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gear machining

Everything You Need to Know About Gears Machining

The concept of gears machining has been around for a while because they are among the oldest mechanical components still in use today. Gears offer several benefits in a wide range of applications. They are used in various products and industries, including automotive, aerospace, industrial, and more.

Gears can be created using techniques such as casting, forging, extrusion, powder metallurgy, blanking, and gear milling. However, the machining process is crucial in achieving the final gear size, shape, and surface smoothness.

This distinctive guide will explain all you need to know about gear machining, including its importance. We will delve into the various methods for gears processing, including important tips for material selection.

The Importance of Gears in Machinery

gear machining process
Gear Machining Process

Gears have several importance in machinery, and some of them include:

Setting the Rotate Speed

The gear cutting process plays a crucial role in regulating the rotational speed of mechanical systems. A prominent illustration of this function can be observed in the utilization of gears within motor engines. These gears are responsible for finely tuning the rotational velocity of the engine by employing specific gear ratios. Including gears with distinct ratios, such as a 1:2 ratio for an electric motor operating at 1400 rpm, facilitates the modulation of motor revolutions per minute. This enables precise control over the rotational speed.

Transmitting Power

An essential functionality of gears lies in their ability to transmit power between interconnected components without encountering slippage-related issues. A common instance of this capability is evident in the context of lathe machines.

A motor is not directly linked to the primary shaft for maneuvering the chuck within a lathe machine setup. Gears are strategically employed to bridge the gap between the motor and the shaft to ensure adequate power transmission. This facilitates the reliable movement of the chuck.

Changing Torque

Torque is an engine’s rotational force, which is significant in facilitating acceleration. Gear blank play a pivotal role in regulating torque output. The impact of gear diameter on torque production exemplifies this principle.

Larger gear diameters generate higher torque levels, a principle that operates in both directions. The choice of gear blank diameter enables precise adjustments to the torque characteristics of an engine, thereby influencing its acceleration capabilities.

Changing the Power Direction

Gear cutting process facilitates alterations in the direction of power transmission. In addition to their role in regulating speed and torque, gear blank can affect a change in the power’s trajectory. Gear cutting is used in structures such as dam gates and reservoir mechanisms.

A notable example can be observed in operating a door through gears. By employing gears, the manipulation of a door handle can be translated into vertical motion. This enables the controlled upward and downward movement of the door.

What is Gear Machining: An Overview

Gear machining involves the precise creation and gear shaping, which are integral components used in machinery to transmit torque. A gear, characterized by its rotating nature, features gear teeth that interlock with those of another toothed mechanism. This mechanism enables the seamless transfer of mechanical power.

The gear cutting process involves meticulously carving gear teeth onto a spherical blank, forming a perimeter adorned with these essential features. The specialized art of gear cutting encompasses various machining techniques, each designed to produce high-accuracy gears.

The crafting of gears is achieved through various means, including machining, powder metallurgy, casting, and stamping. Among the many available techniques, the most precise and popular ones are gear milling, grinding, broaching, and hobbling methods. These techniques ensure the creation of intricate and well-defined gear profiles.

There are several materials used in the construction of gears, including metals, plastics, and even wood. Advancements in technology have brought forth alternative approaches, wherein metal and plastic gears can be formed through die casting or injection molding. Therefore, manufacturers can look beyond the traditional gear manufacturing process. However, it is imperative to acknowledge that certain instances demand post-production machining to refine the final gear product.

Types of Manufacturing Processes for Gear Processing

gear machining process 2
Gear Hobbing

Let’s take a look at the various machining processes for gear manufacturing and their unique applications:

Casting

CNC gear hobbing machines are used to produce the teeth of gears. However, casting is a simpler process that is usually used to prepare blanks or cylinders for gears. It is preferred for gear blank because of its ability for mass production and relative simplicity.

