Liquid Silicone Rubber Molding

Our liquid silicone rubber (LSR) molding process produces custom prototypes and end-use production parts in 15 days or less. We use aluminum molds that offer cost-efficient tooling and accelerated manufacturing cycles, and stock various grades and durometers of LSR materials.

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Choose RJCmold for Custom Tooling and Manufacturing

Silicone rubber injection molding has been around for more than half a century since the late 1970s. The silicone rubber injection molding process has two molding methods: liquid silicone rubber injection molding (LSR) and solid silicone rubber molding. Silicone rubber injection molding has thousands of applications in various industries such as medical, automotive, and electronics.

As one of the professional silicone injection molding companies, RJC has been producing silicone rubber injection molds for many years. Especially for liquid silicone rubber injection molding, we have become an OEM supplier of BD Medical for the production of medical rubber catheters. We have the ability to provide liquid silicone rubber injection molding services from prototyping to mass production manufacturing.

At RJC, we have over 9 liquid silicone rubber injection molding machines with ISO Class 8 cleanrooms available for medical contract manufacturing needs. We are able to provide fast, high-quality service, and our professional engineering team with extensive experience in liquid silicone rubber injection molding is here to assist you throughout the project. If you need liquid silicone rubber injection molding service, please contact us today.

Who We Are

We make custom molded rubber, silicone molding, LSR molding and custom tooling. We handle the entire process, from prototype to production.

  1. Choose us for your custom molded rubber, LSR, and silicone injection parts.
  2. We make tens of millions of customized parts every year.
  3. Our CNC shop produces hundreds of new tools annually.
  4. Our custom molded silicone parts are made and developed in the USA.
  5. Single ownership for more than 20 years.
  6. We have the industry’s fastest and most complete silicone prototyping with silicone production services.

Liquid Silicone Rubber Molding Capabilities

Our basic guidelines for silicone rubber molding include important design considerations to help improve part moldability, enhance cosmetic appearance, and reduce overall production time.

US Metric
SIZE 12 in. x 8 in. 4 in. 304.88mm x 203.2mm x 101.6mm
VOLUME 13.3 cu. in. 217,948 cu. mm
DEPTH No greater than 2 in. from any parting line; deeper parts are limited to a smaller outline No greater than 50.88mm from any parting line; deeper parts are limited to a smaller outline
PROJECTED MOLD AREA 48 sq. in. 30968 sq. mm

Tolerances: RJCmold can maintain a machining tolerance of +/- 0.003 in. (0.08mm) with a linear tolerance of +/- 0.025 in./in. (0.025mm/mm).

Custom Silicone Rubber Injection Molding Service For Your Business

Liquid silicone rubber injection molding parts have the feature of durability with good tensile strength and are used to high volume, tight tolerance. Therefore it is widely used in various industries especially for medical parts.

Here are the advantages of liquid silicone rubber:

  • Excellent insulating properties, good for tight tolerance/precision components
  • Good tensile strength  with high/low-temperature extremes
  • Good resistance for water, oxidation also some chemical solutions like acids.
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Liquid Silicone Rubber Injection Molding Materials

A wide variety of LSR materials for various applications and industries is available. Popular options include standard silicones along with medical-grade and fuel-resistant grade materials.

  • Standard Silicone (30, 40, 50, 60, and 70 durometers)
  • Medical-Grade Silicone
  • Optical-Grade Silicone
  • Fluorosilicone (fuel and oil resistant)

Surface Finish Options

PM-F0 non-cosmetic, finish to Protolabs’ discretion
PM-F1 low-cosmetic, most toolmarks removed
PM-F2 non-cosmetic, EDM permissible
SPI-C1 600 grit stone, 10-12 Ra
PM-T1 SPI-C1 + light bead blast
PM-T2 SPI-C1 + medium bead blast
SPI-B1 600 grit paper, 2-3 Ra
SPI-A2 grade #2 diamond buff, 1-2 Ra

Why is Liquid Silicone Rubber ideal for injection molding applications?

Manufacturers in various industries, including automotive, healthcare, general industrial, infant care, consumer goods and electronics require easy-to-mold (and demold) low or high-viscosity rubber silicones to produce parts efficiently and cost-effectively.

Liquid silicone rubber (LSR) is the material of choice for injection molding applications. The silicone backbone is composed of repeating Si-O chains which are extremely flexible in nature giving this chemical structure unique properties such as a broad operating temperature range, weatherability, hydrophobicity, bio-inertness, electrical insulation, and a sustainable life span.

Liquid injection molding

Liquid injection molding is the process used with liquid silicone rubber (LSR) to fix the material from an uncured state into a cured part.

  • The highly viscous LSR is extracted from drums or pails using a dosing unit and injected into a closed mold in the press.
  • The mold is then heated, and the heat combined with pressure applied to the LSR results in the rubber becoming a solid part.

Liquid Silicone Rubber for general purpose applications.

Producing quality parts rapidly is essential in the LSR molding market.  Liquid injection molding provides the most efficient and economically viable process using Liquid Silicone Rubber (LSR).  Elkem Silicones offers a robust general purpose product range of LSR materials including durometers from 01-70 Shore A.   These materials are specifically designed with a fast cure and excellent mold release as well as excellent physical and mechanical properties.

Silicone Rubber Injection Molding Process

Composed A and composed B pumps one Part A silicone and one Part B silicone via separate hoses to the static mixer. Cylinder A contains the basic material. while cylinder B contains a catalyst. In addition,  color is pumped to the static mixer via another hose. The mixed components are then fed into the throat of the injection molding barrel by way of a shut-off valve. This is the whole silicone rubber injection molding process.

Once the silicone material is inside the barrel, a shot of the cool mixed silicone advances to the mold as the nozzle seals firmly against the silicone rubber liquid mold.

The nozzle shut-off valve opens and a measured shot of cool liquid silicone is injected into a hot (275F to 390F) clamped silicone rubber molded parts.

The nozzle shut-off valve opens and the barrel retracts from the silicone rubber liquid mold, while the screw begins to build another measured shot of cold liquid silicone.

After the cycle is complete, the mold opens and the piece and flashing can be taken off automatically or by an individual worker.  After that, the mold closes and repeats the procedure.

After removing the article from the mold, the post-molding process may include demisting, post-curation, inspection, and packing.

Applications and Advantages of LSR Injection Molding

-Silicone rubber injection molding can be qpplied in molding parts. Moulded part is a good way for low quantity production from dozen to hundred of the part even millions of parts. The molding part is better than the part machined by CNC or 3D printing with the same material. The right choice for resin used in the molding part allows for a wide range of properties. Mold is essential medial for the molding part. So molds machined by CNC and Wire cut EDM with high precision and tolerance are enable make thousands of parts.

-We cercitified with ISO9001, ISO13485 and equipped with ISO 8 medical cleanroom molding

Rapid processing mold with low cost and enable to make molded products with 10 days at a competitive price.

LSR molded parts offer great UV and ozone resistance and outstanding electrical insulation

Range from 10 to 80 durometer shore A

LSR molding is a great for gaskets, cushioning pads in portable communications, ruggedized electronic devices, and many more applications.

Related Injection Molding Services From RJC

Ready to Get an LSR Injection Molding Quote?

We appreciate the opportunity to provide you with continual support, fast delivery, and the highest quality items available. Please contact us further for more information on the services and items we provide to make your life and business easier. If you would like a price quote on a specific project, please contact our customer service number or fill out the online form. We look forward to serving your needs for all your projects, large and small.

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