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TOP-MSURE: Selection & Use of Measuring Equipment


SCOPE: This procedure covers the selection and use of precision measuring equipment for verification of product dimensions. Note: If there is any question at any point about this procedure, contact the QC Specialist, QC Supervisor, or Machining Department QC Inspector.







1 Anyone (typically QC Inspector) As needed to take precision measurements Possibly Production Floor Traveler, Machining Department Inspection Order, print or inspection sheet Determine which measurements are to be taken and, if appropriate, the frequency with which they are to be taken and any special sampling or other criteria; determine the accuracy required for the reading (5% of the tolerance interval, .003" maximum for forging, .002" maximum for machining) Clear mental picture of the needs of the measuring task at hand
2 Anyone After Step 1 Decision from Step 1; Inspection Order, Machining Department Inspection Order, print or Part Inspection Sheet Choose the correct measuring equipment to be used per these criteria:

1) Equipment specified by the QC Forging Supervisor, CMM Programmer/Operator, QC Specialist, QC Machining Supervisor or Machine Operator.

2) Equipment specified on the Traveler or noted on the Part Inspection Sheet. Machining Department

3) [Forge Division only] Equipment chosen per the table below.

Measuring equipment choice
3 Anyone After Step 2 Decision from Step 2 Obtain the necessary measuring equipment (if do not already have ready access to needed equipment, see QC Specialist, QC Forging Supervisor, Calibrations Clerk, or QC Machining Supervisor; ensure that equipment has been calibrated/verified per TOP-CALIB. DO NOT adjust the equipment so as to invalidate the calibration; when employees own their own measuring equipment, the selection of equipment is covered in Step 2 Needed measuring equipment ready to use; equipment not adjusted by unauthorized personnel
4 Anyone Before tool is used to verify dimension Decision from Step 1; Inspection Order, Machining Department Inspection Order, print or Part Inspection Sheet Record Tool ID Number, Date, and Operator Stamp on Tool Verification Log Sheet. Traceability of tool recorded.


Typically use standard-issue 8" digital calipers, unless measuring a dimension with a tolerance interval of less than .060" or where the configuration of the part indicates one of the following.

For tolerance intervals of less than .060" use a micrometer or a caliper specifically verified to be accurate to within 1/20 of the tolerance interval.

For dimensions beyond 8" use longer digital, dial or vernier calipers.

For an external distance perpendicular to a large, flat surface, use a height gage on a surface plate.

For measuring the depth of a depression, use a depth micrometer.

For measuring the thickness of webs, use spring calipers.

For measuring radii use a radius gage or CMM.

For measuring angles use angle plates or CMM.

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