Effects of screw insertion on screw withdrawal strength

The effect of chipboard screw sizes on screw withdrawal strength was investigated using different screw insertion technique. Large diameter chipboard screw has a thicker screw thread depth than small size chipboard screw. If large chipboard screw tested on screw withdrawal test, then it will have significantly, higher screw withdrawal strength than smaller chipboard screw because it will have better particle grip during screw insertion. The objective of this study is to determine screw withdrawal strength of three difference sizes chipboard screw using different types of screw insertion technique; self-drilling, pilot-hole and P+CSK insertion technique. Screw withdrawal strength of different sizes of chipboard screw was measured through its resistance after insertion to the particleboard panel using different style of screw insertion technique. Results obtained shows that the best practice for screw selection was based on screw insertion technique. Samples from three different screw sizes with self-drilling screw insertion technique have met the minimum requirement of screw withdrawal strength. Smaller chipboard screw which is 3.5M CS has the highest screw withdrawal strength when applied with self-drilling screw insertion technique. However, this small diameter of chipboard screw did not meet minimum standard requirement when applied with both screw insertion technique which used pilot-hole pre-drilling; pilot-hole and P+CSK screw insertion technique. The result shows only large chipboard screw applied with pilot-hole insertion technique has better screw withdrawal strength compared to small chipboard screw. There is no significant different of screw withdrawal strength for self-drilling screw insertion technique. This suggests that chipboard screw sizes or screw thread depth did not affect the screw withdrawal strength unless it was applied with pilot-hole pre-drilling. (C) 2015 IASE Publisher. All rights reserved.