Low Compression Set Silicone Gasket | OEM Manufacturer

If you are sourcing a silicone gasket that must maintain sealing force after years of thermal cycling, the critical spec is compression set per ASTM D395 Method B. For overseas buyers with active POs, we routinely extrude low compression set silicone gaskets that achieve ≤15% set at 175°C for 22 hours, ensuring long-term sealing integrity in ovens, solar enclosures, and medical equipment. This article walks through factory capabilities, MOQ, tooling cost, and how to send CAD drawings that eliminate revision loops.

Why Compression Set Matters in Silicone Gaskets

Low compression set is the elastomer's ability to return to original thickness after sustained deflection. Standard silicone gaskets often exhibit 25-40% set, leading to leaks within 6 months. For overseas B2B specifiers, specifying ≤20% set at 175°C per ASTM D395 is the baseline for demanding applications. Our formulation achieves 12-18% set depending on durometer, with tensile strength of 7.5 MPa and elongation of 400%.

Material Property Comparison

Custom Extrusion Process for Low Compression Set Silicone

In our Hunan factory experience, a German medical device buyer rejected three suppliers before coming to us—their problem was compression set creeping past 25% after 1000 hours thermal aging at 150°C. We solved it by adjusting the vinyl content in the polymer matrix and extending vulcanization time by 12%. That project taught us: overseas buyers need process transparency, not just a datasheet.

Step 1: CAD Drawing Review

Send a .dwg or .step file with:

• Cross-section dimensions with tolerances (we hold ±0.25mm on solid profiles, ±0.50mm on hollow)
• Hardness requirement (durometer)
• Compression set target and test method
• Surface finish (smooth, matte, or textured)

Avoid: sending PDF scans or hand sketches. We provide a drawing checklist with every inquiry.

Step 2: Tooling Fabrication

• Extrusion die: $350-$800 depending on complexity (single cavity vs. multi-cavity)
• Vulcanization mold: $1,200-$3,500 for continuous cure line
• Lead time: 7-12 working days for die, 15-20 for mold

Step 3: Material Compounding

We blend methyl-vinyl silicone gum with reinforcing silica, heat stabilizers, and a peroxide curing system optimized for low compression set. Each batch is tested for rheology before extrusion.

Step 4: Extrusion & Vulcanization

Continuous extrusion through a heated die, followed by a 10-meter hot-air vulcanization tunnel at 200-250°C. Speed is adjusted based on wall thickness and cure rate.

Step 5: Post-Cure & Quality Testing

Post-curing at 200°C for 4 hours reduces volatile content and stabilizes compression set. We then sample every 50 meters for:

• Compression set (ASTM D395)
• Hardness (Shore A)
• Dimensional check (optical comparator)
• Thermal aging (ASTM D573, 70h @ 200°C)

How to Send Proper CAD Drawings to Reduce Back-and-Forth

Overseas buyers waste an average of 3 days per revision because of incomplete drawing data. To get a quote within 24 hours, include:

1. Cross-section view with all internal radii and wall thicknesses
2. Tolerance callouts – we recommend ±0.25mm for solid profiles, ±0.50mm for hollow
3. Material spec – e.g., "Silicone, 60 Shore A, compression set ≤15% per ASTM D395"
4. Application context – clamping force, temperature cycle, fluid contact
5. Quantity – affects tooling amortization and per-meter price

We accept .dwg, .dxf, .step, .stp, and .pdf with dimensioned views. For complex profiles, a 3D step file is preferred.

MOQ, Tooling Cost & Sample Lead Time

Applications for Low Compression Set Silicone Gaskets

• Oven and appliance door seals – continuous 200°C exposure requires ≤20% set
• Solar photovoltaic junction boxes – 25-year lifespan demands thermal aging stability
• Medical device enclosures – sterilization cycles (autoclave, EtO) degrade standard silicone
• LED lighting fixtures – heat buildup accelerates compression set in standard materials
• Aerospace interior seals – flame retardancy (UL 94 V-0) and low outgassing (NASA low outgassing spec)

For similar profiles, explore our door sealing strips and silicone series. For rigid enclosure seals, see our cabinet seals or WPC profiles.

Frequently Asked Questions

What is the MOQ for custom low compression set silicone gaskets?

Our standard MOQ is 500 meters per profile. For first-time overseas buyers, we can combine multiple profiles into one production run to meet the MOQ. For smaller quantities, we offer sample lengths (3-10 meters) at a flat fee of $150 plus shipping.

What is the typical lead time for samples and production?

Samples require 10-15 working days after drawing approval and tooling fabrication. Production lead time is 20-30 working days after sample sign-off. For urgent projects, we can expedite samples to 7 working days with a 30% surcharge on tooling.

What extrusion tolerances can you hold?

We hold ±0.25mm on solid cross-sections and ±0.50mm on hollow profiles. For critical dimensions (sealing lips, grooves), we can achieve ±0.15mm with secondary calibration. All tolerances are verified with an optical comparator and documented in the COA.

How are the gaskets packed for export?

Gaskets are wound on cardboard reels (max 50 kg per reel), wrapped in PE film, and packed on plywood pallets with steel strapping. For delicate profiles, we use cardboard interleaving. Each pallet is shrink-wrapped and labeled with part number, quantity, and net weight. FOB Shanghai or CIF terms available.

Can I get a sample before placing a production order?

Yes. We provide 3-10 meter samples from the actual production tooling. Cost is $150 + shipping, refundable on the first production order over $3,000. Samples include a material test report with compression set, hardness, and tensile data.

Send your CAD drawing for a 24-hour quote.