Gear Manufacturing Processes

Gear Manufacturing Processes Overview

• Gear manufacturing encompasses various methods to create gears with the required specifications.
• These methods include forming, machining, and finishing techniques.

Forming

• Forming is a mechanical process causing plastic deformation in materials (mostly metals).
• This achieves desired shapes and sizes by applying compression, shear, or tension.
• Roll forming shapes gears using rotating rolls.
• Extrusion/cold drawing pushes or pulls material through dies to create the gear shape.

Miscellaneous Methods

• Casting: A liquid material is poured into a mold, solidifies, and is then ejected.
• Sintering: This process, sometimes called 'frittage', forms solid masses by applying heat and pressure without melting to liquefaction. Involves atoms diffusing across particle boundaries and fusing.
• Injection Molding: Molten plastic is injected into a mold, cooled, and solidified to produce gears.
• Stamping: Sheet metal is pressed using a die to cut or shape the gear.
• Hot Forging: Metal is shaped at high temperatures (about 75% of its melting temperature) through hammering, pressing, or upsetting in a metal shaping process.

Machining

• This involves removing material to create the gear's shape.
• Profiling or form cutter method uses shaped cutters.
  • Gear cutting can be done on milling machines.
  • Shapers or planers are also suitable for gear cutting.
  • Broaching machines cut gears using a toothed tool.
  • Specialized form tools are an option for gear cutting.
• Generation creates gears using a generating motion.
  • Gear shaping employs a reciprocating cutter.
  • Gear hobbing is a continuous cutting process using a hob.

Gear Manufacturing by Metal Removal

• Profiling or form cutter Method shapes gear teeth by using the form of the cutter
  • Gear Cutting on Milling Machine uses a disc cutter or end mill cutter
  • Gear Cutting on Shaper or Planer uses a single point formed tool on shaper / planer
  • Gear cutting on broaching machine creates teeth of small internal and external spur gears. straight or single helical, of relatively softer materials
  • Gear cutting by form tools provides cutting edge of the cutting tool has a shape identical with the shape of the space between the gear teeth and employs milling and broaching.
• Generation Method for production of gear teeth by machining.
  • Gear Planing employs rack type cutters for generation of spur and helical gears.
  • Gear Shaping
  • Gear Hobbing

Gear Cutting on Milling Machine

• Gear form milling cutter's cutting edge shares a shape consistent with the area between gear teeth.
• Milling and broaching operations employed.
• In form milling, the cutter travels along the gear tooth to produce it, the gear blank rotates after each tooth is cut.

Gear Cutting by Disc Cutter

• The gear blank is mounted to an arbor.
• The geometric center of the cutter aligns vertically with the indexing head spindle's center line.
• The machine table is moved upward until the gear blank's periphery is touched.
• Depth of cut changes and repeats until the full tooth depth is created.
• The gear blank moves under the cutter and tooth space cuts

End Mill Cutter

• The end mill cutter's shape is designed to conform to tooth spacing
• Each tooth is cut and indexed to cut the next tooth space
• The end mill cutter is mounted straight on the milling machine spindle through chuck.
• Milling is the least accurate roughing method

Multiple Tool Shaping Cutter Head / Shear speed process

• Using end mills result in poor quality and slow gear manufacturing, avoid this with multiple tools shaping cutter head.
• Cutters arranged radially in the cutter head with number matching desired tooth space.
• the cutters fed radially toward the center of the blank in amount that matches tooth depth and backs out simultaneously.
• For external gear, cutters are around a hollow head.
• In cutting external gears the gear blank are reciprocated into the head on a fixture and the tools fed radially in predetermined increments after each stroke.

Gear cutting with single point formed tool on shaper / planer

• The cutter is single point with a reciprocating motion.
• The tool is ground to align with the tooth shape an reciprocated.
• Once one space is cut, the gear blank is turned.

Broaching

• Broaching produces teeth of both internal and external spur gears –either straight or single helical in shape, on comparatively soft materials.
• External teeth are produced in single pass leading to high productivity and quality. Incurring great cost for machine.

Production of Gear Teeth by Machining on Generation Principle

• Characterized by automatic indexing and a single cutter for a range of teeth numbers.
• Provides high productivity and economy.
• Rack is a gear with infinite radius with its tooth edges being straight.
• An involute curve forms through the relative motion between rack's axial and gear's rotary movement.

Gear Planing

• It's the oldest gear production method.
• Rack type cutters generate spur and helical gears.
• It generates when an involute curve when the gear blank rolls without slip.

