Dongguan Xinjuexin Plastic Hardware Products Factory

Professional one-stop supplier of molds, plastic parts and metal parts, including rapid prototyping, mold making & on-demand production.

LSR injection molding

1. Introduction

Liquid silicone rubber is a high purity platinum cured silicone with low compression set, good stability and ability to resist extreme temperatures of heat and cold ideally suitable for production of parts, where high quality is required. Due to the thermosetting nature of the material, liquid silicone injection molding requires special treatment, such as intensive distributive mixing, while maintaining the material at a low temperature before it is pushed into the heated cavity and vulcanized.

Liquid silicone rubber is high-purity platinum cured silicone. Its physical, chemical and thermal properties make it highly suitable for products where performance, durability and high quality are a necessity.

Additionally, liquid silicone rubber allows for coloring or transparency in the finished product. Depending on their chemical composition, these materials can also serve as insulators or conductors.

LSR liquid injection molding is the preferred method for molding precision, delicate components. The process is clean and offers precision, accuracy, and high output. When combining the properties of LSR with the clean manufacturing process of liquid injection molding, the result is products that offer superior resilience and performance.

Typical applications for liquid silicone rubber

LSR are products that require high precision such as seals, sealing membranes, electric connectors, multi-pin connectors, infant products where smooth surfaces are desired, such as bottle nipples, medical applications as well as kitchen goods such as baking pans, spatulas, etc. Often, silicone rubber is overmolded onto other parts made of different plastics. For example, a silicone button face might be overmolded onto a Nylon 66 housing.

Manufacturing Process of LSR

Liquid silicone rubber (LSR) is a thick liquid polymer that uses a clean liquid injection molding process for producing LSR molded components.

LSR used in the liquid injection molding process are two-part, platinum-cured polymers, the most stable. Platinum-cured LSR is received in 2 drums – A & B. When the A & B material components are pumped into the injection barrel of the molding machine, the materials combine and the vulcanization or curing process begins. If colored parts are desired, a third liquid with the color pigment is pumped into the barrel as well. The curing process is further accelerated when it is injected into the heated mold cavities where it solidifies and forms to the exact part geometry.

Advantages of injection molding:
  • Reduced cycle time
  • Flashless tooling
  • Economical process for high volumes of medium to high precision components
  • Capable of producing overmolded components
  • Minimal material waste
3.Tolerance Standard

We can make parts according to your tolerance requirements, if you do not have special requirements on the tolerance,our tolerance is according to the standard of ISO3302:2014 CLASS 2

4. Surface treatment

With compression molding, we can make surface as matte, texture, common polishing, mirror polish, laser engraving, power coating, printing, segmented colors and mixed colors, from below picture, you can find effect of different surface treatment.

5.Process Flow Diagram

Once the order is confirmed, our engineer will provide the DFM report (Design for Manufacturability Analysis) to customer for approval. We’ll start to design the mould drawing and mould making after the DFM report approved by customer. Once the mould making is finished, we’ll make several pieces of pre-production samples for test, if the dimensions are correct, then we will send the samples to customers for final confirmation. If the test failed, we will modify the mould or adjust the molding parameter to make new samples, and test it again. Once the samples are approval by customers, we will purchase the raw material and making quality inspection. Then mixing material, molding and trimming, we will make many times of inspection during the production. Finally we will arrange the assembly and packing. After whole order is ready, we will send the packing list to customer to arrange the shipment.

6.Quality Control

100% inspection for order,we seriously take care of the quality control from IQC to OQC, throughout each step of the production. Let us show you our quality control:

For raw materials, we’ll do the IQC in time. All materials are procured only from the verified suppliers, who have implemented and maintain certified quality management systems in their plants. With full certificates, such as RoHs, Reach, MSDS, FDA, LFGB, UL, EN549, BPA free, EN71, and so on;For pre-production samples, we’ll provide several pieces to our clients for assembly and function testing. We will seal the samples in time once they’re approval.

For Bulk Production, we’ll do the IPQCS & PQC (Multiple Sampling Inspection) during production and we’ll do the FQC (Sampling Inspection) after deburr or breaking sharp edges. In order to timely find problems, solve problems, reduce defective products, reduce manufacturing costs.

After packing and assembling, we’ll do the OQC (Sampling Inspection) to make sure the final goods are qualified.

Below you find find our inspection equipment for your reference.