Steel Framing Connections - Clinching Steel framing promises to be a synch with clinching  Steel framing promises to be a synch with clinching. Clinching is a method of joining two pieces of sheet metal by pressing them together into a die that forms a connection similar to a rivet. Fasteners such as a rivet or self-tapping screw are not required with clinching. This technology, although not new, has only recently seen use for attaching residential steel framing members.
There are several different types of clinching equipment. The majority of clinched connections are made with pneumatic or hydraulic tools, although manual clinchers are available. A clincher makes a connection by driving a punch into a die through overlapping material. When the material is forced to the bottom of the die, the die begins to mushroom. The die expands to allow full development of the connection. When the punch reaches its final position, it is withdrawn and the die returns to its original shape. The result is a connection very similar to that of a rivet. Typical point sizes of the punches are 3/16- and 5/16-inches. The strength of a clinched connection is approximately the same as that of a self-drilling screw. Clinching tools are available that will connect up to14 gauge material. The clinching process will not harm the galvanized coating on framing members. 
 | Once the initial investment in the tools and equipment is made, clinching is affordable. However, the initial investment is quite high, and most builders will not choose to purchase the equipment. |  | Clinched connections, once they are made, are very difficult to take apart. The clinching mechanism does not adversely impact the corrosion resistance of the steel. |
There are several manufacturers of clinching tools, but the majority of these are foreign. Many clinching tools are limited to use in a warehouse/factory environment. It can be difficult to loosen connections when necessary. Clinching technology/equipment is not widely available. The use of clinching tools at the home site for steel framing is not as practical as in the plant because of several limitations: • The equipment is too bulky and heavy to move around a site • Access to both sides of an assembly is required and this is often hard to achieve on site. The tools are too large for many applications, or the use of double or triple members is so frequent that access is restricted. • Both screw guns and clinching tools would need to be used, which would usually require switching back and forth between the two on the same assemblies.
Initial investment in the clinching tools and equipment is high and can be out of reach for most builders. However, non-load bearing members can be clinched together using economical hand-held clinching tools. The most economical use of the clinching tools is in a production setting where repetitive tasks are performed.
The operational cost of the clinching tools is quite high, as several dies have to be made for different material thicknesses. The dies wear out quickly and will require replacement.
The majority of manufacturers of clinching technology have not yet obtained national code approval. Many manufacturers do have testing information available on the strength of their connections. One clinching manufacturer (Attexor) currently has an ICBO ES report (ER 5439) which can be used as a basis for acceptance. An acceptance Criteria (AC 137) has also been developed for clinched connections. This Acceptance Criteria is available for clinching manufacturers to develop other evaluation reports.
Field Evaluation Site - Attexor Corporation: Oahu, Hawaii http://www.toolbase.org/tertiaryT.asp?TrackID=&CategoryID=1505&DocumentID=3969
The installation of clinching connections is very simple, the material to be joined is placed between the jaws of the tool and then the trigger is pulled. Typically, these tools are used in panelization processes where walls are assembled in a manufacturing environment.
Not Applicable
Clinching reduces the amount of screws, rivets or welding needed. Less than one second is required per clinch. A flat connection that will not crack gypsum is produced. The risk of hand injuries from sharp screws and metal burrs is reduced. There are no toxic fumes or loud noises. Clinched connections are less susceptible to loosening over time than other types of connections. Clinching facilitates the panelization process. Costs per clinch have been reported to be a fraction of a screw connection (excluding initial investment, which can be very high). | 
