en>BD2412: Disambiguated: Handbook of Mathematical Functions → Abramowitz and Stegun

2013-04-20T23:54:58Z

Disambiguated: Handbook of Mathematical Functions → Abramowitz and Stegun

← Older revision		Revision as of 01:54, 21 April 2013
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	~~Greetings~~. ~~Let me begin~~ by ~~telling you~~ the ~~author~~'s ~~name - Phebe~~. ~~Years~~ in the ~~past we moved~~ to ~~North Dakota~~. ~~To collect coins is what her family~~ and ~~her enjoy~~. ~~Managing people~~ is ~~his occupation.~~<br><br>~~My site~~ [http://www.~~animecontent~~.com/~~blog~~/~~348813 home std test~~]		'''Tool wear''' describes the gradual failure of cutting tools due to regular operation. It is a term often associated with [[tipped tool]]s, [[tool bit]]s, or [[drill bit]]s that are used with [[machine tool]]s.

			Types of wear include:
			* '''flank wear''' in which the portion of the tool in contact with the finished part erodes. Can be described using the Tool Life Expectancy equation.
			* '''crater wear''' in which contact with chips erodes the rake face. This is somewhat normal for tool wear, and does not seriously degrade the use of a tool until it becomes serious enough to cause a cutting edge failure.
			Can be caused by spindle speed that is too low or a feed rate that is too high. In [[orthogonal]] cutting this typically occurs where the tool temperature is highest. Crater wear occurs approximately at a height equaling the cutting depth of the material. Crater wear depth ~ t<sub>0</sub>
			t<sub>0</sub>= cutting depth
			* '''[[built-up edge]]''' in which material being machined builds up on the cutting edge. Some materials (notably [[aluminum]] and [[copper]]) have a tendency to [[Annealing (metallurgy)\|anneal]] themselves to the cutting edge of a tool. It occurs most frequently on softer metals, with a lower melting point. It can be prevented by increasing cutting speeds and using lubricant. When drilling it can be noticed as alternating dark and shiny rings.
			* '''glazing''' occurs on [[grinding wheel]]s, and occurs when the exposed [[abrasive]] becomes dulled. It is noticeable as a sheen while the wheel is in motion.
			* '''edge wear''', in drills, refers to wear to the outer edge of a [[drill bit]] around the cutting face caused by excessive cutting speed. It extends down the drill flutes, and requires a large volume of material to be removed from the drill bit before it can be corrected.
			[[Image:Crater wear.png\|right\|thumb\|350px\|Crater wear]]

			==Effects of Tool Wear==
			Some General effects of tool wear include:
			* increased cutting forces....
			* increased cutting temperatures
			* poor surface finish
			* decreased accuracy of finished part
			* May lead to tool breakage
			Reduction in tool wear can be accomplished by using [[lubricants]] and [[coolant]]s while machining. These reduce friction and temperature, thus reducing the tool wear.

			==Tool Life Expectancy==
			The '''Taylor's Equation for Tool Life Expectancy''' provides a good approximation.

			: <math>V_c T^n=C</math>

			A more general form of the equation is
			: <math>V_c T^n \times D^x S^y=C</math>
			where
			*<math>V_c</math>=cutting speed
			*''T''=tool life
			*''D''=depth of cut
			*''S''=feed rate
			*''x'' and ''y'' are determined experimentally
			*''n'' and ''C'' are constants found by experimentation or published data; they are properties of tool material, workpiece and feed rate.

			==Temperature Considerations==
			[[Image:Temperature gradient tool.png\|right\|thumb\|400px\|Temperature gradient of tool, workpiece and chip during orthogonal cutting. As can easily be seen, heat is removed from the workpiece and the tool to the chip. Crater wear occurs around the 720 degree area of the tool.]]
			At high temperature zones crater wear occurs.
			The highest temperature of the tool can exceed 700 °C and occurs at the rake face whereas the lowest temperature can be 500 °C or lower depending on the tool.

			==Energy Considerations==
			[[Energy]] comes in the form of heat from tool [[friction]]. It is a reasonable assumption that 80% of energy from cutting is carried away in the chip. If not for this the workpiece and the tool would be much hotter than what is experienced. The tool and the workpiece each carry approximately 10% of the energy. The percent of energy carried away in the chip increases as the speed of the cutting operation increases. This somewhat offsets the tool wear from increased cutting speeds. In fact, if not for the energy taken away in the chip increasing as cutting speed is increased; the tool would wear more quickly than is found.

			==See also==
			*[[machine tool]]
			*[[tool bit]]
			*[[tipped tool]]
			*[[drill bit]]
			*[[drill press]]
			*[[honing]]
			*[[cutting]]

			==References==
			* S. Kalpakjian and S.R. Schmidt. ''Manufacturing Engineering and Technology''. 2000, Prentice Hall, Upper Saddle River, NJ.
			* S. Kalpakjian and S.R. Schmidt. ''Manufacturing Processes for Engineering Materials''. 2002, Prentice Hall, Upper Saddle River, NJ.
			* K. Kadirgama et al. 2011, "Tool Life and Wear Mechanism" "http://umpir.ump.edu.my/2230/"

			==External links==
			*[http://nsmwww.eng.ohio-state.edu/6thCIRP_toolwear_Toronto.pdf Tool Wear Prediction and Verification in Orthogonal Cutting]
			*[http://www.tech.plym.ac.uk/sme/mfrg315/cuttool1.htm Manufacturing Process Educational Website]
			*[http://gundrillingsolutions.com/Pages/toolwear.html Information Page on Gundrilling tool wear]
			*[http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TGJ-4FJKWTY-K&_user=716796&_coverDate=05%2F15%2F2005&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000040078&_version=1&_urlVersion=0&_userid=716796&md5=9735141ec2c84f4ea04e63f11af30d59 Study of tool wear and surface roughness in machining of homogenised SiC-p reinforced aluminium metal matrix composite]

			{{DEFAULTSORT:Tool Wear}}
			[[Category:Metalworking]]
			[[Category:Apparels clothing]]

			[[ru:Износ (техника)]]

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2011-11-18T15:04:40Z

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Greetings. Let me begin by telling you the author's name - Phebe. Years in the past we moved to North Dakota. To collect coins is what her family and her enjoy. Managing people is his occupation.<br><br>My site [http://www.animecontent.com/blog/348813 home std test]

Conical function - Revision history

en>BD2412: Disambiguated: Handbook of Mathematical Functions → Abramowitz and Stegun

en>Asymptoticus: /* External links */