GEAR MANUFACTURING PROCESSES Machining milling Gear Hobbing Gear Broaching Gear Shaping Casting Sand Casting Die Casting - Extrusion - Coining - Powder Metallurgy - Stamping - Hot Rolling Other

Gear machining – form milling (single gear tooth cutter)

Gear machining – form milling

GEAR MANUFACTURING PROCESSES GEAR BROACHING: Broaching tool is used in vertical broaching machine. Speedy and accurate process. Tooth space is produced in single stroke More blanks can be mounted at a time. Blank is indexed after producing each tooth. Advantages: Finished gears can be obtained. Advisable for small gears. Advisable for internal gears. High production rate. Good accuracy. Economical Disadvantages: Costly tool External gears are difficult to make. Different broaching tools are reqd. for gear having diff. modules. Not preferable for bevel gears.

GEAR MANUFACTURING PROCESSES GEAR HOBBING: It is gear generating method. Fast and accurate. Hob(like worm cutter) is rotary tool on which single or multi start threads are cut. Each thread is having shape of involute tooth. Gear blank is mounted on table. Relative motion between tool and work piece is obtained by gear train. Gear blank is moved up to desired depth. Hob is moved in axial direction of blank.

GEAR MANUFACTURING PROCESSES GEAR SHAPING ( GENERATING METHOD): Cutter is one kind of gear having cutting edge. Pinion or rack type cutter can be used. Gear blank and cutter are rotated with adjusted velocity ratio. One gear tooth is generated by one cutter tooth. Cutter is axially reciprocated with 50 stroke/min. Reciprocating movement is dependent on face width. Cutter is also reciprocated in radial direction to provide full depth mean while blank remains steady.

GEAR MANUFACTURING PROCESSES GEAR SHAPING ( GENERATING METHOD): Rack type cutter is also used, in which blank is rotated and cutter is provided longitudinal motion. Advantages: Spur, helical, rack, internal gears can be manufactured. Cutter is universal for same pitch and it does not depend on numbers of teeth. Advisable for mass production Disadvantages: Production rate is low compared to hobbing Helical guide is required for helical gear. Low rigidity. Sufficient undercut are required.

GEAR MANUFACTURING PROCESSES GEAR FINISHING METHODS: Gear shaving: - Rack type - Rotary type In rack type, shaving tool is kept below gear and reciprocated. Grooves are made on cutter. In rotary type, grooves are made on gear shaped cutter.

GEAR MANUFACTURING PROCESSES GEAR FINISHING METHODS: Gear Grinding: 1.) Form grinding Involute shaped grinding disk is used to finish each teeth one by one. Indexing mechanism is used to rotate blank. Sometimes two disk wheels are used to reduce time. 2.) Generation Grinding Spiral, bevel gears are grinded by this method. Grinding wheel is also moved in tooth space. 3.) Grinding by threaded wheel Similar to hobbing Grinding wheel is having helical threads.