If you are installing hardware such as hinges on plastic you will want to avoid drilling the pilot hole fully through the material for aesthetic reasons. Each screw size is described using two numbers – the ‘M’ number and a number indicating the length of the shank, in mm, so M2 screw dimensions of M2 x8, are 8mm long, measured under the screw head. Trilobular stainless steel self-tapping screws are ideal in situations where vibration is present as their thread design reduces friction during thread forming whilst providing resistance to vibrational loosening.

They differ from self-tapping screws as they drill their own pilot holes and tap threads simultaneously. Simply put, if you attach thick pieces of material, you will need a self-drilling screw with a flute to match. The flute on these screws is very small and the diameter of the hole it drills is smaller than the diameter of the outside screw thread.Boat engines cause the boat frame to vibrate which can result in other fasteners such as nails or regular screws falling out. For hard substrates such as metal or hard plastics, the self-tapping ability is often created by cutting a gap in the continuity of the thread on the screw, generating a flute and cutting edge similar to those on a tap. Flute Length – The length of the flute determines the thickness of the metal that a self-drilling screw can be used on.

To ensure a tight fit when reattaching window furniture, extra thickness is added to UPVC screws to ensure a secure fit and material for the screw to bite into. Suitable for a variety of jobs our wood screw range contains features such as shanks that reduce wood split, twin threads for a fast and accurate drive and tips that do not require any pre-drilling. The “M” designation for metric screws indicates the outer diameter of the screw in millimetres, so for an M2 screw, the outer diameter is 2mm. When using self-tapping screws in plastic it is advised that you drill a pilot hole before screwing in the self-tapping screw. The advantage of self-tapping screws for aluminium is that they don't need pre-drilling and are easily removed without damaging the metal.When using self-tapping screws in fibreglass, you will find that the drilling tip of the screw becomes dull quickly as it comes into contact with the glass fibres, which leads to cracking in the glass fibres and the gel coat.

The drill point creates a hole, and then the screw's threads engage the material, providing secure fastening. Thread-Tapping: These screws do not require a pilot hole but one can be drilled to make fastening easier. When using self-tapping screws on aluminium, choose a self-tapping screw with a drill-like point and sharp cutting blade threads that extend down the whole length of the screw.

When selecting the screw length, you should account for the length of material you are drilling through. This will avoid the drill head melting if too much RPM is applied or snapping if too much pressure is applied. When the wings engage with the metal they will break off, allowing the threads to engage in the metal. Self-tapping screws are different from traditional screws as they tap their own threads when screwed into plastic, wood, or metal. The action of driving the screw in will result in the self-tapping screw cutting a thread into the material and securing the materials together.