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Why LSR work better than traditional compression molding?

Liquid Silicone Rubber Molding

Liquid silicone rubber (LSR) molding is a thermoset process that mixes a two-component compound together, 

which is then heat cured in the mold with a platinum catalyst to produce a final part. LSR parts are formed 

through an injection-molding process similar to that of conventional plastic injection molding with one major 

difference — the material delivery system is cooled and the mold is heated.

Final LSR parts are strong and elastic with excellent thermal, chemical and electrical resistance. They maintain 

their physical properties at extreme temperatures and can withstand sterilization. LSR parts are also biocompatible, 

so they work very well for products that have skin contact. Those benefits lend themselves well to automotive, medical 

and food appliance industries, typically in the form of seals, gaskets, valves and cables.


The LSR molding process starts with proper part design. Anyone familiar with designing parts for injection molding 

should find designing an LSR part to be similar. However, the shrink rate on LSR is fairly high, and the material 

also tends to flash very easily during molding. LYA mold helps mitigate challenges related to high shrink rates by 

planning appropriate tolerances and incorporating additional features into the mold design to help reduce flash. LSR 

typically fills thin wall sections with minimal challenges and is accommodating to variations in wall sections as sink 

is almost nonexistent.

Mold production

When an order is placed, Shenzhen LYA Silicone will then design an LSR molding tool. Due to the flexible nature of LSR, parts are 

manually removed from the mold, and thus, ejector pins are not built into the mold design. Like a standard Protomold aluminum 

tool, an LSR molding tool is fabricated using a combination of CNC milling and CNC electrical-discharge machining (EDM) to create 

a high-temperature aluminum tool built to withstand the LSR molding process. After milling, the tool is polished by hand to customer 

specifications, which allows six standard surface finish options: PM-F0, PM-F1, SP-C1, PM-T1, PM-T2 or SPI-A2. Others may be available 

by request.

Part production

The finished tool is loaded into an advanced LSR-specific injection-molding press that is precision geared for accurate control of 

shot size to produce the most consistent liquid silicone rubber parts. LSR molding shares many similarities with conventional injection 

molding, but there are a few notable differences. Unlike thermoplastic resin, which is melted before injection, LSR is a two-part thermoset 

compound that is chilled before being injected into a heated mold and ultimately cured into a final part. Note that LYA mold uses an automated

 meter mixing pump to assure the exact combination of the two-part compound; nothing is hand mixed. Since LSR is a thermosetting polymer, its 

molded state is permanent — once it is set, it can’t be melted again like a thermoplastic.

Tim report:

Shenzhen LYA Silicone Rubber Products CO,.LTD

Add: New Building 2, Baohua Industrial Zone, Gongye Road,
Longhua New District, Shenzhen,CN, 518109
Tel: 86-134 2430 6032
Fax: 86-755-29550519

Http: www.lyasilicone.net 

Keywords in the article: liquid silicone injection mold, how LSR work, compression molding, shenzhen LYA Silicone