We have a couple of Extrusion Mandrels used in the making of copper tubing. The existing drawings are being converted over to GD&T dimensioning. Straightness of these parts is very critical. These Mandrels extend into and through a mating die. Heated copper (1500 degrees F) is extruded through the annular gap created between these two parts to make copper tubing. If the Mandrel is not straight the wall thickness of the tubing that is produced will not be concentric and out of specification.
Firist, I am not sure the parts are GD&T dimensioned correctly.
Second, After these parts are produced they may be sent out for Nitriding or other heat treating or coating processes. They will need to be inspected again to be sure they have not warped during this treatment.
Would it be better to show the surface and not the axis of the area marked as "B" as the main datum and do Total Runnout referenced to this surface? That would make inspection easier? Would we get the straightness, etc. needed?
Another question I have is with regards to the threaded portion of the Mandrel. Is it possible to call out a runnout for these threads as I have shown? The Mandrel screws into a holder that has mating threads and matching diameters to the two shaft diameters on each side of the threads. There is a .002" to .009" clearance to these diameters.
One additional note. The center hole in the Mandrel is for a cooling water tube that is inserted into it. Water flows out the end of this small tube near the end of the Mandrel and back along it and out the end of the Mandrel. If the center hole of the Mandrel is not concentric the uneven heating of the Mandrel due to different wall thickness can cause the Mandrel to warp. In the "Part B" shown on the sketch I guess the only way to inspect this center hole would be with Ultrasonics? The same with Part A?
Thanks for any help or suggestions.
Bob
Firist, I am not sure the parts are GD&T dimensioned correctly.
Second, After these parts are produced they may be sent out for Nitriding or other heat treating or coating processes. They will need to be inspected again to be sure they have not warped during this treatment.
Would it be better to show the surface and not the axis of the area marked as "B" as the main datum and do Total Runnout referenced to this surface? That would make inspection easier? Would we get the straightness, etc. needed?
Another question I have is with regards to the threaded portion of the Mandrel. Is it possible to call out a runnout for these threads as I have shown? The Mandrel screws into a holder that has mating threads and matching diameters to the two shaft diameters on each side of the threads. There is a .002" to .009" clearance to these diameters.
One additional note. The center hole in the Mandrel is for a cooling water tube that is inserted into it. Water flows out the end of this small tube near the end of the Mandrel and back along it and out the end of the Mandrel. If the center hole of the Mandrel is not concentric the uneven heating of the Mandrel due to different wall thickness can cause the Mandrel to warp. In the "Part B" shown on the sketch I guess the only way to inspect this center hole would be with Ultrasonics? The same with Part A?
Thanks for any help or suggestions.
Bob