However, casting is the most often used production technique in one specific field. That is the manufacture of enormous gears. Gear cutting and other gear hobbing techniques could be more practical in large diameters. Larger gears usually have spur gear construction.

The most popular casting techniques for making gear are shell casting, die casting, sand casting, and permanent mold casting. In other scenarios, other strategies are only partially useful. Nonetheless, those mentioned above are the most common in the manufacturing sector.

Forging

This is an alternative method of production. It is capable of yielding both blank components and pre-fabricated gears. The forging process finds practical usage, mostly in cases involving relatively uncomplicated gear blank designs.

Theoretically, forging is a highly effective technique for fabricating gears intended for heavy-duty applications. This application arises from the necessity of subjecting forged components to a heat treatment process. Thereby impacting the resulting gears with enhanced fatigue-resistant properties. Nonetheless, it is essential to acknowledge that the formidable forces demanded by the forging procedure impose limitations on the dimensions and thinness achievable through this method.

In practice, forging demonstrates optimal efficacy when producing gears ranging from 6 to 10 feet in diameter. Notably, the specific variant of forging utilized, such as precision forging, may dictate whether subsequent machining processes are requisite to achieve the final gear specifications.

Extrusion and Cold-drawing

machined metal gears
Machined Metal Gears

This represents an alternative method for gear cutting processes that offers versatility while maintaining simplicity. Extrusion, the technique in question, demonstrates advantageous cost efficiency through reduced tool requirements. However, it is essential to note that this factor may not solely determine the ultimate economic viability.

Extrusion, as the term implies, involves the passage of a heated metal profile through a predefined shape of smaller dimensions. This process yields a solid bar possessing the desired geometric configuration, characterized by a robust and impeccably smooth exterior surface.

An analogous procedure, known as the cold drawing process, resembles extrusion, albeit with particular distinctions. Firstly, while extrusion propels the blank through a die, cold drawing pulls it through. Additionally, a contrasting aspect pertains to temperature manipulation. Unlike extrusion, the cold drawing process abstains from heating the initial billet, consequently enhancing the mechanical properties of the resultant product, albeit at the expense of escalated costs.

Powder Metallurgy

Powder metallurgy is a sophisticated technique that has advanced enormously in recent years. It is now employed in various gear manufacturing processes, including internal gears fabrication. So, how exactly does it work? From the outside, it is pretty straightforward. However, there are numerous complexities involved.

Everything begins with metal powder. The first step is to shape all the powder into the desired shape. After that, the next stage ensures that the entire arrangement is compact, which results in higher mechanical properties. After that, carefully heat the whole arrangement.

It is very efficient, simple, and cost-effective in large quantities. No post-processing will be required, and the product will be ready to use. However, the resulting internal gears have size constraints and cannot withstand excessive load. Furthermore, the initial cost of any powder metallurgy system is relatively costly, making it unsuitable for low-volume gear hobbing. 

Blanking

gears cnc grinding
Gears CNC Grinding

The blanking technique closely resembles extrusion, albeit with some limitations on its three-dimensional capabilities. In this gear manufacturing process, sheet metal is employed with a series of dies to achieve the desired shape. A diverse array of gear types can be fabricated through blanking, emphasizing achieving optimal outcomes when producing spur gears.

The blanking approach to gear manufacturing finds application across many industries, particularly in contexts necessitating lightweight solutions. Noteworthy sectors encompass office equipment, hydraulic systems, minor medical apparatus, and other instances where minimal load prerequisites are pertinent. 

Gear Machining Process

This is a prevalent gear cutting procedure due to its adaptability. While conventional machining methods have historically been employed for gear cutting and production, computer numerical control (CNC) machining has markedly propelled its ubiquity.

Material Selection for Gear Machining

machined part materials
Material Selection for Gear Machining

Gears have a wide range of options regarding the machining materials they can be made from. The earliest gears were crafted from wood, and nowadays, various materials are utilized in gear production across different industries. These materials encompass a spectrum, ranging from robust steel or iron for large-scale industrial gears to lightweight plastic for small gears found in toys. The possibilities for material combinations seem limitless.

