| Property | Value |
|---|---|
| Temperature range | -60 °C to +230 °C |
| Hardness | 20–80 Shore A |
| Best at | Temperature range, ozone and UV, inertness, high-temperature compression set |
| Contains fluorine | No |
HCR and LSR are the same chemistry, different process
High consistency rubber is milled and molded by compression, transfer, or injection like any other solid elastomer. Liquid silicone is pumped and injected. The polymer family is the same; the decision is a manufacturing one driven by part geometry, volume, and tolerance. Small, complex, high-volume parts favour LSR; larger parts, thicker sections, and lower volumes usually favour HCR, and HCR reaches higher hardnesses.
We mold both, so the recommendation is not constrained by what we happen to have on the floor.
How we compound and test it
Silicone needs a post-cure for most applications, to complete the cure and drive off volatiles. For food-contact, medical, and low-outgassing parts, the post-cure schedule is part of the specification rather than an afterthought, and we document it.
Its strength is compression set at temperature: where an organic rubber has taken a permanent set after a few hundred hours at 200 °C, a properly cured silicone is still recovering. That is what makes it a high-temperature sealing material despite the low tensile numbers, and it is what we measure.
The two mistakes buyers make
The first is expecting mechanical toughness. Tear strength and abrasion resistance are low, so a silicone part that is handled roughly, stretched over an assembly, or exposed to a moving edge will fail mechanically long before it fails thermally. Geometry has to be designed for that.
The second is putting it in fuel or oil. Silicone swells substantially in petroleum products. If the part needs silicone's temperature range and also sees fuel, the answer is fluorosilicone, at a considerable price step.