LSR vs HTV vs HCR: process selection
All three are "silicone molding". The material form, the machine, the cycle time and the tool cost differ enough that the wrong choice adds either weeks to the schedule or tens of thousands of RMB to the part price. This page maps the trade-offs so you can read the DFM memo with confidence.
Process at a glance
LSR (Liquid Silicone Rubber) is a two-part platinum-cured liquid pumped at a 1:1 ratio through a static mixer into a screw injection barrel. It cures under heat in the mold in seconds. The tooling is a cold-runner system with a heated cavity, similar to plastic injection molding. Flash is minimal and the cycle is fast — typically 30–90 seconds for a small medical or consumer part.
HTV (High Temperature Vulcanising) is a solid silicone gum, supplied in slabs or strips. It is loaded into a compression mold by hand or by a pick-and-place robot, then cured under heat and pressure. Cycle times are longer (3–8 minutes per cavity) and flash is heavier, but tooling is the cheapest of the three.
HCR (High Consistency Rubber) is the same gum as HTV but processed differently: it is pre-formed into a blank or extruded as a strip, then placed into a transfer pot and forced through a runner into the cavity. Better dimensional accuracy than HTV compression, faster cycle than HTV, and cheaper tooling than LSR — useful for medium-volume parts that need a precise flash-free geometry.
When to pick which
LSR when: the part is small (under ~200 g), the annual volume is in the thousands or tens of thousands, the geometry has thin walls or undercuts, the tolerance is tight (±0.10 mm or better), and the application is medical, baby-care or food contact. Cycle time, automation potential and flash control justify the higher tool cost.
HTV when: the part is large or thick-walled (gaskets, boots, vibration pads), the annual volume is hundreds or low thousands, the geometry is forgiving on flash, and tooling cost is the binding constraint. HTV compression is the cheapest way to mold silicone, but it is also the slowest and the most labour-intensive.
HCR when: the geometry is between LSR and HTV — too complex for clean HTV flash, too low-volume for LSR tool cost to amortise. Common in automotive seals, valve diaphragms and large O-rings.
Decision table
| Decision factor | LSR injection | HCR transfer | HTV compression |
|---|---|---|---|
| Annual volume (small part) | >5,000 pcs | 1,000–10,000 pcs | <2,000 pcs |
| Tool cost (single cavity) | Highest | Medium | Lowest |
| Cycle time | 30–90 s | 2–6 min | 3–8 min |
| Hardness range (Shore A) | 10–80 | 30–80 | 30–90 |
| Flash control | Excellent | Good | Average |
| Tolerance achievable | ±0.05–0.15 mm | ±0.15–0.25 mm | ±0.20–0.40 mm |
| Thin walls (<1.5 mm) | Excellent | OK with care | Difficult |
| Multi-cavity | Up to 64 cavities | Up to 16 cavities | Up to 8 cavities |
| Automation potential | High (lights-out) | Medium | Low (operator needed) |
| Material cost (per kg) | Higher | Medium | Lower |
What we run
Our Shenzhen plant runs LSR injection in a Class 8 cleanroom with cold-runner tools up to 64 cavities. Our Dongguan plant runs HTV compression for industrial parts up to 1.2 kg shot weight. Our Suzhou plant runs both LSR (medical) and HCR (transfer) for Class 8 medical parts. The recommendation is in the DFM memo you get back within 48 hours.
FAQ — LSR vs HTV vs HCR
Is LSR always better than HTV?
No. LSR has higher tooling cost and is over-engineered for low-volume, thick-walled parts. For a 200-piece annual run of a 500 g gasket, HTV compression is the correct choice.
Can LSR be food-safe?
Yes. Platinum-cured LSR is the cleanest food-contact silicone available. We mold FDA 21 CFR 177.2600 and LFGB §31 grades in our Shenzhen food-grade cell.
How does the tooling cost differ?
Indicatively, a single-cavity LSR tool is roughly 2–3× the cost of a single-cavity HTV compression tool, and a multi-cavity LSR cold-runner tool can be 4–8× the cost. The break-even depends on annual volume and cycle time savings.
Which process gives the tightest tolerance?
LSR. The closed-loop injection process holds ±0.05 mm on critical dimensions when the tool is balanced and the cavity is vented correctly. HCR can hold ±0.15 mm and HTV compression ±0.25 mm on the same geometry.