However, among the various materials, certain ones stand out as frequently employed in gear cutting processes. These materials are:

Several distinct factors must be considered when selecting the appropriate material for gears. The specific application of the gear determines the material’s suitability. The chosen material must possess the right balance of tensile strength and endurance for the intended purpose. Another vital consideration is the coefficient of friction, as gears rely on continuous contact. Furthermore, the ease of processing is crucial, as the gear cutting process requires meticulous precision and accuracy. Material may be strong, but it can pose challenges during manufacturing if it’s easier to work with.

The above materials strike a harmonious equilibrium between these essential properties, making them well-suited for their respective applications. This explains their prevalence in the composition of many gears encountered in various settings.

Types of Gears Used in Different Industries

There are several types of gears used in different industries, and some of them include:

Spur Gear

spur gear
Spur Gear

The spur gear is very common and finds use in power plants, aerospace parts, industrial machines, and more. These gears have straight teeth, which are easy to make and can handle high speeds and heavy loads. However, they can be pretty noisy and better than smooth and quiet operations.

Spur gear can mesh with other gears of the same kind or with internal/external gears. You can see spur gears in various gear setups, like a basic rack and pinion arrangement or a planetary gear system.

Their simplicity makes them easy to create and maintain with precision. Also, spur gear hobbing don’t produce much force in the axial direction, so they work well in gear setups where you want to minimize energy losses.

Worm Gears

worm gears 1
Worm Gears

The worm gear system comprises two main parts: a worm wheel and a screw-like gear. It’s commonly used in aerospace, industrial machines, elevators, and car steering.

The worm wheel gear geometry setup doesn’t provide high speed or efficiency. Instead, it has a unique feature needed for self-locking systems. Sometimes, the worm can turn the wheel, but the opposite usually can’t occur due to the angles of the gears. Additionally, worm-wheel gears create a lot of friction and might need ongoing friction to work well.

Helical gears

helical gears
Helical Gears

Helical gears are almost like spur gears, but their teeth are twisted around a cylinder. This design lets them work well with shafts in different positions. They only mesh correctly with other helical gears having the same twist angle.

Helical gear is used for similar tasks as spur gears. However, the angled teeth help reduce impact and make gear cutting smoother. This leads to less noise, but it does lower efficiency. Helical gears have more energy losses than spur gears and need thrust bearings due to their shape.

From a manufacturing viewpoint, helical gears are more challenging than spur gears. Getting the twist angles right within tight tolerances is tricky. Also, their machining costs and the need for extra parts limit their use to specific tasks.

Bevel Gears

bevel gears
Bevel Gears

Bevel gears differ from regular cylindrical gears. They operate on a slanted surface, which enables altering the transmission’s direction between crossing shafts. While typically used at 90-degree angles, bevel gears can also be applied in different setups. Several common bevel gear types are:

  • Straight bevel gears
  • Spiral bevel gears
  • Miter gears
  • Crown gears
  • Hypoid gears

These types are widely utilized across various applications.

Conclusion

Gear hobbing has transformed as advanced machinery now substitutes traditional hammers. Yet, it remains a precise process, demanding durable gears for harsh conditions. One needs an accurate and efficient gears machining process and well-designed production parts in appropriate quantities to make gears effectively.

at machining corner gear machining
AT-Machining Corner Gear Machining

AT-Machining offers you outstanding gears machining services for a wide range of applications. Our machine shop perfectly combines technical expertise and extensive gear manufacturing capabilities to deliver high-quality prototypes and production parts. Our strict quality control system also ensures we efficiently meet your unique demands. Contact us now, and let’s get your project underway.

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From AT-Machining, I’m a CNC Machining Expert in this field for more than 20 years.  We offer cost-effective machining services from China. Ask for a quote for your ongoing or upcoming projects now!

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