold, cut it into two halves. One the cutting is completed, gently pull the two mold parts apart. Then, pull the master part out and now we have the mold, we can cast parts.