Star Prototype’s polyurethane vacuum casting service produces quality polyurethane casted parts at low cost to the customer. The vacuum casting process allows for extensive prototyping services, and strict scheduling ensures on-time delivery. Star Prototype offers professional customer support in multiple languages during every step of the polyurethane casting process.
Polyurethane Casting Process
Polyurethane casting is a multi-step process requiring thorough engineering. In general, we make a master model by stereolithgraphy and then apply whatever surface finish is needed to it. We then pour liquid silicone rubber around the master model in a casting box. Once cured, we split the silicone rubber mold and can then use it to cast up to 20 polyurethane parts.
We can make your parts soft like rubber, tough, heat resistant, clear & rigid, clear & soft, colored, textured and more. Our most popular resin is ‘STAR-PU Classic ABS’ which has similar material properties to ABS material. If you would like to review all of your material options please download our “vacuum casting material sheet“. In it we list all materials, explain the coloring options, and also explain some material properties.
Advantages of Vacuum Casting
Polyurethane vacuum casting offers a wide range of options for companies needing specific finishes, textures, materials, or other features in their prototypes. We have the ability to simulate a full range of thermoplastics and elastomers, and we can also over-mold one material over another to simulate, for example, rubber over ABS, or opaque plastic over transparent plastic. It is also possible to over-mold threaded inserts.
After casting, painting and printing is common, although polyurethane casted parts can be colored and textured in the mold. Star Prototype also specializes in producing high-gloss clear parts by using a CNC machined and polished acrylic master model. Polyurethane casted clear parts are very high quality. Parts made by vacuum casting at Star Prototype are practically indiscernible from production injection moldings.
The finished dimensions of vacuum cast parts are primarily dependent upon the tolerance of the master model (see SL tolerances) with a tolerance of +/- 0.15% added as a general rule. This varies depending upon weak geometry. To ensure the accuracy of Star Prototype’s polyurethane parts, we usually machine a Tufnol fixture for post-heat-treatment. This ensures that the part does not shrink upon heat treatment.