Flat Washers Manufacturers

Flat Washers We Manufacture

Our flat washer production is a dedicated part of the Dongbo fastener programme, supported by a full-process system that starts with precision rolling of raw strip steel and ends with barcode-controlled packaging. The current flat washer range centres on DIN 988 load-distributing washers, supplied in thicknesses from 0.1 mm to 2.0 mm and outside diameters from 6 mm to 115 mm.

These washers are used where a bolt or nut must not damage the clamped surface, where a precise spacer height is required, or where load must be spread across a wider area. We produce both hardened and non-hardened variants so that the washer can match the joint behaviour rather than simply the bolt size.

DIN 988 Range and Size Coverage

The DIN 988 series is the core of our flat washer catalogue. Standard nominal sizes run from 3 mm to 95 mm, with matched inner and outer diameters. Thickness is controlled to the tolerances shown below, which is critical when the washer is used as a shim to set bearing preload, gear clearance or shaft end-float.

For sizes outside the standard DIN 988 table, we manufacture to drawing. The same stamping and finishing lines that produce our Non-standard Stamping Parts are used for custom flat washer profiles, so a non-standard outer diameter or a special hole shape does not require a separate supply chain.

Material and Surface Treatment Options

Material selection drives strength, corrosion resistance and cost. We stock and process carbon spring steel, stainless steel and mild steel, and we confirm the grade against the joint load, environment and required service life before quoting.

• Carbon spring steel: 65Mn, C67S, C75S — high hardness and fatigue resistance for hardened shim washers.
• Stainless steel: 301, 304, 2Cr13, 1.4122 — corrosion resistance for outdoor, marine and food-adjacent equipment.
• Mild steel: DC01, SPCC — cost-effective for non-hardened spacing and load-distribution washers.

Surface treatment is selected to match the corrosion class of the surrounding assembly. Available finishes include phosphating (zinc or manganese), mechanical galvanizing, coloured zinc, Dacromet, Gumet, electrophoresis, galvanized nickel and passivation. Salt-spray test duration is confirmed against the customer specification, and colour can be matched to an existing finish on the line.

Where Our Flat Washers Fit

Flat washers are rarely a standalone purchase. They are specified alongside bolts, circlips and spring washers, and the washer must be compatible with the joint design, the mating surface and the assembly sequence. Our range is used across the following application areas:

When a flat washer is used next to a retaining ring, we can supply both from the same production system. Our Internal Circlips and External Circlips ranges are produced to DIN 471, DIN 472 and related standards, which simplifies the bill of materials and the incoming inspection routine.

Quality Control and Acceptance

Every flat washer passes through in-process inspection after stamping, heat treatment and surface finishing. Finished parts are checked for dimensions, hardness, surface condition and plating thickness before packing. Our testing centre holds CNAS accreditation and is equipped for material element analysis, mechanical properties, hardness and metallography.

For project supply, we agree the inspection plan with the customer before production. This can include first-article inspection, dimensional reports, hardness and salt-spray results, and full inspection of finished goods where the application requires it. Automatic optical screening is used to remove parts with burrs, cracks or dimensional deviations before they reach the packing station.

Configuration and Customization

Flat washers are often the simplest part to customize and the easiest to get wrong. We work from the drawing or sample and confirm the following variables before production:

• Inner diameter, outer diameter and thickness with tolerance class.
• Material grade and hardness condition (hardened or non-hardened).
• Surface treatment, colour and salt-spray requirement.
• Edge condition, flatness and burr limits.
• Packaging format and quantity per bag, box or kit.

Custom flat washers can be supplied as loose parts, in blister packs, on masking paper or strip, in oil paper bundles, or in a customized repair kit. Our Product Customization service covers thickness, diameter, material and surface treatment changes without a separate tooling programme where the profile is already in our standard range.

Information We Use to Configure Your Solution

To prepare a flat washer proposal that can go straight into production, we need the following project inputs. Where a drawing is not yet available, a sample or a description of the joint is enough to start.

Production, Documentation and Delivery

Dongbo operates a full-process production system with an annual capacity of 3.5 billion pieces. Raw material precision rolling, mould design, stamping, heat treatment, surface treatment, ultrasonic cleaning, automatic optical screening, performance testing and packaging are completed in our factory. The ERP production management system and barcode traceability support first-in-first-out control and lot identification from strip steel to finished carton.

Standard documentation includes material certificates, dimensional and hardness reports, surface-treatment records and packing lists. Where a project requires it, we can provide PPAP-level documentation and inspection records aligned with the agreed control plan. Delivery scope is confirmed at order stage and can include mixed packaging, kit assembly and labelled cartons for line-side use.

Frequently Asked Questions

What is the difference between a hardened and a non-hardened flat washer?

Hardened washers are heat-treated to resist deformation under high bolt loads and are used in suspension, hydraulic and structural joints. Non-hardened washers are softer and more formable, which suits spacing, surface protection and applications where the washer must conform slightly to the mating surface.

Can you produce flat washers outside the DIN 988 size table?

Yes. We manufacture to drawing or sample, including non-standard inner and outer diameters, special thicknesses and shaped profiles. The same stamping and finishing process is used, so a custom profile does not require a different quality route.

Which materials are available for corrosion-resistant flat washers?

Stainless steel grades 301, 304, 2Cr13 and 1.4122 are available for corrosion resistance. Carbon spring steel grades 65Mn, C67S and C75S can be combined with zinc plating, Dacromet, Gumet or mechanical galvanizing where a specific salt-spray performance is required.

How do you control thickness tolerance on shim washers?

Thickness is controlled during stamping and verified after heat treatment and finishing. For 0.1 mm and 0.15 mm washers the tolerance is 0 / -0.03 mm; for 0.2 mm it is 0 / -0.04 mm; and for 0.3 mm to 2.0 mm it is 0 / -0.05 mm. Tighter tolerances can be discussed for specific shimming applications.

What information is needed for a flat washer quotation?

A drawing or sample, material and hardness requirement, surface treatment and salt-spray target, annual volume, inspection level and packaging format are the core inputs. With these, we can confirm the production route, tooling position and delivery scope.

Do you supply flat washers together with retaining rings?

Yes. Flat washers, internal circlips, external circlips, snap rings and Belleville spring washers are all produced within the Dongbo factory. Combined supply reduces the number of incoming inspection routines and simplifies traceability across the fastener set.