Problems

44 Campanelli Parkway ~ Stoughton, Massachusetts 02072
800-343-3633 / 800-343-9664

Featured in American Fastener Journal July/August Issue 1999
Featured in Fastening Magazine cover story March 2001

Resolving Common Blind Rivet Problems

John LoConte has been involved in the manufacturing and engineering of blind rivets for over 28 years In his capacity of Quality Control Manager for several years he became familiar with every aspect of the manufacturing process from raw material procurement to final inspection. In 1994 he was instrumental in the preparation of the product-training program. Currently, Mr. LoConte's position is National Sales Application Engineer & National Training Manager.

Alcoa Fastening Systems manufactures and distributes blind rivets, structural rivets, rivet nuts and assembly tools.

For more information
contact
Alcoa Fastening Systems - Stoughton Operations
44 Campanelli Parkway
Stoughton, MA 02072

For those of us who use blind rivets we occasionally run into some problems.
Listed below are a few of the most common problems and their solutions.

Mandrel pulling through leaving a burr outside of the eyelet flange.

One of the most common complaints when using blind rivets can easily be resolved by drilling or punching the correct specified hole size for the selected rivet. When the recommended hole size is exceeded, the mandrel head of the rivet can drag its way through the rivet body almost as if the rivet was being set without putting it into an application. Selection of the correct rivet material is also an important safeguard. An example of this is setting a stainless steel rivet in soft material such as plastic without the use of a back up washer. This will cause the mandrel head to drag through the rivet body leaving a protruding burr outside the flange of the rivet. Back up washers should be used, whenever the material being set is softer than the selected rivet material.
Another cause of pull-through is using a rivet below the minimum grip range. As an example, a blind rivet that has a grip range of .250-. 375 and the actual total material work thickness in the application is measuring .125. A pull-through is most likely to occur in rivets that have the smaller size grip ranges.

Head of mandrel popping off (blind side) after rivet is set

This occurrence is usually caused by the total material work thickness exceeding the specified grip range of the selected rivet. As an example, when a rivet is selected that has a maximum grip range of .250 it will not set correctly if the material work thickness exceeds .250. How much can the material thickness exceed .250 before there is a failure? This all depends on the mandrel head thickness and diameter, but it is recommended that the next size rivet be used in order to eliminate this problem from occurring.

Rivets not setting properly
(not sitting flush / loose fitting)

When the rivet flange is not flush against the work after being set it may be an indication that the operator did not firmly push the rivet into the hole before setting. It may also be caused by an undersize hole in the material being set. The undersize hole can cause the radius between the flange and the rivet body not to seat properly in the hole.

Loose fitting rivets can be caused by a number of possibilities. A power tool air pressure used over the manufacturers specification can cause the rivet mandrel to set so fast that the mandrel may break prematurely. In addition to breaking the mandrel prematurely excessive air pressure can damage your tool.

Using an incorrect size rivet to set material that is well below the minimum specified grip range can also cause loose fitting rivets.

Corrosion problems (Galvanic Reaction)

Galvanic corrosion may occur when dissimilar metals are in contact or in the presence of moisture (electrolyte). To prevent this from happening, whenever possible the blind rivet should be of the same metal as the parts that are to be joined. Realizing that this is not always possible the best safeguard against corrosion would be to separate the metals with a dielectric material such as paint or any other type of material or coatings.

Summary

it is always recommended that you follow your supplier’s specifications when choosing a blind rivet for your application. Hopefully, this information will provide you with a solution to some of the most common blind rivet problems.