Skiving (metalworking): Difference between revisions

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Skiving or scarfing is the process of cutting material off in slices, usually metal, but also leather or laminates. Skiving can be used instead of rolling the material to shape when the material must not be work hardened, or must not shed minute slivers of metal later which is common in cold rolling processes. It can also be used to create fins on a block of metal, not shaving the part entirely off.

In metalworking, skiving can be used to remove a thin dimension of material or to create thin slices in an existing material, such as heat sinks where a large amount of surface area is required relative to the volume of the piece of metal.

The process involves moving the material past precision-profiled tools made to an exact shape, or past plain cutting tools. The tools are typically made of tungsten carbide-based compounds. It requires a minimum material feed rate to cut successfully. At speeds below those of metal planing or about 10 meters/minute (33 feet/minute), the skiving tools can be vibrated at high frequency to increase the relative speed between the tool and workpiece.

In early machines, it was necessary to precisely position the strip relative to the cutting tools, but newer machines use a floating suspension technology which enables tools to locate by material contact. This allows mutual initial positioning differences up to approximately 12 mm (0.47 in) followed by resilient automatic engagement.

Products using this technology directly are automotive seatbelt springs, large power transformer winding strips, rotogravure plates, cable and hose clamps, gas tank straps, and window counterbalance springs. Products using the process indirectly are tubes and pipes where the edge of the strip is accurately beveled prior to being folded into tubular form and seam welded. The beveled edges enable pinhole free welds.

Another metal skiving application is for hydraulic cylinders, where a round and smooth cylinder bore is required for proper actuation. Several skiving knives on a round tool pass through a bore to create a perfectly round hole. Often, a second operation of roller burnishing follows to cold-work the surface to a mirror finish. This process is common among manufacturers of hydraulic and pneumatic cylinders.^[1] Compared to honing, skiving and roller burnishing is faster.

Skiving can be applied to gear cutting, where internal gears are skived with a rotary cutter (rather than shaped or broached) in a process analogous to the hobbing of external gears.^[2]

Heat sinks

Skiving machine producing copper heat sink fins.

Skiving is also used for the manufacturing of heat sinks for PC cooling products. A PC cooler created by skiving has the benefit that the heat sink base and fins are created from a single piece of material (copper or aluminum), providing improved heat dissipation and heat transfer from base to fins. Additionally, the skiving process also increases the roughness of the fins. Unlike the underside of a heat sink, which needs to be smooth for maximum contact area with the heat source, the fins benefit from this roughness because it increases the fins' surface area on which to dissipate heat into the air. The fins may be made much thinner and closer together than by extrusion or formed sheet processes, which can offer greater heat transfer in high-performance waterblocks for water cooling.

References

^ "Combination Skiving and Burnishing for Cylinder Bores". Retrieved August 13, 2012.
^ Weppelmann, E; Brogni, J (March 2014), "A breakthrough in power skiving", Gear Production: A Supplement to Modern Machine Shop: 7–12, retrieved 2014-03-11.

External links

[1] "Combination Skiving and Burnishing for Cylinder Bores". Retrieved August 13, 2012.

[2] Weppelmann, E; Brogni, J (March 2014), "A breakthrough in power skiving", Gear Production: A Supplement to Modern Machine Shop: 7–12, retrieved 2014-03-11.

