Non-standard size or section
Housings designed around a dimension no catalogue covers.
Compression moulding · O-ring compression
O-ring compression moulding.
Catalogue O-rings cover most needs. When yours falls outside them — an odd size, a special compound, a colour for identification — compression moulding is how custom O-rings get made.
The detail
When to mould rather than buy
If a standard size in a standard compound works, buy it. It will be cheaper and faster than anything custom. We say this to customers regularly.
Custom moulding makes sense when the size is non-standard, the compound is specific to your application (a particular silicone, fluorosilicone or EPDM), the colour has to identify the part on an assembly line, or you need a documented material record that catalogue parts don't carry. For the product side of O-rings, see our O-rings page.
Where it fits
Good reasons to go custom
Specific compound
A grade chosen for temperature, fluid resistance or approval.
Colour coding
Different colours for different sizes or functions, so the right ring goes in the right groove.
How we run it
How custom O-ring tooling works
Section and ID check
We review the groove design and recommend a section and stretch that will seal properly.
Multi-cavity tool
O-ring tools usually carry many cavities in rings across the plate.
Mould and deflash
Parts are compression moulded, then deflashed — cryogenically for most O-rings.
Measure and pack
Inside diameter and section checked per batch, packed in counted lots.
To quote it
To quote it
ID and cross-section
Or the groove dimensions, and we'll work back.
Compound
If you're unsure, the fluid, temperature and pressure it will see.
Quantity
Per batch and per year.
Colour and paperwork
Any identification colour and material documentation needed.
At a glance
The idea in a picture.
Which route suits your quantity
Swipe to see the whole diagram
Questions
What people usually ask.
Can you match an O-ring we can't identify?
Often. Send a sample and details of where it's used, and we'll check the size and suggest a compound.
Why compression rather than injection for O-rings?
At most volumes, compression tooling is far cheaper and the parts are just as good. Injection only wins at very high, steady volumes.
Keep exploring
More from compression moulding.
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Back to the overviewDesigned and developed in the UK. UK moulding capability, with some higher-volume production placed with trusted partners where that's the right commercial answer.
Get in touch
Tell us the part, the volume, and the timeline.
Rough annual volume, target unit price, and any deadlines. That's enough to work out whether compression, LSR injection or something else is the right tool.
Real people, a real workshop
You deal with the people who make it.
No call centre and no middlemen. When you contact TCI Products, you speak to the team who design, build and check your mould.
- A real Warwickshire workshopUnit 15, Waterloo Park, Bidford-on-Avon, Alcester B50 4JG.
- Real people on the phoneCall the team on 01789 224228, Monday to Friday.
- The same team on every jobDesign, production and aftercare come from the people you see here.
- Part of TCI GroupFive specialist brands, one engineering team. Visit TCI Group.
Thomas LaneManaging Director
George PrestonDesign & Project Manager
Kelly BallingerHead of Partnerships
Jim AndertonProduction Manager
TheodoreEmployee Welfare