worm gear

Worm Gear. Image Credit: Howstuffworks.com  Spur Gears. Image Credit: Promark Offroad

Gear manufacturing services design and fabricate gears to customer specifications.

They differ in terms of product capabilities, manufacturer capabilities, and materials.

Selection Criteria

Production capabilities for gear manufacturing services may be divided into gears and other, related components.

Type of Gears

There are many different types of gears. Examples include

  • Anti-backlash gears are designed to take up or eliminate backlash between gears, typically with a spring or other mechanical assist. Backlash is defined as clearance between mating components. Generally backlash should be zero but in certain applications it is useful to prevent gear jamming allow for lubrication, manufacturing errors and thermal expansion. Backlash is undesirable when the gears need high accuracy such as in radio tuning dials.
  • Bevel and miter gears are designed to transmit motion between intersecting axes, which are usually at right angles. Miter gears are bevel gears specifically made for a 1:1 ratio at 90°.

bevel and miter gear

Bevel and miter gear. Image Credit: gearsandstuff.com

  • Change gears resemble spur gears. They are hubless with a keyway that mates with a hub for rapid changing (used in machines where gear ratios are changed frequently).
  • Cluster gears are spur gears with an integral hub whose end can accept a second, hubless gear.
  • Differential gears are gears and gear assemblies that transfer power froma single drive shaft to two wheels, typically on an axle perpendicular to the drive shaft. The differential allows the wheels to be driven at different speed to avoid wheel or tire scuffing during turning. Central to automotive and other vehicle powertrain design.

Differential explained. Video Credit: allegroracing

  • Gear blanks have the hub and O.D. already formed. Theymay be hobbed or ground to any tooth configuration.
  • Gear stock/pinion wire is a length of rod with gear teeth already furnished for custom width machining.
  • Helical gears transmit power and motion between parallel axes (opposite hand) or right-angle axes (same-hand). They have a cylindrical shaped gear with helicoid teeth which allow the load to be distributed over several teeth. Helical gears tend to run quieter and smoother than spur gears due to the increased number of teeth in constant contact at any one period of time.
  • Herringbone gears resemble two helical gears side-by-side.Theytransmit power and motion between parallel axes and may or may not have a center groove. Herringbone gears are also known as double helical gears.

Herringbone gear

Herringbone gear. Image Credit: gearsandstuff.com

  • Hypoid gears are arranged to allow the translation of torque ninety degrees. They combine the rolling action and high tooth pressure of spiral bevels with the sliding action of worm gears. This gear type is generally found within the differential of automobiles
  • Internal gears are typically cylindrical shaped gears with straight teeth on the inner diameter and a circular outer diameter. Often used with a spur gear. Internal ring gears may be used within a planetary gear arrangement.
  • Miniature gears are smaller gears which require precision machining operations on their smallparts to achieve intricate details.
  • Racks have straight component with gear teeth; typically straight-toothed. Theymate with pinion (spur gear) for linear-rotary power transmission.
  • Planetary gears have a gearing arrangement comprising of a central or "sun" gear, multiple "planet" gears that surround and are driven by the sun gear, and typically an internal gear driven by the planet gears. Useful for good power transmission efficiency in a compact, in-line gear train application.

Planetary gear

Planetary Gear. Image Credit: Wiki Commons

  • Spur gears are straight-toothed and transmit power and motion between parallel axes. Tooth contact is primarily rolling, with sliding occurring during engagement and disengagement.
  • Worm gears are screw-like devices whose spiral teeth mate with the teeth of a round worm gear or worm wheel. Typically the worm is driven, and the worm wheel transmits power at a non-intersecting 90° axis. Worm gear drives are often used for high torque, high reduction ratio drives; they are also compact is size.

Gear Related Components

Gear manufacturing services can specialize in gear related components such as:

  • Brakes and brake parts include friction, toothed, or magnetic devices that are engaged to slow or stop moving loads.These brake components include shoes, drums, etc.
  • Chain drives are power transmission assemblies that utilizechain and sprocketsto transmit torque to the driven load.
  • Clutches are power transmission assemblies that engage and disengage drives from the driven load via clutch plates or other methods that use friction, toothed, or magneticengagement.
  • Gages and masters can serve as elements for calibration, testing, and inspection of gears.
  • Gearboxes and transmissions are assemblies with multiple matched gears that transmit power for a drive to a driven load. The transmission typically involves a change of speed, torque, direction, or other aspect of the drive.
  • Impellers include devices that move the fluid for pumps, fans, etc. These can come in a number of configurations such as vane propeller-type impellers, impeller gears in gear pumps, and other styles.
  • Industrial drives is a term describinga variety of geared power transmission assemblies that provide motive force and torque to machinery such as conveyors, elevators, filtration equipment such as thickeners and clarifiers, and other industrial equipment.
  • Splines are shafts or rods with circumferential grooves machined to mate with a female or complementary hole in the center of a gear or pulley for drive traction. Splines can be involuted or straight sided.
  • Rollers are used for conveyors and other belt drives.
  • Sprockets include toothed components that engage a chain or perforations in a driven belt. They are usually used in conveyor systems.
  • Timing pulleys contain grooves that mate with complementary grooves on a belt for maintenance of speed and timing; there is no slip in the belt drive. Many English and metric standard tooth profiles and pitches are available.
  • V-belt pulleysdrive and contain a belt with sloped sides and grooves; several standard English and metric pitches are available. Belt slip is possible, and can be used as a torque limiting technique.

Manufacturing Services

Manufacturer capabilities for gear manufacturing services may be divided into primary and secondary operations.

Services

Primary operations indicate the main functions of gear manufacturing services.

