3D CAD design for plastic injection molding

Over the years, 3D CAD systems such as SolidWorks have become more and more integrated into the design and manufacturing processes. Plastic injection molding is no exception. Industrial designers use 3D CAD to make ergonomic and aesthetic contours which would be next to impossible to communicate in 2D drawings. Modern toolmakers must use 3D models to make the mold cavities. Also, most rapid prototyping machines accept only 3D files to create parts.

Rebling Plastics has extensive experience using SolidWorks and CADKEY to design parts for plastic injection molding. While formats are constantly changing, we have successfully imported from and exported to virtually all other CAD programs, including Pro/ENGINEER, CATIA, Solid Edge, Inventor, and AutoDesk/AutoCAD. In addition, we use universal formats such as IGES, STEP, DXF, DWG, parasolid (x_t), STL, and many others.

SolidWorks and CADKEY

SolidWorks, currently the most popular 3D design software, has enabled Rebling Plastics to be on the cutting edge of plastic injection molding part design. We have used SolidWorks for part design, assembly fit and design, stress analysis, animation, realistic CAD “photos”, 2D drawings, part weight calculation, and comparing features of similar parts.  We have also used a few SolidWorks features that are specifically used for plastic injection molding. In a few seconds, we can analyze the draft angles on a part model. “Adding draft” means tapering the molded parts to allow them to easily release from the mold. This draft analysis tool is very useful when designing parts with a large number of faces. SolidWorks also has features which allow quick creation of the mold cavity model from the part model. This feature enables our plastic injection mold suppliers to quickly design the mold.

While we have used CADKEY for 3D design, we mostly utilize CADKEY for dealing with 2D drawings and sketches. It also gives us better flexibility for working with customers who use only 2D for their plastic injection molding designs.

Case Study: Ceramic Probe Body Replacement

Heraeus Electro-Nite, a long-time Rebling Plastics customer, asked our engineers to assist with a cost-saving project. Several of their molten metal instruments use a ceramic cup to enclose a disposable probe. With the cost of ceramic parts rising, they wanted to know if switching to a thermoset plastic injection molding material would save money on some of these high volume parts.

Rebling Plastics researched the materials, and designed two similar parts in SolidWorks while keeping in mind the thermoset plastic injection molding process. From these designs, Rebling Plastics quoted prices for tooling and production- all at no charge. As it turned out, some applications were cost effective to make the switch to thermoset plastic.

From the 3D model drawn in SolidWorks, Rebling Plastics engineers were able to instantly convert to eDrawings, which enabled the customer to view, manipulate and measure the part without installing any software. The customer approved the design for rapid prototyping. Once the design was set, a prototype mold was ordered to make limited runs of test parts in various applications.