HCR / HTV / Solid Silicone Rubber O-rings
Manufacturer & Custom Solutions
HCR / HTV / Solid Silicone Rubber O-rings
At ZSR Silicone, we press HCR and HTV solid silicone rubber into durable O-rings. This is the classic, cost-effective choice for static seals, gaskets and general industrial use. Hardness options range from 30 to 80 Shore A. Colors and custom formulations are available.
FDA 21 CFR 177.2600
Rubber Articles Intended for Repeated Use
LFGB 30&31
EU Food Contact Materials
USP Class VI / ISO 10993
Biocompatibility of Medical Devices
RoHS / REACH
Environmental Compliance
UL 94
Flammability of Plastic Materials
Built to Your Exact Spec
Custom Silicone O-Rings Options
Every Silicone Grade, One Perfect Seal
Every O-ring starts with the right compound. Platinum-cured and peroxide-cured systems are available for all grades — we recommend platinum cure for food and medical contact.
| Grade | Hardness (Shore A) | Temperature | Compliance | Best For |
|---|---|---|---|---|
| Industrial VMQ | 30 – 80 | -60°C to +230°C | RoHS / REACH | General industrial sealing |
| FDA Food Grade | 30 – 70 | -60°C to +230°C | FDA 21 CFR 177.2600 | Food & beverage equipment |
| Medical Grade (Platinum) | 10 – 70 | -60°C to +230°C | USP Class VI | Medical devices & laboratory |
| High Temperature | 40 – 80 | up to +300°C | RoHS | Ovens, lighting, engine bays |
| Fluorosilicone (FVMQ) | 40 – 80 | -60°C to +200°C | RoHS | Fuel, oil & solvent exposure |
| LSR (Liquid Silicone) | 10 – 80 | -60°C to +230°C | FDA / medical grades | High-volume precision parts |
| Transparent / Clear | 30 – 70 | -60°C to +200°C | FDA options | Visual inspection points |
From 0.5 mm ID to Oversized Joint Rings
Size, cross-section and tolerance are fully custom. Send a drawing, a standard size number (e.g., AS568-214), or a physical sample — we handle the rest.
| Item | Range / Options |
|---|---|
| Size Range | ID 0.5 – 500 mm+; molded or vulcanized-joint for oversized IDs |
| Cross-Section | 0.5 – 10 mm; round (standard), square-cut, custom profile |
| Size Standards | AS568 · JIS B2401 · BS 1806 · DIN 3771 · ISO 3601 · ISO 6149 · AN6227 / AN6230 (see standards table below) |
| Tolerance | ISO 3302-1 class per size & process; ±0.05 mm on small molded rings |
| Custom Geometry | Non-standard ID / cross-section from your drawing or sample |
| Surface | Standard finish / PTFE-coated for low friction |
Any Color Your Brand or Assembly Needs
We color-match silicone compounds to Pantone or RAL references, including translucent and transparent grades for visual inspection points.
Your Brand, Built Into the Part
Branding, part numbers and batch traceability — molded in, engraved or printed, without compromising the seal.
Molded, Spliced or Coated — One Factory
Molding, splicing and finishing under one roof — we match the process to your volume, size and tolerance target.
