Ribbed Safety Lock Washer S Series - Regular Duty | A4 Stainless Steel (SUS316)

FULLERKREG Ribbed Safety Lock Washers S Series (Regular Duty) in A4 Stainless Steel (SUS316 / 1.4401) conform to DIN 9250 Type S. These conical washers feature fine radial ribs on both bearing faces. Under bolt load, the conical profile flattens elastically to maintain clamp force, while the ribs grip mating surfaces to prevent rotation and self-loosening - ideal for marine, chemical, and high-corrosion environments where A2 grade is insufficient.

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Product Overview

• Standard: DIN 9250 Type S (Schnorr-type ribbed safety lock washer, Regular Duty)
• Series: S - Regular Duty (standard wall thickness and cone height)
• Material: A4 Stainless Steel (SUS316 / 1.4401)
• Surface Treatment: Passivated & Whitened
• Thread Range: M1.6 - M30
• Serration: Fine radial ribs on both top and bottom faces
• Function: Anti-loosening, vibration resistance, elastic pre-load retention
• Also known as: Schnorr washer, conical spring washer, Belleville lock washer, toothed conical washer

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Dimensional Data - DIN 9250 Type S Regular Duty (A4 Stainless Steel)

All dimensions in mm. Data per DIN 9250 Type S standard.

Thread Size	Inner Dia. d1	Outer Dia. d2	Thickness s	Height h (Min)	Height h (Max)
M1.6	1.7	3.2	0.3	0.5	0.6
M2	2.2	4	0.35	0.5	0.6
M2.5	2.7	4.8	0.45	0.6	0.8
M3	3.2	5.5	0.45	0.8	0.9
M3.5	3.7	6	0.45	0.8	0.9
M4	4.3	7	0.5	0.9	1.0
M5	5.3	9	0.6	1.0	1.1
M6	6.4	10	0.7	1.1	1.2
M6.35	6.7	9.5	0.7	1.1	1.2
M7	7.4	12	0.7	1.2	1.3
M8	8.4	13	0.8	1.3	1.4
M10	10.5	16	1.0	1.5	1.6
M11	11.6	15.5	1.0	1.5	1.6
M12	13	18	1.1	1.6	1.7
M12.7	13.7	19	1.1	1.7	1.8
M14	15	22	1.2	1.9	2.0
M16	17	24	1.3	2.0	2.1
M18	19	27	1.5	2.2	2.3
M20	21	30	1.5	2.3	2.4
M22	23	33	1.5	2.4	2.5
M24	25.6	36	1.8	2.6	2.7
M25.4	27	38	2.0	2.7	2.8
M27	28.6	39	2.0	2.8	2.9
M30	31.6	45	2.0	3.1	3.2

Note: All A4 Stainless Steel fasteners may exhibit slight magnetic properties due to cold forming. Refer to ISO 3506-2 Annex I. For sizes M33 and above, please contact FULLERKREG for availability.

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A4 vs A2 - Which Grade Should You Choose?

Property	A2 (SUS304)	A4 (SUS316) - This Page
Base Alloy	18% Cr, 8% Ni	16% Cr, 10% Ni, 2% Mo
Molybdenum Content	None	2-3% - key for chloride resistance
Corrosion Resistance	Good - indoor / mild outdoor	Excellent - marine, chemical, coastal
Chloride Resistance	Limited	Superior (pitting and crevice corrosion)
Recommended Environment	General industrial	Marine, food processing, chemical plant
Price	Standard	Premium

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Selection Guide - S Series vs VS Series

Series	Duty	Wall Thickness	Cone Height	Spring Force	Best For
S (this page)	Regular Duty	Standard	Standard	Medium	General industrial, standard bolt loads
VS	Heavy Duty	Thicker	Higher	High	Heavy machinery, high pre-load, severe vibration

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How It Works - Schnorr Ribbed Safety Lock Washer

The S Series washer operates on two simultaneous locking mechanisms:

• 🔩 Conical spring action - the cone profile stores elastic energy under bolt load. As the bolt tends to loosen, the washer pushes back, maintaining clamp force and preventing loss of pre-load.
• 🔒 Radial rib grip - fine ribs on both faces bite into the bolt head/nut bearing surface and the joint surface, creating mechanical resistance to rotation in both directions.

Washers can be stacked in the same direction to multiply spring force, or in opposite directions (back-to-back) to increase deflection range while maintaining locking grip.

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Standard & Compliance

DIN 9250 specifies ribbed safety lock washers (Schnorr-type) in two series:

• Type S - Regular Duty (standard dimensions, this page)
• Type VS - Heavy Duty (increased thickness and cone height)

DIN 9250 is functionally equivalent to and cross-referenced with:

• NFE 25-511 (French standard, serrated conical washers)
• ISO 10673 (plain washers, related geometry)
• Schnorr original specification (industry reference)

FULLERKREG washers are manufactured to full DIN 9250 Type S dimensional compliance. Material certification (EN 10204 3.1) available on request for bulk orders.

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Material & Surface Specification

Property	Specification
Material Grade	A4 Stainless Steel (SUS316 / 1.4401)
Surface Treatment	Passivated & Whitened
Corrosion Resistance	Excellent - suitable for marine, coastal, and chemical environments
Magnetic Properties	Slightly magnetic after cold forming (per ISO 3506-2 Annex I)
Temperature Range	-196°C to +300°C (continuous service)
RoHS Compliant	Yes

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Key Features & Technical Advantages

• 🔩 Dual locking mechanism - conical spring pre-load + radial rib grip on both faces
• 🔄 Reusable - washers retain locking strength if not deformed or damaged during removal
• ⚡ Electrical conductivity - ribs penetrate oxide layers for reliable grounding and bonding
• 🌊 Superior corrosion resistance - A4/SUS316 with molybdenum for marine and chemical environments
• 📐 Precision manufactured - tight dimensional tolerances per DIN 9250
• 🔀 Stackable - stack same-direction for higher force; back-to-back for greater deflection
• 🏭 Bulk supply ready - available in bags, boxes, and custom packaging for production lines

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Typical Applications

• Marine and offshore structures, deck fittings, and hull assemblies
• Coastal and waterfront construction
• Food processing equipment and pharmaceutical machinery
• Chemical plant pipework and pressure vessels
• Swimming pool and water treatment installations
• Electrical cabinets in humid or corrosive environments
• Rail and transportation equipment in salt-spray zones

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Product Gallery

Ribbed Safety Lock Washer S Series Regular Duty - A4 Stainless Steel

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Why Choose FULLERKREG?

🏆 Standard Compliance - Full DIN 9250 Type S dimensional conformance, with NFE 25-511 cross-reference support
🔬 Material Traceability - EN 10204 3.1 mill certificates available for A4 grade
📦 Flexible MOQ - Small batch samples to full production quantities; custom packaging available
🌍 Global Shipping - Reliable export logistics to Europe, North America, Southeast Asia, and beyond
💬 Technical Support - Engineering team available for selection guidance, stacking calculations, and custom specifications
⚙️ Broad Range - S Series and VS Series available in A2, A4 stainless steel and 65Mn spring steel grades