The present invention provides {HEAD ~ a cage} in which {TAIL ~ a nitride layer} is formed on the surface by using an iron and steel material with a carbon content of 0.25% by weight or less, fabricating it into a predetermined shape and conducting nitriding, which is more excellent in slidability and wear resistance than conventional one 
The present invention provides { HEAD ~ a cage } in which { TAIL ~ a nitride layer } is formed on the surface by using an iron and steel material with a carbon content of 0.25 % by weight or less , fabricating it into a predetermined shape and conducting nitriding , which is more excellent in slidability and wear resistance than conventional one
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