{"id":1812,"date":"2026-04-21T03:48:19","date_gmt":"2026-04-21T03:48:19","guid":{"rendered":"https:\/\/meitu-engelhardt.com\/?p=1812"},"modified":"2026-04-21T03:48:19","modified_gmt":"2026-04-21T03:48:19","slug":"lsr-vs-hcr","status":"publish","type":"post","link":"https:\/\/meitu-engelhardt.com\/fr\/lsr-vs-hcr\/","title":{"rendered":"Caoutchouc silicone 1TP15 T vs HCR : une comparaison c\u00f4te \u00e0 c\u00f4te des mat\u00e9riaux et des processus pour les ing\u00e9nieurs"},"content":{"rendered":"
Engineers comparing LSR vs HCR<\/strong> silicone rubber for a new program rarely settle the question on chemistry alone. The decision usually turns on cycle time at target volume, achievable tolerance against the part drawing, the post-cure burden downstream qualification can absorb, and whether tooling investment amortizes inside an acceptable payback window. This guide pulls together datasheet figures from Dow and Xiameter grades, peer-reviewed cure-chemistry research from NIH and the Royal Society of Chemistry, and production observations from a dual LSR + HCR molding floor \u2014 so the trade-offs land in numbers, not adjectives.<\/p>\n
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Quick Specs: LSR vs HCR at a Glance<\/h3>\n\n\n\n\n\n\n\n\n
Cure chemistry<\/td>\nLSR: Pt-addition (typical) \u2014 HCR: Peroxide or Pt<\/td>\n<\/tr>\n
Cycle time<\/td>\nLSR 30\u201390 sec \/ HCR 2\u20135 min<\/td>\n<\/tr>\n
Achievable tolerance<\/td>\nLSR \u00b10.025\u20130.05 mm \/ HCR \u00b10.08\u20130.15 mm<\/td>\n<\/tr>\n
Tooling investment<\/td>\nLSR $15K\u2013$80K \/ HCR $3K\u2013$30K<\/td>\n<\/tr>\n
Ideal annual volume<\/td>\nLSR \u226510,000 parts \/ HCR <50,000 parts<\/td>\n<\/tr>\n
Biocompatibility path<\/td>\nLSR: no byproducts \/ HCR (peroxide): post-cure required<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

LSR vs HCR at a Glance: An 8-Dimension Comparison<\/h2>\n

\"LSR<\/p>\n

Both are silicone-based elastomers built on a polysiloxane backbone, and both are suitable for injection moulding \u2014 yet their viscosity, cure pathway and cost stack differ sufficiently to push manufacturers toward different choices. The table below covers the eight dimensions engineers tend to weigh during material selection.<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n\n
Dimension<\/th>\nLiquid Silicone Rubber (LSR)<\/th>\nHigh Consistency Rubber (HCR)<\/th>\n<\/tr>\n<\/thead>\n
Material form at room temp<\/td>\nTwo-component liquid (50,000\u2013500,000 mPa\u00b7s)<\/td>\nSolid, gum-like; supplied in bales or strips<\/td>\n<\/tr>\n
Dominant cure chemistry<\/td>\nPlatinum-catalyzed addition<\/td>\nPeroxide or platinum (both common)<\/td>\n<\/tr>\n
Typical cycle time<\/td>\n30\u201390 seconds (mold heated 150\u2013200\u00a0\u00b0C)<\/td>\n2\u20135 minutes (compression \/ transfer)<\/td>\n<\/tr>\n
Achievable tolerance<\/td>\n\u00b10.025\u20130.05 mm<\/td>\n\u00b10.08\u20130.15 mm<\/td>\n<\/tr>\n
Tooling investment<\/td>\n$15K\u2013$80K (cold runner, multi-cavity)<\/td>\n$3K\u2013$30K (compression \/ transfer)<\/td>\n<\/tr>\n
Material waste<\/td>\n<1% (cold-runner gating)<\/td>\n3\u201315% (flash + sprue)<\/td>\n<\/tr>\n
Automation level<\/td>\nFully automated cells (lights-out capable)<\/td>\nSemi-automated; operator loading common<\/td>\n<\/tr>\n
Post-cure requirement<\/td>\nGenerally none (Pt-addition leaves no byproducts)<\/td>\nPeroxide grades: 2\u20134 hr at ~200\u00a0\u00b0C to remove acidic residue<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

