Standard Washers and Spacers
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Surface Protection and Load Distribution
The primary function of our standard flat washer collection (DIN 125 / ISO 7089) is to protect the surface of the mating part from damage during the tightening process. When a bolt or nut is torqued, the rotational friction can mar the substrate, particularly if it is a softer material like aluminum or plastic. By placing a plain washer between the fastener head and the workpiece, the clamping load is distributed over a larger surface area. This reduces the localized pressure (psi) preventing the fastener from embedding into the material or crushing it. Our washers are stamped with precision to ensure a flat, smooth bearing surface, which is essential for achieving a consistent preload in critical bolted joints across manufacturing sectors.
Vibration Control with Helical Spring Washers
For assemblies subject to dynamic loads or machine vibration, relying solely on torque is often insufficient to prevent loosening. Our spring lock washer series (DIN 127B) addresses this by introducing a mechanical locking function. These washers are split and formed into a helical shape. When compressed, the split washer exerts a continuous spring force against the nut and the mating surface. This tension increases the friction at the thread interface, counteracting the rotational forces that lead to loosening. Additionally, the trapezoidal cross-section of the split ends bites slightly into the metal surfaces, providing a physical barrier against back-off rotation, making them a staple in automotive and heavy equipment maintenance.
Material Grades for Corrosive Environments
We manufacture every washer in our catalog to withstand specific environmental challenges. Our inventory is heavily focused on Stainless Steel grades A2 (304) and A4 (316). The A2 grade provides excellent resistance to atmospheric corrosion and is ideal for general outdoor or indoor use. For marine environments or chemical processing plants where chloride exposure is a concern, our A4 flat washer offers superior pitting resistance. We also supply standard carbon steel washers with zinc plating for general industrial applications. The strict control of material hardness is crucial; our washers are hard enough to prevent deformation under the bolt head but ductile enough to seat properly without cracking.
Advantages
Optimized Geometry for Fastener Compatibility
The dimensional accuracy of a plain washer dictates its effectiveness. A hole that is too loose can cause the washer to shift off-center, leading to uneven loading, while a hole that is too tight may interfere with the bolt shank radius. Screwtool manufactures DIN 125 washers with precise clearance hole tolerances to ensure perfect concentricity with standard metric bolts. This geometric precision ensures that the washer sits flat and maximizes the contact area. Furthermore, the chamfered edges on our high-end washers prevent potential injury to assembly line operators and ensure no burrs interfere with the seating of the bolt head.
Reactive Spring Tension Mechanics
The technical advantage of a spring lock washer lies in its reactive energy. Unlike a static flat washer, the helical design acts as a stored energy spring. If the bolted joint undergoes thermal expansion and contraction, or if the gasket material settles over time (embedment relaxation), the split washer expands to maintain tension on the assembly. This “live” load helps preserve the integrity of the connection even when the initial torque preload drops slightly. This simple yet effective mechanical principle eliminates the need for expensive chemical thread lockers in many applications, simplifying maintenance and disassembly processes.
Consistent Hardness and Finish
A common failure mode in cheap fasteners is the “dishing” or yielding of the washer under high torque, which effectively results in a loss of clamping force. Our flat washer production involves rigorous heat treatment and hardness testing to ensure the steel meets the required Vickers or Rockwell hardness standards. This ensures that the washer remains rigid and does not cup under the load of Class 8.8 or 10.9 bolts. Additionally, the surface finish is controlled to ensure a consistent friction coefficient (K-factor), which is vital for automated torque-controlled tightening strategies used by modern OEMs.
Use Scenarios
Electrical Cabinet Assembly
An Electrical Engineer assembling control panels requires secure connections for grounding and terminal blocks. The engineer utilizes Screwtool’s brass or stainless steel plain washer to ensure a conductive, flat contact area between the cable lug and the busbar. Because copper lugs are soft, the washer prevents the nut from chewing into the lug during tightening. To ensure the connection does not loosen due to the 50/60Hz hum vibration typical in transformers, the engineer adds a split washer under the nut. This combination ensures electrical continuity and mechanical security for the lifespan of the equipment.
Heavy Machinery Maintenance
A Maintenance Technician repairing an excavator needs to replace bolts on the hydraulic pump housing. The machine operates in a high-vibration environment. The technician selects Screwtool’s DIN 127B spring lock washer made from A4 stainless steel. The choice of A4 is critical because the machine is often washed down with harsh detergents. As the technician tightens the bolts, the split ends of the washer bite into the cast iron housing and the steel bolt head, locking the assembly. The technician relies on the proven spring force of the washer to prevent the hydraulic pump fittings from backing out during digging operations.
Solar Racking Installation
A Solar Installer mounts photovoltaic panels onto aluminum rails. The installer uses M8 bolts equipped with our large diameter flat washer (DIN 9021 or wide DIN 125). The extra surface area of the wide washer is crucial to span the slots in the aluminum rail and prevent the bolt head from pulling through the soft aluminum extrusion. Since the installation is outdoors and exposed to rain, the plain washer must be 316 stainless steel to prevent rust streaks from staining the roof. The durability of the washer ensures the racking system withstands wind uplift forces for decades.
About Us
Shanghai Screwtool Industrial Co., Ltd. is a specialized manufacturer and global supplier of industrial fasteners, operating as a key subsidiary of the Victor Screw Group. Established in 2011, we connect the manufacturing power of China with the quality requirements of the international market. While we produce a vast array of screws and nuts, our stamping and pressing facilities in Lianyungang are dedicated to producing high-precision spacers and the washer category. We supply standard DIN/ISO parts including the flat washer, spring lock washer, and custom stamped parts. Our quality control system ensures full traceability and adherence to material specifications, providing Mill Test Certificates for our stainless steel products. We serve industries ranging from construction and solar energy to automotive and heavy machinery, offering factory-direct pricing and professional logistical support for shipments of any size.
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FAQ
What is the difference between DIN 125 and DIN 127?
DIN 125 is a standard flat washer (or plain washer) used to distribute load. DIN 127 is a helical spring lock washer (or split washer) designed to prevent loosening due to vibration.
Do you supply washers in A4 stainless steel?
Yes, we stock both flat washer and spring washer types in A4 (316) stainless steel for superior corrosion resistance in marine environments, as well as A2 (304) for general use.
Which way should a spring lock washer be installed?
The split washer is typically placed between the nut and the plain washer (or the workpiece). The split ends are designed to bite into the nut to prevent it from turning counter-clockwise.
Can I use a flat washer and a lock washer together?
Yes, it is common practice. The flat washer goes against the part to protect the surface, and the spring lock washer goes on top of the flat washer, under the nut, to provide the locking function.
What is the Minimum Order Quantity (MOQ) for washers?
For standard sizes like M6-M20, we have flexible MOQs, often starting at one carton. For custom-sized spacers or non-standard washer dimensions, the MOQ will depend on the production run requirements.
