Description

AM Steel Plain Washers are simple, flat discs with a central hole, placed beneath a bolt head or nut to spread the clamping force over a wider bearing surface. This even load distribution reduces surface damage, prevents the fastener from digging into softer materials, and helps maintain consistent clamping pressure over time. Manufactured under the AM Steel brand, these washers follow the modern ISO 7089 (flat, without chamfer) and ISO 7090 (flat, with chamfer) standards – both of which effectively replaced the older DIN 125 standard, which had itself split into two types (DIN 125A without chamfer, DIN 125B with chamfer) now carried forward as their ISO equivalents.

One detail worth understanding when specifying plain washers: the hardness classification changed between the old DIN standard and the current ISO standard. DIN 125 used a single 140 HV hardness rating, whereas ISO 7089/7090 introduced two distinct hardness classes – 200 HV and 300 HV for steel washers (and 200 HV for stainless steel). According to ISO 7089, a 200 HV washer is intended for use with bolts and screws up to and including property class 8.8, while a 300 HV washer should be used with property class 10.9 bolts and screws, since a softer washer can deform or “dish” under the higher preload these stronger bolts generate – a detail that’s commonly overlooked but important for joint reliability.

AM Steel plain washers are available in steel (200 HV and 300 HV, in plain, zinc-plated, zinc-flake, or hot-dip galvanized finishes) and stainless steel (A2/304 and A4/316, both typically at 200 HV), covering everything from general indoor assembly to outdoor and corrosive environments. Whether you’re assembling machinery, securing structural connections, or completing general construction work, AM Steel plain washers provide the load distribution and surface protection every properly engineered bolted joint needs. As with all AM Steel products, this plain washer is available in metric sizing (M1.6 to M64 per ISO 7089/7090), in multiple hardness classes, materials, and finishes to suit both industrial-grade and everyday fastening needs.

Key features:

• Flat, circular design distributes clamping load over a wider bearing surface
• Manufactured to ISO 7089 (without chamfer) and ISO 7090 (with chamfer) standards
• Available in 200 HV and 300 HV hardness classes to match bolt property class
• Available in steel (plain, zinc-plated, HDG) and stainless steel (A2/304, A4/316)
• Reduces surface damage and helps maintain consistent clamping pressure
• Backed by the quality assurance of AM Steel

Ideal For

AM Steel Plain Washers are ideal for:

• General machine and equipment assemblers needing reliable load distribution beneath bolts and nuts
• Construction and structural contractors protecting timber, steel, and other bearing surfaces from fastener damage
• Automotive technicians ensuring consistent clamping pressure in bolted assemblies
• Precision engineering and manufacturing requiring correctly matched washer hardness for higher-grade bolts
• DIY and general maintenance work wherever a bolted joint needs a simple, dependable washer

Choosing the Right Plain Washer

Selecting the correct plain washer from the AM Steel range depends on several factors:

1. Hardness Class – 200 HV for use with property class 8.8 bolts and screws; 300 HV for property class 10.9 bolts and screws, since higher-grade bolts generate more preload than a softer washer can safely handle.
2. Chamfer – ISO 7089 (no chamfer/flat edge) for general use; ISO 7090 (chamfered edge) where specified, functionally similar but with a sloped edge detail.
3. Material – Stainless steel (A2/304 or A4/316) for outdoor, marine, or corrosive environments; steel for general indoor or cost-sensitive use.
4. Size – Match the washer’s inner diameter to the bolt or screw diameter, and outer diameter to the required bearing surface area.
5. Finish – Zinc-plated or zinc-flake for indoor/general outdoor use; hot-dip galvanized for long-term outdoor exposure.
6. Bolt Property Class Compatibility – Always cross-check the washer’s hardness class against the property class of the bolt or screw it will be paired with, per ISO 7089 guidance.

