MIL-STD-120 Military Standard: Gage Review

The MIL-STD-120 standard, a United States military defense standard, provides relevant technical information applicable to the inspection of gauges, special tools, and measuring devices. The main topics covered are:

• Terminology
• Tolerances and fits
• Measuring instruments and equipment
• Infinitives
• Measurement and inspection methods

This standard is designed to establish uniform practices throughout the military services for the maintenance and use of inspection gauges and special measuring instruments used in conjunction with the dimensional control of all products and equipment supplied by the US Air Force Command.

The measurements made basically determine the following:

• Compliance of the component parts of a mechanical product with the dimensional requirements of contracts, drawings and specifications
• Whether this product is made by a single manufacturer or by more than one manufacturer

In this way, mastering ensures the proper functioning and interchangeability of parts, meaning that a part fits in the same place as any similar part and performs the same function whether the part is for original assembly or for service replacement.

In accordance with this standard, indicators and measuring equipment are classified as:

• Length standards
• main infinitives
• inspection gauges
• manufacturer gauges
• Non-precision measuring equipment
• precision measuring equipment
• Comparators
• Optical comparators and meters

For the purposes of this standard,

• A dimension is a particular dimension of a geometric feature such as diameter, length, angle, perimeter, or center distance.
• The nominal size is the notation used for general identification purposes.
• The base dimension is the theoretical dimension from which the dimension limits for that dimension are derived by applying allowances and tolerances.
• The design dimension is the dimension to which tolerance limits are assigned for that dimension.
• Actual size is the size of that size measured on a single piece.
• Size limits are the maximum and minimum sizes allowed for a given size.
• Fit is the relationship between two mating parts based on the amount of space or interference available when they are installed.
• Tolerance is the total allowable change in size or the difference between size limits.
• What is allowed is an intentional difference in the associated dimensions of the mating parts.

Among the numerous test, measurement, analysis and evaluation studies it provides for businesses in various sectors, our organization also provides inspection and testing services for gage inspection, within the scope of MIL-STD-120 standard, with its trained and expert staff and advanced technological equipment.