Almost every machine, vehicle and enclosure has joints where two surfaces meet and something must not get through: oil, water, gas, dust or noise. A gasket is the part that fills that gap. It is easy to overlook, because it is usually hidden between two flanges or behind a cover, but when a gasket is wrong, the result is a leak, a breakdown or a product returned under warranty.
This article explains what a gasket does, when a custom gasket is the better choice than an off-the-shelf one, the materials and cutting methods used, and where custom gaskets are found across industry.
What a gasket does
No two machined surfaces are perfectly flat or perfectly smooth. Bolt them together and microscopic gaps remain. A gasket is a layer of softer material placed between them: when the joint is tightened, the gasket compresses and flows into those irregularities, creating a seal.
A good gasket has to do three things at once. It must seal against whatever is on the other side, whether that is oil, coolant, water, air, gas or dust. It must survive the conditions in the joint, such as temperature, pressure, chemicals and vibration, for its whole service life. And it must hold its seal as the joint moves, heats up, cools down and is taken apart for maintenance. The material, the thickness and the shape all decide how well it does that.
Why custom rather than off the shelf?
Standard gaskets work well for standard joints. A custom gasket is the better answer when:
- the shape is not standard: covers, housings and flanges with unusual outlines, bolt patterns or cut-outs;
- the material matters: the joint needs a specific resistance to oil, fuel, heat, chemicals or weather, or a food-grade material;
- the thickness matters: a particular compressed thickness to set a gap or a component height;
- the quantity is small or changing: prototypes, short runs and spares for older equipment that is no longer supported;
- the gasket does more than seal: insulating electrically or thermally, damping vibration, or spacing parts apart.
PSG cuts custom gaskets to your drawing, from simple rings to complex profiles, in the material and thickness the joint needs.
Gasket materials and how to choose
The material is the most important decision. The table shows the gasket materials PSG cuts most often, with the thicknesses we supply them in, and the general strengths of each type of material.
| Material | PSG thicknesses | General strengths | Typical uses |
|---|---|---|---|
| Klingersil® compressed fibre | 0.250 to 3.000 mm | Holds its seal under pressure and heat | Pipe flanges, pumps, valves, steam and fluid lines |
| Neoprene and nitrile bonded cork | 0.800 to 25.000 mm (by material) | Compressible, conforms to uneven or lightly bolted flanges | Sumps, covers, transformers, gearbox housings |
| Nitrile rubber | 1.000 to 25.000 mm | Good resistance to oils and fuels | Engines, hydraulics, fuel and oil systems |
| Neoprene rubber | 1.000 to 25.000 mm | Good resistance to weather and ozone | Outdoor equipment, enclosures, marine fittings |
| Food-grade silicone rubber | 1.000 to 10.000 mm | Wide temperature range, suitable for food contact | Food and drink processing equipment, ovens, appliances |
| PVC, polyethylene and neoprene foams, Plastazote® | 1.000 to 50.000 mm (by material) | Low closing force, cushioning and dust or splash sealing | Enclosures, cabinets, lighting, packaging inserts |
| Polymex® polyester and polypropylene | 0.012 to 3.000 mm | Thin, rigid, insulating, colour-coded by thickness | Thin gaskets, insulating washers and spacers |
Choosing well starts with four questions: what must the gasket seal against, what temperatures and pressures will it see, how much can the joint be tightened, and does it need to do anything else, such as insulate or set a gap. Our technical team will help you answer them and recommend a material. Other materials and thicknesses are available on request.
How custom gaskets are made
PSG cuts gaskets in three main ways, chosen to suit the material, the shape and the quantity:
- Die cutting: a steel-rule or press tool cuts the shape in one stroke. Fast and repeatable, it suits production runs.
- Precision laser cutting: no tooling is needed, and the laser follows fine detail and tight tolerances on complex profiles, so it suits prototypes and intricate parts.
- Water jet cutting: a high-pressure jet cuts cleanly through thicker materials without heat.
All three work from your drawing, so a design can move from prototype to production without being redrawn.
Where custom gaskets are used
Automotive
Engines, gearboxes, brakes, clutches and sensors all contain joints that must resist oil, fuel, heat and vibration over long service intervals. Cork-rubber and nitrile gaskets seal covers and housings, and thin polymer gaskets and shims set and insulate components. See our work in the automotive sector.
Aerospace and defence
In hydraulic and electrical systems, gaskets must seal reliably while saving weight, often with thermal or electrical insulation, and with the quality, traceability and certification a regulated industry requires.
Industrial machinery, pumps and valves
Hydraulic and pneumatic pumps, taps, valves, transmissions and gearboxes rely on gaskets that resist oils, coolants and pressure. The right material extends maintenance intervals and reduces downtime, which is why plant engineers specify it carefully. More in our industrial sector overview.
Marine and subsea
Saltwater, cold, pressure and sunlight attack gasket materials in different ways, and on ships, platforms and pumping stations a failed seal is costly to reach. Materials are chosen to resist all four while keeping their compressive strength. See our marine and subsea work.
Energy and power
Mechanical seals for water pumps, high-speed compressors and battery and fuel cell technologies all need gaskets and insulating components that withstand heat, pressure and corrosion.
Food, drink and appliances
Processing equipment, ovens and appliances use food-grade silicone gaskets, which stay flexible across a wide temperature range and are suitable for contact with food.
Electronics and enclosures
Control cabinets, lighting and electronic enclosures use foam and rubber gaskets to keep dust and water out and to cushion components, and insulating polymer gaskets and washers to separate conductive parts.
Gaskets, washers and shims
Gaskets often sit alongside two close relatives. An insulating washer is a small ring-shaped gasket that separates a fixing from a surface, and a shim sets a precise gap. PSG's colour-coded Polymex® polymer gaskets use the same idea as our shims: each colour identifies a thickness, so the right part can be picked by sight. For gap-setting parts, see our custom shims, or use the shim stack calculator to work out the fewest stock shims that make up a measured gap.
How to get a custom gasket made
To quote accurately, we need four things:
- The shape: a drawing (DXF, DWG, PDF or STEP), a sample, or the dimensions and bolt pattern;
- The material: if you know it, or what the gasket must seal against and the conditions in the joint;
- The thickness: in millimetres, and whether it sets a gap;
- The quantity: for a prototype, a one-off batch or regular production.
Have a drawing or a sample? Send it to our technical team for a quote, and we will recommend the material and cutting method for your custom gasket. Everything you send is handled in confidence.
Klingersil® is a trademark of Klinger. Plastazote® is a trademark of Zotefoams. Polymex® is a trademark of PSG.
