SELF TAPPING, SELF DRILLING, THREAD CUTTING

Explaining the Confusion !!

Self Tapping, Self Drilling, Thread Cutting …. So what is what ???

Self Tapping Screws work in most materials, but often can require a pilot hole.  There are 3 different types of thread and point patterns.

Type A: Found on Sheet Metal (Tapping) Screws

Type A tapping screws have coarse threads and gimlet points. They are used in thin metal, resinous plywood, and various composite boards.

Type AB: Found on Sheet Metal (Tapping) Screws
Type AB tapping screws have spaced threads and gimlet points. Like the Type A, they are used in thin metal, resinous plywood, and various composite boards. Type AB screws offer a wider range of applications over Type A screws.

Type B: Found on Sheet Metal (Tapping) Screws

Type B tapping screws have spaced threads and a blunt point with incomplete entering threads. They are used in thin metal, nonferrous castings, resinous plywood, plastics, and various composite boards.

Self Drilling Screws (AKA Tek Screws) are for metal only and do not work well in wood because the hole that they drill in the wood is too large and the screw loses much of its initial holding power.

Teks screw (Self-Drilling Screw)
Type 2

 Type 3

Teks screws, also known as self drilling screws, drill their own hole in thin sheet metal, heavier gauge metals and other materials, then form close mating threads in the hole. The Teks screw is ideal for automated assembly and reduces or eliminates the need for drill bits or taps. Once the hole is drilled, Teks screws (self drilling screws) tap the hole in the same way as thread forming or thread cutting screws do in a pre-drilled hole. They are also designed to eliminate paint build-up, weld flash, or foreign material that may occur in pre-drilled or pre-punched holes.

Thread Cutting Screws like self tapping screws have a variety of points. They work best in thicker materials as they cut their own threads similar to a Tap.

Type 25: Found on Thread Cutting Screws

Also known as Type BT, Type 25 screws have spaced, incomplete tapered threads with a blunt point and tapered entering edges, with one or more cutting edges and chip removal indentations. They are used in plastic, asbestos compositions, and other composites.

Type F: Found on Thread Cutting Screws

Type F screws have machine screw threads with a blunt point and tapered entering edges, with one or more cutting edges and chip removal indentations. They are used in nonferrous castings, steel sheets, plastics, brass, cast iron, etc.

Type 23: Found on Thread Cutting Screws

Also known as Type T, Type 23 screws have machine screw threads with a blunt point and tapered entering edges, with one or more cutting edges and chip removal indentations. In this sense they are similar to Type F screws. The cutting edge on the point, however, is broader and deeper than that of the Type F. Type 23 screws are also used in nonferrous castings, steel sheets, plastics, brass, cast iron, etc.

 

 

 

Posted by Mark and Joni Corby

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