How a self-drilling screw is produced h1>
Using the example of a so-called bi-met screw, we show how an EJOT self-drilling screw is produced in a few work steps.
The base material is wire. Since our example is a bi-met screw, the wire is made of stainless steel. The wire is coiled and thus needs to be straightened and cut to the appropriate length.
The wire is upset through cold forming...
...and the final head geometry is made depending on the required screw head. In our example, it is a hexagon screw head.
The upper part of the bi-met self-drilling screw consists of stainless steel so that it offers an ideal corrosion protection and can be used in weather-exposed areas. The lower part, where the drill point is manufactured later on, is made of carbon steel. The advantage of this material compared to stainless steel is that it can be hardened and is thus able to penetrate steel structures without any difficulty.
Now the two materials are welded.
Subsequently, the typical drill point is created. We call this procedure "pinching".
The screw thread is formed with the aid of rolling dies. This is a forming process, no swarfs are created: The screw is now finished and has its final shape.