8 minute read
RIVETS
CFS, Product Manager — Proferred Rivets Brighton-Best International
What are the typical riveting faults and how can they be avoided?
To select the correct length for a rivet, measure from the underside of the head to the tip of the stem. The head itself is not included in this measurement.
“These rivets are faulty” or “These rivets don’t seem to work with this rivet gun” are phrases you might have heard (or said before) if working in the construction or fastener industry. Even the best of the best rivet distributors must deal with inexperienced end-users, buyers, and newbies.
Product knowledge and experience are invaluable. If you’ve never affixed a rivet, ask your fastener supplier to show you how to pull a rivet and hold a rivet gun. With strong product knowledge, you’re better equipped to safely and effectively get the job done — or teach others how to get the job done! First…the basics A rivet is a permanent, non-threaded mechanical fastener typically made of steel or aluminum. It has a head on one end and a cylindrical stem (the “mandrel”) on the other, which looks like a metal pin. The mandrel deforms during installation, expanding to securely hold the rivet in place.
Riveting is ideal for the quick, costeffective yet durable fastening of plastic or metal and, particularly, when the assembly remains permanently affixed or if access is limited.
The type of rivet and tool used depends on the application, and there are several choices available.
As one example, blind rivets use a clamping force and are ideal for use when only one side of an assembly is accessible (making them “blind” to the opposite side). They’re mostly tubular with a mandrel through the center. When inserted into drilled holes, a tool is used to draw the mandrel through the body of the rivet, which expands and deforms the back of the body. The mandrel then snaps off, leaving a clean, finished-looking application.
On the other hand, solid rivets are one of the oldest, most commonly used fasteners and require access to both sides of an application for installation. They’re ideal for important structural joints and are often used in several critical industries. During the installation process, the rivet flattens against the back of the hold so
that it can never unscrew. However, these fasteners can be removed or uninstalled with a drill.
These are only two options. There are several types of rivets with different features — such as those that are waterproof and sealed or split (which are ideal for wood assemblies). There are also rivet nuts that are threaded and add strength to an application.
Additionally, there are several types of rivet guns for installations, including:
• Hand riveters are a manually operated tool used to install blind rivets. They have a simple lever and use a squeeze technique to work. • Pneumatic rivet guns are powered by compressed air, with a built-in catch, to quickly install blind rivets. These tools require a hosed, compressedair connection. • Battery-powered rivet guns offer more maneuverability and versatility, since there’s no cord, and work with the push of a button. There are two main tool types: the first one pulls mandrels into a mandrel holder so a user only has to empty the catch; the second one spits out the mandrels from the front of the tool. Within those options, there are choices related to ergonomics, power rating, and battery life. Ultimately, the ideal choice comes down to the assembly requirements. This should include an assessment of the clearance to determine if the tool will fit a given space to be used correctly.
Common riveting failures Typically, the rivets or tools are not to blame for riveting failures. In most cases, the operator holds the tool incorrectly when drilling the hole — and often perpendicularly, creating an oversized or irregular hole. As a result, a blind rivet will not perform properly.
If the mandrel breaks off above the rivet face, leaving a portion that sticks out of the rivet, this is called a high mandrel break.
There is more than one potential root cause, including that the:
• Assembly material for riveting is too thin or soft • Grip thickness is below the minimum recommended amount • Hole diameter is over or under-sized • Hole conditions are improper and not ideal, such as if there’s an: o Excessive variation in size o Improper alignment of the tooling for an application
If the mandrel head of the rivet pops out, this is called a pull-thru or partial pull-thru.
The cause could be because the:
• Body length is too short • Grip range is above the maximum recommendation • Hole diameter is oversized or above the maximum recommended size • Assembly or hole conditions are not ideal. Examples include: o An excessive variation in hole size o A non-circular or a tapered hole o Burrs or sharp edges (can occur when drilling and should be removed before riveting)
Calipers are a good way to determine your proper grip range to avoid grip thickness — whether over the maximum or under the minimum. It’s important to ensure your rivet tool is perpendicular to avoid improper alignment and to minimize the occurrence of unsuitable hole conditions.
rivets
o The assembly material for riveting is too soft or there’s a gap between the material thickness o Improper alignment of tooling to application and the use of a nonperpendicular set o The wrong nosepiece used for tooling
Some other potential riveting challenges or failures are less common but can occur, including if:
• A rivet’s head unexpectedly pops off (the “head popper” problem) • A tool experiences a loose set • The rivet length is insufficient, not allowing for the proper formation of a secondary head at the back of the application (the “sheared” secondary head) Depending on the problem, you’ll want to check for if the:
• Grip thickness is above the maximum or below the minimum recommended amounts • Hole diameter is below the minimum recommended size • Assembly or hole conditions are not ideal. Examples include: o An excessive variation in hole size o A non-circular or a tapered hole o Burrs or sharp edges (can occur when drilling and should be removed before riveting) o The assembly material for riveting is too soft or there’s a gap between the material thickness o Improper alignment of tooling to application and the use of a nonperpendicular set o The wrong nosepiece used for tooling o An insufficient secondary side clearance
A rivet supplier should be able to help you determine the cause of any installation problems and suggest the ideal rivets and tools for use, depending on the application. It’s important to work with a company that has experience and genuine confidence in its product lines.
If you’re a supplier, when you focus on selling solutions instead of products, your customer interactions will be much more successful.
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