MICROMETER CALIPERS MICROMETER, VERNIER, AND DIAL CALIPERS Micrometer Calipers Machinery's Handbook, 31st Edition
766
Classification .— The definition of the various classifications of micrometers was estab lished in the Federal Specification GGG-C-105 and provided the basic requirements that were to be met by manufactures for sale to the Federal Supply Service, General Services Administration. As stated in the GGG-C-105C (1987); Federal Specifications do not in - clude all varieties of the commodity as indicated by the title of this specification or which are commercially available, but intend to cover only those generally used by the Federal Government. This Federal Specification would become the guideline for manufacturers throughout the United States. Not only was the Federal Government a large consumer of the precision measurement instruments produced by domestic manufacturers, but the establishment of the design and accuracies provided a direction for further development and responded to the needs of the growing quality systems that were, by necessity, playing a greater and greater role in the manufacturing of high quality parts and systems. As the complexity of the systems grew, the greater the need for precision measurement instru- ments that could provide the measurement assurance needed to support those systems. Establishing the design and accuracies for these instruments was a necessary step and provided the foundation for all future developments. Types, Classes, and Styles
Type I – Caliper, Micrometer, Outside ( page 767 ) Class 1: Enameled (I-Beam or Hollow Tubular) Frame Style A: Solid Anvil Style B: Interchangeable Anvil Style C: Tubing, Ball Anvil Style D: Tubing, Upright Anvil Class 2: Finished Frame Style A: Solid Anvil Style B: Paper Gage Style C: Tubing, Ball Anvil Style D: Thread Type II – Caliper, Micrometer, Inside ( page 776 ) Class 1: With Jaws Class 2: Rod and Sleeve Class 3: Tubular Style A: Interchangeable Head Style B: Fixed Head Type III – Gage, Depth, Micrometer ( page 780 ) Class 1: Interchangeable Measuring Rods
Style A: Full base Style B: Half base Type IV – Micrometer Heads Class 1: High Accuracy Mechanical Class 2: High Accuracy Digital Class 3: Extended Travel
Construction Requirements.— Materials: The micrometer spindles and anvils and component parts of the Type II and Type III caliper micrometers and gages having utile measuring surfaces shall be made of high grade tool steel or alloy steel. The source stock shall be assured of a refined crystal structure with a uniform carbide distribution, and shall be sound and free of injurious porosity, soft spots, hard spots and other defects. All materials shall meet the minimum requirements for hardness, stability and strength.
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