A great deal of research data on cold-welding originated from NASA reports of accidental cold-welding in outer space.
Conditions for these “accidents” were perfect: The materials were of the highest purity, surfaces superbly machined and thoroughly cleaned, and placed in the high vacuum of space.
Even a small amount of exerted force would bring atoms close enough together to form a metallurgical bond or cold weld.
A good pinch-off is no accident; the correct conditions must be created.