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-{{no footnotes|date=June 2009}}
+{{more footnotes|date=June 2009}}
+{{Short description|Used to cut metal in slices}}
+'''Skiving''' or '''scarfing''' is the process of cutting material off in slices, usually [[metal]], but also [[Skiving (leathercraft)|leather]] or [[laminates]].  Skiving can be used instead of [[rolling (metalworking)|rolling]] the material to shape when the material must not be [[work hardening|work hardened]], or must not shed minute slivers of metal later which is common in [[cold rolling]] processes. It can also be used to create fins on a block of metal, not shaving the part entirely off.
+In metalworking, skiving can be used to remove a thin dimension of material or to create thin slices in an existing material, such as [[heat sinks]] where a large amount of surface area is required relative to the volume of the piece of metal.
-'''Skiving''' or '''scarfing machines''' cut material off in slices, usually [[metal]], but also [[leather]] or [[laminates]].  The process is used instead of [[rolling (metalworking)|rolling]] the material to shape when the material must not be [[work hardening|work hardened]], or must not shed minute slivers of metal later which is common in [[cold rolling]] processes.
+The process involves moving the material past precision-profiled tools made to an exact shape, or past plain [[cutting tool]]s. The tools are typically made of [[tungsten carbide]]-based compounds. It requires a minimum material feed rate to cut successfully. At speeds below those of metal [[planing (shaping)|planing]] or about 10 meters/minute (33 feet/minute), the skiving tools can be vibrated at high frequency to increase the relative speed between the tool and workpiece.
-The skiving process, meaning "to slice", can be applied to a variety of applications and materials.  In leather, skiving knives trim the thickness of the leather, often around the edges, to thin the material and make it easier to work with.  In metal working, skiving can be used to remove a thin dimension of material or to create thin slices in an existing material, such as heat sinks where a large amount of surface area is required relative to the volume of the piece of metal.
+In early machines, it was necessary to precisely position the strip relative to the cutting tools, but newer machines use a floating suspension technology which enables tools to locate by material contact. This allows mutual initial positioning differences up to approximately {{convert|12|mm|in|abbr=on}} followed by resilient automatic engagement.
-Another metal skiving application is for [[hydraulic cylinder|hydraulic cylinders]], where a round and smooth cylinder inside is required for proper actuation.  Several skiving knives on a round tool pass through a bore to create a perfectly round hole.  Often, a second operation of [[roller burnishing]] follows to cold-work the surface for mirror-finish.  This process is common among manufacturers of hydraulic and pneumatic cylinders. <ref>{{cite web |url=http://www.mmsonline.com/articles/combining-skiving-and-burnishing-for-cylinder-bores |title=Combination Skiving and Burnishing for Cylinder Bores|accessdate=August 13, 2012}}</ref>
-The process involves moving the strip past precision-profiled slotted [[tool]]s made to an exact shape, or past plain [[cutting tool]]s.  The tools are all usually made of [[tungsten carbide]]-based compounds. In early [[machine]]s, it was necessary to precisely position the strip relative to the cutting tools, but newer machines use a floating suspension technology which enables tools to locate by material contact. This allows mutual initial positioning differences up to approximately {{convert|12|mm|in|abbr=on}} followed by resilient automatic engagement. Products using this technology directly are automotive [[seatbelt]] [[spring (device)|springs]], large [[power transformer]] winding strip, rotogravure plates, cable and [[hose clamp]]s, [[gas tank]] straps, and window counterbalance springs. Products using the process indirectly are tubes and [[pipe (material)|pipe]] [[mill (factory)|mill]]s where the edge of the strip is accurately beveled prior to being folded into tubular form and [[seam welding|seam welded]]. The finished edges enable pinhole free welds.
+Products using this technology directly are automotive seatbelt springs, large [[power transformer]] winding strips, [[rotogravure]] plates, cable and [[hose clamp]]s, [[gas tank]] straps, and window counterbalance springs. Products using the process indirectly are tubes and pipes where the edge of the strip is accurately [[beveling|beveled]] prior to being folded into tubular form and [[seam welding|seam welded]]. The beveled edges enable pinhole free welds.
+Another metal skiving application is for [[hydraulic cylinder]]s, where a round and smooth [[cylinder bore]] is required for proper actuation. Several skiving knives on a round tool pass through a [[boring (manufacturing)|bore]] to create a perfectly round hole. Often, a second operation of [[roller burnishing]] follows to [[Cold working|cold-work]] the surface to a mirror [[Surface finish|finish]]. This process is common among manufacturers of hydraulic and pneumatic cylinders.<ref>{{cite web |url=http://www.mmsonline.com/articles/combining-skiving-and-burnishing-for-cylinder-bores |title=Combination Skiving and Burnishing for Cylinder Bores|accessdate=August 13, 2012}}</ref> Compared to honing, skiving and roller burnishing is faster.
-For lines which use low speed welding processes, such as [[laser welding]], the skiving tools cannot normally cut - for example at speeds below metal [[planing (shaping)|planing]] speeds or about 10 meters/minute (33 feet/minute). In these cases the tools can be vibrated at high frequency to artificially increase the relative speed between the tools and strip.
+Skiving can be applied to [[gear cutting]], where internal gears are skived with a rotary cutter (rather than [[gear shaper|shaped]] or [[broaching (metalworking)|broached]]) in a process analogous to the [[hobbing]] of external gears.<ref>{{Citation |last1=Weppelmann |first1=E |last2=Brogni |first2=J |date=March 2014  |title=A breakthrough in power skiving |journal=Gear Production: A Supplement to Modern Machine Shop |pages=7–12 |url=http://gear.epubxp.com/i/262216 |accessdate=2014-03-11 |postscript=.}}</ref>
 ==Heat sinks==
-[[Image:Skiving.jpg‎|frame|right|Skiving machine producing copper heat sink fins.]]
+[[Image:Skiving.jpg|frame|right|Skiving machine producing copper heat sink fins.]]
-'''Skiving''' is also used for the manufacturing of [[heat sink]]s for PC cooling products. A PC cooler created with the use of skiving has the benefit that the heat sink base and the heat sink fins are created from one piece of material (copper or aluminum). This provides optimal dissipation and transfer of the heat from the base to the fins. Additionally, the skiving process also increases the roughness of the heat-sink's fins. Unlike the underside of a heat-sink which needs to be smooth for maximum surface area contact with the heat-source that it cools, the fins benefit from this roughness because it increases the fins' surface area which serves to provide more area on which to release heat into the ambient environment.
+Skiving is also used for the manufacturing of [[heat sink]]s for PC cooling products. A PC cooler created by skiving has the benefit that the heat sink base and fins are created from a single piece of material (copper or aluminum), providing improved heat dissipation and heat transfer from base to fins. Additionally, the skiving process also increases the roughness of the fins. Unlike the underside of a heat sink, which needs to be smooth for maximum contact area with the heat source, the fins benefit from this roughness because it increases the fins' surface area on which to dissipate heat into the air. The fins may be made much thinner and closer together than by [[extrusion]] or formed sheet processes, which can offer greater heat transfer in high-performance [[Water block|waterblocks]] for [[Computer cooling#Liquid cooling|water cooling]].
+==See also==
+*[[Skiving (leathercraft)]]
 ==References==
+{{Reflist}}
-*[http://www.patentstorm.us/patents/5761947-description.html Skiving machine patent]
-*[http://www.thefabricator.com/Articles/Printer_Friendly_Article.cfm?ID=625 The little-known life of the scarfing tool]
+==External links==
-*[http://www.mmsonline.com/articles/combining-skiving-and-burnishing-for-cylinder-bores Combining Skiving and Burnishing for Cylinder Bores]
+*[https://archive.today/20130421212447/http://www.patentstorm.us/patents/5761947-description.html Skiving machine patent]
+*[http://www.thefabricator.com/article/tubepipefabrication/the-little-known-life-of-the-scarfing-tool The little-known life of the scarfing tool]
 [[Category:Machine tools]]