Is Tab Washer the Best Bolt Locking Method?
Tab washers or Nord-Lock washers? Finding the ultimate bolt securing system is no easy task. Here is a guide to making the right choice.
|Tab Washers||Nord-Lock Wedge-Locking|
|Locking capability||Relatively good||Reliable|
|Range||Normally not available for large sizes.||M3-M130 (standard range)|
|Temperature||Same temperature characteristics as regular bolts/nuts.||Same temperature characteristics as regular bolts/nuts.|
|Assembly/disassembly routines||Complex and time-consuming assembly/disassembly. Requires enough space, additional tools and a skilled operator.||Simple and rapid assembly/disassembly. No special tools or preparation required.|
|Control of clamp load||Friction conditions must first be verified in order to predict the clamp load.||Linear relationship between torque/load – thus possible to predict the clamp load.|
|Risk of damage to assembled parts||Some risk. Requires deformation of the washer through shocks, which can damage the assembled parts.||No risk. Fine impression marks on bolt head/nut, as well as underlying surfaces.|
|Environment and safety||Recyclable. Manual assembly routines and long assembly time increase risk of injury, human error
and damage to parts.
|Recyclable. Minimal risk of human injury or error. Rapid assembly time results in minimal exposure in dangerous areas.|
|Lubrication||Possible to lubricate.||Possible to lubricate.|
|Use in confined spaces||Limited use in confined spaces, due to complex assembly requirements.||Suitable for use and easy to assemble in confined spaces.|
|Use with through holes||Time-consuming and difficult to use with through holes. Note that washers on both sides of the assembled parts are required.||Suitable. Note that washers on both sides of the assembled parts are required.|
|Use with hex cap screw (ISO 4762)||Not possible||Possible|
|Life cycle cost (LCC)||High. Short life cycle. A large number of units must be purchased as washers are neither reusable nor standardized.||Low. Relatively high price per unit. Long life cycle. Standardized and reusable items improve stability and minimize maintenance costs.|
Junker vibration test comparison of tab washers vs wedge-locking washers