Gear manufacturing refers to the making of gears. Gears can be manufactured by a variety of processes, including casting, forging, extrusion, powder metallurgy, and blanking, shaping, grinding, and Computer Numerical Control (CNC) machining. As a general rule, however, machining is applied to achieve the final dimensions, shape and surface finish in the gear. The initial operations that produce a semifinishing part ready for gear machining as referred to as blanking operations; the starting product in gear machining is called a gear blank.[1] The manufacturing process has evolved with the technology given in production starting with most gears being produced by hand to now being produced by multiple methods.
The origin of gears dates back as early as 4th century China. Gears were also found in recorded work of the ancient Greeks and Romans. The ancient Greek mathematician Archimedes advanced the understanding and application of gears. Early gears were typically made of wood or stone, later using bronze gears. During the Middle Ages, gears began to be crafted out of various metals to accommodate for the need for durability and precision. During the Industrial Revolution, gears were used in powering the machinery and factories, leading to advancements in gear manufacturing.[2][3] This led to mass production of gears and other metal components.
Gear properties
The gear material should have the following properties:[4]
Gears are essential as they are part of most transmission systems.[7] These systems allow the user to switch gears, and to change both the power and speed of the vehicle to suit whatever driving conditions are necessary
Along with changing the speed and power, gears are also used for steering systems such as a steering wheel which allows for changing the direction of rotational motion
Gears are the pillar of traditional clock mechanisms, using many gears to translate small amounts of energy or work to keep up with the precise measurements of time
These gears are smaller than others but the intricate design allows for great longevity and accuracy with timekeeping
Similar to cars, gears enable precise movements and also greater control and robotic mechanisms
Because of their ability to change speeds intricately and transmit power, they are integral to robotic manufacturing, healthcare, and exploration missions
Their efficiency also leads to many developments in robotics, helping to achieve more difficult tasks that humans would not be able to do alone
Nuclear reactors use gears in flow control systems to help regulate coolant flow, which helps to ensure the safety of nuclear plants
Gear manufacturing processes
There are multiple ways in which gear blanks can be shaped through the cutting and finishing processes.[9]
Gear forming
In gear form cutting, the cutting edge of the cutting tool has a shape identical with the shape of the space between the gear teeth. Two machining operations, milling and broaching can be employed to form cut gear teeth.[10]
Broaching can also be used to produce gear teeth and is particularly applicable to internal teeth
The process is rapid and produces fine surface finish with high dimensional accuracy
Because broaches are expensive and a separate broach is required for each size of gear, this method is suitable mainly for high-quality production
Gear generation
In gear generation, the tooth flanks are obtained as an outline of the subsequent positions of the cutter, which resembles in shape the mating gear in the gear pair. There are two machining processes employed shaping and milling. There are several modifications of these processes for different cutting tool used.[16]
Gear hobbing:[17] Gear hobbing is a machining process in which gear teeth are progressively generated by a series of cuts with a helical cutting tool. All motions in hobbing are rotary, and the hob and gear blank rotate continuously as in two gears meshing until all teeth are cut.
Finishing operations
As produced by any of the process described, the surface finish and dimensional accuracy may not be accurate enough for certain applications. Several finishing operations are available, including the conventional process of shaving, and a number of abrasive operations, including grinding, honing, and lapping.[18]
Gear failures and mistakes
Even with current technologies, gears are still susceptible to errors during production.[19][20] There are issues with misaligning the installations, wearing down the teeth on a gear from the lack of lubrication, corrosion, and added stress that can be put to damage gears.
Modern advancements
Developing technology has allowed for progression in the production of gears ranging from prototyping to quality control.[21]3-D printing has been used as early as the 1980s for printing and manufacturing gears. This allows for rapid prototyping and also the production of smaller-scale productions. Advancements in gear designs and quality detection have improved with the integration of Artificial Intelligence. Artificial Intelligence has been used for refining control systems, allowing for fewer mistakes to be made. The use of robotics and CNC technology has contributed to furthering production by increasing speed while maintaining precision. The use of robotics leads to lower production costs and higher mass production.
Environmental impact
Gear manufacturing has an environmental footprint due to waste product and supply usage.[22] There have been advancements made to be more sustainable such as:
Biodegradable materials
Recycling plastics
Utilizing renewable energy sources to power manufacturing plants
Companies using low-emission production techniques
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