Tips to keep in mind when buying gears

Buying gears can be a difficult task if you don’t have the basic knowledge on the types of devices out on the market and the characteristics that set them apart from each other. There is a wide range of gears that can be categorized based on the material that they are made of, their design or their functionality.

In order to reduce doubts as much as possible during your gear acquisition process, we leave you this article with tips and guidelines to select the most adequate gears:

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What is gear manufacturing?

We call gear manufacturing to the gear manufacturing process, whether it involves casting, extrusion, cutting or forging the materials that they are made of. This manufacturing process can be subdivided into two categories: forming and machining.

  • Forming consists of the direct casting, the drawing, modelling or extrusion of different types of tooth shapes in casting materials, whether powdered or molten.
  • Machining relates to both grinding and finish operations.

The Gear manufacturing process demands high levels of precision and supervision, since any mistake in the shape, finish or size may be critical. The procedure requires several processing operations in sequence, depending on the material and type of gears, and the desired quality.

  • First, raw parts are pre-formed
  • Then, they are sectioned with a cutter that moves axially along the entire length of what will later become the gear itself.
  • Milling and broaching methods are used to manufacture the teeth of the gear; the latter is particularly used for internal teeth.
  • The second to last step of the manufacturing process is the hobbing, which is a process by which teeth are gradually created and completely or superficially hardened.
  • The last process is the tooth finishing, whether by sanding, shaving, etc.

A last inspection of the finished gears guarantees the quality of the device.

Types of gears

There are different types of gears; however, we can differentiate them based on the criteria that we used to classify them: by their material, shape or function.

Based on their material

Even though steel is the most common material for most gears – especially across various industrial sectors – we can find devices that are manufactured with many other materials, such as bronze, tin, aluminum, cast iron, ductile iron or even powdered metals. There are also plastic gears.

Related reading: Why you should improve your safety devices using fireproof plastics

One of the main reasons for steel being a highly used material is that it offers an excellent mix of durability, resistance and weight. In addition to the resistance to wear, its cost is not too high, and thanks to its heat treatment this material’s physical and mechanical properties can be improved.

Based on their shape

The shape of the gear is determined by the position of their axes; whether parallel, intersecting and non-intersecting. From there, we can talk about spur, bevel, helical, rack & pinion and other types of gears.

  • Spur gears

Spur gears are used frequently for many purposes, because they offer a high precision and do not require complex or costly production processes.

They are based on cylindrical wheels, which are straight-toothed wheels, parallel to the shaft with a cylindrical pitch surface.

They do not provide for axial loads (thrust load).

  • Bevel gears

In this case, the gears have a bevel shape and the two axes meet at a certain point.

Both the pitch surface and the gear teeth are cut along the bevel.

Among bevel gears we can find spiral bevel gears, angular gears, crown gears, miter gears, hypoid gears and zerol bevel gears.

  • Helical gears

What sets this type of gears apart is that they are used with parallel axes similar to those of spur gears, but these are cylindrical gears whose wound teeth mesh at an oblique angle from the axis of rotation.

They are commonly used in applications that require speed, since they are capable of transferring higher loads, generating much less noise than spur gears.

The use of helical gears generates a thrust force in the axial direction, which makes it necessary to use thrust bearings.

  • Rack gears

Rack gears are characterized by their teeth having an identical shape and size, in addition to being cut at the same distance along a straight bar or flat surface.

The radius of the pitch cylinder of a rack is infinite, which is why the linear rotary motion results from the meshing with a cylindrical pinion gear.

Racks can be divided into straight tooth racks and helical racks, but they both have rows with straight teeth.

Based on their function

The use of gears is quite widespread in either industrial machines, the automotive industry and tools, as well as in items such as appliances, toys, etc.

We can categorize gears into various groups depending on their role:

  • Spur gears

These are used in parallel shaft transmissions, in all kinds of machinery (their use is quite widespread). They are employed in sectors that require a slow motion where noise is not a significant factor, such as in vending machinery or security systems.

Spur gears are also commonly used to increase or decrease the power of an object, such as washing machines, blenders, clothes dryers, construction equipment or fuel pumps.

Another of its uses is related to speed adjustment. When used for this purpose, they can be found in wristwatches and kitchen mixers.

  • Bevel gears

This gear family solves the transmission between intersecting, crossed axes. They may be:

  • Straight: used in drills, bottling equipment, vending machines, lathes and milling machines.
  • Spiral: these devices work at high speeds: in bicycles, motorcycles and other small vehicles, industrial engineering or naval architecture.
  • Hypoid: automotive industry, as well as harvesting machines or actuators for mills and excavators, such as wheeled excavators.  
  • Helical gears

Helical gears are commonly applied to machinery where the actuators need to work with higher speed ranges (hospitality machines) or lower noise levels (automotive, HVAC).

They are also normally applied in machines that require a high torque transmission with parallel shafts.

  • Rack gears

Rack gears are commonly used as part of a simple linear actuator, where the rotation of a wheel that is manually or motor-operated is turned into a linear motion.

One of its most widespread applications is power steering, as well as in railroad tracks in places with a steep slope, sliding doors and pneumatic actuators.

If you want to know more: How to calculate the gear ratio in your geared projects

Where to buy gears

Buying the right gear is essential to avoid incidents that can turn out to be quite costly.

One of the aspects that directly affect the service life of gears is the vibration that is generated as a result of the meshing, which also causes noise.

This, along with its design and resistance to bending – also known as contact force – determines the durability of a device that is fundamental for the correct operation of machines employed in various sectors.

Which is why it is essential to purchase gears from specialized vendors that have a wide catalog of top-quality gears.

If you are planning to buy gears and need guidance, at CLR we offer the most complete engineering advice and prototype design services to the full satisfaction of our clients.

CLR is a leading gear motor and speed reducer manufacturer with over two decades specializing in finding the best actuator solutions for businesses.

A well-rounded team of engineers works to obtain perfect results thanks to a combination of know-how and experience. Engineering and bleeding-edge technology go hand in hand so that your products exceed the highest expectations.

All of this makes CLR the ideal partner in manufacturing, logistics and customer service, since your first idea to the final product. Get in touch with us and successfully start creating your new project.

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