Self-Clinching Fasteners: What You Need To Know

What Is A self-clinching Fastener?

Self-clinching fasteners are engineered threaded devices that are used to hold thin, light materials (i.e. sheet metal or aluminum) together. They come in a variety of sizes, materials and configurations, including Nuts, Studs, Standoffs and Spacers. Additional series available include, but are not limited to, floating, self-locking, blind-hole, flush, and broaching styles. They are sometimes referred to as press-fit or clinch style captive fasteners.

How Does A Self-clinching Fastener Work?

A self-clinching fastener works by being pressed into an existing hole in ductile parent material that is softer than the fastener device. Parallel Squeezing forces are applied to both sides in a specific way to cause the fastener material to cold flow into the parent material. The fasteners have knurls, ribs or serrated rings that helps create the bond with the parent material and provide torque resistance. This cold flow creates a strong bond where the fastener becomes a permanent part of the parent sheet metal.

Captive self-clinching fasteners are pressed into holes in sheet metal by applying a steady squeezing force. This results in the cold-flow of sheet material, which is displaced by the knurl, into the undercut area on the shank of the fastener. Once fully embedded, the knurled area prevents torque-out during tightening of the mating part. Captive broaching fasteners are pressed into printed circuit boards and non-ductile materials and held permanently in place by an interference fit. Both self-clinching and broaching types withstand high push-out and torque-out forces. Captive weld nuts are self piloting into holes and are round, eliminating the need for indexing. Pilot shanks protect threads from weld spatter.

What are the advantages of Self-Clinching fasteners?

Some of the key advantages include:

COST EFFECTIVE: Minimal assembly process, fewer parts, reduced installation time

STANDARD PLAIN ROUND HOLE INSTALLATION: No chamfering or special hole preparation is needed

MORE HOLDING POWER: Can be stronger than stamped or tapped threads especially in thin material

Installation of Self-Clinching Fasteners

One of the benefits of Self-Clinching Fasteners is there quick, easy, cost-effective 3 step installation process. In three easy steps, self-clinching fasteners can be installed with and anvil and any parallel acting press that can be adjusted to optimum installation forces.

Dos and Don’ts of Self-Clinching fastener Installation?

Captive Fasteners of New Jersey, one of the world’s leading manufacturers of Self-Clinching Fasteners, has published a hand list of the top 11 Installation best practices, including videos.

To achieve the correct installation results for Captive Self-Clinching Fasteners, please follow the 11 simple rules listed below:

DO:

1. Provide the properly sized mounting hole for each fastener.
2. Place fastener in hole on punched side of panel.
3. Be sure the fastener shank or pilot is squarely within the hole before pressure is applied.
4. Apply a steady squeezing force between press and anvil.
5. Use sufficient force to embed the clinching ring around its entire circumference.

DO NOT:

1. Do not install steel and stainless fasteners in aluminum before the panels have been anodized.
2. Do not deburr mounting holes, as the rough metal is used to help clinch the fastener into the sheet.
3. Do not install the fastener closer to the edge of the sheet than specified in the dimension table for the fastener in use.
4. Do not over squeeze, as this may flatten the fastener head, distort the thread and buckle the panel.
5. Do not install fastener with a hammer blow; doing so does not allow sufficient time for the sheet metal to flow into the clinching profile. A squeezing force is required for optimum performance.
6. Do not install the screw in the head side of the fastener, but from the opposite side, which directs the load toward the sheet.

Other Notes: The parent material MUST be harder than the host sheet material, you must have access to both sides of the sheet metal. All that is needed to prepare the parent material is for the proper size hole to be drilled or punched to accept the fastener.

PEM®, Captive, Generic & Functional Self-Clinching Equivalents

The oldest OEM and the most recognizable name in the Self-clinching device space is PEM® Engineering. Self-clinching fasteners are often called out by the PEM® OEM brand name. Captive Fastener is a USA based OEM in New Jersey stocking functional equivalents to PEM® branded self-clinching fasteners. Other options such as major national catalog brands, including Mcmaster-Carr, Grainger, Fastenal, MSC stock self-clinching fasteners. frequently referred to by the OEM brand name PEM®. These functional alternatives will be equivalent in form fit and function and offer similar performance.

When purchasing functional equivalents, ensure they confirm to the industry or OEM standard to ensure interchangeability. COnformance to the industry standards, will enables them to be fed through all standard automatic insertion equipment, and provide a substitute for form, fit and function.

To see if using alternative brands or functional equivalents will work for your business, refer to our handy guide.

Cross Reference

We have also included a cross reference lookup table for PEM® product types vs. Captive product series that can be found on our site.

Industries and applications

Self-clinching fasteners are used in both commercial and military applications by producers of telecommunication, computer, medical, automotive, and aerospace equipment and systems.

 Here is a list of applications:

• ATM’s
• Agriculture Equipment
• Air bags
• Alarm Systems
• Appliances
• Arcade Games
• Automotive
• Avionics
• Black Boxes
• CATV
• Computers
• Control Panels
• Copiers
• DVD Players
• DVR’s
• Fabricated Metal
• Facsimile
• Food Processing
• Gaming Machines
• Gas Pumps
• Hospital Beds
• Laser Equipment
• Medical Equipment
• Microwave Equipment
• Modems
• Office Furniture
• Power Supplies
• Printers
• Stereo Equipment
• Telecommunication
• Telephone Systems
• Televisions
• Test Equipment
• Truck Roll-up Doors
• Vending Equipment

Other Factors to Consider

One of the best ways to save on cost and cut delivery time is to cross the OEM brand part on your bill of materials to a functional equivalent. Among the most popular brands are: 

This is a handy Functional Equivalent check list to see if you must use an OEM brand or if your customer will allow you to cross to a functional equivalent.

If you’re looking for an accurate, high-quality manufacturer & distributor of self-clinching fasteners, partner with MF Supply. They have both the most common and unusual Self-clinching fasteners, including commercial and mil-spec parts in inch and metric, special sizes, materials, and platings. You can review their catalog and easily place your product order, right here! They live up to their tagline: MF Supply, The Right Screw for you!