A Short History of Gears and Where Gear Manufacturing Is Today

 

CNC Gear Hobbing Machine

 

Gears were a logical continuation of the invention of the wheel. That gears are called the biggest invention after the wheel is not unthinkable. In any case, we can't live a normal day in our lives without gears: without gears no production, no energy, and no transport. The use of gears is so obvious that we never dwell on where they come from. In this article, out of respect for the gear, we will detail the interesting history.

Gears are such a common simple machine that it's hard to think there was ever a time before they were used. But just like the wheel or any other man-made invention, gears had a starting point and a course of evolution over thousands of years that have led to their current state today.

 

Gears Are Actually a Natural Product

baby-lantaarnachtigeBut were the ancient Greeks really the inventors/ Research biologists at the University of Cambridge are certain that the ancient Greeks were not the first. The three-millimeters small bug Issus coleopterans, a lantern bearer like those in Europe and North Africa, uses this mechanism already for millions of years. The gear is not a human invention of the ancient Greeks, but a mechanism that arose through evolution in nature.

Nymphs of the insect have an ingenious system of gears that causes their rear legs “click” together and at the same time run away and then jump forward. Using electron microscopy and high-speed cameras biologists captured the precise operation of the insects' mechanisms. It is known so far as the first working gear system from nature.

>> Shop for our CNC gear hobbing machines here

 

 

CNC 5 Axis High Speed Gear Hobbing Machine

 

First gear was developed

It's hard to say when the first gear was developed, but some of our earliest records point back to around 2700 BCE, with gears featuring in a device called the Chinese South-Pointing Chariot. This chariot featured a gear that would automatically turn a directional arrow so it always pointed south, no matter which way the chariot itself turned. It was one of the earliest ways to gauge cardinal directions without the use of magnets.

Gears were also formally mentioned by Aristotle in some of his writings around 400 BCE. He described gears as capable of reversing the direction of momentum, and we've found artifacts dating back almost this far with gears as central components, such as in wheels and rudimentary clocks. Gears also featured prominently in inventive sketches by Leonardo da Vinci, circa 1500.

By the 1600s, scientists and engineers were figuring out mathematical concepts like velocity ratios and involute curves, allowing them to use gears for more complex and more heavy-duty tasks, but it wasn't until the 1800s when the first form cutters and gear hobbing machines emerged, allowing gears to be mass-produced and refined in terms of form and performance.

The next major step forward was in 1897 when Herman Pfauter invented the machine that could cut both traditional “spur” gears and helical gears, driving production further forward. Over the next hundred years or so, the development of NC hobbing machines and full 6-axis machines would start to perfect how we design, cut, and manufacture gears.

 

Today Gear Manufacturing

Today, gear manufacturers primarily use CNC machines to cut gears from blanks, and our level of precision is driven by sophisticated design software and advanced engineering theories. Modern gears are exceptional pieces of work, capable of lasting centuries (or longer, if cared for properly), and technology continues to advance to bring us better ways of producing gears.

 

If you are interested in CNC Gear Hobbing Machine or need a quote for a large project, be sure to contact us today!

Difference Between Gear Milling and Gear Hobbing

 

CNC Gear Hobbing Machine

 

Gear is a vital component for rotating machines, with teeth mesh with another toothed part to transmit torque. How gears are made? Other than casting, forging, CNC machining can be applied to achieve the final shapes, dimensions, and surface finish of a gear. Here we introduce and compare two gear manufacturing methods – gear milling vs gear hobbing, what are the differences between them?

 

What is Gear Milling?

 

Gear milling is a common CNC milling operation and gear-cutting process of creating a gear. It can be operated either after or instead of forming processes including casting, forging, and extruding. Gears are usually made from metal, plastic, and wood. Many metal and plastic gears made by die-casting, injection molding, or additive manufacturing may not require cutting. For coarse-pitch gears, the generative gear milling technology can improve efficiency, expand the pitch capacity of the machine, reduce cutter cost, and may decrease the machining times.

 

What Cutter Used in Gear Milling?

