Inspection: is a procedure in which a part or product characteristic, such as a dimension, is examined to determine whether or not it conforms to the design specification.

Two types:

Inspection by variables: is to measure the product or part variables (such as dimensions) by the appropriate measuring instruments.

Advantage: the actual part information (such as size) can be obtained and analyzed.

Disadvantage: slow and maybe cost more.

Inspection by attributes: is to determine whether or not a part is within tolerance limits by using a gage.

Advantage: quick and low cost.

Disadvantage: not data.

Testing: is a procedure in which the product, subassembly, part, or material is observed under conditions that might be encountered during service.

Destructive Testing, Nondestructive Testing (NDT).

100% inspection ¹ 100% good quality (compounded errors + cost.)

Contact inspection: involves the use of a mechanical probe or other device that makes contact with the object being inspected.

Non-contact inspection: utilizes a sensor located a certain distance from the object to measure or gage the desired features.

Conventional Measuring Instruments:

Precision gage blocks: are the standards against which other dimensional measuring instruments and gages are compared.

Made of alloy steel, hardened to 65 HRc and carefully heat treated to relieve internal stresses.

Grades 0.5 (grand-master) blocks are used as a basic reference standard in calibration laboratories;

Grade 1 (precision-grade, or AA) blocks are used for checking and calibrating other grades of gage blocks;

Grade 2 (precision-grade, or A+) blocks are used for checking Grade 3 blocks and master gages.

Grade 3 (working-grade, or B) blocks are used to calibrate or check routine measuring devices such as micrometers, or in actual gaging operations.

Surface plate: is a large, solid block whose top surface is finished to a flat plane used for precision measurement.

Caliper: inside caliper, slide caliper, vernier caliper.

Micrometer: external micrometer, outside micrometer, depth micrometer.

Fixed Gages is a physical replica of the part dimension to be inspected or measured.

Master gage: is fabricated to be a direct replica of the normal size of the part dimension.

Limit gage: is fabricated to be a reverse replica of the part dimension and is designed to check the dimension at one or more of its tolerance limits.

Protractor

Roughness: