Rubber Material Engineering Guide
Silicone Rubber (VMQ): Properties, Grades, Applications & Selection Guide
Silicone rubber (VMQ) is a heat-resistant, flexible elastomer family widely used for seals, gaskets, tubing, diaphragms, boots, electrical parts and custom molded components. It can remain flexible across a broad temperature range and provides strong ozone, weathering and electrical-insulation performance, but standard VMQ is not the first choice for hydrocarbon fuels, many petroleum oils or demanding abrasion. The correct specification must also distinguish HCR from LSR, peroxide cure from platinum addition cure, and generic silicone from an application-specific compliant compound.
Silicone Fundamentals
What Is Silicone Rubber?
VMQ is the common designation for silicone rubber based mainly on a polysiloxane backbone with methyl groups and a controlled level of vinyl functionality for crosslinking. This inorganic-organic backbone is fundamentally different from carbon-backbone elastomers such as NBR, EPDM and many general-purpose rubbers, helping explain silicone's broad-temperature flexibility and resistance to ozone and weathering.
“Silicone” or “VMQ” is not a complete finished-material specification. Polymer structure, reinforcing filler, pigment, additives, cure system, post-cure, processing route and cleanliness controls can all change the finished compound. Two VMQ parts with the same Shore A hardness can therefore differ in tear strength, compression set, transparency, extractables, heat aging and regulatory suitability.
It is also important to separate material family from process form. HCR (high consistency rubber, often called HTV solid silicone) and LSR (liquid silicone rubber) can both produce VMQ elastomers, but their viscosity, mixing, tooling, molding and automation strategies differ. Cure chemistry is another independent choice: HCR may be peroxide-cured or platinum/addition-cured, while commercial LSR systems are commonly platinum addition-cured.
Silicone is usually a strong candidate when
- The part must remain flexible across low and elevated temperatures.
- Ozone, UV and long-term outdoor weathering resistance are important.
- Electrical insulation or stable dielectric behavior is part of the requirement.
- A molded, extruded or LSR component needs clean surfaces, color options or fine feature reproduction.
Silicone needs another look when
- The part is continuously immersed in gasoline, diesel or aggressive hydrocarbon solvents.
- High abrasion, cut growth or tear propagation is the dominant failure risk.
- Low gas permeability is critical; standard VMQ is relatively permeable compared with many sealing elastomers.
- “Food grade” or “medical grade” is requested without an exact regulation, test or material specification.
Performance Profile
What Are the Key Properties of Silicone Rubber?
Silicone rubber is best understood as a temperature-flexible, weather-resistant elastomer family with useful electrical properties and a wide choice of molding and extrusion routes. Its trade-offs are just as important: standard VMQ is not a universal oil/fuel elastomer, can have relatively high gas permeability, and may need careful geometry and compound selection when tear or abrasion dominates.
Heat & Cold Flexibility
VMQ can retain useful elasticity across a broad temperature range. Exact continuous and peak limits must come from the selected compound and be validated under the actual mechanical and media exposure.
Ozone & Weathering
The siloxane backbone gives standard VMQ strong resistance to ozone, UV and outdoor weathering, making silicone a useful candidate for exposed seals, boots and electrical components.
Electrical Insulation
Silicone is widely used in electrical insulation, connector seals and cable-related components. Exact dielectric requirements still need to be specified and verified on the chosen grade.
Cleanliness & Color
Selected VMQ compounds can offer high transparency, controlled color and low-volatility options. These are compound and process attributes, not automatic properties of every silicone part.
Compression Set
Low-compression-set silicone grades exist, but sealing-force retention depends on compound, cure state, post-cure, temperature, time and compression. Validate the actual part requirement.
Tear, Abrasion & Fuels
Standard VMQ is not normally chosen primarily for abrasion or hydrocarbon-fuel resistance. High-tear grades, fluorosilicone or another elastomer may be better depending on the dominant risk.
Polymer & Processing Form
What Is the Difference Between VMQ, HCR, HTV and LSR?
VMQ describes the silicone rubber material family; HCR and LSR describe processing forms. HCR means high consistency rubber and is commonly supplied as a solid or gum-like material. HTV is frequently used for heat-vulcanized solid silicone. LSR means liquid silicone rubber and is supplied as a pumpable multi-component system for liquid injection molding and related processes.
