The heat hardening process may be individually controlled for {TAIL ~ each spring}, and it may be performed in a very short period of {HEAD ~ time} 
The heat hardening process may be individually controlled for { TAIL ~ each spring } , and it may be performed in a very short period of { HEAD ~ time }
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD