Assembly in Action: Thread-Forming Fasteners Deny Rejects
"Both the tilt head and the main body of the steering column are made from die cast magnesium," says Mark Laws, product and quality engineering supervisor at Toledo Machining (Toledo, OH). "Magnesium is lighter than steel or aluminum, easier and less expensive to process and machine, and has good fatigue strength, dimensional stability, and sound and vibration dampening qualities."
"However," Laws says, "its ductility is low and is easily deformed. This can lead to slivering, layer eruption, chipped threads and fracturing using standard threaded fasteners. Removing and reinserting these fasteners can weaken or destroy threads, creating magnesium powder, debris and contamination."