Strategies to Choose the Right Product

• Always match washer hardness to bolt grade – Use 200 HV washers with Class 8.8 bolts and 300 HV washers with Class 10.9 bolts, since this is a commonly overlooked detail that affects long-term joint integrity.
• Match material to environment – Choose stainless steel (A2/304 or A4/316) for corrosive, outdoor, or washdown environments; steel for general indoor use.
• Confirm chamfer requirements – Check whether your application or drawing specifies ISO 7089 (no chamfer) or ISO 7090 (chamfered) before ordering in bulk.
• Buy in matched sets – Purchase plain washers alongside compatible bolts and nuts of the correct property class for a properly engineered joint.
• Prioritize certified standards – Look for ISO 7089/7090 compliance for guaranteed dimensional and hardness consistency, especially important for structural or safety-critical joints.
• Consider bulk vs. individual packs – Bulk packs suit production assembly or large construction projects; smaller packs suit repairs or small builds.

Mechanical Properties

AM Steel Plain Washers are manufactured to meet recognized mechanical and dimensional standards, ensuring reliability across general assembly, construction, and precision engineering applications:

These mechanical ratings confirm that AM Steel plain washers meet current ISO 7089/7090 standards – always match the washer’s hardness class to the property class of the bolt or screw being used for a properly engineered joint.

Frequently Asked Questions (FAQs)

1. What is a plain washer used for? A plain washer is used beneath a bolt head or nut to distribute clamping load over a wider bearing surface, reducing surface damage and helping maintain consistent clamping pressure in a bolted joint.

2. What’s the difference between ISO 7089 and ISO 7090? ISO 7089 covers a flat washer without a chamfer (sloped edge), while ISO 7090 covers the same washer with a chamfered edge – both replaced the older DIN 125A and DIN 125B standards respectively, with no significant dimensional changes.

3. Are AM Steel plain washers different from generic flat washers? AM Steel plain washers are manufactured and quality-tested under the AM Steel brand, ensuring consistent dimensions, hardness class, and finish across every batch, per ISO 7089/7090.

4. What’s the difference between a 200 HV and 300 HV plain washer? A 200 HV washer is intended for use with bolts and screws up to Property Class 8.8, while a 300 HV washer is designed for higher-strength Property Class 10.9 bolts and screws, since a softer washer can deform under the greater preload these bolts generate.

5. Do I need to match my washer hardness to my bolt grade? Yes – using a washer with insufficient hardness for a high-grade bolt can lead to washer deformation (“dishing”) under load, reducing the clamping force and reliability of the joint over time.

6. Are plain washers corrosion-resistant? Yes, especially AM Steel stainless steel plain washers (A2/304 or A4/316), which resist rust in outdoor, marine, or corrosive environments; hot-dip galvanized steel washers also offer strong outdoor protection.

7. What sizes do plain washers come in? AM Steel plain washers are available in a range of sizes, typically M1.6 to M64 in metric, per ISO 7089/7090.

8. Is DIN 125 still used, or has it been replaced? DIN 125 has been officially withdrawn and replaced by ISO 7089 and ISO 7090, though DIN 125 washers remain commonly referenced and available, particularly in the United States; there are no significant dimensional differences from the current ISO standards.

9. What material should I choose for a plain washer? Choose stainless steel (A2/304 or A4/316) for outdoor, marine, or corrosive environments; steel with a zinc-plated, zinc-flake, or hot-dip galvanized finish for general indoor or standard outdoor use.

10. Can plain washers be reused? Yes, as long as the washer isn’t deformed, cracked, or excessively worn, plain washers can typically be reused in non-critical applications; deformed or “dished” washers should be replaced.

11. What’s the difference between A2 and A4 stainless steel plain washers? A2 (304) stainless offers good general corrosion resistance for most indoor and outdoor use, while A4 (316) stainless provides superior resistance to chlorides and marine environments.

12. Do plain washers affect bolt preload or torque? Yes – the presence, hardness, and finish of a washer can affect the friction and preload achieved for a given torque, which is why properly matched, standard-compliant washers are important in torque-critical applications.

13. What’s the difference between a plain washer and a fender washer? A plain washer follows standard proportions (per ISO 7089/7090), while a fender washer has a significantly larger outer diameter (roughly 3 times its inner diameter) relative to the bolt size, providing extra bearing surface for softer materials or larger clearance holes.