Manufacturers of knock-down furniture often ship the parts with threaded inserts and other kinds of knock-down fasteners pre-installed. HELICOIL® plus has a reduced diameter first coil allowing it to be screwed into the hole without the need for prewinding and this simplifies the tooling significantly and makes it simpler and quicker to install. The issue with the tool is that the shaft, that pulls the rivnut (there-by crushing the back of the rivnut against the sheet metal) is made of a steel that is to soft for common steel rivets.
Threads in wood have been around a long time, infact before they were in metal. I used a cordless impact driver to install and it ripped apart the nubs on the nuts, maybe because they were brass and I was installing them in white oak. It’s sized for the machine screw but the outside diameter is the same as the hole that the threaded inserts go into.
However, installation of inserts after molding reduces costs by shortening molding time. To insert the insert, select a long screw which is threaded all the way up to the head. While not as small and elegant as these threaded inserts, perhaps this may be of utility in fused filament parts too; with the advantage that you can get them at any hardware store.
With both thermal and ultrasonic installation methods, the insert is embedded into a molded or drilled hole by remelting the plastic. One other thing to consider with just tapping directly into the wood is to use a bottoming” or finishing tap that doesn’t have the taper. Upon ultrasonic installation, the plastic is liquefied so that it can flow into the undercut of the SONICSERT® thread insert.
Avdel Cherry’s threaded insert tooling utilizes leading-edge technology to provide a range of installation equipment, to best suit each applications requirements. Design and Manufacturing Engineers in Defense, Aerospace, Naval, and Heavy Equipment industries now have an alternative that overcomes limitations associated with traditional threaded inserts. The threaded inserts themselves may vary slightly depending on where you get them from. This reduces the insertion torque required and helps prevent splitting of the bearer wood.
HeliCoil Screw Lock Inserts have all the characteristics of free running inserts but in addition, one or more coils in the middle of the screw lock insert are polygon shaped. HeliCoil screw thread inserts have a driving tang” for installation which is notched for easy removal. Continue with downward pressure until the insert is at the desired depth, then remove the heat and hold the bolt steady long enough for the plastic to stiffen. C Series Chevron Threaded Inserts – Designed for straight holes using ultrasonic or thermal processes.