Understanding the Two Dominant Silicone Manufacturing Processes
When sourcing custom silicone products from China, one of the most important technical decisions is choosing between Liquid Silicone Rubber (LSR) injection molding and High-Temperature Vulcanizing (HTV) compression molding. These two processes have fundamentally different characteristics that affect product quality, production speed, cost structure, and design flexibility. Making the wrong choice can result in higher costs, longer lead times, and quality issues.
Liquid Silicone Rubber (LSR) Injection Molding
The Process
LSR molding uses a two-part liquid silicone (Part A contains platinum catalyst, Part B contains cross-linking agent) that is precisely metered, mixed, and injected into a heated mold. The material cures in the mold within 10-60 seconds, depending on part thickness and complexity. The process is fully automated and produces flash-free parts with excellent dimensional accuracy.
Advantages of LSR Injection Molding
- No flash ? LSR molds are carefully designed to prevent excess material, eliminating the need for deflashing
- Excellent dimensional accuracy ? Tolerances of ?0.05mm are achievable
- Fast cycle times ? 15-60 seconds per cycle, enabling high-volume production
- Complex geometries ? LSR flows into intricate mold details that would be impossible with compression molding
- Consistent quality ? Automated metering and mixing eliminate human error in material preparation
- Overmolding capability ? LSR can be molded over plastic, metal, or fabric inserts
- Cleanroom compatibility ? LSR molding can be done in cleanroom environments for medical/infant applications
Disadvantages of LSR
- Higher tooling cost ? LSR molds require precision machining and often cost 2-3x more than compression molds
- Higher raw material cost ? LSR material typically costs 20-40% more than HTV
- Longer setup time ? Material changeovers and color changes take more time
HTV Compression Molding (And Transfer Molding)
The Process
HTV (also called HCR ? High Consistency Rubber) is a gum-like solid silicone that is pre-formed into “preforms” (cylinders, discs, or custom shapes), placed into a heated mold, and compressed under high pressure (100-200 tons). The heat and pressure cause the material to flow and cure. Cycle times are typically 2-5 minutes.
Advantages of Compression Molding
- Lower tooling cost ? Compression molds are simpler and cost 30-50% less than LSR molds
- Lower material cost ? HTV raw material is significantly cheaper than LSR
- Shorter lead time for molds ? Simpler mold design means faster mold fabrication (15-25 days vs 25-40 for LSR)
- Color flexibility ? Pigments can be added to preforms quickly for small batches
- Better for thick-wall parts ? HTV cures more uniformly in thick cross-sections
Disadvantages of Compression Molding
- Flash ? Excess material forms at parting lines, requiring manual deflashing (adds cost)
- Slower cycle times ? 2-5 minutes per cycle vs 15-60 seconds for LSR
- Less precise tolerances ? Typically ?0.15mm to ?0.3mm
- More labor intensive ? Each part requires manual loading of preforms
- Not suitable for complex geometries ? Undercuts, thin walls, and intricate details are difficult
Decision Matrix: Which Process for Your Product?
| Factor | Choose LSR Injection | Choose Compression |
|---|---|---|
| Order quantity | >10,000 pcs/month | <10,000 pcs/month |
| Tooling budget | Budget OK for $3,000-$8,000 mold | Limited budget, <$2,000 mold |
| Part complexity | Intricate details, thin walls, inserts | Simple shapes, thick walls |
| Tolerance requirement | ?0.05mm to ?0.1mm | ?0.15mm to ?0.3mm acceptable |
| Surface finish | Flash-free, no post-processing | Flash acceptable (can deflash) |
| Material certification | Medical/food-grade LSR available | Food-grade HTV also available |
Cost Analysis: A Real-World Example
Consider a silicone baby feeding bowl (100g material weight, 5,000 pcs/month):
- LSR option: Mold $5,000 + material $3.50/kg + cycle 30s = ~$1.85/pc at 5,000 pcs/month
- Compression option: Mold $2,000 + material $2.80/kg + cycle 180s + deflash = ~$1.45/pc at 5,000 pcs/month
At 5,000 pcs/month, compression is cheaper. But at 20,000+ pcs/month, LSR becomes more cost-effective due to faster cycles and less labor.
How Taihexin Supports Both Processes
SHENZHEN TAIHEXIN SILICONE PRODUCTS CO., LTD. operates both LSR injection molding and HTV compression molding production lines in our 10,000 m? Shenzhen facility. Our engineering team evaluates each client”’s product design, order volume, tolerance requirements, and budget to recommend the optimal manufacturing process.
We provide DFM (Design for Manufacturability) feedback before mold fabrication, helping you optimize part design for the chosen process. Our mold workshop can deliver LSR molds in 25-35 days and compression molds in 15-25 days. All molds are tested with pre-production samples before full production begins.
Contact our engineering team to discuss which molding process is right for your silicone product. Email: zhangling2020xx@163.com | Tel: 13760267566
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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.