LSR vs HTV

Liquid pumped.
Gum compressed.
Different volumes.

Both LSR (liquid silicone rubber) and HTV (high-temperature vulcanized) produce silicone rubber parts. LSR is injection molded from 2-part liquid. HTV is compression molded from solid gum stock. Different economics, different part characteristics.

Get a Quote DFM guide

01 · At a glance

Side-by-side summary.

Option A

LSR (Liquid Silicone)

Two-component liquid pumped into heated mold. Cures in seconds. Injection molding cycle 30-90 seconds. High-volume precision small parts. Medical, baby products, electronics seals.

Option B

HTV (High-Temp Vulcanized)

Solid gum stock compressed in heated mold. Cure time 2-10 minutes. Compression or transfer molding. Lower tooling cost, larger parts possible, lower-volume economical.

02 · Detailed comparison

Feature-by-feature breakdown.

Attribute	LSR	HTV
Raw material form	2-part liquid	Solid gum (millable)
Process	Injection molding	Compression/transfer molding
Cycle time	30-90 seconds	2-10 minutes
Tooling cost	$15K-50K	$3K-15K
Volume economical	10,000+ parts	100-10,000 parts
Max part size	Small-medium (200mm)	Large possible (500mm+)
Precision	High (±0.05 mm)	Moderate (±0.15 mm)
Color consistency	Excellent	Good
Automation	Full automation possible	Some manual handling
Flash (excess material)	Minimal	More common
Medical grade available	Yes (USP Class VI)	Yes
Typical applications	Medical, baby, precision	Gaskets, large seals, low-volume

03 · Decision guide

When to choose each.

Choose LSR (Liquid Silicone) when:

High volume production (10,000+)
Small precision parts
Medical devices (consistent quality)
Baby products (automated, clean)
Multi-cavity parts (efficient)
Tight tolerance required

Choose HTV (High-Temp Vulcanized) when:

Lower volume (100-10,000 parts)
Larger parts (beyond injection press)
Prototype silicone parts
Custom gasket production
Tool cost constrained budget
Heavy-walled parts

FAQ

Common questions.

LSR tool: $15-50K. HTV tool: $3-15K. Tool cost difference ~$12-35K. Per-part LSR cost is lower (faster cycle, less labor, less waste). Typical breakeven: 5,000-15,000 parts depending on part complexity. Below: HTV wins. Above: LSR wins. For production programs expecting 50,000+ parts lifetime, LSR is nearly always right. For ≤5,000 parts, HTV usually right.

LSR: liquid is pre-mixed, injected into hot mold (160-200°C), cures rapidly (seconds). Small parts cycle 30-45 sec total. HTV: gum stock placed in mold, pressure applied, cure requires 2-5 minutes at temperature for crosslinking. Opening mold, removing part, cleaning, loading next takes additional 30-60 sec. Total cycle 3-10 min per part. For volume production, LSR efficiency advantage compounds.

LSR injection molding: precision comparable to thermoplastic injection. ±0.05mm on critical features, ±0.1-0.15mm overall. Consistent cavity-to-cavity in multi-cavity tools. HTV: ±0.15mm typical, can have more variation between parts. For precision parts (medical device seals, precision gaskets): LSR preferred. For general rubber parts where ±0.2mm is acceptable: HTV works.

Both available in medical grade (USP Class VI, ISO 10993). LSR preferred for medical volume production because of: automated processing, reduced handling contamination, consistent part quality, compatible with medical device quality systems. HTV medical grade available for lower-volume or larger specialty parts. Most newer medical silicone parts: LSR.

Yes — both processes support overmolding onto rigid substrates. LSR 2K molding: plastic first, silicone second in same machine. HTV insert molding: place pre-molded plastic in silicone mold. LSR overmolding is more automated and consistent; HTV is lower-volume option. For overmolded products, process choice depends on volume and precision needs.

LSR: tool fabrication 6-10 weeks. HTV: tool fabrication 4-6 weeks. Both: first-article production 1-2 weeks after tool. Overall programs: LSR 8-12 weeks from design to first production, HTV 6-10 weeks. HTV slightly faster for tool, LSR slightly faster for production.