Skiving

A t5q)ical skiving tool can be seen in Fig. 7.1. For relatively thin tapes (50-250 pm) it should be set on the center line of the stock, but for higher thickness tape the blade should be set above the center line of the molding. Sheets up to 400 pm thickness and 30 cm width can be skived on a 20 cm wide lathe. 

The blade should be fabricated from high-quality tool steel or tungsten and regularly sharpened. Skiving speed should be low and the chuck speed should be in the range of 20-30 rpm. 

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Skin-care products Skin effect Skin flotation Skin infections Skin packaging Skin-So-Soft Skin stains Skiving... 

Eor processing after sintering, in the least expensive method for sintered PTEE tape or sheet, a large billet is skived on a lathe after it has been sintered and cooled. High precision articles are machined from ram-extmded rods. 

Other Properties. With respect to dry-cleanabiUty, vinyl-coated fabrics are worse than the others due to dissolution of plasticizer in the cleaning solvent. Only man-made leathers with poromeric nonwoven can be skived, spHt, and cut in the same manner as leather. 

Skiving is a variant in which the base metal surface oxides are mechanically removed foUowed immediately by pressure rolling of a precious metal or alloy strip. This is commonly used for inlays for electrical contacts and for jewelry fabrication. The common inlay materials include gold, silver, copper, brass, and solder. No heat is needed, and the coating is appHed only to designated areas so there is Htde waste (3,50). 

PTFE is commercially available in three forms (1) skived films (2) powder and (3) aqueous dispersions. Of the three forms, the aqueous dispersion provides the most suitable medium to approach a level of mixing and uniformity of the host matrix and dopant that is achieved when transparent matrices and sensitizers share... 

FIG. 10-107 Butt (a) and skive (h) joints for compression packing rings. 

Skive - A cut made on an angle to the surface to produce a tapered or... 

Skive butt seam - Two skived edges joined edge-to-edge to form a smooth surface. Usually each edge is cut at a 45° bevel so the seam fits snugly. 

Skm packaging Skin-So-Soft Skin stains Skiving... 

ASTM D318316 deals only with cutting test pieces from rubber that is not in the form of sheets, but the content is very similar to the relevant parts of ISO 4661, covering slicers, skiving machines, buffing wheels and abrasive bands. Apparently, buffing wheel apparatus is known as an Emerson type rubber buffer in the USA, presumably after a manufacturer. 

FIGURE 4.7 Typical arrangement of skiving knife. (Courtesy of DuPont Fluoropolymers)... 

FIGURE 4.8 Modem skiving machine. (Courtesy of Dalau, Inc.)... 

THV Fluoroplastic can be processed by virtually any method used generally for thermoplastics, including extrusion, coextrusion, tandem extrusion, blown film extrusion, blow molding, injection molding, vacuum forming, and as skived film and solvent casting (only THV-220). 

Skived film — A PTFE film prepared by peeling from a sintered billet using a sharp cutting tool in a similar fashion as, for example, wood veneer. 

Plastics film and sheet can be made in a number of different ways (including casting film from solvent or plastisols, pressing, and skiving from material in block form) but in commerce the most important processes for making these intermediates from thermoplastics are calendering and extrusion. 

An example of an exception to the use of a screw operating extruder occurs when a very low melt plastic such as PTFE (polytetrafluoro-ethylene) is to be used where its specialty properties are needed. PTFE does not easily melt, particularly in the production of heavy wall PTFE wire coatings, so ram extrusion is used. Ram extrusion is used for these wire and cable jobs and also for producing rods, tubes, and large round solid cakes that are later skived to make PTFE film. 

For most applications, toner removal is accomplished by skive blades, magnetic brushes, or fiber brushes. Low-volume applications usually use metal or polymeric blades. Magnetic brushes are used in some mid-volume applica-... 

Unsintered tape is used for sealing threads of pipes for water and other liquids. Pressure-sensitive tapes with silicone or acrylic adhesives are made from skived or cast PTFE films. 

Ease of fabrication is one of the many advantages of polyethylene foam. It can be skived to precise thickness, cut and shaped to form custom parts, and joined to itself or to other materials without major investment in complex equipment. It can also be vacuum formed. Expanded polyethylene will adhere to itself by the use of heat alone. Hot air, or a plate heated to approximately 350°F (177°C) can be used to simultaneously heat the surfaces of two sections of foam to be joined. Upon softening, the two pieces are quickly joined together under moderate pressure, and an excellent bond formed, with only a short cooling period required. Release of the melted foam is aided by a coating of fluorocarbon resin or silicone dispersion on the heating surface. The foam may also be bonded to itself and to other materials by the use of solvents or commercially available adhesives (6). 

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