 

The gear can be cut on a milling machine or jig grinder utilizing a gear cutter and indexing head or rotary table, the quantity of gear cutter is determined by tooth count of the gear required. Various types of cutters can be used for producing gears, for example, the rack shaper, with six to twelve teeth, straight and move in a direction tangent to the gear. The cutter has to move back to the beginning position for the new round cut.

 

What is Gear Hobbing?

 

Gear hobbing is also a gear manufacturing method to cut teeth into the blank with a hob like an index hob and master hob on CNC gear hobbing machines. The hob and gear blank rotate at the same time in a mesh and cut the teeth by continuous cut, the rotating hob is fed inward until achieving proper depth, then work for the entire gear. Gear hobbing is a great choice for medium to high volume production runs. The hobbing features for gears including straight, helical, straight bevel, face, crowned, worm, and chamfering.

 

How to differentiate gear hobbing and gear milling?

 

1. The way gear teeth are produced

 

In gear milling, a single tooth spacing or gap between gear teeth will be created by a rotating multi-edge cutter at a time, the cross-section of generated teeth is similar to that of the cutter. In gear hobbing, the gear teeth are progressively produced by a series of cuts with a hob. So the hob cuts several gaps simultaneously.

 

Hobbing Machine

 

2. Cutter

 

Gear milling uses a rotating form cutter, when each tooth space is cut, the cutter will return to the starting point and gear blanks are indexed for next cutting process; gear hobbing uses a helical hob cutter, the hob and the workpiece are both rotating constantly when the hob is fed across the face width of the blank.

 

3. The number of teeth cut in one time

 

Each cutter in gear milling is designed to cut a range of tooth numbers, while in gear hobbing, both the hob and gear blank rotate continuously as in two gears meshing until all teeth are cut.

 

4. Price of tool

 

Generally, the gear milling cutting tool is cheaper than that of hobbing, but the productivity of gear hobbing may be higher.

 

5. Application

 

Gear hobbing is more often used for high production runs, and gear milling is a low production process.

 

6. Others

 

– Gear milling requires deburring

– Gear milling is often used when other generating processes are unavailable.

 

If you’re eager to learn more about the gear hobbing machine, or if you have an order you’re ready to place, contact GEEPRO today! We’ll have a quote back to you in less than 24 hours.

The 5 Advantages of Gear Hobbing

Gear manufacturing gives us lots of options. There are a handful of different processes we can use to make dozens of different gear types from dozens of different materials. Accordingly, when we choose a gear manufacturing method, it’s because it’s the best one for the job.

Gear hobbing is just one way we can manufacture gears. It relies on a special form milling machine with a tool known as a hob, which generates the teeth in both gears and splines.

 

CNC 5 Axis High Speed Gear Hobbing Machine

 

So What Are The Advantages of This Process?

1. Speed. Some gear manufacturing processes take a long time, but gear hobbing is relatively fast. The machine is simple, so it doesn’t require as much operational attention, and for some gears, we can stack multiple units to hob them all at the same time.

2. Flexibility. There’s more than one type of hob—and more than one type of hobbing machine. There are countless variations that cater to specialized applications, so you always have options available.

3. Applications. While hobbing is often used for spur gears, the process can be used for a variety of other gears, such as cycloid gears, helical gears, worm gears, ratchets, splines, and sprockets (as long as you have the right tools for the job).

4. Related processes. One of hobbing’s only weaknesses is that it does not work for internal gears (with inward-facing teeth). However, there’s a related process called shaping that can be used instead—with all the same advantages of hobbing.

5. Precision. That said, not just anyone can operate a hobbing machine. With the right expertise, hobbing can be highly precise, resulting in high quality gears.

 

The Perks of Precision in Gear Hobbing

In the world of gear manufacturing, precision makes all the difference. Every stage of the process needs attention, from the initial design of the gears in a given system, to the manufacturing and finishing equipment used to create new gears, to the engineers and operators in charge of overseeing the final production of each gear.

 

Why Precision is So Important?

