Coaxiality (Part ll) - 2018 (#10A)
(In accordance with the ASME Y14.5-2018 standard)
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As pointed out in last month’s Tip, a lot of confusion exists over the meaning of the geometric tolerances shown in the chart. Tip 9A illustrated possible inspection methods for position at MMC and RFS. This month’s Tip continues with sample inspection methods for circular and total runout and profile.
Circular runout requires inspecting circular elements individually. Because of this, circular runout will not detect changes in size. Any barreling, waisting or taper should be ignored. These conditions will be controlled by the size tolerance.
Total runout requires determining the full indicator movement over the entire feature. Total runout, therefore, detects any changes in size, i.e. barreling, waisting or taper. Although changes in size are controlled, the actual size of the feature is determined and controlled by the size dimension and tolerance. A feature may be manufactured to a very tight size tolerance but due to eccentricity, the runout could be large. Total runout controls location, orientation, and form (if the runout tolerance is tighter than the size tolerance), but not size.
Profile controls everything that total runout does as well as size if the size dimension is made BASIC.
This tip is in accordance with ASME Y14.5-2018. This tip was originally released in March 1998.
