"Eye Washer" co-developed by TODA and Katecs is a color-forming special lock washer used with bolts, through which the user can determine the axial force on the lock bolt by visual check. TODA and Katecs stick two pressure-measuring films on the back of plastic washers.

As the pressure starts to act on the washer, the color former will come out and color the washer red. The operator can check the diameter of the red zone with his naked eye to determine the axial force acting on the bolt head. This is a way cheaper than using an axial force gauge and the setup is easy.

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