What happens during installation
A self-drilling screw first establishes the point, drills through the steel, engages its thread and then clamps the connected parts. Problems often occur when the driver is treated as an on-off tool and the change from drilling to thread engagement is ignored.
Rotational speed
Running too fast can create unnecessary heat at the point and reduce drilling efficiency. Very low speed can also give poor or unstable drilling with some screw and substrate combinations. The suitable range depends on the product, so a controllable driver is preferable to operating continuously at maximum RPM.
Axial pressure
Enough axial pressure is needed to keep the cutting edges working. Too little pressure can make the point rub or skate on the surface. Too much can overload the point and makes the screw harder to control when it breaks through the steel.
At breakthrough
Tool resistance changes quickly when the point exits the steel. The screw then moves from drilling into thread engagement. Good control at this stage helps avoid point damage, thread stripping and sudden overdriving.
Final seating
With sealing washers, the target is correct washer compression rather than maximum tightening. Too little compression can leave an incomplete seal. Too much can distort the washer, damage the sheet or strip the engaged thread.
Common site problems
- using a screw beyond its stated drilling range;
- running the driver continuously at excessive speed;
- insufficient pressure while the point is drilling;
- driving the screw at an angle;
- continuing to tighten after the washer is correctly seated;
- reusing a stripped hole without checking whether the connection is still acceptable.
Site check
Use the installation parameters given for the selected screw where available. In the field, watch drilling time, alignment, point behaviour and final seating. A noticeable change in any of these is worth investigating before continuing with a large number of fixings.
This resource explains selection principles. Final product suitability, drilling range and resistance must be verified against the applicable JOPAL technical data for the specific fastener and project condition.
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