Injection Molds for Liquid Silicone Rubber, LSR

Liquid Silicone Rubber (LSR) introduced multiple challenges from a tooling standpoint. Because of the “liquid” nature of the material, LSR flashes in spaces of .0002 inches or less. Therefore, molds for LSR molding require extreme precision throughout the mold building process to be capable of producing flashless parts.

There are many differences between a thermoplastic injection mold and a mold designed for LSR. Some key design considerations include:

  • Detailed designs with every aspect of the process designed in
  • Mold features such as ejection and venting may be similar in theory to thermoplastics yet can’t be approached the same because of the possibility of introducing flash onto the part.
  • LSR molds are processed at temperatures of 300° – 400°F which introduces the challenge of thermal expansion of the steel that design must accommodate

Other considerations when choosing a mold for LSR molding include:

  • Skilled mold makers with knowledge of the LSR process
  • State-of-the-art machinery capable of the exacting precision required
  • The latest in machining techniques and mold makers with the skills and knowledge in these machining techniques

A weakness in any one of these areas makes the challenge of flashless molded parts in LSR that much greater. At Built-Rite Tool & Die, we have invested in the latest, state-of-the-art machine technology and upgrades to accommodate the precision needed to manufacture molds for LSR.  That along with the experienced, talented professionals on the Built-Rite mold making team ensures that our customers get the highest quality molds for LSR molding or over-molding using LSR.

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