S-91166A230 4.3 mm ID x 9 mm OD DIN 125; ISO 7089 General Purpose Washers

Key Features & Benefits at a Glance

• Superior corrosion resistance with zinc plating that protects against rust and extends service life in demanding environments
• Exceptional load distribution thanks to precise 9mm OD and 4.3mm ID dimensions, preventing surface damage and loosening under M4 screw pressure
• Enhanced durability from Rockwell B75 hardness, maintaining shape and performance under repeated stress and vibration
• Guaranteed interchangeability through compliance with DIN 125 and ISO 7089 standards, ensuring reliable fit in global metric applications
• Consistent thickness control (0.7-0.9mm) for uniform clamping force and reduced assembly variability
• Environmental compliance with RoHS 3 and REACH regulations, making them safe for restricted substance-sensitive industries
• Cost-effective maintenance by reducing fastener replacement frequency through robust zinc-plated steel construction

Professional Applications & Engineering Value

These M4 flat washers deliver critical engineering value by solving common industrial fastening challenges. The zinc plated steel construction provides a sacrificial layer that combats corrosion in humid or chemical-exposed settings, preventing thread seizure and joint failure. With precise metric dimensions adhering to DIN 125 and ISO 7089, they ensure perfect alignment and pressure distribution for M4 screws, reducing stress concentrations on soft materials. This is vital in assembly lines, machinery, and automotive applications where vibration resistance and long-term reliability are paramount. The consistent 0.7-0.9mm thickness and Rockwell B75 hardness further prevent embedding and deformation, offering predictable performance in high-cycle production environments.

Specification Summary & Compliance

This flat washer maintains tight dimensional tolerances as per DIN 125 and ISO 7089 standards, with inner diameter of 4.3mm, outer diameter of 9mm, and thickness ranging 0.7-0.9mm. It is manufactured from zinc plated steel with a hardness of Rockwell B75, suitable for screw size M4. The product fully complies with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring adherence to environmental and safety requirements for industrial use.