This distinction matters commercially because the same finished component category may be produced by compression molding HCR, injection molding HCR or injection molding LSR. Tool construction, material feeding, automation, flash strategy, cycle time and part economics can change substantially even when the cured elastomer is still VMQ.
| Term | What It Describes | Engineering Meaning |
|---|---|---|
| VMQ | Silicone elastomer family designation | Defines the polymer family, not the molding process, hardness, cure system or compliance grade. |
| HCR | High consistency silicone rubber | Solid/gum-like silicone processed by methods including compression, transfer, injection, extrusion or calendering depending on grade. |
| HTV | Heat-vulcanized silicone terminology | Commonly associated with solid silicone compounds cured at elevated temperature; terminology can vary by supplier. |
| LSR | Liquid silicone rubber | Pumpable system typically processed by liquid injection molding; useful for automation, complex geometry and repeatable high-volume production. |
| Platinum / addition cure | Cure chemistry | Used in LSR and selected HCR grades; catalyst contamination and inhibition control are important. |
| Peroxide cure | Cure chemistry used with selected HCR grades | Established option for molded, extruded and other solid-silicone products; post-cure requirements depend on compound and application. |
| FVMQ / fluorosilicone | Different silicone-family chemistry | Consider when silicone-like temperature behavior must be combined with improved resistance to hydrocarbon fuels or oils. |
| Sponge silicone | Cellular product structure | Used where compressibility, cushioning or low closure force is needed; do not apply solid-rubber tolerances or properties automatically. |
Engineering note: VMQ tells you the elastomer family. HCR/LSR, cure system, hardness, additives, post-cure and compliance requirements still need to be defined for the actual part.
Vulcanization
Peroxide-Cured vs. Platinum-Cured Silicone: What Changes?
Solid HCR silicone is available in both peroxide-cured and platinum-catalyzed addition-curing systems, while commercial LSR is typically platinum addition-cured. The cure route affects processing, byproducts, contamination sensitivity, post-cure strategy, cleanliness and the achievable balance of finished properties. It is not simply a premium-versus-standard quality ranking.
| Selection Factor | Peroxide-Cured Silicone | Platinum / Addition-Cured Silicone |
|---|---|---|
| Common process fit | Established for many HCR molding, extrusion and calendering applications. | Used for LSR and available in HCR grades for molding and extrusion. |
| Cure reaction | Organic peroxide initiates crosslinking and can generate peroxide decomposition products. | Addition cure does not generate peroxide decomposition products from the cure reaction. |
| Post-cure | Frequently specified to reduce volatile/byproduct levels or stabilize properties, depending on the exact compound and end-use. | May still be required for particular performance, volatile, food-contact or customer specifications; never assume it is unnecessary. |
| Contamination sensitivity | Processing controls remain important, but platinum catalyst inhibition is not the governing cure mechanism. | Platinum cure can be inhibited by contaminants such as certain sulfur compounds, amines and other catalyst poisons. |
| Color / odor / cleanliness | Can be suitable for many industrial products; final appearance and volatile requirements depend on compound and post-cure. | Often selected when clean cure chemistry, transparency or low odor/volatile requirements are important, subject to grade validation. |
| Compliance | Does not automatically determine FDA, medical or other compliance. | Platinum cure does not automatically make a part food-grade or medical-grade; the specific material and finished process must meet the stated requirement. |
Durometer Selection
What Silicone Rubber Hardness Should You Choose?
Silicone rubber is available across a wide Shore A spectrum, from very soft elastomers to much firmer grades. The correct hardness is a functional decision based on sealing compression, insertion force, wall stability, pressure, tactile behavior, tear risk and manufacturing method. The exact available grade and hardness tolerance are to be confirmed for each project.
Hardness alone does not define tensile strength, tear strength, compression set, transparency, heat life or compliance. An HCR and an LSR with the same nominal Shore A hardness can have different processing behavior and different mechanical-property profiles.
Lower Hardness
Can improve conformity to mating surfaces and reduce closure force. Pressure and gland geometry must still prevent over-deformation or extrusion.
Medium Hardness
Often used for general molded seals and components because it can balance flexibility, handling, compression and load support.
