Self Drilling Screws are designed specifically for drilling through thin sheet metal, and are available in a range of head types and drives. Stainless Steel Self Drillers are manufactured from 410 grade stainless steel which is harder than the 300 series grades.
The key feature apart from the grade of stainless steel is the self drilling tip which is the part of the screw that drills the hole, the specially shaped flute clears the swarf from the hole for the threaded part of the screw to tap. The main thing to remember is that the total thickness of the sheets being fastened cannot exceed the length of the self drilling tip of the screw, otherwise the thread will strip or the screw will jam in the hole.
Countersunk Head Square Drive Self Drillers have a countersunk or flat head so that when drilled into the sheet the head of the screw will sit flush with the surface of the sheet metal. Identified by their head type, drive, nominal diameter in gauge and length (overall length) they are available in 8 and 10 gauge and from 3/4Â to 2Â in length.
Pan Head Self Drilling Screws are available in square and phillips drive and have a flattened dome head shape with a flat base. The wide flat base of the head offers excellent holding ability, also identified by their head type, drive type, nominal diameter in gauge and length (from under the head).
Countersunk Head Square Drive Black Self Drillers the countersunk head on these screws allows them to sit flush with the surface of the object, these screws are black in colour while still made of 410 grade stainless steel, commonly used in the aluminium joinery industry. Identified by their head type, drive, colour, nominal diameter (as a metric value) and overall length.
Bimetal HWF Self Drillers take their name because they have a 304 grade stainless steel head and body with a steel tip, they offer a cheaper alternative to the Hardtec and Marutex range and can also preform better in the head and body than their 410 grade counterparts in corrosive environments. Often used with Alucabond and other forms of Aluminium cladding because 304 grade stainless is less passive than 316 grade or Hardtec/Marutex which means their will be slightly less galvanic corrosion with the Aluminium. As an added feature the Bimetal Self Drillers are coated with Ruspert Coating for an extra 500 hours salt protection.
Bimetal Self Drillers are identified by their Material Type (Bimetal), Head type, nominal diameter and length (from under the head).
Hardtec and Marutec HWF Self Drillers are branded types of Stainless Steel similar to 410 grade stainless the Marutex and Hardtec offer higher resistance to corrosion more in line with the 300 series grades, greater breaking torque than the 300 series grades and are hardened for better drilling. They are available in HWF head type only and can be driven with a nutsetter.
Wingtek Self Drillers have a countersunk head and are available in Phillip's drive only, they feature wings at the base of the thread but above the self drilling tip. Designed for drilling through wood and then into metal, the wings create a larger hole through the timber than the diameter of the thread of the screw keeping the thread clear of debris, when the wings hit the steel they break off and the thread taps itself into the steel.
For Australian customers - see also Stainless Steel Self-drilling Tek Screws Australia