NP
Contact us You can contact us using any of the methods below. Unit 3 Durham Lane Armthorpe Doncaster South Yorkshire DN3 3FE England +44 (0)1302 836010 +44 (0)1302 836012 sales@npfasteners.com
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NORTHERN PRECISION LTD
Accreditations Northern Precision Ltd operate a quality management system in accordance with ISO 9001:2008. The ISO 9001:2008 standard is recognised worldwide and you can be assured of the benefits of working with a certified company knowing that our management systems are constantly assessed and improved.
Registered in England & Wales Company number 3275391
V.A.T Registration number GB 684 1384 17
NP
NORTHERN PRECISION LTD
Specialist Fasteners for Sheet Metal
+44 (0) 1302 836010
+44 (0) 1302 836012
Tel:
Fax:
sales@npfasteners.com
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When installing our self-clinching fasteners, providing all technical requirements are met and installation instructions are followed, you shouldn’t have any issues. There are so many permutations of fastener type, size, panel material characteristics, hole preparation,  installation and tooling configuration that it is impossible to cover absolutely everything here. This is the reason we state that the performance figures given for our fasteners are offered as guidance only. Installing self-clinching fasteners in harder panels presents its own set of challenges and potential issues, so it is important to stay within recommended limits, follow the installation instructions and use the correct punch and anvil for each fastener.
Problem Tight threads, poor performance. Part falls out of panel.
Cause The panel is above the recommended hardness limit for the fastener. Solution For correct installation, self-clinching fasteners need to be harder than the panel material they are being installed into. You must pay attention to the maximum panel hardness limitation for the specific fastener type you are installing.
Fastener deformed, bulging sides and tight threads. Limited displacement of panel material.
Fastener Material vs Maximum Panel Hardness
Fastener Material
Max. Panel Hardness
Aluminium Unhardened Steel 300 Stainless Steel Hardened Steel Hardened Stainless Steel
HRB 50 HRB 60 HRB 70 HRB 80 - 85* HRB 88 - 92* * Dependent on fastener type
Typical panel hardnesses
Panel Material
Panel Hardness
5052-H32 Aluminium Cold-rolled Steel 6061-T6 Aluminium Annealed 304 Stainless Steel High Strength Low Alloy Steel (HSLA)
HRB 15 - 30 HRB 40 - 75 HRB 50 - 55 HRB 80+ HRB 80-85 Properties vary so testing is recommended
It is important to understand how self-clinching fasteners work. The fasteners serrated clinching ring, knurl, ribs, or hexagon head is pressed into the panel surface, displacing material into a specially designed annular recess in the body, shank or pilot of the fastener. The metal displaced into the undercut secures the fastener against axial movement (push-out), while the knurling, ribs or non-round head resists rotation (torque-out). Due to the requirements of this process, metal panels into which the fastener will be installed must have  adequate ductility to allow the displaced panel material to cold flow into the undercut without fracturing. Also, the host metal panel must always be sufficiently softer than the fastener to prevent fastener deformation during installation and provide the required performance in service. Some important points to consider when installing self-clinching fasteners in stainless steel panels. The panel must meet the minimum thickness recommended for the fastener. Specify the proper stainless alloy for fastener installation into stainless steel panels. A common misconception is that all stainless self-clinching fasteners can be installed in all stainless steel panels. This is not true. Standard stainless self-clinching fasteners made from 300 series stainless cannot be installed in 300 series stainless panels, because of the hardness differential between fastener and panel. Only 400 series stainless or parts made from precipitation hardened stainless are suitable for installation in stainless steel panels. Make sure your selected fastener material meets the required corrosion requirements. The panel material should be in the annealed condition. Make sure that the mounting hole is the specified size for the fastener you are installing. Maintain the hole  punch diameter to no greater than +0.025 mm over the minimum recommended mounting hole. Make  certain that hole punch is kept sharp to minimize work hardening around hole. Always install from the punch side of the panel. Is is important that the fastener is not installed adjacent to bends or other highly cold-worked areas, as localised work hardening can mean that panel material hardness around the hole can be above the hardness limit of the fastener. Make sure you have determined the optimum installation force for the application by testing prior to  production runs. Some fasteners may call for an anvil with a staking ring to act as a second displacer. It is important that this type of anvil is used when installing into stainless steel panels to ensure correct installation and optimal performance.  
ANVIL PUNCH
SELF-CLINCHING FASTENERS INSTALLING IN HARDER PANELS