Higher Hardness
Can improve resistance to deformation or extrusion under load, but usually requires greater assembly or compression force.
Specify the hardness method, nominal value and tolerance on the approved material specification. ISO 48-4 or ASTM D2240 are common Shore-durometer references for vulcanized rubber.
Thermal Limits
What Temperature Range Can VMQ Silicone Rubber Handle?
As a family-level engineering reference, silicone rubber is commonly considered across approximately -60°C to +200°C, with special compounds formulated differently. This is not a guaranteed service range for every VMQ part. Continuous temperature, peak duration, surrounding air or fluid, compression, stress, required life and the exact compound all affect the usable limit.
Heat resistance is also not the same as sealing-life prediction. A silicone part can tolerate a short temperature peak yet lose sealing force too quickly under continuous compression. Conversely, low-temperature survival does not prove that a dynamic lip, diaphragm or boot will remain flexible enough to function at that temperature.
Low Temperature
Define whether the part only needs storage survival or must still flex, seal, rebound or move. Functional requirements are more meaningful than a generic minimum-temperature number.
Continuous Heat
Long exposure can change hardness, elongation and compression set. Use compound-specific heat-aging data and the required service life rather than a family maximum.
Peak Temperature
State peak value, duration and frequency. Short peaks should not be converted into a continuous-service rating without compound data and validation.
Hot Fluid / Steam
Water, steam, oil, chemicals and pressure can change aging behavior. For hot-water or steam duty, compare VMQ with EPDM or other materials using the actual temperature and exposure cycle.
Media Compatibility
What Fluids and Chemicals Is VMQ Silicone Compatible With?
Standard VMQ has useful resistance to many environmental exposures and selected fluids, but its broad temperature capability should never be confused with universal chemical resistance. Hydrocarbon fuels, many petroleum oils, concentrated chemicals and solvents can cause swelling or property loss. Exact formulation, concentration, temperature and exposure time always matter.
| Medium / Environment | General Silicone Direction | Engineering Note |
|---|---|---|
| Air / ozone / outdoor weather | Generally strong | A core VMQ strength; validate heat, stress and life requirements for the actual part. |
| Water at moderate conditions | Often workable | Suitability depends on temperature, time, pressure and compound; demanding steam service needs separate review. |
| Glycol-based environments | Application-specific | Exact glycol chemistry, additives and temperature must be reviewed; EPDM may also be a strong candidate. |
| Animal / vegetable oils | Compound-specific | Do not infer food-contact suitability from fluid compatibility; both chemistry and compliance need confirmation. |
| Mineral / petroleum oils | Limited to compound-specific | Standard VMQ can swell; NBR, FKM or fluorosilicone may be better depending on oil and temperature. |
| Gasoline / diesel / hydrocarbon fuels | Usually not first choice | Fluorosilicone or FKM is commonly evaluated when fuel resistance is a primary requirement. |
| Aromatic / chlorinated solvents | Often unsuitable | Swelling can be significant. Test the exact chemical or select a more compatible elastomer. |
| Dilute acids / alkalis | Requires review | Concentration, temperature and duration can change compatibility; never generalize from the polymer family alone. |
| Concentrated acids / strong alkalis | Requires exact review | Use compound-specific chemical data and immersion testing where the service is critical. |
| Steam / pressurized hot water | Service-dependent | Pressure, temperature and cycle duration matter. EPDM or specialty grades may outperform standard VMQ in some steam services. |
| Fluorosilicone (FVMQ) option | For fuel/oil upgrade | FVMQ can extend hydrocarbon fluid resistance while retaining silicone-family temperature characteristics; it is a different material specification. |
Material Selection
Silicone vs. EPDM, NBR and FKM: Which Should You Use?