What this should make clear is that one material isn’t simply “better.” Both belong to the same elastomer family, just supporting two different manufacturing logics. LSR rewards high-volume programs that need tight tolerance and clean processing. HCR keeps low-volume runs and high-durometer parts economically viable.<\/p>\n

What Is LSR (Liquid Silicone Rubber)?<\/h2>\n

\"What<\/p>\n

Liquid silicone rubber is a two-part platinum-catalyzed silicone elastomer supplied as a low-viscosity liquid. Component A carries a platinum complex; Component B contains a methylhydrogensiloxane crosslinker plus an inhibitor that holds the pot life until heat triggers the addition reaction. Once the two streams are metered through a static mixer at a 1:1 ratio (typically held to \u00b11%) and injected into a mold heated to 150\u2013200\u00a0\u00b0C, crosslinking finishes in seconds.<\/p>\n

What does LSR stand for in silicone?<\/h3>\n

“LSR” stands for liquid silicone rubber<\/em>. Here, “liquid” describes its room-temperature state, not its cured behavior \u2014 once injected and crosslinked, LSR is a solid elastomer that holds its elastic properties from roughly \u221260\u00a0\u00b0C to +250\u00a0\u00b0C continuous service. The liquid form matters because it allows precise pumped metering, low-pressure cavity filling for thin walls (down to about 0.3 mm), and fully automated cells where parts demold robotically. [NIH\/PMC]<\/a><\/p>\n

What are the different types of LSR?<\/h3>\n

Standard LSR covers most industrial sealing and electrical applications. Beyond that, suppliers offer medical-grade LSR<\/em> qualified to USP Class VI \/ ISO 10993, food-contact grades<\/em> meeting FDA 21 CFR 177.2600, optical-grade LSR<\/em> with high transparency for lens and light-pipe parts, and fluorosilicone LSR (F-LSR) hybrids<\/em> that combine the chemical resistance of fluorosilicone with the processing ease of standard LSR for fuel and oil exposure. Self-bonding LSR grades carry adhesion promoters for two-shot overmolding onto thermoplastics or metals.<\/p>\n

What Is HCR (High Consistency Rubber)?<\/h2>\n

\"What<\/p>\n

High consistency rubber \u2014 also called heat-cured rubber or HTV silicone \u2014 is a solid, gum-like silicone elastomer with a high-molecular-weight backbone. It ships as pre-mixed compounds, master batches, or partially vulcanized sheet, typically in bales of 25 kg or strips for direct extrusion feeding. Vulcanization happens through either a peroxide free-radical mechanism or a platinum addition mechanism, and the choice of catalyst is independent of the material form. Stockwell, Shin-Etsu and Dow all publish both peroxide- and platinum-catalyzed HCR grades.<\/p>\n

\n
\u26a0\ufe0f<\/span> Common Misconception<\/strong><\/div>\n

Engineering teams often default to HCR for high-volume programs because per-kilogram material cost is lower and tooling looks cheaper on paper. In production, the longer cycle (often 4\u20136\u00d7 LSR’s), higher trim and scrap losses, and operator-dependent loading typically erase that advantage above roughly 10,000 parts per year. The decision framework in the cost section below shows where the crossover falls.<\/p>\n<\/div>\n

Cure Chemistry Compared: Platinum-Addition vs Peroxide<\/h2>\n

\"Cure<\/p>\n

Cure chemistry is the single biggest driver of biocompatibility, post-processing time, and which downstream qualifications a part can claim. Two mechanisms drive the cure in silicone rubber, and they work very differently:<\/p>\n

