Galling and Seizing

When you screw together two pieces of metal (cold welding), the threads of the screw will experience adhesive wear as you tighten the screw. This is caused by the sliding of the threads of the screw over the surface of your device / machine as you tighten the screw. Adhesive wear means that the action of turning the screw causes you to lose material, either on the screw or the machine. When you can no longer turn the screw because of the wear, we call this thread galling and seizing.
In threaded bolts the galling and seizing leads to freezing of the threads, and applying further tightening force may simply shear off the head of the bolt, strip the threads, and damage the recess and tools. Because of thread galling, it not only takes more time and labor to remove the screws, but also there is the risk of device being damaged.
We recommend fluorine coating as a solution when fighting against Galling and Seizing.

Test result of Anti-Galling (Anti-Seize)

Observe the surface of screw thread (internal thread screw) after tightening with an air impact wrench.

external thread screw SUS304
internal thread screw SUS304

external thread screw SUS304 + Fluorine Coating
internal thread screw SUS304

It is confirmed that Fluorine Coating is effective for prevention.

Special Surface Hardened Screws

Hex Socket Head Cap Screws - SUS316L
/ Surface hardening treatment
SNSL-PN

Hex socket Head Cap Screws with Ventilation Hole
/ Surface Hardening Treatment
SVSL-PN

"What is a Screw?" Guide

A basic course on screws called "What is a Screw?" is available.
"What is a Screw?" explains galling and seizing in more detail.