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Shot Peening

In shot peening, the workpiece surfaces hit repeatedly with a large number of cast steel, glass, or ceramic shot(small balls), which make overlapping in dentation on the surface. This action causes plastic surface deformation, at depth up to 1,25 mm(0,025 in), using shot sizes that range from 0,125mm to 5mm (0,005in to 0,2 in.) in diameter.

Because the plastic deformation is not uniform through out to parts thickness, shot peening causes compressive residue stresses on the surface, thus improving the fatigue life of the component. This process used extensively on shafts, gears, spring, oil-well drilling equipments, and jet engine parts (such as turbine and compressor blades). (Kalpakjian, Smith; Manufacturing Engineering and Technology 4^th Edition; pg. 904)

Resolution

Resolution, also called sensitivity, is the smallest difference in dimension that the instrument can detect or distinguish. A wooden yardstick, for example, has far less sensitivity than finely graduated steel rule. (Kalpakjian, Smith; Manufacturing Engineering and Technology 4^th Edition; pg. 946)

Rule of 10

An instrument or gage should be 10 times more accurate than dimensional tolerances of the part being measured. (A factor of 4 is known as the Mil Standard rule). (Kalpakjian, Smith; Manufacturing Engineering and Technology 4^th Edition; pg. 961)

Acceptance Sampling

Acceptance sampling consists of taking only a few random samples from a lot and inspecting them to judge whether the entire lot is acceptable or whether it should be rejected or re-worked. Developed in the 1920’s and used extensively during WW2 for military hardware (MIL STD 105), this statistical technic is widely used valuable.

Acceptance sampling is particularly useful for inspecting high-production-rate parts where % 100 inspections would be too costly. There certain critical devices, however (such as pace makers, prosthetic devices, and components of the space shuttle), which must be inspected %100. (Kalpakjian, Smith; Manufacturing Engineering and Technology 4^th Edition; pg. 991)