Aluminum Washers & Pressed Aluminum Washers – Plain, Sealing & Shakeproof | Brass & Copper Parts India

Aluminum washers and pressed aluminum washers are precision-punched or turned flat rings manufactured from AA1050, AA1100, AA3003, AA5052, and AA6061 aluminum alloys for use as load-distributing, sealing, electrical isolation, and shim components in electrical equipment, plumbing, automotive, aerospace, and industrial assembly applications. Brass & Copper Parts India manufactures aluminum washers to DIN 125, DIN 433, ASME B18.22.1, and ISO 7089/7090 dimensional standards — supplying USA electrical OEMs, power utility equipment manufacturers, fastener distributors, and EPC contractors. Aluminum washers are preferred over steel washers where galvanic compatibility with aluminum structures, non-magnetic properties, weight reduction, and corrosion resistance are required.

Product Overview

Aluminum washers are produced by punch pressing from aluminum sheet or strip using compound dies (blanking and piercing in one stroke) or CNC-turned from aluminum bar for precision machined washers. Standard plain washers are flat annular rings conforming to DIN 125 (metric) or ASME B18.22.1 (imperial) dimensional standards. Sealing washers incorporate a rubber (EPDM, NBR, neoprene) bonded face for fluid-tight bolt connections. Shakeproof and serrated washers are available in AA5052 and AA6061 for vibration-resistant fastening. Custom washers to OEM drawings — non-standard OD/ID combinations, non-circular profiles, and slotted or tabbed designs — are produced from prototype quantities.

Key Features

• Wide Alloy Range: AA1050 (high conductivity, soft), AA3003 (general purpose, corrosion resistant), AA5052-H32 (high fatigue strength, marine grade), AA6061-T6 (structural, heat treatable) — selected to match the fastening system’s strength and environment.
• DIN and ASME Standard Dimensions: Manufactured to DIN 125A/B (metric), DIN 433 (small OD), ISO 7089/7090, and ASME B18.22.1 (inch) for direct interchangeability with standard hardware.
• Precision Punched Tolerances: ID tolerance ±0.1 mm for standard washers; ±0.05 mm for precision-punched washers; OD tolerance ±0.2 mm standard.
• Sealing Washer Option: Bonded aluminum/rubber sealing washers with EPDM, NBR, or silicone elastomer face for fluid-tight electrical conduit fittings, hydraulic ports, and plumbing connections.
• Non-Magnetic and Non-Sparking: Aluminum washers are fully non-magnetic and non-sparking — required for use on magnetic minesweeper vessels, in oxygen-enriched atmospheres, and in MRI facility construction where ferrous contamination is prohibited.
• Surface Treatments: Natural mill finish, anodized (Type II clear), chromate conversion (per MIL-DTL-5541), and passivated finishes available; custom color anodize for identification and corrosion protection.

Technical Specifications

Aluminum Alloy Grade Equivalents for Washers

Product Types and Variants

Plain Aluminum Flat Washers (DIN 125 / ASME B18.22.1)

Plain aluminum flat washers are the standard load-distributing washer form used under bolt heads and nuts to spread clamping load across the parent material surface and prevent thread pull-through in soft aluminum or composite structures. Manufactured to DIN 125A (normal series) and DIN 125B (large OD series) in M3 to M48 metric sizes, and ASME B18.22.1 Type A (narrow) and Type B (wide) in #4 through 2″ imperial sizes, from AA1050, AA3003, or AA5052 sheet. These are supplied in bulk polybag packing for distributor stocking and OEM assembly line use.

Aluminum Sealing Washers (Bonded Rubber-Faced)

Bonded aluminum sealing washers combine a stamped aluminum carrier ring with a vulcanized EPDM, NBR, or silicone rubber sealing face, providing a combined load distribution and fluid seal function in a single fastening element. Used extensively on electrical conduit fittings, hydraulic adaptors, compressed air line connections, and fuel system banjo bolts where a metal-to-metal joint would leak under vibration. Available in M6 to M20 metric and ¼” to ¾” imperial sizes, with EPDM (water/steam), NBR (oil), or silicone (high temperature) elastomer options.

Aluminum Shim Washers (Precision Thickness)

Shim washers are precision-controlled thickness washers used to set bearing end-float, adjust shaft preload, align flanged joints, and compensate for manufacturing tolerances in mechanical assemblies. CNC-turned from aluminum bar stock (AA6061 or AA2024) to a controlled thickness tolerance of ±0.02 mm per DIN 988 (precision shim ring standard). Available in standard DIN 988 sizes (M8 to M40) and to custom OD/ID/thickness specifications for OEM gearbox, pump, and motor assembly applications.

Large Diameter Aluminum Washers (Backing Plates)

Large OD aluminum backing washers (also called backing plates or spreader plates) are used under bolt heads or nuts in thin sheet or GRP (glass-reinforced plastic) panel fixing applications where the normal washer OD is insufficient to prevent pull-through. Manufactured from 2.0–4.0 mm AA5052 or AA3003 sheet in OD sizes from 40 mm to 150 mm with various hole diameters. These are used in solar panel mounting systems, composite panel cladding, boat deck fittings, and thin-wall enclosure assembly applications.

Custom Aluminum Washers to OEM Drawing

Non-standard washer profiles — square, rectangular, kidney-slotted, D-shaped, or multi-hole — are manufactured from aluminum sheet using compound or progressive dies for OEM programs with specific fit and function requirements. Custom washers may incorporate formed tabs for locking, countersunk holes for flush assembly, or multiple bolt holes for use as tie plates or mounting flanges. All custom washer tooling is produced in-house with CAD-based die design and first article inspection per the customer’s acceptance criteria.

