Vacuum Casting

Urethane Vacuum Casting:  ProtoTech Machining, on the leading edge of vacuum casting technology, can create silicone rubber molds producing urethane cast parts quickly and accurately. 

Vacuum Casting Materials

Gallery of Vacuum Casting Parts

We have been helping various industries such as aerospace, automotive, medical devices and other industries to develop various elastomeric vacuum cast parts for 20 years.

Surface Finish for Vacuum Casted Parts

With an extensive array of surface finishes, ProtoTech Machining can create unique surface layers for your vacuum casting parts. These finishes help you meet your products’ appearance, hardness, and chemical resistance requirements. Depending on your material selection and part applications, we can offer the following surface finishes:

Full Glossy

Highly reflective surface finish created by polishing the master pattern before mold making. The high-gloss finish offers high transparency useful for cosmetic parts, lenses, and other cleanable surfaces.


This B grade finish is not highly reflective but offers some sheen. Using gritty sandpaper, you will get smooth, cleanable surfaces between high-gloss and matte.
vaccum casting

Matte Finish

Vacuum cast parts will have a satin-like finish through the bead or sand blasting of the master pattern. The C-grade finishes are ideal for high-touch areas and handheld components.

Custom Texture

ProtoTech Machining can also provide custom finishes through additional processes. On request, you can get unique secondary finishes for the best results.

Silicone Rubber Mold Making

The master pattern serves as the basis for the creation of the silicone rubber mold, also referred to as an RTV mold, frequently used in urethane casting due to its chemical stability, self-releasing properties, and flexibility.

The lifespan of the silicone mold in prototype manufacturing is closely tied to the complexity of the casting part, generally producing 12-15 parts before deterioration. Simple designs allow for more output, possibly 20 parts from a single mold.

The passage discusses the use of a master model in urethane casting or aluminum casting molds. The master model is coated with thin films to aid the CNC machining process and serves as a seam for the final product. It is suspended in a fixture with gates, vents, and risers, resembling a Coordinate Measuring Machine (CMM) process. Silicone is then used in vacuum casting to cover the master model, and a vacuum is applied to remove air. The mold undergoes curing in an oven at 40℃ for 8-16 hours, akin to Fused Deposition Modeling (FDM).

Polyurethane Casting Process Detail

Urethane casting at ProtoTech Machining effectively aligns with clients’ demands, whether it’s color, texture, glossiness, insert and over-molding, or even achieving optical clarity. Our standardized procedures assure precise part replication and uniform mechanical properties. Our experts control all operations: from mixing to de-molding, facilitating near-flawless replicas of the master pattern with a standard tolerance of ± 0.15mm/100mm and highest precision reaching ± 0.05 mm for prototype manufacturing.

Urethane casting matches client specifications, including color, texture, glossy finish, and clear features. The process involves placing a silicone mold in an oven, preheating polyurethane resins, mixing them in precise proportions, and degassing in a vacuum. The resin is poured into the mold under computer control, cured in the oven for 1-6 hours, and then the part is extracted from the mold.

Polyurethane Vacuum Casting Applications

Due to its fast production, low costs, and durable parts, our vacuum casting service is the favored option for making custom parts used in the automotive, medical, consumer goods, and other industries.

Low Volume Manufacturing / Short Production Runs

Utilize our advanced manufacturing services, including vacuum casting, CNC machining, and 3D printing, for rapid prototyping and low volume production of high-quality plastic prototypes and custom production parts. Avoid the need for costly investment in injection molding and lengthy production tooling lead times. Benefit from faster turnaround times and achieve complex designs efficiently through our innovative technologies.

Engineering Verification / Functional Testing

Utilizing urethane casting, which involves low-cost tooling, enables economical engineering verification, design iterations, and functional testing prior to mass production. This process proves beneficial for assessing product performance, obtaining certification approvals, and generating detailed reports.
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