Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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Page 43 of 707

Buffing fixtures are unique to each part being processed, although some may be adapted to an assortment of similarly shaped parts. The design of fixtures is extremely important. Unless a part can be fixtured properly at a reasonable cost, the economical utilization of finishing equip- ment cannot be justified. TYPES OF BUFFING MACHINES Buffing machines fall within three broad categories: manual, semiautomatic, and fully automated. Manual Machines Manual buffing machines are used in low- volume applications and applications involving the buffing of extremely com- plex workpieces. Manual machines, when used in conjunction with the proper buff wheel and buffing compound, can be manipulated. Fig. 11. Flap buff. Semiautomatic Machines Semiautomatic buffing machines are used in lower volume applications where a single finishing operation is performed on a vari- ety of parts. Initial investment and fixturing and operating costs are low. Semiautomatic finishing machines can be used with a single- or double-end lathe. One operator can be employed to load, unload, and operate equipment. Semiautomatic machines hold the workpiece and present it to the buff wheel. A timed cycle controls dwell and retraction. Only one fixture is required for each machine for each type of part finished. Because the machine supports the part, operator fatigue is minimized. Various types of rotation also can be performed, depending on the type of semiautomatic machine selected. Production of semiautomatic buffing machines depends on part configuration and the degree of finishing required. By using a double-end jack with two semiau- tomatics, an operator can load one machine while the other is finishing a part. This can double production without increasing labor costs. Fully Automatic Machines Fully automatic machines are used in high-volume applications and where mul- tiple surfaces of a workpiece must be finished. The two most common types of automatic buffing machines are rotary automatic and straight-line machines. Rotary Automatic Machines Rotary machines have round tables with finishing heads located around the periphery of the table. This type of machine is typically used to finish simple, round parts requiring high production. The number of finishing heads and production determine the size of the rotary. The table of the rotary machine can move continuously or index to start, stop, dwell, and then start again, with the length of the dwell controlled by a timer. The configuration and area of the product to be finished determine which is best. Production is higher on a continuous rotary machine because the table does not 42

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