Metric single tab safety lock washers, defined in the DIN 93 standard published by the German Institute for Standardization (DIN), are used as locking devices designed to prevent the washer from turning relative to the bolt or shaft. Long-claw washers have a single outer tab that protrudes from the washer, and it is this tab that, when correctly positioned, prevents the washer from turning. Single tab safety lock washers are manufactured from steel and stainless steel with diameters ranging from M1 to M39.
The requirements in the DIN 93 standard are under the following headings:
Metric tab washers are used with hex head screws or hex nuts to prevent them from turning. Most lock washers rely on friction or spring load between the fastener and mating surface to keep a fastener from coming loose, whereas tab washers are bent against the side of the fastener to prevent it from turning. Metric tab washers have a tab and a large outer diameter. The protrusion bends against part of the mating surface, and part of the round part of the washer bends against the head of the fastener.
Stainless steels for single tab safety lock washers are divided into three groups: austenitic, ferritic and martensitic. Austenitic steel is by far the most common type (more than 90 percent of commercial fasteners). Steel groups and strength classes are indicated with four-digit letters and numbers as shown in the table in the standard. The DIN EN ISO 3506 standard contains the requirements for screws and nuts made of stainless steel.
Washers are normally used to distribute the load of threaded fasteners such as screws or nuts. A locking washer, with a side tab that can bend against a nut, has a metallic or non-metallic, tabbed washer notch that prevents rotation relative to the spindle or fastener.
Among the numerous tests, measurements, analyses, and evaluations our organization provides for businesses in various sectors, we also offer testing services for single-thread safety lock washers in accordance with the DIN 93 standard, thanks to our trained and expert staff and advanced technological equipment.
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