RTV

(Room Temperature Vulcanized - Rubber Molding of Urethanes)

 

 

 

What is RTV ?

 

Room Temperature Vulcanizing (RTV), AKA Rubber Mold Process, is a common process in the rapid prototyping industry.  RTV is typically used for the production of a small series of functional plastic prototypes. A broad range of liquid thermoset plastics are available for casting these parts. The most frequent use for silicone tooling is in the casting of polyurethane to reproduce quickly and economically, multiple functional copies of original component forms. Polyurethanes offer a wide variety of physical property capabilities and enable the production of prototypes capable of being used for functional testing and design verification.

     

 

How Does RTV Work ?

 

Typical procedure for RTV molding and casting includes:

 

1. Produce one or more high quality Stereolithography (SLA) parts.  The SLA part is made oversize to compensate for shrinkage that occurs when the mold is made and the urethane is cast.  After customer approval, the master SLA part is hand-finished to a high level, on all exterior surfaces. Texturing, if required, is also done at this time.  (positive model)
2. Produce a rubber mold using the Stereolithography master parts. (negative model)
3. Produce accurate multiple parts using the castable material of choice in the rubber mold.   Gravity, Vacuum or Pressure molding (positive model)

 

 

              

 

 Shooting a                 Opening a rubber mold                  Rubber mold open

  small part          
 

What types of Materials are used with RTV ?

 

Soft flexible (25 Shore A) materials to hard durable urethanes (85 Shore D) are available. These prototype urethane materials are used to approximate thermoplastic engineering resins, simulating the form, fit, and function of an injection-molded component.  

 

·         Cast-in custom coloring and texturing

·         “Soft touch” grip

·         Component and gasket overmolding.

·         Materials with UL ratings are available.

 

When should RTV be considered?

 

• Ideal for < 100 marketing samples. 
• Low volumes of prototype parts can be produced quickly, without hard tooling. These parts may serve a variety of purposes, such as sales and marketing demos, conceptual models, durable representative and functional models, pre-production parts for trade shows, rapid and inexpensive test assemblies, etc.

 

Design Considerations for RTV

 

• 36 x 36 x 24 size envelope
• Threaded inserts, studs, brackets, wires or any custom parts can be fully encapsulated in the material.
• Water clear or light color base materials can be directly pigmented to the required color otherwise painted to the customer specific color
• High surface finishing quality comparable to injection molding. Texture finish can be applied to painted parts in the form of a texture coat, varying from an EDM type light texture, to a heavy texture.

 

RTV Volume Appropriateness:

 

• 1 or more
• 5-15 typical
• 15 to 35 cast urethane parts can be produced from each RTV mold, depending on geometry.

  

Contact me for a quick response with the options available to meet the requirements of your engineered mechanical components for design, performance and speed of delivery

 

Ron Humphrey 425.450.0099

rhumphrey@humphrey-associates.com