3D printing makes it extremely easy to produce small batches of plastic parts, but getting rid of the appearance of 3D printing can be tricky and time-consuming. When you need a smooth and polished surface, or when you want to make an exact copy of an existing injection molded part, Cast resin parts in silicone molds It is a good choice. [Eric Strebel] He has a wealth of experience in the production process and demonstrated this process in detail when making a copy of the violin chin that is no longer in production. This is an interesting application, where 3D printing layer lines is not only an aesthetic issue, but if it exists, it can also irritate the user’s skin.
Creating a silicone mold requires some careful consideration of mold design. You want to choose the dividing line so that the finished part can be taken out as easily as possible, while also placing resin pouring ports and vents to prevent air bubbles from being trapped in the mold.exist [Erics] In this case, it was impossible to use a simple plane dividing line, so he installed the main part on a piece of wood and used cardboard and modeling clay to create a volume in which the second side of the mold would protrude on the first side. It is important to note that sulfur-free clay must be used, otherwise the silicone may not be cured.
Cast one side of the silicon mold first, and then put it back into the mold box together with the master mold after curing, so that the other side of the mold can be cast.at this point [Eric] Before forming the second side, the gate former and exhaust rod are strongly glued to the master mold. Add a release agent composed of petroleum jelly and naphtha where both sides of the mold are in contact to prevent them from sticking together.
Air bubbles are your enemy during resin casting, so ideally, you need a vacuum chamber to degas the silicone and resin before casting, and a pressure chamber to cure the resin part. When pouring silicone for the mold, place the mold box on the vibrating table to allow any air bubbles to rise to the surface. Although the entire mold manufacturing and molding process is very time-consuming, the copied parts are almost indistinguishable from the original parts.
[Eric] In the past, it also showed us how to make larger silicone molds. If you find yourself making many mold boxes of different sizes, it may be worthwhile to build an adjustable mold box.