Applications by Industry

• Electrical Equipment Assembly: Load-spreading washers under electrical terminal bolts, bus bar connections, and ground lug fasteners in distribution boards, switchgear, and panel boards where galvanic compatibility with aluminum conductors is required.
• Plumbing and Hydraulics: Bonded aluminum sealing washers in hydraulic port plugs, compression fittings, water meter connections, and conduit glands for leak-free fluid-tight sealing.
• Automotive and Transportation: Structural flat washers and shim washers in body panel fastening, suspension system assembly, and powertrain mounting in aluminum-intensive vehicle structures.
• Marine and Offshore: AA5052 washers for through-deck fastenings, deck fittings, and mooring equipment where seawater corrosion resistance and non-magnetic properties are required.
• Solar and Renewable Energy: Large OD aluminum backing washers and standard flat washers in solar panel racking systems, mounting bracket assemblies, and junction box fixing points.

Manufacturing Process

Standard aluminum washers are produced by compound die press operations where blanking (cutting the OD) and piercing (cutting the ID) occur simultaneously in one press stroke. Aluminum sheet or strip coil is fed into the die at a controlled pitch; a tandem operation produces washers at 200–500 strokes per minute. Die clearance is set at 5–8% of sheet thickness to control burr height. Parts are tumbled to remove sharp edges and inspected by gauging a sample for ID, OD, and thickness against AQL 2.5. CNC-turned shim washers are produced from aluminum bar on CNC lathe centers to ±0.02 mm thickness tolerance. Surface treatment (anodize, chromate) is applied post-punching before final inspection and packing.

Quality Standards and Certifications

• ISO 9001:2015 Certified
• Dimensional conformance to DIN 125, DIN 433, DIN 988, ISO 7089/7090, ASME B18.22.1
• Material conformance to ASTM B209 / EN 485 with chemical composition test reports
• RoHS and REACH compliant; non-magnetic certification available
• Bulk packaging with part number, material grade, lot number, and country of origin labeling

Why Choose Brass & Copper Parts India

• DIN and ASME Both Covered: We manufacture to both metric DIN/ISO and imperial ASME standards from a single facility — simplifying dual-market procurement for USA-based distributors supplying both markets.
• Material Traceability: Full heat-traceability of aluminum sheet with ASTM B209 / EN 485 material certs — essential for OEMs requiring documented material supply chains.
• Sealing Washer Capability: Bonded rubber-aluminum sealing washer production in-house — a specialized product typically sourced from multiple suppliers, available here from a single source.
• High-Volume Bulk Supply: Millions of washers per month capacity; distributor-pack bulk cartons with OEM labeling available.

Frequently Asked Questions

What is the difference between DIN 125A and DIN 125B aluminum washers?

DIN 125A is the “normal” (standard) OD series where the washer OD and thickness are sized to the bolt diameter. DIN 125B is the “large OD” series with a larger outside diameter for greater load distribution on softer materials. Both are available in AA1050, AA3003, and AA5052 from stock.

Why use aluminum washers instead of steel washers?

Aluminum washers are used instead of steel when: (1) galvanic compatibility with aluminum structures is required to prevent bimetallic corrosion; (2) non-magnetic or non-sparking properties are needed; (3) weight reduction is a design requirement; or (4) corrosion resistance in outdoor, marine, or chemical environments is required without additional surface treatment.

What is the conductivity of AA1050 aluminum washers?

AA1050 (99.5% pure aluminum) has an electrical conductivity of approximately 57–61% IACS (International Annealed Copper Standard), making it suitable for use as electrical bonding washers, grounding lug spreaders, and current-carrying structural components where moderate conductivity is required.

Can you supply metric and imperial sizes in the same order?

Yes. We maintain tooling and stock for both DIN/ISO metric sizes (M3–M48) and ASME/ANSI imperial sizes (#4 through 2″). Mixed metric/imperial orders are supplied in the same shipment with clear per-SKU labeling.

What is the minimum order quantity for aluminum washers?

For standard DIN 125 / ASME B18.22.1 sizes in AA3003 or AA5052: no minimum order for catalog sizes; bulk pricing starts at 1,000 pieces per SKU. Custom washers: MOQ 500 pieces with tooling. High-volume distributor orders: 100,000+ pieces with container-load pricing.

Are your aluminum washers RoHS compliant?

Yes. All aluminum alloy washers supplied by Brass & Copper Parts India comply with RoHS 3 Directive 2011/65/EU (amended 2015/863) and REACH SVHC requirements for export to USA and EU markets.

Can you supply anodized aluminum washers with specific colors?

Yes. Type II anodize is available in clear (natural silver), black, blue, red, green, and gold colors for product identification and aesthetic purposes. Color consistency within a batch is controlled by anodize time and dye concentration. Please specify the RAL or Pantone color reference for custom color requirements.

What is the flatness tolerance for aluminum sealing washers?

For bonded aluminum sealing washers to achieve effective fluid sealing, the aluminum carrier ring is produced with a flatness of ≤ 0.1 mm per 25 mm diameter. This ensures even compression of the rubber face during assembly and a consistent seal line around the full circumference of the washer.

Suggested Internal Links

• All Aluminum Parts
• Aluminum Stamped Parts (related product)
• Aluminum Brackets and Pipe Brackets (related product)
• Fasteners and Fixings

Request a Quote for Aluminum Washers

Brass & Copper Parts India supplies aluminum flat washers, sealing washers, shim washers, and custom aluminum washer forms to USA distributors, electrical OEMs, and industrial assembly manufacturers. Specify your standard (DIN/ASME), size, alloy, quantity, and surface treatment for a competitive quotation. Contact us today.