Description

AM Steel Star Washers are toothed lock washers featuring a ring of flexed teeth, arranged either around the outer edge (external tooth, DIN 6797 Type A) or around the inner bore (internal tooth, DIN 6797 Type J). Manufactured under the AM Steel brand, the teeth on both configurations bite into the surface of the fastener head and the mating material as the joint is tightened, creating mechanical resistance to loosening while also helping absorb shock, vibration, and minor slippage in the connection.

The choice between external and internal tooth star washers depends primarily on the fastener’s head diameter: external tooth star washers are best suited to fasteners with larger head diameters – such as pan head, button head, and truss head screws – since the teeth need enough head surface to bite into for a strong locking grip. Internal tooth star washers, by contrast, are the better choice for fasteners with smaller heads, such as JIS machine screws or cheese head screws, and offer the practical advantage of a smooth outer edge that won’t catch or snag on nearby components or wiring – a useful feature in electronics and enclosure assembly.

AM Steel star washers are available in steel (zinc-plated, black phosphate, or bare finishes) and stainless steel (A2/304 general-purpose, and A4/316 marine-grade for wet or corrosive environments), covering diameters from M2 up to M30 and beyond. Whether you’re assembling electronics enclosures, automotive components, HVAC equipment, or general machinery, AM Steel star washers provide a widely used, cost-effective option for basic anti-loosening protection. As with all AM Steel products, this star washer is available in metric sizing per DIN 6797, in multiple grades, materials, and finishes to suit both industrial-grade and everyday fastening needs.

Key features:

• Flexed teeth bite into both the fastener head and mating surface for locking grip
• Available in external tooth (DIN 6797-A) and internal tooth (DIN 6797-J) configurations
• Internal tooth style has a smooth outer edge to avoid snagging nearby components
• Helps absorb shock, vibration, and minor slippage in the joint
• Available in steel (zinc-plated, black phosphate) and stainless steel (A2/304, A4/316)
• Backed by the quality assurance of AM Steel

Ideal For

AM Steel Star Washers are ideal for:

• Electronics and enclosure assemblers using internal tooth star washers where a smooth, snag-free edge matters
• Automotive and machinery technicians securing components subject to vibration
• General equipment manufacturers using external tooth star washers with larger-headed screws like pan or truss head
• HVAC and electrical panel installers needing basic, cost-effective vibration resistance
• General maintenance and repair work wherever a widely available, simple lock washer is needed

Choosing the Right Star Washer

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

1. Tooth Configuration – External tooth (DIN 6797-A) for fasteners with larger head diameters (pan, button, truss head); internal tooth (DIN 6797-J) for smaller heads (JIS, cheese head screws) or where a smooth outer edge is needed.
2. Material – Stainless steel (A2/304 or A4/316 marine-grade) for corrosive, damp, or outdoor environments; steel (zinc-plated or black phosphate) for general indoor use.
3. Size – Match the washer’s inner diameter to the bolt or screw diameter, per DIN 6797 sizing (M2 to M30 and beyond).
4. Snag Risk – Choose internal tooth washers in electronics or wiring-dense assemblies where an external tooth’s protruding edge could catch or snag.
5. Surface Finish Sensitivity – Consider that the teeth will mark or bite into the mating surface, which may not be desirable on finished or cosmetic surfaces.
6. Vibration Level – Star washers suit general, moderate-vibration applications; for more demanding joints, evaluate whether a stronger locking method may be warranted.

Strategies to Choose the Right Product

• Match tooth style to fastener head size – Use external tooth star washers with larger-headed screws for the best locking grip; use internal tooth washers with smaller heads or where a smooth edge is needed.
• Match material to environment – Choose stainless steel (A2/304 or A4/316) for damp, corrosive, or outdoor environments; zinc-plated or black phosphate steel for general indoor cost-effective use.
• Avoid star washers on cosmetic or finished surfaces – Since the teeth bite into the mating material, consider a plain washer or alternative locking method where surface marking isn’t acceptable.
• Buy in matched sets – Purchase star washers alongside compatible bolts, screws, and nuts sized to the correct diameter.
• Prioritize certified standards – Look for DIN 6797 compliance for guaranteed dimensional and tooth-geometry consistency.
• Consider bulk vs. individual packs – Bulk packs suit electronics or machinery production runs; smaller packs suit repairs or small assemblies.

Mechanical Properties

AM Steel Star Washers are manufactured to meet recognized mechanical and dimensional standards, ensuring reliability across electronics, automotive, and general machine assembly applications:

These mechanical ratings confirm that AM Steel star washers are well suited to general vibration-resistance applications – always match tooth configuration to the fastener head size for the best locking performance.

Frequently Asked Questions (FAQs)

1. What is a star washer used for? A star washer is used beneath a bolt or screw head to resist loosening from vibration, with its teeth biting into both the fastener head and the mating surface for a locked, secure connection.

2. What’s the difference between an external tooth and internal tooth star washer? An external tooth star washer (DIN 6797-A) has teeth extending outward from the outer edge, best suited to larger-headed screws, while an internal tooth star washer (DIN 6797-J) has teeth extending inward from the inner bore, better suited to smaller heads and offering a smooth, snag-free outer edge.

3. Are AM Steel star washers different from generic toothed lock washers? AM Steel star washers are manufactured and quality-tested under the AM Steel brand, ensuring consistent tooth geometry, dimensions, and finish across every batch, per DIN 6797.

4. Why would I choose an internal tooth star washer over an external tooth one? Internal tooth star washers have a smooth outer edge that won’t catch or snag on nearby wiring or components, making them a common choice in electronics and enclosure assembly, especially with smaller-headed screws.

5. Are star washers corrosion-resistant? Yes, especially AM Steel stainless steel star washers (A2/304 or A4/316 marine-grade), which resist rust in damp, corrosive, or marine environments; zinc-plated steel offers moderate protection for general indoor use.

6. What sizes do star washers come in? AM Steel star washers are available in a range of sizes, typically M2 to M30 and beyond in metric, per DIN 6797.

7. Will a star washer damage the surface it’s tightened against? Yes, to some degree – the teeth are designed to bite into the fastener head and mating surface to create locking resistance, which means star washers aren’t ideal for cosmetic or finished surfaces where marking isn’t acceptable.

8. Can star washers be reused? Generally not recommended for critical applications, since the teeth can bend or flatten once compressed and loaded, reducing their locking effectiveness on reinstallation.

9. What’s the difference between A2 and A4 stainless steel star washers? A2 (304) stainless offers good general corrosion resistance for most indoor and outdoor use, while A4 (316), considered marine-grade, provides superior resistance to chlorides and wet or coastal environments.

10. Are star washers suitable for high-vibration or safety-critical applications? Star washers provide general, moderate vibration resistance; for particularly demanding or safety-critical joints, many engineers supplement or replace them with alternative methods such as thread-locking compound or prevailing-torque lock nuts.

11. What tools do I need to install a star washer? No special tools are needed for the washer itself – installation uses whatever tool matches the drive type of the bolt or screw being tightened through it.

12. What industries commonly use star washers? Common applications include electronics and enclosure assembly, automotive components, HVAC and electrical panel installation, and general machinery manufacturing.

13. Do star washers work with all screw head types? Star washers work best when matched appropriately – external tooth washers with larger-headed screws (pan, button, truss head) and internal tooth washers with smaller-headed screws (JIS, cheese head) – for the most effective locking grip.