Custom Silicone Seals, Gaskets & O-Rings

Silicone seals, gaskets and O-rings rated from −40 °C to 230 °C, made by compression moulding, extrusion or die-cutting depending on the shape. Send seven data points and we can quote without a week of questions.

−40 to 230 °C
Moulded / extruded / die-cut
MOQ from 500
In-house tooling

Get a quote Ask a question

Line illustration of an O-ring with cross-section callout plus a flat gasket and washer below — Illustration, not a photo. We do not publish customer character designs — actual samples are sent on request.

Specification — what you are actually ordering
Material	HCR silicone; fluorosilicone on request for oil resistance
Temperature	−40 to 230 °C continuous
Hardness	Shore A 30–80 (ASTM D2240)
Process	Compression moulded · extruded profile · die-cut sheet
Cross-section	O-ring cord 1–20 mm · custom profile on drawing
Tolerance	±0.1 mm moulded · ±0.3 mm extruded
MOQ	500 pcs (stock O-ring) / 1,000 (die-cut) / 3,000 (new mould)
Tooling	Die $150–600 · extruded die $300–1,500 · compression mould $1,500–8,000
Sampling	3–7 days for existing tooling · 10–15 days for a new mould
Lead time	15–25 days after sample approval
Testing	Hardness per ASTM D2240 · RoHS / REACH arranged per order

Values marked on request depend on your drawing. Send it and we will confirm in writing.

Can we make yours?

O-rings, flat gaskets, washers, custom profiles
−40 to 230 °C continuous service
Shore A 30–80, moulded, extruded or die-cut
Compression set and hardness reports on request
500–100,000 pcs per order

Where we stop

Hard plastic injection moulding (ABS / PC structural parts)
Metal machining, stamping or plating
Factory-level certificates — we arrange third-party testing per order instead

Process and material

Pick the process by shape, not by habit

A round O-ring with existing tooling costs nothing to tool and runs from 500 pcs. A flat gasket is usually die-cut from sheet. A custom profile is extruded, or moulded if it has features along its length. Choosing wrong is the main reason quotes differ by 4× for the same drawing.

What we need to quote

Seven things: seal family (O-ring / moulded / extruded / die-cut), critical dimensions and cross-section, target Shore A and tolerance, service temperature and contact medium, silicone grade, annual volume, and colour. With those we can quote without coming back with questions.

Compression set matters more than hardness

A seal that leaks after six months usually failed on compression set, not on hardness. If the joint stays compressed at temperature, tell us — we will recommend a grade and post-cure that holds its shape rather than just matching a durometer number.

A row of vertical compression moulding presses along a green epoxy floor in a small workshop, with blue storage bins and extraction ducting overhead. — AI-generated illustration A typical compression moulding floor in a plant of this size: vertical presses in a row, each with its own tool mounted on the lower platen. Layout varies by factory — what does not vary is that the tool is changed per order, not the machine.

Questions buyers ask about silicone seals & gaskets

What is your MOQ for a custom gasket?

500 pcs for stock O-ring sizes, 1,000 for die-cut flat gaskets, and 3,000 for a new compression mould. The MOQ follows the tooling cost, not our preference.

What information do you need to quote a seal?

Seven things: seal type, dimensions, hardness and tolerance, temperature and medium, silicone grade, annual volume, and colour. Send those and the quote comes back without a round of questions.

Can you do fluorosilicone for oil contact?

Yes, for applications where standard silicone swells in oil or fuel. It costs more and has a narrower temperature window, so we only recommend it when the medium requires it.

What temperature range is realistic?

−40 to 230 °C continuous for standard grades. Short excursions to 250 °C are survivable but shorten life. Below −40 °C the material stiffens and sealing force drops.

Do you provide hardness certificates?

We measure hardness in-house per ASTM D2240 on every batch, and can arrange third-party verification for your order if you need a lab report rather than our own reading.

Silicone Seal RFQ Worksheet

The spec table above, the tolerance notes, and the list of what we need from you — as a two-page PDF you can forward to your team.

Request the PDF

Related products

Waterproof Accessories IPX8 / 3 m depth · TPU or PVC Silicone Keypads & Buttons MOQ 500 pcs · 1–5M cycles Character Sleeves One-piece moulded · Shore A 20–60

Not sure which material fits your project? Silicone vs PVC — which material for your part →

Send your spec, get a quote

Tell us what you need and how many. within 1 business day (GMT+8) — usually much sooner. If you already have a drawing or 3D file, attach it and skip the back-and-forth.