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Cutting speed may be defined as the rate at the workpiece surface, irrespective of the machining operation used. A cutting speed for mild steel of 100 ft/min is the same whether it is the speed of the cutter passing over the workpiece, such as in a turning operation, or the speed of the cutter moving past a workpiece, such as in a milling operation.
A machinist calculator is a hand-held calculator programmed with built-in formulas making it easy and quick for machinists to establish speeds, feeds and time without guesswork or conversion charts. Formulas may include revolutions per minute (RPM), surface feet per minute (SFM), inches per minute (IPM), feed per tooth (FPT).
The major minus pitch technique also works for inch-based threads, but you must first calculate the pitch by converting the fraction of threads-per-inch (TPI) into a decimal. For example, a screw with a pitch of 1/20 in (20 threads per inch) has a pitch of 0.050 in and a 1 ⁄ 13 in pitch (13 threads per inch) has a pitch of 0.077 in.
A metric ISO screw thread is designated by the letter M followed by the value of the nominal diameter D (the maximum thread diameter) and the pitch P, both expressed in millimetres and separated by a dash or sometimes the multiplication sign, × (e.g. M8-1.25 or M8×1.25). If the pitch is the normally used "coarse" pitch listed in ISO 261 or ...
It relates to spindle speed via variables such as cutter diameter (for rotating cutters) or workpiece diameter (for lathe work). SFM is a combination of diameter and the velocity ( RPM ) of the material measured in feet-per-minute as the spindle of a milling machine or lathe . 1 SFM equals 0.00508 surface meter per second (meter per second, or ...
Incorrect speeds and feeds will cause damage to the tool, machine spindle, and even the product. The quickest and simplest way to find these numbers would be to use a calculator that can be found online. A formula can also be used to calculate the proper speeds and feeds for a material. These values can be found online or in Machinery's Handbook.
For example, British Standard BS 328 defines 230 sizes from 0.2 mm to 25.0 mm. From 0.2 through 0.98 mm, sizes are defined as follows, where N is an integer from 2 through 9: N · 0.1 mm
Safe running speeds for various nut materials and loads on a steel screw [17] Nut material Safe loads (psi) Safe loads (bar) Speed (fpm) Speed (m/s) Bronze 2,500–3,500 psi 170–240 bar Low speed Bronze 1,600–2,500 psi 110–170 bar 10 fpm 0.05 m/s Cast iron 1,800–2,500 psi 120–170 bar 8 fpm 0.04 m/s Bronze 800–1,400 psi