VMQ is a strong starting point when temperature flexibility, weathering and electrical performance dominate. EPDM can be stronger for many water, steam and glycol duties; NBR is a common economical choice for petroleum oils; FKM is used where higher-temperature hydrocarbon or broader chemical resistance is required. No family wins every column.
| Selection Factor | Silicone (VMQ) | EPDM | NBR | FKM |
|---|---|---|---|---|
| Broad temperature flexibility | Core strength | Strong in its service range | More limited at high heat | Strong high-temperature family; low-temperature depends on type |
| Ozone / outdoor weather | Excellent starting point | Excellent | Limited | Excellent |
| Petroleum oils | Often limited / compound-specific | Generally poor | Core strength | Generally strong |
| Hydrocarbon fuels | Usually not first choice | Generally poor | Selected grades | Often strong; chemistry-specific |
| Water / glycol service | Application-specific | Often a strong starting point | Application-specific | Application-specific |
| Electrical insulation | Major strength | Useful in selected compounds | Not normally the primary selection reason | Application-specific |
| Tear / abrasion | Grade- and geometry-sensitive | Compound-specific | Often useful | Compound-specific |
This comparison is directional. Final selection requires the exact compound, fluid, temperature, pressure, motion, environment, expected life and applicable specification. FVMQ should be evaluated separately when fuel resistance and silicone-like temperature behavior must be combined.
Industrial Applications
Where Is Silicone Rubber Used?
VMQ is used where temperature stability, flexibility, weather resistance, electrical insulation, controlled cleanliness or precise molding are more important than maximum resistance to hydrocarbon fuels and abrasion. The exact grade must still match the media, mechanical load, regulatory requirement and manufacturing process.
Seals, Gaskets & O-Rings
Static seals, enclosure gaskets and O-rings for compatible fluids and temperatures, particularly where heat, weathering or low-temperature flexibility matters.
Tubing, Hoses & Profiles
Extruded silicone tubing, hose, cord and profiles for industrial equipment, appliances and clean-contact applications when pressure, reinforcement and media are properly specified.
Electrical & Connector Parts
Connector seals, cable boots, insulating sleeves, grommets and high-voltage components where silicone's electrical and weathering properties are useful.
Food & Beverage Components
Selected compliant compounds can be used for gaskets, tubing, valves and molded parts in food-contact equipment. The exact regulation and processing conditions must be confirmed.
Medical & Healthcare Components
Specific silicone grades are used for medical components and fluid-contact parts, but biocompatibility, cleanliness, sterilization and regulatory requirements are grade- and application-specific.
Diaphragms, Boots & Custom Molding
Flexible diaphragms, bellows, protective covers, masking parts, grips and complex HCR/LSR moldings can use VMQ where geometry and service conditions suit the material.
Compression Set & Failure Analysis
Why Do Silicone Parts Tear, Swell or Lose Sealing Force?
VMQ failures are often design-and-application mismatches rather than evidence that all silicone is unsuitable. Tear at a sharp corner, compression set, fluid swelling, extrusion, heat aging, bond failure and cure inhibition each have different causes and need different corrective actions.
Compression set is particularly important in static sealing because a part can look intact but recover poorly after prolonged compression. For platinum-cured materials, manufacturing contamination also deserves attention: catalyst inhibition can create locally under-cured or tacky material even when part geometry is correct.
| Observed Symptom | Possible Causes | What to Review |
|---|---|---|
| Tear at edge / hole / thin wall | Sharp radius, high local strain, low tear-strength grade, demolding damage or nick | Geometry, tear specification, mold release, parting line and handling. |
| Excessive swelling / softening | Oil, fuel, solvent or chemical incompatibility; excessive exposure temperature | Exact medium, ISO 1817 / ASTM D471 data and alternative VMQ, FVMQ, FKM, NBR or other compound. |
| Permanent flattening / leakage | Compression set, excessive temperature, over-compression, cure state or aging | Gland compression, cure/post-cure, ISO 815-1 / ASTM D395 conditions and retained sealing force. |
| Hardening / loss of elongation | Thermal aging, incompatible media or exposure beyond the compound's validated service window | Actual temperature history, aged tensile/elongation and service-life target. |
| Nibbling / extrusion | Pressure, excessive clearance, low hardness or insufficient backup | Gland design, pressure peaks, hardness, backup rings and extrusion gap. |
| Tacky / under-cured areas | Platinum catalyst inhibition, contamination, incorrect mixing, time/temperature imbalance | Contact materials, sulfur/amine contamination, mix ratio, mold cleanliness and cure conditions. |
| Bond / overmold failure | Substrate preparation, primer/adhesive mismatch, contamination, shrinkage or cure process | Substrate grade, pretreatment, bonding system, cure route and agreed peel/bond test. |
Manufacturing
How Are Custom Silicone Rubber Parts Manufactured?
