Rivet Nuts and Rivet Studs

[Billfred]

1293 used them in 2006 to allow access into the ball elevator if need be. It was one of the few parts of the shooting mechanism that worked well. There wasn't much load on the rivet nuts, but they were just what we needed for the application. 1618 has the equipment to do them, but we have yet to have the right application.

[Jay H 237]

We've never used them on 237's robots but we do use them on some of our plastic injection molding robots where I work. They are used on our smaller robots on the lighter duty axis to attach linear bearing rails and brackets.

The ones we have are ribbed on the outside so they "bite" in the hole as you tap them in place with a hammer. Hole size is critical as Al said, otherwise they won't grab. We don't use/have a tool to insert them. Once they are tapped in place the bearing rail is installed. As the screws are tightened the rivet nuts expand and hold in place for good. We use rib washers* and Loctite too, either 222 or 242, depending on the size of the screw. Vibration and loosening fastners is something we're very worried about with our equipment due to the constant movement of the robot and the press and even vibratory bowl feeders when used.


*Rib washers are these things. I've never seen them used anywhere before other than all of our equipment. Might be a European thing . Rib washers aren't anything you'll find at Home Depot or Lowes either. We never use regular split lock washers.

[DonRotolo]

We used Rivnuts two years ago, but found they are really for light/moderate duty only. Anything subject to impact stresses, particularly in aluminum, will make them loosen.

Sure beats having to try to put a nut inside a piece of square tubing, 24 inches from the end...

[Dick Linn]

There are any number of "rivet" type inserts and studs and fasteners that have very good application possibilities. This is especially true for high speed assembly of mass-produced commercial products where labor costs are high. If you don't mind going out and fund-raising to get the $$$ to buy some of the (sometimes) required insertion tools, great. To my mind, they are great for fastening thin panels where you have no access to the back, and not enough thickness to tap a hole. They do prevent a loose nut from going missing in electronic components as well.