How to choose between silicone compression molding and LSR molding techniques?

Silicone compression molding and LSR molding are two commonly used processes for silicone products. The following comparison will help our customers choose the appropriate process for their products.

1. Manufacturing Process

Silicone compression molding:

Solid silicone raw material is placed in a heated mold cavity. Pressurization forces the material to fill the mold. The mold is then vulcanized at high temperature to set the shape.

Features: The process is relatively simple, but it relies on manual labor. The molding time is typically 5-15 minutes, making it suitable for thick-walled or large parts.

Liquid silicone injection molding:

Liquid silicone is injected into a sealed mold under high pressure using an injection molding machine. It rapidly vulcanizes within the mold within a few seconds to tens of seconds.

Features: Fully automated production with high precision, suitable for complex and delicate products such as medical supplies.

2. Material

Compression molding: Solid HCR silicone is used, with a hardness range of 20-80 Shore A and requires the addition of a vulcanizing agent.

Liquid silicone rubber molding: This liquid cures after mixing components A and B. It is soft (10-40 Shore A) and exhibits excellent fluidity.

3. Cost and Scrap Rate

Initial Investment:

Silicone ‌hot press molding: A single press costs 50,000–150,000 RMB. The equipment is inexpensive, the molds are simple.

Liquid silicone molding: This requires a dedicated injection molding machine and precision molds, costing 500,000-2,000,000 RMB.

Mass Production Cost:

Silicone rubber compression molding: High labor costs and a scrap rate of approximately 5-10%.

LSR: Automation reduces labor costs, resulting in a scrap rate of less than 1%, making it suitable for high-volume production.

4. Applicable Applications

Silicone compression molding:

Simple structural products or thick-walled parts such as silicone gaskets and kitchenware handles.

Large flat products or relatively simple designs such as industrial seals.

Low-cost prototypes or small-batch production.

Typical Applications: Automotive weatherstrips, iron soleplates, and simple silicone buttons.

LSR injection molding:

Products with complex and delicate structures, such as baby pacifiers and contact lenses.

Thin-walled or miniaturized parts, thickness <1mm

High precision requirements, dimensional tolerance ±0.05mm

Typical applications: Medical device seals, electronic waterproof connectors, optical lenses

Compression Molding Vs. LIM