| Process | How It Works | Best For |
|---|---|---|
| Compression Molding | Pre-formed silicone pressed and cured in a heated mold | Medium volumes, large cross-sections |
| LSR Injection Molding | Liquid silicone injected into closed molds | High volumes, tight tolerances |
| Vulcanized Joint (Spliced) | Extruded cord cut to length and vulcanized into a ring | Oversized IDs, low volumes, fast tooling |
| PTFE Coating | Low-friction coating applied to finished rings | Dynamic sealing, easy installation |
| Rapid Prototyping | Prototype tooling before production mold | Fit & function validation |
Related Silicone O-ring
| Image | Product | Type | Short Info | Action |
|---|---|---|---|---|
| BS 1806 Silicone O-rings | Standard & Size | British Standard inch-size silicone O-rings. Common in UK and Commonwealth industrial equipment. | View Details |
| DIN 3771 Silicone O-rings | Standard & Size | German metric standard O-rings for hydraulic and pneumatic sealing in European machinery. | View Details |
|
| Custom Molded Silicone O-rings | Standard & Size | Custom-shaped silicone O-rings molded to your exact drawing or sample. No standard size limitations. | View Details |
| AS568 Silicone O-rings | Standard & Size | Inch-size silicone O-rings that follow the AS568 standard. Widely used in North American machinery and hydraulic systems. | View Details |
| AN6227 Silicone O-rings | Standard & Size | Aerospace-standard O-rings with small cross-section. Used in aviation and military-grade sealing. | View Details |
| JIS B2401 Silicone O-Ring | Standard & Size | Japanese industrial standard O-rings commonly used in Asian-manufactured machinery and automotive equipment. | View Details |
| ISO 3601 Metric Silicone O-Rings | Standard & Size | Metric silicone O-rings manufactured to ISO 3601 dimensions. Fits international equipment groove standards. | View Details |
| ISO 6149 Metric Silicone O-Rings | Standard & Size | Metric O-rings designed for hydraulic and pneumatic fluid power sealing applications under ISO 6149 standards. | View Details |
| FDA Food Grade Silicone O-Rings | Grade | Food-safe silicone O-rings compliant with FDA regulations. Safe for repeated food contact. | View Details |
| Industrial Grade Silicone O-ring | Grade | General-purpose silicone O-rings for industrial sealing. Cost-effective with reliable performance. | View Details |
| Medical Grade Silicone O-ring | Grade | Biocompatible silicone O-rings for medical devices. Passes USP Class VI and supports sterilization. | View Details |
| High Temperature / Heat Resistant Silicone O-Rings | Special Function | Silicone O-rings that stay flexible at temperatures above 200°C. For ovens, engines and furnaces. | View Details |
| Oil-Resistant / Fuel-Resistant Silicone O-Rings | Special Function | Modified silicone O-rings that resist swelling in oils, fuels and petroleum-based fluids. | View Details |
 | VMQ Silicone O-Rings | Materials | Heat and cold-resistant silicone O-rings for food, medical, automotive, and industrial applications. | View Details |
| HCR / HTV / Solid Silicone Rubber O-rings | Materials | Durable solid silicone rubber O-rings made by compression molding. The standard choice for general sealing. | View Details |
| Fiberglass Reinforced Silicone O-rings | Materials | High-strength silicone O-rings reinforced with fiberglass fabric. Withstands extreme heat and pressure. | View Details |
| Liquid Silicone Rubber (LSR) O-rings | Materials | Injection-molded liquid silicone rubber O-rings with tight tolerances and clean surfaces. Ideal for high-volume production. | View Details |
| Platinum Cured Silicone O-rings | Materials | Ultra-clean silicone O-rings cured with platinum catalyst. Lower extractables for food and medical use. | View Details |
 | Fluorosilicone (FVMQ) O-rings | Materials | Fuel and oil-resistant silicone O-rings for aerospace, automotive and chemical applications. | View Details |
| Transparent / Clear Silicone O-rings | Color | See-through silicone O-rings for visual inspection and clean-looking medical or food equipment. | View Details |
| Custom Colors Silicone O-rings | Color | Silicone O-rings matched to your exact color sample or specification. | View Details |
What Is HCR / HTV / Solid Silicone Rubber?
HCR (High Consistency Rubber), HTV (High Temperature Vulcanized), and Solid Silicone Rubber all refer to one family of silicone elastomers. They are made from high-molecular-weight polysiloxane polymers — long chains of silicon and oxygen atoms with organic side groups attached. Before curing, the material looks and feels like a thick, gummy solid, usually supplied in blocks, sheets, or strips.
How It Is Made
At ZSR, we start with a raw silicone base compound. We add fillers (such as fumed silica) to improve strength, pigments for color, and curing agents. The mixture is rolled into a uniform sheet, cut into preforms, and placed into a heated mold. Under high temperature (typically 160°C–200°C) and pressure, the material cures into a flexible, elastic rubber part. This process is called compression molding, and it is the most common way to make HCR O-rings.
