What are Most Common Methods for Sheet Metal Fastening?

Sheet metal fastening methods are an integral part of manufacturing, construction, and even simple day-to-day applications from simple staples to heavy-duty attachments used in many industries. Sheet metal fastening methods are used to join multiple components made up of sheet metal or any other material. They are available in a wide range of standard shapes, sizes, and materials, and can also be produced custom for specific needs.

Sheet metal fasteners are usually separated into two distinct groups – those that produce a permanent bond and those requiring either a releasable or a sliding bond. The primary benefit of sheet metal fasteners is that they are able to bear significant loads before reaching a breaking point. They are mainly classified in two ways:

• Light-Duty Sheet Metal Fasteners: They are used in standard commercial applications and even in some medical items, for example, pet buckles, hip pins, tactical products, tent applications, bags, and straps, etc.
• Heavy-Duty Sheet Metal Fasteners: They are standard in manufacturing or hefty applications, like vehicle and aircraft cargo tie-downs. Some of these metal fasteners can sustain loads of 750 pounds and more before hitting a breaking point.

With an appropriate investment in right bolts, screws and rivets for any planned job, right metal fastening technique is also an important consideration. For e.g. in the automotive world, appropriate metal fasteners are critical for holding major components together so the car can function smoothly. One has to ensure that fasteners are installed properly ensures the quality of the repair and improves the look of the components that have been brought together.

The Most Common Sheet Metal Fastening Method is as follows:

• Welding: Welding is historically one of the most common sheet metal fastening methods. This process is versatile, being applicable in a wide variety of projects and jobs. The welding technique is a fabrication process consisting of two or more parts fused through heat or pressure. This process involves melting the edges of two metal pieces and letting them cool together and fusing them. The pieces are connected with a strong and nearly unbreakable bond. The durability achieved with this sheet metal fastening method is unmatched. Welded joints can be stronger than the combined base metals, perfect for items that need a lot of stabilization. While that strength is an advantage, it also means the results are permanent so it's not useful for items that has to be removed or to be adjusted in future.

Conventional fasteners used for this method include tack weld and spot weld fasteners. They provide physical, strong bonds between sheet metals, resulting in high structural performance. During welding, sheet metal can get extremely hot which may reduce the sheet metals' strength, damaging crucial service coating. Welding can be dangerous due to the amount of hands-on work and high temperatures involved. It produces sparks and other fire risks when in close contact. As with various engineering methods It’s a lengthy and time-consuming manual process that requires a high degree of skill. Finding the right people for the job can be costly as it requires a lot of special training and a proper workspace.

• Self-Clinching: Self-Clinching technology is an innovative and most commonly used sheet metal fastening method that provides environmental benefits and saves time and money. It is found in all those industries where two components need to be held together. This method involves installing the fastener into an anvil hole and placing the mounting hole over the fastener's shank. Using accurate self-clinching technology can push the metal to deform, causing it to cold flow into a specially designed recess in the shank or pilot of the fastener. The most important consideration while applying self-clinching sheet metal fastening method is to analyze the hardness of the sheet metal. Knowing the sheet metal hardness can enable self-clinching selection for any type of standard material, including stainless steel and aluminum panels. As a robust solution for any type of sheet metal, self-clinching fasteners can provide stable threads or attachment in a sheet metal as thin as 0.30 mm/.012”.

Specific self-clinching fasteners used for sheet metal fastening include: floating nuts, blind and flush nuts, miniature nuts, flush-head studs, pins etc. This sheet metal fastening method minimizes energy consumption, thus its cleaner and more environmentally friendly method with no weld splatter and less carbon footprint. It can be installed, easily and efficiently, into a plain round hole, with no secondary operations needed. Due to the lack of heat source this sheet metal fastening method ensures that there are no weak points which makes the joints stronger and reduces the chance of thermal stress. As this sheet metal fastening method has a less installation cycle times and good in-die installation capability for both medium-volume and high-volume applications, this leads to shorter production cycles and cost savings. It also provides truer thread positional tolerance.

• Bolting: This is another sheet metal fastening method which is pretty straightforward and involves using bolts, nuts and washers to secure components. This method gives a strong and stable hold quickly, and if it is to be removed, it can be tightened or loosened as per the need. This makes bolting a good option for items that may require adjustment in the future. To get the best hold and stabilizing effect, one has to ensure the right size and shape bolts for the job. Each bolt must be tightened to the proper torque to have a lasting hold. One has to pay attention to the type of material used to make the bolts, nuts and washers since certain metals can react to one another and potentially corrode, leading to breakage.

• Riveting: Riveting is a well-established sheet metal fastening method, and the outcome is a strong bond created by the process. A metal rivet is lined up with premade holes in metal pieces. Then the rivet is driven through the hole, and one end of the rivet deforms, locking the parts in place. When done correctly, riveting can offer as much stability as welding but with less equipment and setup. Rivets hold up to high-stress environments very well, making them suitable for cars and machines that are subject to a lot of movement. This is one of the sheet metal fastening method that is meant to be permanent, and thus the rivets should be placed very carefully.
• Adhesive Bonding: While many sheet metal fastening methods are meant to mechanically fit into the sheet metal holes, adhesive bonding method is sometimes used to secure parts as well. For metal work, adhesive bonding is achieved by using high-strength glues and compounds to secure parts. Surfaces need to be prepared properly so the adhesive can form a solid bond.

• Threaded Inserts: Using many sheet metal fastening methods on soft or thin materials can be tough, but threaded inserts are a good option. A space is made for a small cap, called a tap bolt, and the fastener is screwed or threaded into that cap rather than directly into the material. This prevents tearing or warping that can happen when dealing with materials that aren't very tough. The threads create a tight and secure hold for all the parts. Threaded inserts can withstand high loads and prevent stripping or wear on the components. They are also good for situations where disassembly and reassembly are likely occurrences since they can be unscrewed and replaced easily.

Also Read: Basics of Sheet Metal Fabrication, a Cost-Effective, Time-Sensitive Manufacturing Process