Spur Gears

Spur Gears

Spur gears are common for transmitting motion between parallel shafts. They are visualized easily and classified as cylindrical gears as a result of their shape. Their tooth surfaces are placed parallel to the axis of mounted shafts and this leads to no thrust force being generated in axial direction. Spur gears can be manufactured to very high degrees of precision as their production is an easy process.

The following is a capability table for shaping, hobbing and internal spur gears –

Efficient Gearing Solution

Spur gears have always been accepted as highly efficient types of gearing solution, particularly when you have to apply transmitting power and rotary motion from a parallel shaft to another. Spur gears generate functioning speed with a steady drive as they are determined by the distance at the center. This driving speed can be increased or decreased by the varied numbers of teeth which are there in the driving gear.

Spur gears are cut straight and are considered as the simplest kinds of gears. They are made up of a cylinder or a disk that has projecting teeth which are radial. The left and right surfaces of spur gears’ teeth are generally made symmetrical and are regarded to be basic when the thickness of the teeth when measured along the circle of the pitch is half of that circular pitch.

Types of Spur Gears

Vestavia has considerable experience as a premium supplier of spur gears for original equipment manufacturers through the European Union and the rest of the world. Many of its custom spur gears have been utilized in gear train applications when several gears are needed to have a similar diameter pitch and the pressure angle. Spur gears are made available in non-metallic, plastic, steel, brass and cast iron. These machined components are manufactured with precision in many styles and types ranging from plain to web and to web with spokes and web with lightening holes. They can be made available with and without the hubs.

• Steel – Their tooth finish is cut and it is non-ground. They are made available in a vast selection of number of teeth and modules. They are economical and have many uses.
• Gears with built-in clamps – They can be mounted to shaft in a one-touch miniature size without a hub.
• Ground – These are gears whose surface is treated with hear and secondary operations are possible. They have superior strength and they function with a reduced friction, leading to a highly compact design.
• Plastic – Their tooth finish is also cut and non-ground.
• MC Nylon – These spur gears can easily be used without the need for lubrication and they are highly suitable for machines that process foods.
• Injection-molded – They can be mass produced and save manufacturers on cost. They are also suitable for light duty applications as in the case of office equipment.

Capabilities of Spur Gears

Spur gears could be manufactured as internal gears and rings and as cluster gears. Internal spurs have cylindrical pitch surfaces and teeth that are parallel to their axis. The teeth are formed on inner surfaces of the cylinders. The cluster gears are manufactured through a cluster or precision array of spur gears. This is done with the help of contrasting bores on shafts or gear blanks. These gear assemblies are used by original equipment manufacturers of automotive, marine industry and off-highway niche applications.

Vestavia’s cluster gears have been utilized in numerous application kinds that have included low to heavy torque power transmissions. The cluster teeth and their bores and pitches are precision-machined to tight tolerances with the use of high-grade steels and special alloy metals.

The units that indicate sizes of spur gears are stated commonly as specified by International Standard Organization to be `module’. It is customary since the past few years to set pressure angles to twenty degrees. In the case of commercial machineries, it is common to use part of involute curves as teeth profiles.

Tooth Forming Process

The teeth form of spur gears is generally shown as plane curves on cross section perpendicular to the shafts. Hence, pitch circles are used in the place of pitch cylinders. The contact points of two pitch circles are known as the pitch points. These are points that two pitch circles touch during the rolling contact. These are spots that have no relative motion between gears. The process of tooth forming is divided into two types known as gear form milling and gear form generating methods. The gear form generation is a method that is used widely and it allows for mass production of involute gears with high precision.

Manufacturing of Spur Gears

Most spur gears and helical gears are manufactured with the help of cutting. Yet, there are many other methods like casting, rolling and forging. In the case of plastic spur gears, in addition to tooth cutting such as with metal gears, injection molding is used depending on the quantity of production.

The steps of manufacture for metal spur gears generally involve cutting off round rod materials, turning blacks on lathe machines and tooth cutting screw keyways and holes that can be added whenever required. This is generally the case when hardness and high accuracy are not required. After cutting of gears, grinding of tooth surface and shaving process is used often to enhance strength and accuracy. Gear grinding is done to enhance the surface roughness and accuracy of gears. It will indicate the grinding process of gear tooth surfaces after tooth cutting and treatment by heat with a polishing stone that rotates at very high speeds and this is done on special tooth grinding machines.