  • Design and development- Supplier can assist with concepts, manufacturing costs, manufacturing techniques and material considerations. Supplier may also be able toassist in upgrading or redesigning, re-evaluating or modernizing existingproducts to increase performance and/or reduce manufacturing costs. Some suppliers offer material sourcing and CAD modeling as well.
  • Failure analysis- Forensic analysis of used or damaged gears and assemblies to improve future design, provide forensic or quality documentation, etc.
  • Inspection and testing- Supplier provides full inspection and/or testing of gears and geared assemblies; includes testing to certification standards.
  • Just-in-time (JIT) manufacturing- Supplier has Just-In-Time (JIT)manufacturingcapability ofgears or geared assembliesin order to reduce need for inventory maintenance.
  • Prototyping- Service includes providing sample or prototype product quantities for testing, design approval, etc.
  • Production manufacturing- Supplier has full gear and assembly manufacturing capability for production quantity orders.
  • Repairs and reconditioning- Repair of damaged gears or assemblies, or reconditioning for worn components and geared products. May involve processes such as regrinding, backlash elimination, component replacement, relubrication, etc.
  • Reverse engineering- Engineering and design of new products aided by analysis or testing of existing components and assemblies. Often used for replacement parts that are required to fit into existing machinery.

Operations

  • Broaching is a process where a non-rotating tool is pressed through material to create a hole or other internal shape.High precision and good surface finishes are possible with broaching, and non-round centers such as square, hex, or star bores can be created.

Broaching Demo. Video Credit: Cubic Machinery

  • Casting, such as metal casting, involves the shaping of free-flowing liquid metals through the use of dies, molds, or patterns. Castings are generally roughly finishedand frequently require additional finishing.Common metal casting processes include sand casting, die casting, permanent mold casting, investment casting, centrifugal casting, and lost foam casting.
  • Gear shaving, also known as gear tooth finishing, is a process involving light for precise material removal by specialized rotating cutters to provide precise tooth form and size.
  • Grinding capability can provide very smooth and precise material finishes, and can be used to finish high-hardness wear surfaces such as gear teeth.
  • Heat treating and hardening is a broad category of processes used to treat metals such as annealing, passivation, hardening, etc.Stress relieving may be important to relieve residual stresses imposed during thehobbing, forming, or other gear fabricationprocess.
  • Hobbing is a specialized machining process using rotating cutters to form gear tooth profiles. The video below is a quick demonstration of this process.

Video Credit: dino161284

  • Lapping and honing is a process for removing small amounts of material to provide good surface finish and/or precision tolerances.
  • Surface finishing includes capabilities for finishing for esthetic and corrosion resistance considerations such as anodizing, plating, painting,powder coating, etc.

Specialty gear manufacturing services that perform unlisted, specialized or proprietary operations are also available.  

Materials

Material capabilities for gear manufacturing services may be divided into metals and plastics / other materials.

Gear manufacturing services that work with specialty and proprietary plastics such as Delrin (DuPont) are also available. A class of homopolymer, Delrin offers high tensile strength, impact resistance, stiffness, and outstanding fatigue endurance.

Quality Standards

Quality standards and certifications for gear manufacturing services include,

  • AS9000 is a standard known as the Aerospace Basic Quality System Standard. The scope is "to assure customer satisfaction, aerospace industry manufactures must produce world class quality products at the lowest possible cost".
  • QS 9000 stands for Quality System Requirements is an international quality management system standard for the automotive industry. All manufactures of automotive parts must complied to the standard for product materials, production and service parts, heat treatment, painting, plating, and other finishing services.
  • ISO 9001 is part of the International Organization for Standardization (ISO) 9000 family of standards related to quality management systems. It is designed to help organizations ensure they meet the needs to customers and other stakeholders. The document covers items such as, ensuring the quality policy is a formal statement from management but is understood by all employees, decisions about the quality system are based on recorded data, the system is regularly audited, etc.
  • MIL-SPEC is a military standard to ensure interoperability with multinational partners and among the Military Departments, information sharing among systems and personnel requires standard data and equipment interfaces and performance requirements.

Applications

Industries served include:

  • General Industrial- power transmission and machinery application; wide range of possible uses.
  • Aerospace- aerospace applications, or rated to aerospace or aviation standards.
  • Agriculture- use in tractors, combines, planters, seeders, or other farming or agricultural equipment.
  • Automotive- use in automobiles, trucks, and other vehicles, or rated to automotive standards or specifications.
  • Construction- heavy equipment such as construction or earthmoving machinery, construction site elevators, concrete or asphalt machinery, etc.
  • Machine tools- suitable for uses in manufacturing equipment such as mills, lathes, grinding machines, presses, etc.
  • Marine- designed or rated for use on ships or shipboard equipment, offshore installations, etc.
  • Heavy transportation- suitable for use with heavy trucks, trains, etc., or rated to applicable standards in those industries.
  • Material handling- handling applications such as conveyors, winches, automatic cranes, hoists, hoppers, etc.
  • Medical and pharmaceutical Designed or rated for use in medical or pharmaceutical machinery such as pump motors, sanitary transfer machines, or other health-related equipment.
  • Military- military or defense equipment rated or designed.
  • Petrochemical- oil and gas exploration, drilling, and processing machinery.
  • Power generation- equipment for use in power plants and associated equipment such as ejectors, steam recovery equipment, power plant cooling, generators, etc.
  • Robotics-gearing and machinery for precision automation robotic equipment, including robotic welding and assembly machinery, pick and place systems, robotic cranes and other automated equipment.

Resources

AS9000 and AS9100 Aerospace Quality Systems

DSP POLICIES & PROCEDURES

Gear Terms & Definitions

Gear Design and Engineering Data

How A Gear Works

QS-9000 Standard 

Selection and use of the ISO 9000 family of standards