Sunderland Method using Rack Type Cutter

• For cutting spur gears, the cutter will reciprocate parallel to the work axis, but swiveled the same for cutting single helical gears.
• The cutter gradually feeds to desired cut depth which then remains constant.
• Reciprocating motion for rack, and rotary motion for gear blank.
• During cutting, relative motion between the rack and gear generates the form and if rack is long indexing required.
• During stroke/cutting the cutter is in contact with teeth at the same time but with the different part of the tooth.

The principle of generation process

• The rack moves towards each other, and the pinion-gear rolls, the favorable use of cutting teeth or herring bone.
• The downside is the rack needs indexing.
• With the 'rotating-pinion cutter' therefore is more productive

Gear Shaping

• External gear teeth generation by rack type cutter.
• Gear teeth generation by gear shaping (a) external and (b) internal spur gear

Gear Shaping Process

• The gear blank (mounted on a vertical spindle) and the cutter (on the other, vertical, reciprocating spindle) and cutting either downward or upward stroke (depending on the design).
• In each return stroke, table/blank or cutter is withdrawn to prevent rubbing/damage on the cutter's cutting edges and tooth profiles.
• To start the gear cutting, the tool is fed into the bank before cut and when deep starts slowly by rotating is meshed. The rotary motions are through gears, therefore the surface speeds are all the same.

Gear Shaping: Advantages

• One cutter usable for any spur gears with the same module, no matter the number of teeth.
• Teeth cut up close to shoulder only require slight clearance recess.
• Cluster gears particularly suitable due to cutting stroke adjustability.
• This versatile method cuts many types: spur, helical, herring-bone, internal, cluster gears, racks, splines, pawls etc.
• Accurate because cutter profile generates.
• Suitability for medium and large batch production.

Gear Shaping: Limitations

• Time is only spent in metal removal as cutting action is reciprocating.
• Specific helical guide needs helical gear of particular helix angle.

Gear Shaping: Applications

• Gear shapers are applicable in automobiles, clocks, machines.

Hobbing

• Teeth are made to math tooth space is interrupted with grooves to provide cutting and axis.
• Its accurate because repositioning not needed, with high wear resistance and reliability.
• Hob teeth are shaped to match the tooth space and are interrupted with grooves to provide cutting surfaces. It rotates about an axis normal to that of the gear blank, cutting into the rotating blank to generate the teeth as shown in a given figure.
• The cutter (hob) rotates with each contact with each tooth in the gear produces many flats
• Rotation of a screw is similar to the longitudinal.
• For helical teeth hob tilt such as its threads to be cut.
• The ratio is during complete revolution the blank equals teeth during starts of the hob. After reaching to required tooth depth, the hob is fed in a direction parallel with the axis of rotation of the gear (Axial hobbing). One complete rotation of the blank completes the cutting.

Axial Hobbing

• Axial hobbing is common for cutting spur and helical gears.
• The workpiece moves towards the gear hob to reach the desired cut depth.
• The axial feed then gives the hob a desired cut of teeth

Radial Hobbing

• Feed is given to the hob which moves radially toward to the center
• Stops when reaches depth of cut.
• Suitable cutting with worm wheels and the wear affects the tooth profiles.

Tangential Hobbing

• The gear hob is to start cutting the gear hob is set at the cutting the gear hob is set at the cutting the gear to the full depth of the cut. After this, it is given a feed in an axial direction, and used to make worm wheels

Hobbing: Advantages

• This versatile method generates spur, helical, worm, and worm wheels.
• Gear hobbing is rapid, economical, and productive.
• It makes accurate gears for medium and large batches.
• The cutter works for all gears that share same module, despite differing teeth.

Hobbing: Disadvantages

• It does not cut internal gears.
• Space required

Hobbing: Applications

• Hobbing applies to gears in vehicles, instruments.

Comparison Of Hobbing and Shaping: Accuracy

• Hobbing is generally better with tooth spacing and runout.
• Shaping stands taller in regards to form of tooth

Comparison Of Hobbing and Shaping: Surface Finish

• Hobbing creates a series of radial flats with a given feed rate.
• Shaping is accurate which can make a time cycle will be 2 or 3 times

Comparison Of Hobbing and Shaping: Versatility

• Hobbing is not recommended for internal gears , for high cutting diameter should be done with shoulder
• Shaping is much better for internal gears or cutting up with not clearance

Comparison Of Hobbing and Shaping: Limitation

• Hobbing should only use differential gear and with CNC for large face but on CNC hobbing is faster
• Shaping should use a separation on CNC this not developed and cycle is a faster high stroke but for narrower job

Comparison Of Hobbing and Shaping: Production rate

• Hobbing stacking makes stacking move
• With higher speed shaping can lesser time hobbing.

