Washers BR10

BR10 washers are flat washers in polyamide PA66 with the same basic geometry as the steel washer to DIN 125. The difference is in the material: a washer in PA66 does not conduct current, never rusts and does not scratch painted or anodized surfaces. It also weighs only a fraction of the equivalent steel washer; the density of polyamide at 1.14 g/cm³ can be compared with 7.85 for steel.

The series covers eight sizes that fit screw sizes from M3 to M16. The outer diameter runs from 7 to 30 mm and the thickness from 0.5 to 3 mm, with holes that follow the same clearance fit as standard washers in steel. You pick the size as a variant on the product page. The washers are delivered in natural color with a glossy surface and are sold only in full packs of 1000 pieces, a level that suits assembly in series production rather than one off manufacturing.

PA66 is one of the most used engineering plastics for fasteners, and for good reason. The material is tough and hard wearing, takes repeated assembly without cracking and handles considerably higher temperatures than simpler plastics; a common rule of thumb for PA66 is continuous service around 100 °C. Chemically the material holds up well against oils, greases, fuels and most solvents, while strong acids and oxidizing media should be avoided.

In Swedish workshop industry the plastic washer turns up in more places than many people think. Electrical cabinets and equipment building are the classic case, where the washer insulates the joint electrically and stops leakage currents. In joints between different metals, for example an aluminum profile against a stainless screw, an insulating washer breaks the galvanic contact and slows the corrosion. And in sheet metal structures a thin PA washer works as protection against squeaks and rattles. Two sheets that would otherwise sing against each other go quiet.

The washer springs a little under clamping force. That gives the joint some protection against vibrating loose, but at the same time it puts demands on the assembly. Polyamide creeps under high constant load, so tighten with moderate torque and pick a larger outer diameter that spreads the pressure rather than tightening harder. Retightening after a week or so of service is cheap insurance in positions exposed to vibration.

Keep in mind as well that PA66 picks up moisture from the surrounding air. For a washer the change in dimension is negligible in practice, but the properties shift somewhat: in a damp environment the material becomes tougher and a little softer, in a very dry environment stiffer. The natural color is unpigmented and can vary slightly in shade between production batches, which is cosmetic and does not affect the function. For outdoor use with UV exposure, though, unpigmented polyamide is not the right choice in the long run.

If the whole joint is to be electrically insulated you complement the washer with a screw and a nut in polyamide, so no metal path is left through the joint. If you need to spread load on soft materials such as wood or composite board, the large 30 mm washer does the same job as a fender washer in steel, but without the risk of rust. Exact dimensions and tolerances per size are in the manufacturer's data sheet.

Compared with washers in softer plastics such as polyethylene, PA66 gives higher stiffness and better load bearing, so the washer works in joints that actually carry load and do not only insulate. For the small screw sizes in electronics the thin washers of half a millimeter are plenty, while the wide sizes do their work where the pressure is to be spread. Keep the most common sizes in the store room; with 1000 pieces per pack a single box covers many assemblies.

Do you have a specific application in mind? We will help you pick the right size.