spot weld vs spot-weld

spot weld and spot-weld both are nouns.

Word	Noun	Adjective	Verb	Adverb
spot weld	Yes	No	No	No
spot-weld	Yes	No	Yes	No

As nouns, spot weld and spot-weld are synonyms defined as:

spot weld and spot-weld: each of the welds made by welding at a separate point

spot weld (noun)	spot-weld (noun)
each of the welds made by welding at a separate point	each of the welds made by welding at a separate point

spot weld (verb)	spot-weld (verb)
	make circular welds