Worldwide, Reishauer gear grinding machines play a major role in the manufacturing process of grinding gears used in automobiles, aircraft, and construction/agricultural machinery.

For more than two centuries, Reishauer has been shaping industrial history.

Since its founding in 1788, the Swiss company has moved from manufacturing precision thread cutting tools to being a market leader in precision gear grinding machines.

“Automobiles, aircraft, and construction/agricultural machinery all require high-accuracy gears for their transmissions,” said Walter Graf, marketing manager with Reishauer. “Worldwide, Reishauer gear grinding machines play a major role in the manufacturing process of grinding gears used in such transmissions.”

A lot of demands are placed on these transmissions, which include the reliable transfer of high torque and power density, low weight, and minimal noise emissions.

“Reishauer precision ground gears ensure the demands placed on transmission gears are fully met,” Graf said.

And Reishauer has been a leader in the field of continuous generation grinding of gear teeth for more than 60 years.

It has accomplished this with twist control grinding and Reishauer fine- and polish-grinding for the Reishauer process, according to Graf.

Continuous generating grinding

First Grinding Machine

But it really started when Reishauer developed its first grinding machine in 1928, he said. It was a thread-grinding machine with a single-rib vitrified grinding wheel.

“This thread-grinding machine required precision gears for setting the pitch of the different threads on taps,” Graf said. “The precision of the threads was directly related to the accuracy of the gears within the machine.”

The engineers at Reishauer were always striving to be better than the status quo of technology. This desire drove them to find a better way to manufacture high precision gears, according to Graf.

“This led them to the invention of a new idea of gear grinding, the continuous generating process of grinding gear profiles, a process for which Reishauer has been famous ever since that invention,” he said. “This process delivered gears that were more accurate, less expensive, and faster to manufacture than any previous methods of tediously grinding gear teeth gap by tooth gap. The success of the thread- and gear-grinding machines prompted Reishauer to halt tool manufacture and concentrate exclusively on building machine tools.”

And as the cost-per-gear-ground diminished with increasing efficiency of the generating grinding process, automotive gear grinding gained more and more interest, Graf said.

“The gear-grinding machine, both in qualitative and quantitative performance levels for the large volume production of high-accuracy gears, is at the core of the continuous generating grinding technology invented by Reishauer in 1945,” he said.

Reishauer has made a constant effort to extend its technical competency and support structure in automation, tooling, application engineering, and service in order to ensure a steady, high-production output of the machines at constant quality and at lower costs per piece, according to Graf.

Gear inspection

Single Source Supplier

This philosophy has allowed Reishauer to become a single source supplier, guaranteeing its customers a long service life of a machine system, which leads to lower life-cycle costs, he said.

As computer systems began to be integrated into Reishauer’s products, the need for innovative software became necessary.

“A wide array of software developed over the past 10 years gives our customers the flexibility to optimize gear tooth forms and surfaces,” Graf said. “Fine- and polish-grinding were developed at Reishauer to greatly improve surface finish by reducing surface roughness of tooth flanks ground with continuous generating process to the level of a super finish process, without affecting the gear geometry, the flank topography, or the peripheral zone. Compared to finish-grinding, the task of polish-grinding is to reduce only the peak height of the roughness profile without changing the flank topography of the tooth flanks in the active area of the face width.”

Increased customer demands have created new challenges for a traditional machine manufacturer, according to Graf.

“Reishauer has developed into a system supplier, and now provides the complete perishable and durable tooling for the Reishauer process,” he said. “All products — including machine, diamond dressing tools, clamping fixtures, and grinding wheels — are engineered and manufactured in-house.”

Today, the company produces its own tooling such as grinding wheels, workholding, diamond dressing rolls, and material-handling automation, according to Graf.

“In this way, Reishauer can truly guarantee that all elements of the grinding process — the machine and the tooling — are fully under control,” he said.

The cornerstone of the Reishauer grinding process is its performance portfolio: the Reishauer Circle of Competence.

Meeting Customer Needs

All of this goes into how Reishauer approaches its customers to assess their needs.

“We start with the design and application of the gear, consider the available plant support equipment and its location and use the EAU numbers to define our design path,” Graf said. “The material and hardness of a gear defines the scope of the grinding process, clamping fixture design selected, diamond dressing tools needed, grinding wheel parameters, and the configuration of the coolant filtration system. Many of our machines are automatically loaded. This process can vary from a one-piece flow to a fully automated integrated loader with on-board inspection. Working with and staying in constant contact with plant personnel during the build process are key elements to a successful installation.”

The RZ gear grinding machine family from Reishauer. (Photos courtesy: Reishauer)

Looking to the Future

The future of gear grinding also holds some interesting challenges for the industry in general and Reishauer in particular.

“What the gear-grinding machine tool will have to accomplish will depend on the types of gears to be ground,” Graf said. “Assuming that in 20 years time some 30 percent of cars will be electric, this will put higher demands on the quality of the ground gears regarding both the gear-flank geometry and the surface structure.”

Gears of electric drives systems turn at much higher revolutions than the ones found in an internal combustion engine (ICE).

“For electric drives, we are looking at 15,000 rpm, and this may be as high as 30,000 rpm in 20 years,” Graf said. “Hence, the question of noise suppression will be much more pertinent as noise generation is exponential to the rotational frequency. Additionally, gears of electric drives do not have the noise masking that transmissions of ICE drives have.”

Because of this, Graf said future hard-finishing machine tools will have to be able to deal effectively with the gear-noise issue by producing the required surface structures and geometrical modifications.

“These requirements will not be limited to the machine tool itself but will extend to the tooling, including the grinding wheels, diamond dressing tools, workholding, and automation, and as a consequence, to the perfect synergy of all of these elements,” he said.

As it meets the challenges of the present and looks to its future, Reishauer has come a long way since the development of its first machine tool — a “taps-lath” with a radial relieving unit built in 1862 to make the first threading taps.

“Reishauer precision-ground gears ensure the demands placed on transmission gears are fully met,” Graf said.