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Machining and Manufacturing

Machining Parameters

Cutting speed, spindle speed, removal rate, cutting time, power, force and torque of a turning, milling or drilling cut; the manual's recommended speed range for the work and tool material (the public-domain speed tables of U.S. Army TC 9-524 and NAVEDTRA 12204); tool life by Taylor's law v T^n = C; the cost and time per piece with the minimum-cost and maximum-production speeds in closed form and a chart of cost against speed; the ideal surface roughness of a round-nosed turning tool; and the shear angle and shear strain from the chip-thickness ratio with Merchant's prediction beside. Default: turning 2-in 4140 steel bar at 500 rpm, 0.010 in/rev and 0.100 in deep over 8 in with a carbide tool (illustrative unit power 1.4 hp-min/in3, Taylor n 0.25, C 400 ft/min).

1 worked example reproduced, listed on the tool page.

Sheet Metal Bend Allowance and Press Tonnage

Flat-pattern layout of a multi-bend sheet-metal part (bend allowance, setback, bend deduction, flats and total developed width by the FAA-H-8083-31B / AC 43.13-1B method with the K-factor entered, from the handbook's empirical formula, at mid-thickness or by an R/t rule table), springback and overbend by the Gardiner radius-ratio relation, the minimum bend radius (AC 43.13-1B Table 4-6 for aluminum alloys or an entered multiple of the thickness), press-brake air-bending tonnage F = k S_u t² / V with the V-die rule, bottoming and coining multiples, the air-bend inside radius and the minimum flange, hole, slot and relief-hole distances, and the blanking and punching force with stripping. Default: 0.0598-in (16-gauge) steel, inside radius 0.06 in, three 90° bends with flanges 1.0 / 2.0 / 1.0 / 0.5 in, 24-in bend length on an 8t V-die (illustrative, stated).

1 worked example reproduced, listed on the tool page.

Other Mechanical Design sections

Shafts · Gears · Bearings · Springs · Fasteners and Power Screws · Pressure Vessels · Tolerances · Mass Properties · Vibration · Acoustics · Brakes, Clutches and Belts · Lubrication and Wear