Thread Forming Screws - Pozidrive Countersunk

A countersunk head is usually used when no part of the fastener head is required to be protruding above the level of the substrate. Countersunk heads can also be recessed and filled over if a hidden fixing is required. Usually abbreviated to CSK.

Thread forming screws are also commonly called taptites or tritap screws, or sometimes thread rolling screws. They are used to form threads during insertion, usually in metal, to eliminate the need for thread tapping as a separate process.

Thread forming screws are manufactured from case hardened steel and are zinc plated. They have what is called a trilobular thread pattern – which actually means three lobes, signifying a shape that is “triangle-round”. This unusual thread pattern reduces friction as the thread is being formed, and adds resistance to vibration.

It is important to understand the difference between thread forming screws and self tapping screws. Self tappers work by cutting out and removing material from the receiving part that they are being driven into. Not much driving force or torque is needed for this operation. Thread forming screws however displace the mating material so that it flows into the threads of the screw. Unlike self tappers no material is actually removed, so this creates a fit that has zero clearance, meaning that lock washers are rarely required. Higher torque is needed to use thread forming screws.

There are various head types available, namely hexagon, countersunk pozidrive or pan pozidrive.