Better structural integrity. Gears that have been designed professionally, with keen attention to detail, tend to have better structural integrity. Those that have no manufacturing or design flaws, will hold up longer over time.

A better fit. Most gears end up in machines that require a perfect or near-perfect fit. If the gear teeth are out of position by any amount, it will compromise the efficiency of the machine and might lead to gear failure.

Less noise. A gear poorly manufactured gear may also result in more noise in the final application.

Less wear and tear. Finally, gears with even the tiniest imperfections can lead to increased wear and tear; if they don’t fit properly or they have existing defects, those defects will only grow over time. This leads to a lower life expectancy for your gear, and in some cases, an entire failure of your machine. This is especially noteworthy because of how subtle the imperfections can be—practically invisible to the naked eye.

 

If you’re eager to learn more about the gear hobbing machine, or if you have an order you’re ready to place, contact GEEPRO today! We’ll have a quote back to you in less than 24 hours.

The Basics of Gear Manufacturing

 

 

Gear Hobbing

Gear Hobbing is a machining process for gear cutting, cutting splines, and cutting sprockets on a hobbing machine, which is a special type of milling machine. The teeth or splines of the gear are progressively cut into the material (a flat, cylindrical piece of metal) by a series of cuts made by a cutting tool called a hob. Compared to other gear forming processes it is relatively inexpensive but still quite accurate, thus it is used for a broad range of parts and quantities.  The hob is basically a worm with gashes cut across it to produce the tooth face cutting edges. All motions in hobbing are rotary, and the hob and gear blank rotate continuously as in two gears meshing until all teeth are cut. Hobbing is one of the most fundamental processes in gear manufacturing. Its productivity and versatility make hobbing the gear manufacturing method of choice for a majority of spur and helical gears.

 

Gear Shaping

Gear shaping is a process for generating gear teeth by a rotating and reciprocating a pinion-shaped cutter.  The cutter axis is parallel to the gear axis. The cutter rotates slowly in timed relationship with the gear blank at the same pitch-cycle velocity, with an axial primary reciprocating motion; to produce the gear teeth. A train of gears provides the required relative motion between the cutter shaft and the gear-blank shaft. Cutting may take place either at the down stroke or upstroke of the machine. Because the clearance required for cutter travel is small, gear shaping is suitable for gears that are located close to obstructing surfaces such as flanges. The tool is called gear cutter and resembles in shape the mating gear from the conjugate gear pair, the other gear being the blank.

Gear shaping is one of the most versatile of all gear cutting operations used to produce internal gears, external gears, and integral gear-pinion arrangements. Advantages of gear shaping with pinion-shaped cutter are the high dimensional accuracy achieved and the less expensive tools. The process is applied for finishing operation in all types of production rates.

When the surface finish and dimensional accuracy are not 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.

 

How Gear Manufacturing Can Overcome the Backlash Problem

In some gear systems, too much or too little backlash can be a problem. Fortunately, there are a few techniques we can use when manufacturing gears to insure proper backlash.   Too much backlash and the gear mesh is sloppy, too little backlash and the gears have a potential to bind.  Because of this it is very important to know how the requirements for the gear system and optimize the backlash for the best performance.

In case you aren’t familiar, gear backlash refers to both an error in motion when two or more gears are moving, as well as the small spaces between gears that are responsible for those errors. Backlash tends to occur in all systems but is most critical in systems where gears reverse direction.  The more backlash, the more “slop” when a system reverses direction.

 

Imagining a System Without Backlash

It’s hypothetically possible to have a system with gears that reverse their momentum, with no backlash. In this system, the gears would need to be manufactured and designed absolutely perfectly. You wouldn’t be able to use any lubricant, and you wouldn’t be able to allow any kind of thermal expansion or retraction. Unfortunately, it’s practically impossible to construct such a scenario. So instead, we need to focus on optimizing backlash.