Platinum-addition (hydrosilylation) cure:<\/strong> The platinum catalyst activates a vinyl group on one polymer chain so it forms a single bond with a silicon hydride (Si\u2013H) group on a crosslinker. This is a clean addition reaction \u2014 no leaving groups, no volatile byproducts. Research published in Biomedical Silicones<\/em> (NIH\/PMC, 2024) confirms that the Pt-catalyzed reaction between Si\u2013H and vinyl groups produces no extractables of toxicological concern, which is why Pt-cured silicones dominate implantable and skin-contact device applications. [NIH\/PMC]<\/a><\/p>\n

Peroxide free-radical cure:<\/strong> Heat decomposes the peroxide initiator into two free radicals, which abstract hydrogen from methyl or vinyl groups on adjacent silicone chains. The resulting carbon radicals couple, forming the crosslink. That mechanism is well-described in the RSC Advances<\/em> (2015) review of silicone network topology by Stricher et al. [RSC Advances]<\/a> Peroxide-cured grades leave acidic residues that can migrate to the part surface as a powdery “bloom”; the standard fix is a 2\u20134 hour post-cure at roughly 200\u00a0\u00b0C in an air-circulating oven.<\/p>\n

Pt-addition is the default for LSR and for any platinum-cured HCR grade. Peroxide remains common for HCR programs that do not need biomedical qualification and where the post-cure step is already built into the production flow.<\/p>\n

Mechanical Properties Side-by-Side<\/h2>\n

Catalog mechanical properties scatter widely across grades, so the figures below should be read as typical ranges<\/em> rather than fixed values. Single-point values cited come from manufacturer datasheets that test per ASTM D412 (tension) and ASTM D2240 (durometer hardness), with compression set per ASTM D395.<\/p>\n

\n\n\n\n\n\n\n\n\n\n
Property (ASTM method)<\/th>\nLSR typical range<\/th>\nHCR typical range<\/th>\n<\/tr>\n<\/thead>\n
Tensile strength (D412)<\/td>\n7\u201311 MPa (Dow Silastic RBL-9200-60: 9.50 MPa)<\/td>\n7\u201311 MPa<\/td>\n<\/tr>\n
Elongation at break (D412)<\/td>\n400\u2013700% standard, up to 950% specialty<\/td>\n200\u2013500%<\/td>\n<\/tr>\n
Compression set (D395, 22h\/175\u00a0\u00b0C)<\/td>\n18\u201325% (Xiameter RBL-2004-30: 21.2%)<\/td>\n10\u201322% (lower with Pt-cured grades)<\/td>\n<\/tr>\n
Hardness range (D2240, Shore A)<\/td>\n5\u201380A<\/td>\n20\u201390A<\/td>\n<\/tr>\n
Tear strength (D624)<\/td>\n10\u201330 kN\/m typical<\/td>\n10\u201349 kN\/m (high-tear specialty)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

What are the disadvantages of LSR?<\/h3>\n

Three trade-offs come up most often. First, peak tensile strength is comparable to HCR, but compression set is generally higher than premium platinum-cured HCR \u2014 meaning HCR keeps a slight edge on long-duty static seals subject to constant load. Second, LSR demands specialized injection equipment with cooled feed sections and platinum-compatible tooling steel; converting a thermoplastic press is not realistic. Third, the upfront tooling cost is roughly 2\u20134\u00d7 a comparable compression-mold tool, which only pencils out above the volume threshold discussed in the cost section.<\/p>\n

“Catalog Shore A values do not predict real elastic recovery \u2014 geometry and wall thickness drive the actual sealing force. Engineers selecting silicone for a load-bearing seal should specify a prototype FEA validation or a representative test cut, not just the durometer call-out.”<\/p>\n