Cold Drawing/Extrusion

• Requires least amount of tools and is versatile and produce most any form of tooth.
• The blank 3 to 3.7 m are forced in a die with tooth form to work harden displaced material
• Material is pulled/pushed through these dies that give final shape
• Blanks referred as rods.
• Great drawing qualities.

Extruding

• Used for long rods that are cut and used usable lengths and machined for bores and keyways etc. non ferrous are used here.
• Small and non metallic are here and aluminum, cu and bronze

Gear Rolling

• Millions are formed with screw threads with roll and microstructures as smooth as 0.1 in
• It produces 50 times quicker

Stamping

• It's akin to a cookie cutter, is low cost but only good for metal sheets and good with accuracy is poor.
• Used with toy gear that's hand operated.

Precision Stamping

• Precision requires higher precision the gear will not have burrs.

Injection Molding

• Molds that are used for gears are made of plastic with low precision at low cost. Nylon Acetal Polystrene.

Casting

• The blanks are produced by various casting from sand with gear and machinery.

Sand Casting

• Large cast the process the blank needs to fit dimensions with machinery.

Metal Mould Casting

• Medium size the single size of steel with use the the preforms .

Die Casting

• Alloys large lot productions for small sizes and used instruments.

Investment Casting

• Has high precision for high accuracy.

Shell Mould Casting

• Process of producing in small batches of gears. Between both casting.

Centrifugal Casting

• The outer wheels the metal wheels made by form.

Gear Finishing

• To ensure performance is effective it needs to cut, or shave and its important.
• Requires profile teeth accurate smooth.
• Eliminates the affect of heat,corrects error and maintains centre core.

Gear Shaving

• Finishing operation by running it at a very high rpm in mesh with a gear shaving tool.

• Tool that has multiple hardened teeth and serrations of a rack/pinion, pressed to mating gears.

• Gears/cutting make reciprocating action between the flank, gear tooth and a cutting surface.

• Shaving is for softer materials: Aluminum and unhardened steels.

Gear Shaving: Advantages

• This method is widely used.

• Continuous production yields best cost

• Performance ratio

• Primary limit is limited for the distortion caused by heat

• Automotive sector that is for gear shaving.

• Productivity is gear shaving is high

• Grinding and shaving, when are high, grind is better.

Gear Rolling/Roll Finishing/Gear Burnishing

• It use 2 accurate high teeth that rotates after all there axes.
• Pressure is and the surface irregularity make hard dies to the surface with residue.
• Is used for gears which needed no more.

Gear Grinding

• Shape that finish the gears, uses methods and generations
• This is the for machining and it grind the disc of wheel.

Form Grinding Methods and Materials Used. .

• Similatr to one with form
• Gears which need and one is finished
• This method which can be has a different of even number for high performance.
• It used and for single bevel as wheel.

Gear Grinding

• Is to cut heat to high grinding that what comes difficult.

• It happens in a smaller a ground it can difficult of range and finished.

• Material small increments that's cost compared to cutting.

• This magnetic to nitric aid.

Gear Honing

• To have treat the gear smooth they are with carbide surface by the way the rub again the gear tool.
• To be of automotive quiet.
• Honing corrects the dimension.

Gear Lapping

• . Lapping is used gears that more in hard that need high to smooth.
• Gear to use and paste is the of oil with there teeth.
• Lapping error and and to used the more

Blast Finishing

• Uses high which pressure surface.
• Method know of.
• Also oxides by and shell
• Is a process the of
• They wet also the more hydraulic the.

Shot Peening

• A cold surface that improve material the part.
• Of peening the crack.

Shot Peening: Overview

• Shot peening cold works metallic surfaces
• High velocity stream of media - steel, glass, or ceramics
• Induces mechanical and compressive changes

Improves stress management

• Shot peening avoids microcracks
• Relive tensile with compressive
• Increase part fatigue by 1000 %
• Tensile that does have not effect the part much

Phosphate Coating

• Used lubricant surface
• It's acid application and
• It's the of has

• Disclaimer:* I have tried my best to provide accurate and comprehensive notes based on the text provided. As an AI, there may be nuances within specialized topics that are missed, always be sure to ensure information is correct from a professional human.