Precision grinding on the Haas Multigrind® increases surface quality and component accuracy.

The creativity of the designers knows no bounds with new drive element and gear geometries. Faced with constantly increasing demands from a wide variety of industrial sectors, today solutions are being sought that often cause major problems in production. The trend toward special products, small and special series, prototypes, and test setups is omnipresent. But can these specific components still be manufactured economically and efficiently, without compromising the required precision and repeatability in the manufacturing process?

Previously, the production of small series had to be carried out at very high cost, which ultimately caused unit costs to explode. Until now.

For bevel gears, there is now a completely new solution on the market that will make both designers and production departments sit up and take notice. Precision grinding of small batches on the Haas Multigrind® significantly increases surface quality and component accuracy, while at the same time reducing manufacturing costs many times over.

Circular arc or cycloid

On the Haas Multigrind® grinding machine, almost all variants of special bevel gears can be ground extremely economically, both circular arc and cycloid geometries. And not only that, but the ground bevel gears set new standards with regard to precision and reproducible quality.   

“In every industry, be it automotive, aviation, robotics, wind power, etc., there are standard requirements for series products and a growing number of specific special applications,” said Wolfram Hermle, chief developer at Haas Schleifmaschinen. “A modern high-performance transmission or differential in a production car can always be produced in series on a conventional milling machine. But not a special gearbox for a racing car. The demands on material and precision are so extraordinary that it makes sense to choose a much more suitable production route. Or let’s think of a satellite, whose awning has to be unfolded reliably after reaching the final position. The conditions in space make a second, third or fourth chance difficult. Also, in the prototype development of the robot industry, no designer wishes that expensive blanks be milled and ground until the desired result is almost perfect.”

Bevel gear production for a small series with a batch size of 1 to 100 can be done on the Multigrind® CA. (Courtesy: Haas Schleifmaschinen)

Bevel gear: Milling or grinding?

Grinding, of course. For special productions in small series, the use of expensive milling tools is not worthwhile. And in order to produce a perfect surface, you would have to regrind anyway. The Haas Multigrind® grinds even highly complex workpieces directly from the solid, faster, more precisely and also, considerably more economically.

Bevel gear all-rounder + problem solver = Multigrind®

In terms of flexibility, precision, and productivity, the Haas Multigrind® grinding machine series is the perfect choice for small series production of highly demanding bevel gears. With at least 5 axes and an enormous drive power in spindle and rotary axes, this production unit offers a maximum of power and dynamics. The machine’s thermostable, vibration-damped cast mineral bed provides the required stability.

Multigrind®: Gear cutting and/or cylindrical grinding in a closed loop

Complex workpieces such as special toothing on bevel gears can be completely machined in a single clamping, which significantly increases precision and saves a lot of unnecessary set-up time. Should, in exceptional cases, further clamping be necessary, this is done with repeat accuracy and without loss of precision.

In automated machining, the patented tool changer precisely guides the required grinding wheels of various sizes and designs to the workpiece. The grinding wheels with a size of up to 300 mm are dressed again and again during the entire grinding process, i.e. brought back to their correct geometric shape. The desired quality can only be achieved with all gearings by exact form dressing in a closed loop.

How new customer requirements push the boundaries of what is feasible

Hermle knows what relevance this new standard will have in bevel-gear production in the various industries.

“With our customer-centric approach, Haas Schleifmaschinen is part of the solution for many design engineers and workpiece manufacturers,” he said. “We are often asked when the limits of what is feasible should once again shift in favor of more precision, economy, and complex special shapes. The fact that a Multigrind® grinding machine, i.e. a universal grinding machine, masters these special tasks best seems to be a contradiction for many people who are not familiar with our technology. Our customers and users know that the high degree of flexibility of our grinding technology is also based on the intelligent control by the Multigrind® Horizon software.”

The Multigrind® grinding machines are developed and produced in the Black Forest. But only in combination with the Multigrind® Horizon software is the full potential fully exploited. (Courtesy: Haas Schleifmaschinen)

The perfect interaction of software and hardware

With the Haas Multigrind®Horizon software, the projected bevel gear is calculated according to exact path specifications and visualized three-dimensionally in a very fast and exact one-to-one simulation. In this way, the real image of the bevel gear to be produced is obtained and minimal programming errors can be resolved in advance. The automatic collision monitoring before the start of production provides additional safety. The path-optimized calculation of traverse movements saves a lot of time later in production.

The Multigrind® Horizon software enables control instructions and machine data such as measured values, sensor data, control variables, and parameters to be configured, controlled, and operated from the tablet. The complex mathematical design data can be described by a few parameters. The result: a user-friendly user interface with an intuitive operating concept. There is no need to spend a lot of time setting up the system individually with “fingertip sensitivity.”

Orders are allocated automatically, either via the RFID codes of the raw parts and comparison with the ERP system or from the online shop. Haas Schleifmaschinen has implemented the integration of production and measuring technology in the closed loop in a practical manner both with its own software and in the Multigrind® grinding machine. Thus, the Multigrind® Horizon software is optimally designed for the production environment of Industry 4.0, a consistent step toward digitization in bevel gear production.

Compact information

Bevel gear grinding on the Multigrind® CA offers maximum flexibility and precision with short throughput times thanks to gear and cylindrical grinding in a single operation, as well as low tool costs and minimum set-up effort. It is suitable for circular arc or cycloid geometries. The production of bevel gears from 10 mm to 150 mm takes place in a closed loop. It is ideally suited for small series for batch sizes of 1 to 100. It’s also suitable for special products, prototypes, and test setups, and is ideal as a useful supplement to the large series production of bevel gears on standard milling machines.

When it comes to shifting the limits of what is possible by a few microns, Haas Schleifmaschinen is the place to go for designers and production specialists.

“We like to make things complicated,” says Managing Director Dirk Wember. “Haas Schleifmaschinen relies on tradition that goes back 80 years. Our niche strategy, our thirst for research, and our consistent customer focus form the basis of our success. We meet every complex new grinding requirement, even if it does not seem feasible at first glance. The inventors at Haas Schleifmaschinen thus perfect their products and market them globally. The sophisticated Multigrind® high-end machines are a model of German engineering artistry and grind all over Europe, North America, China, and Japan. Many different industries already rely on the advantages of the Multigrind® series: highest precision, maximum flexibility, and high efficiency.”

The Multigrind® grinding machines are developed and produced in the Black Forest. But only in combination with the Multigrind® Horizon software is the full potential fully exploited.

“The topics of the future — digitization, automation, and cloud applications — are no longer a vision for Haas Schleifmaschinen,” Wember said. “We are already working on the suitability of these future topics for everyday use and today already offer customer-specific solutions that have proven their worth.”