In some applications, backlash isn’t much of a concern. But for applications where minimizing backlash is a priority, there are some techniques we can use to reduce or eliminate the problem. For example, you can split some gears on a plane perpendicular to their axes, then use the two halves with springs to provide more torque to the system. We can also taper teeth in its axial direction, and then allow the system to take up slack by letting the gear slide in that same direction.

Ultimately, we can also reduce the impact of the backlash problem by doubling down on our commitment to producing top-quality gears.

 

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What Is Spline Milling?

 

What Is a Spline?

Typically made of stainless steel, carbon steel, alloy steel, or aluminum alloy, a spline is a shaft that features a series of equally spaced teeth that can be slotted into a mating piece for the purposes of transmitting torque or serving as a means of anti-rotation. They can be internal or external and comprise a variety of tooth shapes depending on function. Rotary devices such as gears can also be fitted onto the spline to serve a variety of functions. Splines are primarily found in rotating mechanisms such as drive shafts.

 

What Is Spline Milling?

Spline milling is one of the processes of machining grooves into a chunk of raw material to create the teeth of a spline. The following steps outline the process of spline milling:

• The chunk of raw material that will become the shaft of the spline is fitted into the indexing fixture of the milling equipment.
• Side milling cutters are mounted onto the arbor of the fitting equipment with a spacer and shims inserted between them, depending on the desired width of the spline.
• The arbor is mounted onto the spindle of the milling machine, and the cutters are centered over the raw material that will become the shaft of the spline.
• The splines are cut into the shaft by a process called straddle milling. The indexing fixture holds the shaft of the spline steady while a groove is cut by the rotating milling cutters along its length. Depending on the depth of the spline, multiple passes along the same groove may be needed. Multiple passes also help to guarantee uniformity throughout the spline.

 

How to Cut Splines on a Shaft?

Spline milling is one of several processes of spline cutting, which is the process of machining teeth into internal or external splines. Spline cutting can be used to create shafts, gears, and other mechanical components that mesh into one another and allow power to be transferred throughout a mechanical system.

There are four main spline cutting techniques:

• Broaching
• Hobbing
• Milling
• Shaping

 

Know about Geepro Machinery YK631 CNC Spline Milling Machine

 

 

YK631 CNC spline milling machine is five-axis linkage machine tool with the movement form of workshaft, tool spindle, servo feed (X axis), servo feed (Z axis), tool lift (Y axis). Mainly use rolling and milling processing straight slot spline shaft, inclined tooth spline shaft, tooth shaft and straight gear, and can process cone spline and step spline shaft.This machine tool is suitable for the machining of automobile, tractor industry and machine tool manufacturing industry, hydraulic parts manufacturing industry, lifting machinery, construction machinery and other industries.This function realizes the rolling for two or more splines with the same number / analog of teeth on the workpiece.

Rob speed range of this machine tool: from 100-1500 turn CVT adjustable, can double improve the cutting efficiency.The machine tool can select air-cooled and wet cutting according to the tool and production process.

Know The Difference Between Gear Shaping And Gear Hobbing

 

Just like any sheet metal is fabricated to form the right mold, shape, size, and so on, gear manufacturing has certain machining processes such as shaping, hobbing, and so on. Gears are required to be set in motion, rotate, and raise the speed of any machine, industrial equipment, automobiles, and so on. So, how are these gears made? CNC machining methods are widely applied in the last stages of gear manufacturing, and milling, casting, forging, and so on are some of the methods used. Gear shaping and hobbing are also two important processes of gear manufacturing. The process to be used depends on gear specifications such as the shape and size required, among other parameters. This post discusses and compares the two methods- gear shaping and gear hobbing.

 

What is Gear Shaping?

Shaping is almost a subset of the milling process. This process helps form the gear teeth with the help of a rotating cutter tool, wherein its axis is parallel to that of the gear. The rotating speed and velocity of the cutter must match with the gear blank for teeth formation. A train of gears helps achieve the relative motion between the cutter shaft and the gear blank. Here the cutting may happen either at a downward or upward stroke. This is suitable for shaping of gears closely located toward the flanges or other obtrusive surfaces. This is widely used process for making internal and external gears. High dimensional accuracy is one of the major benefits of the shaping process apart from its cost-effective tools. After this process, surface finishing may be required depending upon the application.

