Liquid Silicone Rubber Injection Molding


Course Number: PLSM.7190

Tuition: $1,850

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This seminar provides comprehensive information about the Liquid Silicone Rubber (LSR) injection molding process and covers both the underlying engineering principles as well as their application in the molding environment. Classroom lectures cover the basics of the silicone injection molding materials, the liquid injection molding (LIM) process, and provide practical analyses that yield results and can be applied in the molding shop.

Injection molding workshops supplement the class material to provide experience with actual machine operation and practical molding techniques. Machine start-up, operation and shutdown procedures are demonstrated. Molding trials that show the relationships between processing variables and part quality are conducted.

Workshop emphasis is on practical setup procedures that optimize liquid silicone rubber molding cycle and product requirements. Troubleshooting techniques and solutions to practical molding problems are also addressed.


This course is appropriate for sales managers, account managers, sales and applications engineers, new product development specialists, product marketing professionals, product designers and engineers, industrial designers and industrial engineers, mechanical engineers, materials purchasing managers, manufacturing personnel and technicians, plant managers, production supervisors, quality assurance and quality control personnel, and anyone involved in silicone part or mold procurement.


Introduction to Silicone Materials - Liquid Silicone Rubber focused

  • Overview of silicone materials comparing Liquid Silicone Rubber (LSR), Room Temperature Vulcanizing Silicone (RTV), and Heat Cured Rubber Silicone (HCR)
  • Basic silicone structure, overview of properties and applications
    • Discussion of thermoset vs thermoplastic materials
  • Introduction to silicone viscosity and curing as applicable to injection molding

Introduction to Liquid Silicone Injection Molding Process

  • Detailed overview of the liquid silicone rubber injection molding process. Discussion of silicone mixing and feeding, shot size selection, filling and flow, and pack/hold practices
  • Discussion of filling problems, venting/vacuum, thermal effects, flow length, orientation, runner and gate flows, flow balancing, pressure profiles, and curing and pressure-volume-temperature (PVT) behavior

Liquid Silicone Rubber Injection Mold Considerations

  • Mold types and configurations: two-plate, three-plate, stack, etc.; heating, ejection, and cold runner system.
  • General Design for Manufacturing (DFM): Includes a discussion of undercuts, parting line, fill, and venting.
  • Overmolding Design Considerations: Approaches, materials, and other considerations for overmolding with LSR

Process Setup and Troubleshooting

  • Liquid Silicone Rubber molding and machine concepts, troubleshooting; cycle-time minimization and yield.


Attendees will use hydraulic molding machine and non-instrumented molds.