A ball bar supplier may supply a calibration for its check-standard spheres. But unless the manufacturer is ISO/IEC Guide 25 compliant, and its scope of accreditation includes spheres, the certificate doesn't meet the requirements of QS9000.
Thomson Precision Ball Inc. produces balls to a maximum tolerance of 3 millionths of an inch, 1/10th of one micron.
That's because for a company to be QS9000 compliant, its calibration facilities must meet QS9000 188.8.131.52 and 184.108.40.206 requirements. If this is not the case, then an ISO/IEC Guide 25 accredited calibration laboratory must calibrate their standards.
For example, a facility using a CMM with a ball-bar check standard, must have it calibrated by a laboratory whose scope of calibration includes spheres.
Thomson Precision Ball is said to be the only ball manufacturer to have a gauge laboratory accredited for calibration of spheres by the A2LA. That means its calibration management system has been audited and found to comply with QS9000, ISO9002, ABSI/ISO/ASQ9002, and in accordance with QS's Appendix B Code of Practice.
"The degree of uncertainty that a lab can demonstrate is a good indicator of competency," says Bob Abbandondelo, sales and marketing manager. "We offer an uncertainty of 8 micro inches for diameter, 0.56 micro inches for roundness, and a dead band of less than 4 nanometers for surface-finish calibrations."
To achieve these results, the National Institute of Standards and Technology has calibrated each of the facility's tungsten carbide comparison masters for minimum uncertainty and maximum accuracy. And the gauge environment is controlled to be between Class 1,000 and Class 10,000 cleanliness levels with the temperature regulated to ±0.5F. For more information about sphere calibration from Thomson Precision Ball Inc.: Enter 533