Harrison Silverdale Ltd Unit 1 Traso Business Park. Callywhite Lane. Dronfield, Sheffield, S18 2XR Tel: 01246 296 930 • Fax: 01246 296 940 Email: [email protected] Internet: http:/fwww.harrisonsilverdale.co.uk Series 20117 Type HPI Inserts, offer very hard wearing threads in lighter alloys, preventing the stripping of threads where multiple installation / removal of the mating screw is likely. They are also suitable for repairing damaged threads in alloys and castings.. There is no requirement for pre- tapped holes, they simply press into a pre-drilled hole using a toggle or fly press. All information is given for guidance only and designers should satisfy themselves as to the suitability of the specification by requesting samples