As the housing is heated, the different coefficents of thermal expansion of components of the housing cause the joint between {HEAD ~ the workpiece} and {TAIL ~ housing sections} to be sealed 
As the housing is heated , the different coefficents of thermal expansion of components of the housing cause the joint between { HEAD ~ the workpiece } and { TAIL ~ housing sections } to be sealed
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH