Liquid Silicone Rubber Applications: Industries & Use Cases Guide

Liquid silicone rubber applications span almost every serious manufacturing sector — from implantable medical devices to EV battery seals to baby-bottle nipples to dielectric encapsulation in smartphones. This guide maps where liquid silicone rubber wins, why it wins there, and how to decide if LSR is the right material of choice for a given part. Focus throughout is on concrete product examples, the material properties that drive adoption in each industry, and the decision criteria that separate LSR from its closest alternatives.

What Is Liquid Silicone Rubber, Really?

Liquid silicone rubber is a two-part, platinum-cured elastomer with a silicone–oxygen (siloxane) backbone. Compound A carries the base polymer with vinyl end groups; Compound B carries the platinum catalyst and hydride cross-linker. These two compounds mix 1:1 in a metering unit and cure inside a heated mold. This curing process cross-links the vinyl end groups under heat, converting the viscous liquid into a solid elastomer in seconds. Unlike a thermoplastic, cured LSR does not remelt when reheated — it is a thermoset.

This is what is relevant when talking about the product – not the chemistry lecture. 4 properties matter for the industry application:

• ✔Biocompatibility. The siloxane backbone does not provoke an immune response, so it suits long-term tissue contact and qualifies under ISO 10993.
• ✔Thermal stability. The Si–O bond is stronger than the C–C bond in organic rubbers, so LSR keeps its mechanical properties at temperatures that soften nitrile or EPDM.
• ✔Electrical insulation. Volume resistivity above 10¹⁴ Ω·cm and dielectric strength around 20–25 kV/mm place LSR among the best elastomeric insulators.
• ✔Chemical inertness. LSR resists water, most acids and alkalis, and holds up under steam, ethylene-oxide, gamma and e-beam sterilization.

Every one of the application examples needs to be seen as a consequence of one or more of these four properties pushing cheaper alternatives into the background. I challenge you to look for the application examples below and not see this model explicitly used in the Industry Property Matrix below.

Medical and Healthcare Applications

The application space with the most – and the most stringent – applications for liquid silicone rubber elastomer is Medical. Full compliance with ISO 10993 biocompatibility alone can be enough to justify the switch from other elastomeric material solutions. The reason will be familiar: silicone rubbers is one of the few elastomers that will pass all ISO 10993 biocompatibility testing without additives that would compromise sterilizability. According to Grand View Research (cited by several industry reports), the premium (medical-grade) silicone market from which LSR is a central player was expected to be worth circa USD 1.84 billion in 2025.

Typical product families molded from medical-grade LSR include:

• Optic and other implant components: contact lenses, cochlear implant housings, drug-delivery seals, shunt and pacemaker accessories, tissue contact components on orthopedic instruments.
• Catheters, infusion-pump membranes, and one-way valves for fluid handling.
• Respiratory masks, mask cushions, and CPAP components.
• Wearable medical devices- skin contact biosensor housings, insulin pump seals, continuous-glucose-monitor gaskets.
• Surgical tools: suction-bulb handles, sterilizable keypads, disposable valve diaphragms.

What makes LSR biocompatible for medical implants?

biocompatibility isn’t one property. It is a battery of tests defined by the ISO 10993 family. The FDA guidance document on the use of ISO 10993-1 is the de facto reference for how US device submissions handle biological evaluation. ISO 10993-5 covers in-vitro cytotoxicity, ISO 10993-10 covers irritation and skin sensitization, and ISO 10993-11 covers systemic toxicity. A medical-grade LSR grade from a reputable supplier will come with test reports against the specific sub-parts relevant to the device’s contact duration/contact type.

USP Class VI is relevant but not equivalent. USP Class VI is a six-day rabbit-implantation screen originally developed for plastic packaging. Specifying ‘USP Class VI’ for a long-term implantation is common shorthand in RFQs – but it is technically insufficient. A peer-reviewed review of biocompatibility testing in PMC (PMC10647244) reinforces that long-term implantation selection requires the full ISO 10993 battery, not a Class VI shortcut. This is one of the most common specification errors we see in medical LSR sourcing.

Automotive and Electric-Vehicle Applications

The automotive sector is the second largest consumer of liquid silicone rubber and the fastest growing one. According to Global Market Insights, the global LSR market was valued at USD 3.8 billion in 2024 and is expected to grow at a CAGR of over 6.5% through 2034, with automotive lightweighting and EV electrification specifically cited as the primary demand drivers.

Typical automotive LSR parts include connector seals, wire-loom seals, spark-plug boots, turbocharger and coolant-line gaskets, ADAS sensor housings, headlight bellows, and – most visibly in EVs – battery-pack seals, cable glands, and cell-module gaskets. LSR displaces EPDM or FKM in these locations for one reason: extreme temperatures (heat spikes above +150 °C and cold-soak service at low temperature down to −40 °C), vibration, and chemical resistance against coolants and thermal-management fluids, all in the same part.

Why are automotive OEMs moving from HCR to LSR?

High-consistency silicone rubber (HCR) can equal LSR on temperature and chemical resistance, but it can’t equal LSR on part-to-part consistency at automotive production volumes. LSR is injected under tight process control – shot-size, temperature, and cycle time are all closed-loop. HCR is compression-molded or extruded, and its tolerance band is wider. For safety-critical seals in battery packs where IP67 water ingress is non-negotiable, the LSR tolerance advantage is more important than raw material cost. That trade-off reverses at roughly 20,000 parts per year, where HCR tooling amortizes better – a threshold that appears again later in the decision framework.

“For EV battery-pack sealing and cable-gland applications, LSR is specified when the part must hold a gas-tight seal across the full battery thermal-cycling envelope of −40 °C to +85 °C continuous, with IP67 ingress protection, for the vehicle’s 10-to-15-year service life. That combination of service envelope and tolerance is what LSR does better than any other elastomer.”

— Synthesized from Parker Hannifin’s LSR/LIM and HCR Silicone for EV Electrification brochure

Electrical and Electronics Applications

Electrical applications exploit LSR’s dielectric properties and its ability to be over-molded onto substrates without damaging delicate electronic assemblies. Typical parts include LED and lidar lens encapsulation, waterproof cable seals, smartphone keypads and buttons, hearing-aid tips, IoT-sensor potting compounds, and wearable-electronics housings where skin contact meets sealing.

Dielectric strength, tested per ASTM D149, is the primary electrical specification. Typical medical- and industrial-grade LSR measures 20–25 kV/mm, with volume resistivity above 10¹⁴ Ω·cm and dissipation factor below 0.001 at 1 MHz. Those numbers are closer to rigid thermosets than to most filled elastomers — which is why LSR becomes the material of choice when a part must flex, cycle, and insulate simultaneously.

LED and lidar encapsulation specifically benefits from LSR’s optical clarity. Unlike most elastomers, LSR is naturally translucent, and optical-grade formulations retain high transmission in the visible and near-infrared bands. Combined with excellent UV stability, that makes LSR a default for automotive headlight primary optics, horticulture-LED encapsulation, and the emerging lidar lens market in autonomous vehicles.

Consumer, Baby Products, and Food-Contact Applications

Consumer applications for liquid silicone rubber span kitchenware (spatulas, baking mats, ice trays, reusable food covers), baby products (bottle nipples, pacifiers, teethers), personal-care items (menstrual cups, electric-toothbrush seals, shaver and hearing-aid ear tips), pet products, and fitness-wearable bands. Common thread across every one of these products: either the part contacts food or it contacts skin, and often both.

Food-contact LSR in the United States is governed by FDA 21 CFR 177.2600, which defines the permitted composition of rubber articles intended for repeated food contact. In Europe, the equivalent framework is the LFGB / BfR XV recommendation. For childcare articles specifically, EU standard EN 14350 covers drinking equipment and imposes migration limits on volatile extractives. A reputable medical- or consumer-grade LSR supplier will certify against these standards by default; “food-grade silicone” without a specific standard citation is a red flag in a bill of materials.

Industrial Seals, Gaskets, and O-Rings

Industrial sealing is where liquid silicone rubber competes head-to-head with FKM (fluorocarbon) and EPDM. These three dominate different parts of the elastomer seal design space, and for a part that must span a wide thermal range with low compression set, LSR frequently wins.

Typical industrial LSR seal applications include food-processing gaskets that must survive CIP/SIP cleaning cycles, semiconductor wafer-handling vacuum seals, aerospace fuel-line O-rings in cold-soak conditions, smoke-detector and gas-detector diaphragms, and steam-table service seals. Compression set — the seal’s tendency to take a permanent set under long-term stress — is measured per ASTM D395-18, with Method B (constant deflection) the standard protocol for LSR seals. Broader elastomer classification for industrial seals falls under ASTM D2000.

How do LSR O-rings compare with FKM or EPDM at extreme temperatures?

Read the table as a decision tool, not as a ranking. LSR dominates the wide-temperature low-compression-set niche. FKM wins when the seal contacts fuels or aggressive hydrocarbons. EPDM wins on price when the service envelope is modest and ozone resistance is the main concern.

The Industry × Property Matrix — How Four Properties Drive Every LSR Application

The section above each industry was self – contained. That is how most LSR material write-ups organize themselves, and it obscures a pattern: those same four material properties turn LSR into a versatile material and decide its adoption in every sector, just in different weightings. What follows makes the weighting visible:

Read down a column to see where a single property lands a “Critical” rating. Read across a row to see the property mix that a given industry actually pays for. In short, this is the fastest way to answer the question “why LSR here?” without writing a separate explanation per industry.

A practical use for the matrix: when evaluating whether a new application fits LSR, place it in the row with the closest service profile, and check whether at least two of the four property columns are rated “Critical.” That is the same intuition that underpins the 4-Condition Decision Rule in the next section.

How to Decide If LSR Is the Right Material for Your Application

For any part, LSR’s nearest competitors are high-consistency rubber (HCR), thermoplastic elastomer (TPE), or room-temperature-vulcanizing silicone (RTV). Each wins in at least one combination of volume, tolerance, and property set. This next matrix compresses a lot of sourcing experience into a quick triage.

Blunt note: the volume thresholds listed above are compiled from different industry information — public supplier guidance, published comparison tables, and process experience. Your specific breakeven point depends on part geometry, secondary finishing steps, and supplier relationships. Ask for competitive process quotes from both LSR and HCR molders for your particular part rather than treating any single number as the whole answer.

Once LSR is the right resin choice for your part, the molding process itself drives design decisions on cold-runner vs hot-runner layout, gate placement, venting, and cure profile. For tooling, tolerances, and cycle-time details, see our LSR injection molding guide that covers the production side of the story.

Frequently Asked Questions