Key Characteristics
HCR silicone rubber keeps its flexibility across a very wide temperature range. It stays soft at -55°C and does not melt or degrade at +210°C. It resists ozone, UV light, and moisture. It is also an excellent electrical insulator. These properties make it one of the most versatile sealing materials available. If you need a practical seal for static applications, HCR is often the smartest place to start.
HCR vs HTV vs Solid Silicone — What's the Difference?
If you have seen these three names on different supplier websites, you may wonder whether they are different materials. At ZSR Silicone Parts, we want to make this simple: HCR, HTV, and Solid Silicone Rubber are the same material with different names.
Name | Full Form | What It Means |
|---|---|---|
HCR | High Consistency Rubber | Describes the material's thick, putty-like form before curing. |
HTV | High Temperature Vulcanized | Describes how the material cures — it needs heat and pressure to become solid rubber. |
Solid Silicone Rubber | — | Describes the physical state — it is a solid block or sheet, not a liquid. |
Why so many names?
At ZSR, we use all three terms interchangeably. When you order HCR O-rings, HTV O-rings, or Solid Silicone O-rings from us, you receive the same high-quality material made from high-molecular-weight polysiloxane with excellent heat resistance and flexibility.
Material Properties at a Glance
The table below shows the typical properties of ZSR's HCR / HTV / Solid Silicone Rubber O-rings. These values may change slightly depending on the exact grade (industrial, food, or medical) you choose.
Property | Typical Value | Notes |
|---|---|---|
Hardness | 10 – 90 Shore A | Most O-rings use 40 – 70 Shore A for a good balance of softness and strength. |
Temperature Range | -55°C to +210°C (continuous) | Short-term exposure up to +250°C is possible. High-temperature grades can reach +300°C for brief periods. |
Tensile Strength | 4 – 12 MPa | Strong enough for most static sealing jobs. |
Tear Strength | 15 – 45 kN/m | Higher than LSR, making HCR a good choice for parts that need extra durability. |
Elongation at Break | 300% – 750% | Very flexible. Soft grades can stretch over 700% before breaking. |
Compression Set | 10% – 35% | Good recovery after pressure is removed. Lower values are available for critical seals. |
Density | 1.10 – 1.20 g/cm³ | Lightweight compared to most rubber materials. |
Color Options | Black, white, red, transparent, custom Pantone colors | Food-grade and medical-grade colors are available. |
Standard Sizes | AS568, ISO 3601, JIS B 2401, custom sizes | ZSR can produce any size from 1 mm inner diameter to over 500 mm. |
Cross-Section (Wire Diameter) | 0.5 mm – 20 mm | Standard O-rings usually fall between 1 mm and 10 mm. |
Tolerance Information:
ZSR produces HCR O-rings mainly by compression molding. Standard tolerances follow ISO 3601-3 Grade N (normal grade) or Grade S (special grade) upon request. For most industrial applications, Grade N is sufficient. If you need tighter tolerances for precision equipment, please tell us during quotation and we will adjust the mold design and process control.
When to Choose HCR/HTV O-rings
Not every sealing job needs the most expensive material or the most precise process. HCR/HTV silicone O-rings are the right choice when your project matches one or more of the following conditions:
You need a static seal
HCR O-rings work best in stationary applications — sealing a lid, a pipe flange, or an enclosure cover. They are not ideal for moving parts that rub against metal.
You are cost-sensitive
Compression molding uses simpler molds and lower machine costs than LSR injection molding. For medium to large volumes, HCR often gives you the best price per piece.
Your design is not highly complex
HCR is perfect for standard round O-rings, square rings, and simple custom shapes. If your part has very thin walls or tiny undercuts, LSR may be a better fit.
Your part is large or thick
HCR compression molding handles big O-rings and thick cross-sections easily. LSR injection molding becomes expensive for very large parts.
You need high tear strength
HCR generally has higher tear strength than LSR due to its higher molecular weight and denser cross-linked structure. This enables better resistance to tearing under mechanical stress.
You need fast tooling
ZSR's in-house mold workshop can cut compression molds in 7–14 days, significantly faster than many standard LSR mold lead times in the industry.