Self-clinch fasteners flow and form the panel material into special recesses in the base of the fastener as its being pressed into the metal using a squeezing action. So what do you need to know?
- The fastener must be harder than the material it is being set into. If this is not the case the fastener deforms during installation and can come loose at any time. Aluminium and steel self-clinch fasteners are especially hardened so that they can be installed securely into aluminium or mild steel panels without a problem. Standard CLS or FHS stainless steel self-clinch fasteners can be installed into steel or aluminium – but should not be installed into 300 grade stainless panels. If you need to install a stainless fastener into stainless steel, PEM offers either 400 grade fasteners or especially hardened SP 286 grade fasteners which will install into 300 grade materials. In a nutshell always use the correct grade of fastener for the material you are using.
- Use the correct equipment. As already mentioned self-clinch fasteners must be installed using a squeezing action. This means using a press – hammering and other impact methods are a strict no-no! Fly presses can be used if they can generate enough force, however many users underestimate the loads required to install a fastener. For instance setting an M4 S nut into a steel panel can require up to 2.75 tonnes of force to install it; alternatively an M5 nut can require up to 3.9 tonnes. An FH M4 stud on the other hand can require nearly 3 tonnes and an M6 stud can require up to 4.5 tonnes. Generating these forces are well beyond many manual presses – and equally importantly the operators using them. Obviously at the very least installing self-clinch inserts with a manual press is going to be anything but consistent. Zygology Ltd and PEMSERTER/Haeger offers a complete range of presses suitable for anything from simple single shot installation through to multi-bowl continuous feed.
- Not using the correct tooling. When working with thinner panels special tooling is required to allow the panel material to flow correctly during installation. If incorrect tooling is used the material has nowhere to go and the fastener can easily be deformed rather than installed correctly. This results in the fastener being simply wedged into the hole and failure at some point is almost inevitable.
- The industry is currently flooded with cheap – but extremely poor quality self-clinching fasteners primarily from Asia. These fasteners are responsible for a high proportion of installation failures and other quality issues we are asked to inspect. The standard of fastener manufacture can be amazingly poor. Issues we see include:
- Poorly formed under head clinch elements which mean that installation forces need to be higher – and even then a correct bond is not created.
- Fasteners not hard enough – meaning the fasteners can deform during installation
- Fasteners too hard – means the fasteners can be brittle and fail under load.
- Fasteners within a batch can be too soft and too hard.
- Supposedly stainless steel fasteners which are not actually stainless at all.
- Fasteners from a single supplier sourcing parts from bucket shops can display any or all of these characteristics at any time.
All of the above factors make it almost impossible to get reliable and consistent results – even when you think you are purchasing parts from a single source.
When looking at most assemblies the fastener cost is normally a very small percentage of the total cost of the assembly – so saving even 50% on the fastener cost actually renders very little over all saving, and quite often just a few pence. Given that a fastener failure can require an entire panel to be scrapped or re-worked using poor quality fasteners really is unwise. PEM manufactured parts are made to the highest quality standards in state of the art factories primarily in Galway in Southern Ireland, or North America adhering to stringent quality processes and offering full quality documentation and product traceability.
Given that a part costing so little can have a direct impact on the quality of the work you produce and the image of your company why even think about trying to save on such important parts?
For More information on the PEM range of Self clinching fasteners click here
If you would like to make an enquiry about a standard part, or would like to enquire about having a special part made to your specifications, you can call us on 0808 123 1221 or email sales@zygology.com
