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Project record · Sportswear · Overmoulding

A UK sportswear brand's overmoulded whistle.

A referee whistle with a soft silicone mouthpiece bonded to a rigid plastic body. Not glamorous; used in cold weather, wet weather, and everything else. It had to survive the season without the mouthpiece coming off.

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SportswearSector
OvermouldRoute chosen
SeasonFull outdoor life
2019Established

The brief

A whistle that had to survive a football season without the mouthpiece falling off.

Rigid whistle body with loosened silicone mouthpiece on a worn bench
Prototype whistle with mouthpiece fit problem

A UK sportswear brand was extending its officiating range with a whistle designed for referees. The whistle body was rigid engineering plastic; the mouthpiece was soft silicone for comfort on the lips in cold weather.

The prototype used a silicone mouthpiece pushed onto the plastic body. It worked in the office. In the field, referees found the mouthpiece could come off after being pressed against pockets, gear bags, and — occasionally — being blown particularly hard. Not a safety issue, but a loyalty issue for a premium accessory.

The brand needed the mouthpiece to be permanently bonded to the body, not press-fit. They came to us to move the assembly to overmoulded.

The problem

The press-fit worked most of the time. Most of the time isn't good enough for premium.

Press-fit was cheap to assemble but relied on friction. Silicone stretches; friction fits loosen over time; cold and wet make it worse. For a product being carried and used daily in outdoor conditions, the fit was going to fail.

Overmoulding solved it. Silicone moulded directly onto the plastic body, chemically bonded during cure with mechanical interlock features designed into the body geometry. One part instead of two, permanently bonded.

The plastic body would be supplied by the brand's existing plastic moulder, primed before shipping to us. We'd handle the overmould and the finished part packing.

Gloved hand holding a metal substrate overmoulded with black silicone beside the tool.

What we changed

We overmoulded the mouthpiece onto the primed plastic body.

Small design change on the plastic body; big change in field durability.

  1. Plastic body redesigned for overmould

    Interlock features — small grooves around the mouthpiece attachment area — added to the plastic body geometry. The plastic supplier tooled the change.

  2. Body primed before shipping to us

    The plastic supplier added a light primer coat as their final step. Primer batch recorded and shipped alongside the parts.

  3. Silicone mouthpiece overmoulded

    Silicone injected around the primed and interlocked body. Chemical bond plus mechanical retention. Cycle time optimised for the compact geometry.

  4. Brand colour matched

    Mouthpiece silicone colour matched against a brand chip. Warm coral, consistent across every batch.

  5. Pull test on first-off

    First-off parts pull-tested to failure. The silicone tore before the bond separated — the desired failure mode.

  6. Delivered as finished units

    Overmoulded whistles packaged into brand retail boxes at our facility. Shipped to the brand's fulfilment warehouse.

Open overmould tool holding whistle body with interlock features
Whistle body prepared for silicone overmoulding

The commercial shape

Field failures stopped. Retail returns stopped. Programme continued.

Overmould tooling investment recovered inside the first year, mostly through the disappeared returns and the retained retail placement.

Per-part cost was higher than press-fit assembly would have been, but the brand's retail price already supported the higher cost, and the returns rate on the previous version was making the press-fit route uneconomic anyway.

The programme continues. The whistle is now in its third season with no reports of mouthpiece separation. The brand extended the overmould technique to a companion product the following year.

“The first version cost less per unit. It also had a returns rate we couldn't sustain. This version pays for itself.”
— Product director, UK sportswear brand

Services used

How this programme was actually delivered.

Overmoulding

Silicone or rubber moulded directly onto a pre-made substrate — a plastic housing, a metal insert, a printed circuit assembly — so the finished part…

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Branded part manufacture

Silicone products moulded, finished, packaged and labelled to your brand — ready to ship into your retail, e-commerce or wholesale channel. Your…

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Post-processing and finishing

Deflash, trim, print, bond, assemble, inspect and pack. Everything that has to happen between the press opening and the part being ready for your…

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Next step

If your project rhymes with this one, get in touch.

The commercial shapes described in our project records are examples of what's worked, not prices we're quoting today. Every programme sizes differently based on part geometry, annual volume, material family and paperwork requirements.

For a first conversation about whether we'd be the right supplier for your part, send a drawing or a sample with your rough annual volume. That's enough to know if the fit is real.

Designed and developed in the UK. UK moulding capability, with some higher-volume production placed with trusted partners where that's the right commercial answer.

At a glance

The idea in a picture.

How overmoulding works

Silicone moulded overPlastic, metal or electronicsBonded interface

Swipe to see the whole diagram

The rigid part goes into the tool and silicone is moulded around it, so you get one finished part.

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.

Send an enquiry 01789 224228

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.
The TCI design and project office.
The TCI design and project office.
The TCI workshop, with moulds on the bench mid-build.
The TCI workshop, with moulds on the bench mid-build.
A stack of TCI silicone moulds.
A stack of TCI silicone moulds.
  • Thomas LaneManaging Director
  • George PrestonDesign & Project Manager
  • Kelly BallingerHead of Partnerships
  • Jim AndertonProduction Manager
  • TheodoreEmployee Welfare
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