VMQ can be processed through HCR compression, transfer or injection molding; HCR extrusion and calendering; LSR injection molding; and selected bonding, overmolding or secondary operations. The best route depends on part geometry, material grade, cure chemistry, flash tolerance, cleanliness, volume and automation requirements.
- Application reviewConfirm fluid, temperature, pressure, motion, environment, compliance and expected service conditions.
- Material definitionDefine VMQ grade direction, HCR or LSR form, hardness, color, cure system, post-cure and required physical/compliance properties.
- Tooling / process reviewChoose HCR compression/transfer/injection molding, LSR injection molding, extrusion, calendering, bonding or a combined process based on design and volume.
- Sample validationCheck dimensions, appearance, fit and the agreed material or functional tests before production approval.
- Production controlControl compound batch, cure process, cavities, dimensions, appearance and traceability according to the agreed inspection plan.
HCR Compression / Transfer Molding
Suitable for many seals, gaskets, diaphragms, boots, plugs and complex molded parts. Tool design and cure cycle depend on geometry and compound.
HCR Injection Molding
Solid silicone can also be injection molded with suitable compounds and equipment, supporting repeatable molded-part production at appropriate volumes.
LSR Injection Molding
Metered liquid components are mixed and injected into a heated mold. LSR is attractive for automation, fine details and repeatable high-volume molding when tooling economics fit.
Silicone Extrusion
HCR grades can be extruded into tubing, cord, hose and sealing profiles. Cross-section, cut length, joining, cure and post-cure requirements should be defined.
Overmolding & Bonding
Silicone can be bonded or overmolded onto selected metals, plastics or other substrates with a validated surface and bonding system. Adhesion must be proven for the actual material pair.
Post-Cure & Secondary Operations
Post-curing, trimming, slitting, joining, printing, inspection and cleaning may be required depending on cure chemistry, dimensions, application and compliance specification.
Dimensions & Design
What Tolerances Can Be Achieved on Silicone Rubber Parts?
There is no universal tolerance for “silicone rubber.” Achievable tolerances depend on part size, geometry, HCR versus LSR process, mold-dependent versus mold-independent dimensions, compound shrinkage, tool construction, flash or gate location, post-cure and measurement method.
ISO 3302-1:2014 is a common dimensional-tolerance reference for molded, extruded and calendared solid rubber products. Precision O-rings and similar toroidal sealing rings are normally specified under product-specific standards such as ISO 3601 rather than treating ISO 3302-1 as an O-ring size standard. The correct tolerance system must be agreed before tooling.
Define Critical Characteristics
Identify sealing diameters, wall thickness, compression height, groove interfaces, hole positions and other dimensions that actually control function.
Avoid Unnecessary Tight Tolerances
Tighter tolerances increase tooling, measurement and process-control demands. Apply precision only where it protects fit, sealing or assembly.
Agree Flash & Surface Criteria
Parting line, flash, gate or injection point, trimming, grinding and cosmetic limits should be defined separately from dimensional tolerance.
Confirm Measurement Method
Soft elastomers deform under measurement force. Define conditioning, datums, fixtures and measurement method for dimensions sensitive to compression.
Validation & Quality
Which Tests Should Be Specified for Silicone Rubber?
A useful VMQ test plan starts with the dominant failure risk. Hardness and tensile data alone are not enough if the part must retain sealing force at temperature, survive repeated flexing, meet tear requirements, resist a specific fluid, control volatile/extractable levels or pass an application-specific electrical or functional test.
