Clips not screws – An Alternative
There are times when a screw or threaded product just won’t fit the attachment requirements. Not enough space, backside clearance, not reachable with the attachment tool, has to be installed prior to other sub-assemblies, and a whole set of other problems that preclude the use of the familiar bolt, nut and screw attachment method. Then the use of industrial clips fasteners makes sense. Although the clip may seem more costly at first glance, an examination of their features and usage may surprise you.
Better Strength with less visibility
Most clips are made of high carbon steel which allows for strength without stripping and their design allows them to easily slip over the metal without gouging or jamming. Negatives are the facts that a hole must be formed (drilled or punched in the die forming step of the metal) and the clip located at an edge for installation. Also, there is an extra labour step to install and the added cost of another part increases assembly cost. One often overlooked advantage is the fact that the attachment can be accurately located whereas a screw could possibility is misallocated by an inexperienced operator.
Clips fit in tight spaces
Clips have effectively solved the thin metal problem in a lot of areas. Easy to install (just push on), operator friendly (hand installed), and easy to fasten with the required screw. They come in a variety of shapes to fit specific requirements. The most common type is the “J-U” single impression clip used in many locations in automotive sheet metal attachments. It was estimated several years ago that the daily usage of this part type in the automotive industry was over one million pieces per day.
Better fit newer designs
While the designs of the impression hole of the U-nut (the mating thread area for the screw) have been patented by various companies, they all operate pretty much the same and have so for more than 70 years. Over that time little change has occurred beyond a few minor improvements. A retainer ring was swaged from the inner hole to prevent the part from falling out too easily, variations in nut thickness to accommodate varying metal thickness and stripping properties, and various lengths to accommodate varying edge and locational requirements. The increase in thinner sheet metal meant that retention of the U-nuts to the metal dropped; power tool proliferation meant more cross threads, loosening, and stripped threads.