Three Common Problems of Automatic Screwdriving Machines: Floating, Stripping and Missing Screws

An automatic screwdriving machine cuts the missing-screw rate from a few tenths of a percent (manual) to below 0.02% — provided the equipment stays in a stable state. Floating screws, stripped threads and missing screws are the three most common field problems, and most trace back to incoming parts or parameter settings rather than a broken machine.

1. Floating: the screw is tight but not seated

A floating screw is tightened but not flush with the reference surface. Typical causes: torque set too low, burrs or debris in the hole, or a shorter effective thread when washers are used. Check the hole condition first, then re-verify torque. The equipment-side answer is closed-loop torque plus float detection — if a gap is still detected after the driver completes its stroke, the station alarms and the NG point can be re-positioned and re-driven.

2. Stripping: the thread fails to engage

The signature of a stripped thread is torque reached but no engagement — usually caused by torque too high, re-driving the same hole, or a screw-to-hole mismatch. Prevention beats cure: calibrate the torque window to the screw specification, forbid repeated driving at the same point in the program, and check that screw length matches hole depth. A stripped screw slips and heats; continuing to drive also damages the bit, so stop the machine and handle the point immediately.

3. Missing: the screw never arrives

Missing screws trace back to the feeding chain: a screw jammed in the rail, air-pressure fluctuation in blow feeding, or the program continuing after a failed pick-up. The answer is triple error-proofing — rail empty alarm, pick-up confirmation signal, and cross-checking driven count against point count. Feeding stability also depends strongly on incoming screws: oily screws, mixed specifications or loose washers all cause feeding failures; controlling incoming material works better than tuning the machine.

4. A universal checking routine

When something goes wrong on site, check in a fixed order: first incoming parts (specification, cleanliness, packaging), then the feeding chain (rail, air pressure, separator), then torque and stroke parameters, and only then mechanics and controls. Most "equipment failures" stop at the first two steps.

Send us your parts and screw samples: our automatic screwdriving machines support floating, stripping and missing-screw detection with NG re-driving — run a trial first to verify takt and yield before discussing a proposal.