Can Lock Washers Be Reused?

Reuse of lock washers is generally not recommended. In most cases, they are designed for single-use. However, under certain conditions (such as no distortion of lugs, no damage to the mating surfaces), it can be carefully reused. Here's a breakdown:
1.Reasons for Single-Use
Mechanical Deformation is irreversible
Locking gaskets can bend the gaskets to accommodate the grooves in the nuts or connectors to prevent loosening. After installation, the lugs will undergo plastic deformation (i.e., permanent deformation) and willnot be able to return to their original shape. If reused, the lugs may not deform into tight grooves, causing the lock to be lost.
Risk of damaging the Mating Surface
Bending lugs can lead to scratches or indentations on the surface of nuts or connectors. Repeated use can aggravate these injuries, reduce fitting accuracy, and even cause stress concentration, affecting connection strength.
Industry Norms and standards
According to national standards (e.g. GB/T98-1988 Technical Specification for Lock Cleaning Machines), the technical requirements for lock washing machines are unclear and not to be reused. In practice, in order to ensure safety, companies generally adhere to the principle of "single use", especially in key sectors such as aerospace and rail transportation.
ii. Reusability exceptions
No Plastic Deformation
If the ear of the gasket remains elastic after initial use (i.e., there is no irreversible deformation) and the mating surface is not damaged, try reusing. However, specific tools should be used to test the strength of the ears to ensure sufficient elasticity.
Low-risk, Non-Critical Scenarios
In static or low vibration environment (such as common mechanical equipment mounting bracket), if the gasket and mating surface are in good condition, they can be reused carefully. However, the connection requires to be checked regularly to prevent accidental loosening.
Specially Designed Washers
Some lock washers are made of high-strength materials (such as stainless steel) or have special features (such as adjustable ears) that allow for multiple disassembly and assembly. However, they are more expensive and require strict adherence to the manufacturer's instructions.
III. Pre-Reuse Testing Criteria
If you want to reuse a lock washer, you must meet the following conditions:
Ear integrity Inspections
The ear must be free of cracks, fractures or excessive deformation. The bending angle meets the design requirements (e.g. fully embedded nut slot).
For example, use a caliper to measure the size of a curved lug to ensure that the deviation from the initial value does not exceed ±0.1mm.
Mating Surface Condition Assessment
There are no scratches, indentations or rust on the surface of nut and connectors.
Compatible with The mating surface flatness tolerance not exceeding 0.05mm (detectable by detector).
Risk: Damage to the mating surface may prevent lugs from fastening and reduce the anti-loosening effect.
Material Performance Verification
If the washing machine is made of a high strength material such as stainless steel, make sure it has no hydrogen embrittlement or stress corrosion.
For example, use a hardness test (such as Rockwell hardness tester) to verify that the material's performance is up to standard.
IV. INTRODUCTION Industry Practice Recommendations
At key junctures
In aerospace, nuclear power, etc., Threaded connections must be used once. Even if they appear to be intact, the principle of ``safety first"should be upheld.
In non-critical connections
For example, in building brackets and general mechanical equipment, if gaskets and mating surface are in good condition, they can be reused carefully, but the number of times they are removed and assembled should be recorded and replaced periodically. Manufacturer's Guide: It is best to refer to the washer manufacturer's technical manual. Some products,such as special alloy lock gaskets, may be clearly labelled as "reusable" or "recommended for single-use."