Skiving or scarfing is the process of cutting material off in slices, usually

metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...

, but also

leather Leather is a strong, flexible and durable material obtained from the tanning, or chemical treatment, of animal skins and hides to prevent decay. The most common leathers come from cattle, sheep, goats, equine animals, buffalo, pigs and hog ...

laminates Lamination is the technique/process of manufacturing a material in multiple layers, so that the composite material achieves improved strength, stability, sound insulation, appearance, or other properties from the use of the differing materia ...

. Skiving is used instead of

rolling Rolling is a type of motion that combines rotation (commonly, of an axially symmetric object) and translation of that object with respect to a surface (either one or the other moves), such that, if ideal conditions exist, the two are in contact ...

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. 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 In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is al ...

where a large amount of surface area is required relative to the volume of the piece of metal. The process involves moving the strip past precision-profiled slotted tools made to an exact shape, or past plain

cutting tool In the context of machining, a cutting tool or cutter is typically a hardened metal tool that is used to cut, shape, and remove material from a workpiece by means of machining tools as well as abrasive tools by way of shear deformation. The major ...

s. The tools are usually made of

tungsten carbide Tungsten carbide (chemical formula: WC) is a chemical compound (specifically, a carbide) containing equal parts of tungsten and carbon atoms. In its most basic form, tungsten carbide is a fine gray powder, but it can be pressed and formed into ...

-based compounds. 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 followed by resilient automatic engagement. Products using this technology directly are automotive seatbelt springs, large

power transformer A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer's c ...

winding strips,

rotogravure Rotogravure (or gravure for short) is a type of intaglio printing process, which involves engraving the image onto an image carrier. In gravure printing, the image is engraved onto a cylinder because, like offset printing and flexography, it ...

plates, cable and

hose clamp A hose clamp (hose clip, hose lock or Jubilee clip (UK)) is a device used to attach and seal a hose onto a fitting such as a barb or nipple. Types Many types are available, including : Screw/band (worm gear) clamps Screw clamps consist of a ...

gas tank A fuel tank (also called a petrol tank or gas tank) is a safe container for flammable fluids. Though any storage tank for fuel may be so called, the term is typically applied to part of an engine system in which the fuel is stored and propelle ...

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. Skiving 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. Another metal skiving application is for

hydraulic cylinder A hydraulic cylinder (also called a linear hydraulic motor) is a mechanical actuator that is used to give a unidirectional force through a unidirectional stroke. It has many applications, notably in construction equipment ( engineering vehicles ...

s, where a round and smooth

cylinder bore In a piston engine, the bore (or cylinder bore) is the diameter of each cylinder. Engine displacement is calculated based on bore, stroke length and the number of cylinders: displacement = The stroke ratio, determined by dividing the bore by ...

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. Compared to honing, skiving and roller burnishing is faster and typically provides more precise tolerances and better inside surface finish control. 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.

Heat sinks

Skiving is also used for the manufacturing of

heat sink A heat sink (also commonly spelled heatsink) is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant, where it is dissipated away from the device, th ...

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 Extrusion is a process used to create objects of a fixed cross-sectional profile by pushing material through a die of the desired cross-section. Its two main advantages over other manufacturing processes are its ability to create very complex ...

or formed sheet processes, which can offer greater heat transfer in high-performance waterblocks for water cooling.

References

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External links

Skiving machine patentThe little-known life of the scarfing tool
Machine tools Metalworking

Heat sinks

See also

References

External links