Why Silicone Material Selection Matters for Your Product
Not all silicone is created equal. The two main categories of silicone rubber — Liquid Silicone Rubber (LSR) and High-Temperature Vulcanizing (HTV) — have fundamentally different properties, manufacturing processes, and cost structures. Choosing the wrong material type can result in quality issues, cost overruns, or products that fail in the field.
What is Liquid Silicone Rubber (LSR)?
Material Characteristics
LSR is a two-part platinum-catalyzed liquid silicone system. Part A contains the platinum catalyst; Part B contains the crosslinker and filler. When mixed in precise 1:1 ratio, the material cures rapidly when heated (typically 150-200°C). LSR has a viscosity of 100,000-1,000,000 mPa·s (similar to room-temperature honey), allowing it to flow into intricate mold details.
Material Properties
- Shore A hardness range: 10-80 (very soft to semi-rigid)
- Tear strength: Excellent (20-50 N/mm)
- Transparency: High; can be made crystal clear
- Batch consistency: Excellent; automatic mixing eliminates human error
- Shelf life: 6-12 months (liquid; requires mixing before use)
- Operating temperature: -50°C to +230°C (continuous)
Typical Applications
- Medical devices and components
- Infant and baby products (pacifiers, teethers)
- Food-contact kitchenware
- Seals and gaskets for automotive and industrial applications
- Electronics components
- Overmolded parts (silicone over plastic or metal)
What is HTV Silicone (High-Temperature Vulcanizing)?
Material Characteristics
HTV (also called HCR — High Consistency Rubber) arrives as a gum-like solid or soft solid with a viscosity of 10-100 million mPa·s. It must be mixed with catalysts (peroxides or platinum), colorants, and fillers on a two-roll mill before molding. HTV cures through peroxide or platinum crosslinking at temperatures of 160-200°C. The material is typically supplied as sheets, strips, or pre-formed shapes.
Material Properties
- Shore A hardness range: 20-90 (wider range than LSR)
- Tear strength: Good to excellent (15-55 N/mm depending on formulation)
- Transparency: Limited; typically translucent or opaque
- Batch consistency: Requires careful mixing control
- Shelf life: 2-3 years (stable as solid; catalyst added before use)
- Operating temperature: -60°C to +250°C (higher than LSR for some grades)
Typical Applications
- Extruded profiles and tubing
- Molded rubber parts for automotive
- Industrial seals and gaskets
- Electrical insulators
- High-temperature industrial components
- Complex thick-wall molded parts
Head-to-Head Comparison: LSR vs HTV
| Property | LSR | HTV |
|---|---|---|
| Material form | Liquid, two-part | Solid gum, one-part |
| Molding process | Injection molding | Compression or transfer molding |
| Cycle time | 15-60 seconds | 120-300 seconds |
| Flash | Minimal/none | Present; requires deflashing |
| Tolerance | ±0.05-0.10mm | ±0.15-0.30mm |
| Material cost | Higher ($10-20/kg) | Lower ($8-15/kg) |
| Tooling cost | Higher ($3,000-10,000) | Lower ($1,500-5,000) |
| Transparency | Excellent | Limited |
| Overmolding capability | Excellent | Limited |
| Complex geometries | Excellent | Moderate |
| High-temp grades | Good | Excellent (to 300°C) |
Specialty Silicone Types You Should Know
Fluorosilicone (FVMQ)
Combines silicone’s temperature resistance with fluorosilicone’s chemical resistance. Excellent for fuel systems, solvents, and harsh chemical environments. Higher cost than standard silicone.
Phenyl Silicone
Contains phenyl groups that improve performance at extremely low temperatures (down to -115°C). Used for aerospace and cryogenic applications.
Room-Temperature Vulcanizing (RTV) Silicone
Cures at room temperature without heat. Used for sealants, adhesives, and prototyping. NOT suitable for molded parts that require heat resistance.
Food-Grade and Medical-Grade Silicone
Both LSR and HTV are available in food-grade and medical-grade formulations. Key certifications:
- FDA 21 CFR 177.2600 — US food-contact standard
- LFGB § 30/31 — European food-contact standard (strictest)
- USP Class VI — Medical device material safety
- ISO 10993 — Biological evaluation of medical devices
For consumer products (baby items, kitchenware), FDA food-grade and LFGB-compliant materials are the standard requirements.
How to Choose: A Practical Decision Guide
- Volume requirements — LSR is more economical above 10,000 pcs/month due to faster cycles; HTV is better below 5,000 pcs/month
- Tolerance requirements — If you need ±0.1mm tolerances, choose LSR; otherwise HTV is fine
- Transparency — If your product must be transparent or translucent, choose LSR
- Design complexity — Complex geometries with thin walls or inserts require LSR
- Budget constraints — HTV has lower tooling and material costs; better for startups
- Application temperature — For temperatures above 230°C, choose high-temperature HTV grades
Taihexin: Expert Guidance on Silicone Material Selection
SHENZHEN TAIHEXIN SILICONE PRODUCTS CO., LTD. operates both LSR injection molding and HTV compression molding production lines. Our engineering team evaluates each product to recommend the optimal material type based on your application requirements, volume, and budget.
We source silicone raw materials exclusively from certified suppliers (Dow Corning, Wacker, Shin-Etsu) and maintain full traceability from raw material to finished product. All our silicone materials are available in FDA and LFGB food-grade formulations.
Contact our technical team to discuss which silicone material is right for your product. Email: zhangling2020xx@163.com | Tel: 13760267566
Related Manufacturing & Process Articles
- What are the top ten manufacturers of silicone raw materials in the world?
- How to customize silicone products, and what do you need to customize silicone product molds?
- What Is Food-Grade Silicone? A Complete Guide for Buyers
- Silicone vs Plastic: Why Silicone Products Are the Better Choice for Your Business
Frequently Asked Questions
What is the minimum order quantity for custom silicone products?
MOQ for custom silicone products typically ranges from 500 to 5,000 pieces depending on complexity, mold costs, and manufacturer. Some manufacturers offer low MOQ (100-500) for prototype runs. Mold costs range from $500-$5,000 for compression molding and $5,000-$50,000 for injection molding.
How long does it take to manufacture custom silicone products?
Lead time for custom silicone products: mold fabrication 15-30 days, first production run 10-20 days, repeat orders 7-15 days. Total from design to delivery is typically 35-60 days. Rush orders may be possible at premium pricing.
What certifications should a silicone manufacturer have?
Key certifications include ISO 9001:2015 (quality management), FDA 21 CFR 177.2600 (food contact), ISO 13485 (medical devices), IATF 16949 (automotive), SGS testing reports, and REACH/RoHS compliance for EU markets.