Silicone Casting

Process Overview

Silicone Casting, a close relative of Room Temperature Vulcanization, or RTV Casting, is the process of pouring silicone into a mold - typically a durable resin -  to be cured.  Commonly, the mold is created by 3D Printing a high fidelity mold.  Upon curing the mold, liquid silicone rubber can be poured into the vacated space.  The silicone can then cure in the mold and eventually be removed - a perfect negative of the printed resin mold.

This process is commonly good for quantities from single digits to hundreds of parts.  For small quantities, silicone 3D printing may also be a good option.

Branded Processes (Also Known As)

  • Silicone Molding (Moulding)

Process At A Glance

Common Materials

Liquid Silicone Rubber, Silicone Shore A 30, Silicone Shore A 60

Standard Tolerance

+/-.005" to +/- .02" (.127mm to .500mm) depending on material shrink factor

Stock Surface Finish

~80 µin Ra

Lead Time

10-15 Business Days

Maximum Size

12" x 12" x 12" (300mm x 300mm x 300mm)

Minimum Layer Thickness

n/a

Minimum Feature Size

0.01" (0.250mm)

Minimum Wall Thickness

0.04" (1mm) dependent upon material

silicone casting

Advantages

  • Material Selection - There are a wide range of silicone options available depending on project application
  • Affordable For Medium Run Production - While 3Diligent offers Silicone 3D Printing, there is a subset of part designs that are better 3D Printed than cast.  Generally speaking, for standard geometries and quantities more than a handful, silicone casting is commonly the most cost competitive option
  • Well Defined Characteristics - Molding is a relatively mature technology, meaning that there is a large body of information on the characteristics of different molded silicones

Limitations

  • Not viable for onesy-twosy projects - Building a mold is somewhat labor intensive and time consuming.  This makes the process more costly than printing or machining for most part runs in the single digits, which are better suited for our Silicone 3D Printing capability.
  • Not viable for mass manufacturing projects - While resin tools are sometimes viable for 50 silicone pours or more, typically they are "shot out" at that point.  As a result, injection molding becomes a more desirable option at scale   
  • Silicone limitations - While silicone provides a collection of compelling material properties, its softness and elasticity make it less durable for demanding applications with tearing forces.

Example Machines

  • Custom Resin Molds

Example Materials

  • Liquid Silicone Rubber
  • Silicone Shore A 50
  • Silicone Shore A 60