en>David Eppstein: /* Drinfeld modules */ Matematicheskii Sbornik

2013-10-28T20:49:23Z

Drinfeld modules: Matematicheskii Sbornik

New page

'''Surface feet per minute''' ('''SFPM''' or '''SFM''') is an [[imperial units|imperial]] and [[United States customary units|American customary]] unit of [[speed]], being the number of linear feet that a location on a rotating component travels in one minute. Its most common use is in the measurement of [[speeds and feeds#Cutting speed|cutting speed (surface speed)]] in [[machining]]. It is a [[unit of measurement|unit]] of [[velocity]] that describes how fast the cutting edge of the [[cutting tool (machining)|cutting tool]] travels. It correlates directly to the [[machinability]] of the workpiece material and the [[hardness]] of the cutting tool material. It relates to [[spindle (tool)|spindle]] speed via variables such as cutter diameter (for rotating cutters) or workpiece diameter (for [[metal lathe|lathe]] work).

SFM is a combination of ''diameter'' and the ''velocity'' ([[RPM]]) of the material measured in feet-per-minute as the [[spindle (tool)|spindle]] of a [[milling machine]] or [[lathe]]. The faster the spindle turns, and/or the larger the diameter, the higher the SFM. The goal is to tool a job to run the SFM as high as possible to increase hourly part production. However some materials will run better at specific SFMs. When the SFM is known for a specific material (''ex 303 annealed stainless steel = 120 SFM for high speed steel tooling''), a formula can be used to determine spindle speed for live tools or spindle speeds for turning materials.

In a milling machine, the ''tool'' diameter is substituted for ''stock'' diameter in the following formulas when the cutter is revolving and the stock is stationary.

Spindle Speed can be calculated using the following equation:

:<math>\text{Spindle speed (RPM)} = \frac{SFM}{\pi \times \frac{1}{12} \times \text{stock diameter (in)}} \approx \frac{SFM}{0.2618 \times \text{stock diameter (in)}}</math><ref name="brown">Brown & Sharpe; Brown & Sharpe Automatic Screw Machine Handbook'', Publisher B&S</ref>

SFM can be calculated using the following equation:

:<math>SFM = \text{stock diameter (in)} \times \pi \times \frac{1}{12} \times \text{RPM} \approx \text{stock diameter (in)} \times 0.2618 \times \text{RPM}</math><ref name="brown"/>

==See also==
* [[Speeds and feeds]]

==References==
{{Reflist}}

==External links==
*[http://www.toddlertime.com/machining/feeds.htm Surface Feet per Minute]
* [http://www.dencoonline.com/pdf/milling_formulas.pdf Imperial and metric milling formulae]

[[Category:Machining]]
[[Category:Units of velocity]]
[[Category:Metalworking terminology]]

Drinfeld module - Revision history

en>David Eppstein: /* Drinfeld modules */ Matematicheskii Sbornik