Metal Finishing Guide Book


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fewer buffing heads. Spokeunit or finger-type buffs are made from materials that include soft cloth, stiff cloth, sisal, and coated abrasives. The material is manufactured into units, or fingers, sewn into endless belts, cut to length, wrapped around split drums, and gathered by an "Iris" machine into steel teeth. The spoke unit or finger sisal buff is usually made with woven sisal interlaced with 86/80 cloth. Acid or rope sisal is sometimes used. The cloth Fig. 6. Cloth bias buffs in order of increased may be mill or dip treated (Fig. 10). density from closed face (left to right: 0, 2, 4, 6) The spoke or unit bias buff runs to open face (far right) design. cooler than standard bias buffs and has a knee-action flexibility that gives superior contour-following ability. The width and number of the individual units is varied within limits. The range of buff density, or hardness, is varied by choice of materials, treatments, (buff center size) plies, and type of radial stitching. Some complex products are best finished with this type of buff. FLAP BUFFS The flap buff (Fig. 11) utilizes separate flap units placed at right angles to the direction of rotation of the wheel. Each flap supports the other to produce a smooth running wheel. Flap wheels were originally designed for bumper polishing and buffing operations. Flaps are made of coated abrasives, sisal, cloth and combinations thereof. POLISHING WHEELS Polishing wheels are usually made of conventional cloth buff sections glued or cemented together. Canvas disks are cemented to the sides to protect the sewing. Glue or cement is applied to the face. Faces are struck with a pipe at angles and cross-angles to form a uniform crisscross of cracks on the polishing surface and provide sufficient resiliency to allow the wheel to make better contact with a workpiece. Buff sections used to make polishing wheels are generally spiral sewn and made of various types of cloth, sisal, canvas, or sheepskin. Solid, one-piece wool felt, and bull neck and walrus hide are occasionally used. Conventional straight buff sections that are glued together may cause streaking during polishing. An alternative involves inserting pie-shaped segments or other spacers between the buff sections to result in a "nonridge" polishing wheel that eliminates streaking. Various abrasive and adhesive combinations are used to grind, polish, and satin finish. These include liquid, graded aluminum oxide abrasives, greaseless compounds and burring bar compositions. BUFFING EQUIPMENT Significant improvements have been made in buff wheels and buffing compounds to provide consistent and predictable performance. This has helped manufacturers of automated buffing machines to develop automated equipment for low- as well as high-volume requirements and to minimize labor and overhead in the finishing operation. 43

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