Self Tapping Screws - Design Guide Considerations
Steel self tapping screws are primarily designed to be installed in metals which allow sufficient plastic deformation, enabling the thread to be formed without the removal of any material. In some cases they can be installed into certain plastics, although it is not recommeneded without investigation and performance evaluation.
If you are considering or using self tapping screws in any plastic parent material, we recommend reviewing our purpose-designed threadforming screws for plastics range of Polymate screws and our design guide article.
The scope and specification of this product family includes an array of head, drive and thread form styles. This document summarises the range and preferred method of application in accordance with the specification laid down by the British Standards Insitution BS4174: September 1972.
The following table summarises the screw type and designation.
Table 1 illustrates industry standard self tapper size options most commonly stocked and used commercially, indicated with a shaded background. The gauge is frequently used to identify and specify the screw diameter in the format No.2 x 1/4 long.
|Gauge||Inches||1/8||3/16||1/4||5/16||3/8||1/2||5/8||3/4||1™||1 1/4||1 1/2||1 3/4||2™||2 1/2|
Note: Due to the fact that fastening applications differ greatly, the above information is for guidance only and is correct to the best of our knowledge. The customer must satisfy themselves with the performance of the fastener and validity of the data. TR Fastenings will not be held responsible for any failure that may occur from the use of this information.