| Property / Risk | Common Test Reference | What to Define |
|---|---|---|
| Hardness | ISO 48-4 / ASTM D2240 | Scale, nominal value, tolerance, conditioning and test-piece requirement. |
| Tensile strength / elongation | ISO 37 / ASTM D412 | Minimum values, specimen type and whether results are original or aged. |
| Compression set | ISO 815-1 / ASTM D395 | Compression, time, temperature, recovery method and maximum result. |
| Heat aging | ISO 188 / ASTM D573 | Temperature, duration and permitted hardness / tensile / elongation change. |
| Liquid resistance | ISO 1817:2024 / ASTM D471 | Exact water, oil, fuel, solvent or chemical; temperature, duration and permitted mass / volume / property change. |
| Tear strength | ISO 34-1 / ASTM D624 | Specimen type, minimum value and whether the requirement applies before or after aging. |
| Electrical properties | Customer / application-specific standard | Dielectric, tracking, insulation or other electrical requirements when this is a functional driver. |
| Dimensions / appearance | Approved drawing and inspection plan | Critical dimensions, method, sampling, flash, trimming and visual criteria. |
| Application validation | Customer-specific test | Pressure, fluid, leakage, cycle, friction, fatigue, life or assembly conditions. |
Test standards and editions should be agreed in the purchase specification. Availability of any specific test, report or third-party laboratory service is to be confirmed for the project.
Regulatory & Documentation
Does Silicone Automatically Meet FDA, Medical or Other Requirements?
No. VMQ is a polymer-family designation, not a regulatory approval. Specific silicone grades are marketed for defined food-contact, healthcare, drinking-water, electrical or industrial requirements, but generic silicone—or the words “platinum-cured”—does not automatically make a finished part FDA-compliant, medical-grade, biocompatible or certified.
For food-contact work, state the exact regulation such as the applicable provisions of FDA 21 CFR 177.2600 or the customer's required standard. For medical work, define the exact USP, ISO 10993, pharmacopoeia, sterilization, extractables or device requirement that applies. For drinking water, RoHS, REACH, UL, automotive or PPAP projects, identify the precise standard and required documentation before material approval.
Purchasing Guide
What Information Should You Send for a Silicone Rubber RFQ?
A quote can look complete but still carry material risk if it says only “silicone, 60 Shore A.” HCR versus LSR, cure chemistry, post-cure, temperature, contact media, tear/compression requirements and compliance can materially change both the part design and manufacturing route.
| RFQ Item | Information to Provide | Why It Matters |
|---|---|---|
| Geometry | 2D drawing, 3D model or physical sample; identify revision | Defines tooling, parting, dimensional risk and inspection. |
| Function | Seal, gasket, tube, diaphragm, boot, connector, overmolded part, medical/food-contact component, etc. | Changes the important mechanical, process and validation requirements. |
| Medium | Air, water, steam, oil, fuel, food, chemical or gas; include grade/concentration when relevant | Determines whether standard VMQ is suitable or another silicone/elastomer family should be reviewed. |
| Temperature | Minimum, continuous maximum, peak maximum and peak duration | Controls low-temperature flexibility, aging and compression-set risk. |
| Pressure / vacuum | Normal and maximum pressure; pressure direction if relevant | Affects hardness, extrusion, reinforcement and seal geometry. |
| Motion | Static, reciprocating, rotating, flexing or repeated compression | Changes wear, friction, fatigue and heat generation. |
| Material / process target | VMQ specification if fixed; HCR or LSR preference; hardness, color and cure system if defined | Separates mandatory requirements from process recommendations. |
| Cure / post-cure | Peroxide or platinum requirement; post-cure condition if controlled | Affects processing, cleanliness, volatiles, properties and documentation. |
| Tolerances | Critical dimensions, tolerance standard and inspection method | Controls tooling, process capability and measurement cost. |
| Compliance | Exact food, medical, drinking-water, environmental, electrical or customer standard | Prevents generic silicone or cure chemistry from being mistaken for an approved compound. |
| Testing | Material tests, media aging, leak test, PPAP or customer-specific validation | Allows validation scope, cost and timing to be reviewed before production. |
| Quantity | Prototype quantity, order quantity and annual demand | Influences tooling layout, cavity count and manufacturing route. |
| Packaging / traceability | Label, lot, cleanliness and packaging requirements | Ensures delivery format matches receiving and production needs. |
Silicone FAQ
Frequently Asked Questions About Silicone Rubber
These answers are VMQ material-family guidance. Final performance should always be confirmed against the exact silicone compound, cure/process route and service conditions.
Is silicone rubber the same as VMQ?
VMQ is the common designation for methyl-vinyl silicone rubber and is the standard silicone elastomer family used for many molded and extruded parts. “Silicone rubber” is broader language, so critical specifications should state the exact polymer/compound required rather than relying on the generic word silicone.
