Brake pad quality depends on the mix formulation, preforming and hot press conditions and the curing profile. One of the least discussed links in this chain, yet one that most directly affects line efficiency, is the release agent. A poorly chosen release agent comes back as sticking pads, build-up in the mould, frequent cleaning stops and, most critically, a weaker backing plate bond.
What does the release agent do on a brake pad line?
The friction mix is first shaped by cold preforming, then moulded together with the backing plate in a hot press and cured in an oven. The release agent forms a thin film on the mould and punch surfaces so the pad releases cleanly, and protects mould life by stopping the resin from adhering to the mould. In friction materials it also has a limit: it must do its job on the mould surface and must not be carried onto the backing plate, the friction surface or the paint.
6 key points in the hot press
- Resistance to press temperature: The film must stay effective throughout your press temperature and time without breaking down and leaving residue in the mould.
- No effect on the backing plate bond: If release agent reaches the adhesive-coated backing plate it can reduce bond strength. Product and application method should keep this risk to a minimum.
- Effect on the friction surface: The right product should leave no lasting effect on the pad surface. When switching products, friction tests should be repeated according to your quality plan.
- Compatibility with painting and later steps: Release agent left on the surface can make paint or coating adhesion harder.
- Build-up and cleaning intervals: Build-up causes dimensional drift, surface defects and frequent press stops. A low build-up product extends cleaning intervals.
- Application method, consumption and workplace: Suitability for spray or automatic application, clean release with the thinnest even film, and low mist and odour.
How should a trial be planned?
The soundest way to switch release agents is a press trial with success criteria defined at the outset. Before the trial, press temperature and time, mould material, the current product, application method and consumption are clarified. During the trial, ease of release, mould build-up, backing plate bond test, paint adhesion and consumption are recorded and compared with the current product.
From Biyopol Kimya: We supply release agents for hot pressing and preforming to brake pad and friction material producers and run trials on your line with samples. See our Brake Pads and Friction Materials page for details.