Screwdriver Clutches and Torque Repeatability

The mechanical shut-off clutch in a Kilews Electric Screwdriver is engineered to provide very good torque repeatability. When a fastener is being installed, the screwdriver’s clutch is a key component in the process, but it is only a part of the overall picture – final results will be determined by a combination of the operator input, the screwdriver, the fastener quality, and the consistency of the parts being assembled.

Operator Input – It is important to hold the screwdriver with a firm grip, using enough force to prevent any slippage or rotation in the hand, and to maintain a consistent grip force throughout the rundown. The screwdriver needs to be kept inline with the fastener during the rundown – holding the driver at an angle to the fastener can have a detrimental effect on the results. Remember, in a handheld application the operator acts as the torque reaction arm for the rundown process.

Fasteners and parts – Make sure that you are using the correct screwdriver bit for the fastener being installed, and that the bit stays engaged properly with the head of the fastener during the entire rundown. Use quality fasteners – keep in mind that the screwdriver is applying a rotational torque at speed (eg. 700 rpm) to the head of the fastener. If the fasteners are inconsistent, this can result in variations in frictional losses at the fastener threads and under the head of the fastener during tightening. For the same reason, the parts that are being assembled need to be consistent without misalignment.