The terminology fasteners refer to a fairly extensive category of tools like bolts, nuts, and screws that have the same objective: to hold objects mechanically together. Things such as glue can perform this function, but glue is not a fastener. Thus, we need to make an addition to our definition of fasteners. Hardware fasteners hold objects mechanically together.
Self-clinching fasteners are helpful because they are safely mounted into an enclosure or part. There are two types of self-clinching fasteners. These include flush head fasteners and concealed head fasteners:
Flush Head Fasteners
Flush head fasteners are fasteners pushed mechanically through a hole in the sheet metal from outside. Therefore, they mostly sit flat with the edge outside. There is a little indentation around the metal's exterior from where it gets pushed in that makes them noticeable.
This little indentation can be decreased by grinding the metal so this fastener sits flatter with its host material and can be made even less detectable if a textured powdered coat is applied. When employing both these methods, flush hand fasteners are minimally detectable. Nevertheless, they can yet be felt by touch.
Concealed Head Fasteners
Instead of pushing the fastener through a metal sheet like a flush-head, the insertion of concealed-head fasteners is done into a mechanized blind pocket so that the fastener does not have any contact with the edge outside. The creation of the pockets is done with a computerized numerical control router or mill.
Mainly, concealed head fasteners are employed for cosmetic reasons. Nevertheless, they can also ideally satisfy airtightness and water tightness because the hole for inserting the fastener partly goes only through the metal. Concealed-head fasteners can also meet IP rating needs.
A thing to note if you are opting for concealed head fasteners for your design is that they will need a limited sheet thickness. This will ensure that the computerized numerical control router or mill will have sufficient space to deeply machine the hole enough in the metal to produce the pocket where the fastener will sit.
Differences between Flush Head Fasteners and Concealed Head Fasteners
Whereas flush-head and concealed-head fasteners perform the same task essentially, there are some essential ways in which they are different from each other.
Flush head fasteners are pushed through the metal's exterior, while concealed head fasteners are pushed into a pocket from the side through which they are employed.
The installation methods of these two types of fasteners give them different profiles. Flush head fasteners are a little detectable from the outside, though this can be minimized by applying the powder coat and grinding. The profile of concealed head fasteners cannot be noticed. Due to this; they are most commonly employed provided that esthetics have been prioritized.
Capability of being Airtight/watertight
Flush-head fasteners are not water/airtight as they go through the metal. Contrary to them, Concealed-head fasteners are water/airtight and therefore are a good option; it if is necessary to tighten the enclosure for air, radio waves and water.
The price of flush-head fasteners is slightly lower than that of concealed head fasteners. Concealed head fasteners take more time to install due to their mechanized pocket. Both cost a little more than traditional fasteners, but in general fasteners aren't an expensive component of a custom part or enclosure.
Flush-head fasteners and concealed head fasteners differ in terms of height after the installation of fasteners. The measurement of concealed head fasteners is done from the surface's interior, from where a fastener is installed. On the other hand, flush head fasteners are measured from the surface's exterior of the enclosure, from where they get pressed through the metal.