What is the difference between HCR and LSR silicone?
HCR is high consistency silicone rubber supplied in a solid/gum-like form and processed by molding, extrusion and related methods. LSR is a pumpable liquid silicone system typically meter-mixed and injection molded. Both can produce VMQ parts, but material handling, tooling, cure system and production economics differ.
Is HTV silicone the same as HCR?
The terms overlap in industrial usage. HCR describes high-consistency solid silicone, while HTV emphasizes heat vulcanization. Supplier terminology can vary, so the specific grade, processing instructions and cure system should be confirmed instead of relying on the abbreviation alone.
Peroxide-cured or platinum-cured silicone: which is better?
Neither is universally better. Peroxide curing is established for many HCR products. Platinum addition curing is used for LSR and selected HCR grades and avoids peroxide decomposition products, but it is sensitive to catalyst-inhibiting contaminants. Select the cure system from process, property, cleanliness, post-cure and compliance requirements.
What temperature can silicone rubber withstand?
As a family reference, silicone rubber is often considered around -60°C to +200°C, with special grades differing. Do not use that as a guaranteed specification: continuous versus peak exposure, compression, fluid, stress and required life all change the usable range.
Is Silicone suitable for outdoor use?
Yes, weathering is one of VMQ's important strengths. Silicone generally performs well against ozone, UV and outdoor exposure, but the actual compound still needs to meet temperature, mechanical-load, color and service-life requirements.
Is standard VMQ resistant to oil and fuel?
Standard VMQ is not usually selected primarily for hydrocarbon-fuel resistance and can swell in petroleum oils. The exact oil or fuel must be checked. NBR, FKM or fluorosilicone (FVMQ) may be better candidates depending on temperature, chemistry and low-temperature requirements.
Is silicone suitable for water or steam?
Selected VMQ compounds can be used with water, but demanding hot-water or steam service requires specific review of temperature, pressure and duration. EPDM or another elastomer may be a stronger starting point for some steam applications.
What Shore hardness is silicone rubber?
Silicone is available in many Shore A hardness grades; there is no single VMQ hardness. Select the target from sealing compression, insertion force, pressure, wall stability, tactile requirement and tear/deformation risk. Exact available hardness and tolerance are to be confirmed for the chosen compound.
What causes compression set in a silicone seal?
Compression set depends on compound formulation, cure/post-cure, temperature, compression level, time and surrounding media. Excessive set can reduce retained sealing force even when the seal has no obvious surface damage.
Silicone or EPDM: which should I choose?
Both provide strong ozone and weathering resistance. Silicone is often favored when a broader temperature window, electrical properties or silicone-specific cleanliness is important. EPDM is often favored for water, steam and glycol-based service at an economical industrial cost. The medium and temperature decide the comparison.
Silicone or FKM: which should I choose?
VMQ is attractive for low-temperature flexibility, weathering and electrical applications. FKM is usually a stronger starting point for many hydrocarbon fuels, petroleum oils and high-temperature chemical services. Exact FKM type and exact fluid still matter.
Is Silicone food grade?
Silicone is not automatically food grade. Specific compounds can be formulated and documented for defined food-contact requirements such as applicable FDA provisions, but the exact grade, cure/post-cure, application and finished-part documentation must be confirmed.
Does platinum-cured silicone mean medical grade?
No. Platinum cure describes crosslinking chemistry. Medical suitability requires the exact material, manufacturing controls and the applicable biocompatibility, cleanliness, sterilization and device-specific requirements. A cure system alone is not a medical approval.
What information is needed to quote a custom Silicone part?
Send the 2D drawing, 3D model or physical sample together with temperature, contact media, pressure, motion, hardness, color, HCR/LSR preference if fixed, cure/post-cure requirements, tolerances, compliance/testing needs and expected quantity. Unknown items can remain open for technical review before tooling.
Custom Silicone Components
Have a silicone seal, gasket, tube, diaphragm or molded part to develop?
Send the available drawing or sample information together with temperature, contact media, pressure, hardness, HCR/LSR or cure requirements if already fixed, compliance needs and expected quantity. We can review the VMQ material direction, manufacturing feasibility and the technical information still needed before quotation.