 

What is Gear Hobbing?

Hobbing is a method also used for teeth formation in gear manufacturing. This teeth formation is done on the gear blank with the help of a hob on CNC gear hobbing machines. This machine is a type of special milling equipment. It could be an index hob or a master hob. There are various other types of hobs such as spline, spur, helical, chamfer, roller chain sprocket, straight side, and so on. The gear blank and the hob rotate simultaneously and produce continuous cuts on the blank gear which gives the required depth to the teeth. As mentioned above, the machining processes chosen are largely based on the shape and size of the gear. Likewise, hobbing is applicable for gear shapes such as helical, straight bevel, crowned, worm, face, and chamfering. Also, it is suitable for medium to high production volume. This cost-effective yet efficient process is useful to make several parts irrespective of the quantity.

 

Accuracy

There are benefits that come with each gear production. For example, the movement accuracy of gear hobbing is high. While that is not the case for gear shaping, gear shaping is more accurate in the surface finish. This is because the mechanic gear shaper is more complex. When comparing the two even further, the manufacturing process is simpler and easier to manufacture more accurately.

 

Productivity

In most scenarios, gear hobbing is more productive than gear shaping. This is because, in gear hobbing, there is not a large number of redundant metals. There is an instance, however, where gear shaping can compete with gear hobbing in terms of productivity. That scenario occurs when the gear is smaller in size and the teeth have a large and small-tooth width.

 

The conclusion

Looking at the accuracy and productivity allows you to better see the difference between gear shaping and gear hobbing. These two gear producing systems are alike, yet have their differences. Hopefully, this explanation gives you a better foundation to understand that.

If you notice, the difference between these two methods is really in the way the gear teeth are formed.

If you happen to be searching for a company that can create custom made gears, look no further. Not only do we have skilled professionals who can create exactly what you need, but we will provide you with insight on all things gears as well.

A Short History of Gears

 

 

Gears are considered as one of the oldest equipment known to mankind. The origin of gears goes down to the Chinese South-Pointing Chariot in the 27th Century B.C. This chariot was known to pointing to the south no matter how it was turned.

Aristotle has the credit to his name of giving the earliest description of gears in the 4th century B.C. According to his definition, the direction of rotation is reversed when one ear wheel drives another gear wheel. Gears have been used by the Greek Inventors in water wheels and clocks. The sketches of various types of gears of this time can be found in the notebooks of Leonardo da Vinci.

Even after these ground-breaking discoveries, no major development concerning wheels was made until the 17th Century. In this time, first attempts were made to provide constant velocity ratios. These attempts utilized the involute curves. This was just the beginning of something that changed the world for all the good reasons. However, in the 19th century, form cutters and rotating cutters were first used and it was then in 1835 when the English inventor Whitworth patented the first gear hobbing process.

Various other patents followed until 1897 when Herman Pfauter of Germany invented the first hobbing machine capable of cutting both spur and helical gears. Through the 20th century, various types of machines developed. But, the next major step came in 1975 when the Pfauter Company in Germany introduced the first NC hobbing machine and in 1982 the Full 6 axis machine was introduced.

 

Today

Gears or Cogs are in just about everything containing a spinning part, that is, from cars to clocks. Car's transmissions and engines contain lots of cogs that help in reducing the gear in motorized equipment. There're other lots of important jobs performed by these simple machines.

Besides being used in the industry, gears are also being used in different toys and they are one of the major components in toy cars and other toys to help them move. Even in smaller toys, gears are used in different sizes to ensure the proper functionality of them.

Gear manufacturers primarily use CNC machines to cut gears from blanks, and our level of precision is driven by sophisticated design software and advanced engineering theories. Modern gears are exceptional pieces of work, capable of lasting centuries (or longer, if cared for properly), and technology continues to advance to bring us better ways of producing gears.

 

If you have a custom made gear to order, or need a quote for a large project, be sure to contact us today!