Replacement Options for Legacy Gear Hobbers

As these trusted industrial stalwarts approach the end of their useful service life, the time has come to look at modern replacements.

EMAG has sponsored this post.

(Image courtesy of EMAG.)

(Image courtesy of EMAG.)

For all the hype about the factory of the future and advanced manufacturing technologies, most machine shops and factories in America count on older legacy machines to get the job done. Whether it’s the Bridgeport knee mill still being used for quick-turn jobs and repairs, or a heat-treat oven that may have seen the Eisenhower administration, these tried-and-true machines are still dependable. New machines are efficient and come with plenty of new capabilities, but many plant managers take a pragmatic approach to capital equipment: if a machine still runs and still produces quality parts, why spend the money to replace it?  

One process that often sees companies still counting on older machines is gear hobbing. Traditional gear hobbing machines typically had a closed gear train between the main spindle and hob head, meaning that operators need to change the ratio between the two spindles to produce different gears with different numbers of teeth. Operators need to manipulate change gears to obtain the exact ratio needed.

While these traditional machines may be deeply rooted in your shop floor, today’s gear hobbing machines offer benefits that are leaps and bounds beyond the capabilities of this legacy equipment, and as older equipment reaches the end of its useful life, it’s time to consider the fast ROI that new gear hobbing machines can bring.

What is Gear Hobbing?

Gear hobbing is the machining process by which gear teeth are cut into blanks. While gear blanks can be made by a variety of processes including casting, forging, sintering or even 3D printing, precise teeth are cut into the gears on a gear hobber, which uses a cutting tool called a hob. A hob is a cylindrical tool with many teeth designed to cut the precise tooth profile.

Gear teeth can also be precisely shaped by other processes including shaping, power skiving and grinding. Because of the surface finish and precision required for gears to mesh efficiently and quietly, gear hobbing may require additional grinding processes to reach the final part requirements.

New Gear Hobbing Machines vs. Legacy Equipment

Having to manage change gears is one of the most important differences between legacy machines and today’s machines.

“Nowadays, we have high performance, water cooled, direct drives for the work piece spindle, meaning the C axis, and for the hob head. So we have direct driven, high performance drive and we make sure you have the right ratio by means of an electronic gear box,” explained Joerg Lohmann, director of technology and product management at EMAG Koepfer GmbH.

Rather than work with change gears, operators now follow software prompts to program the machine. The software asks for input such as the module, the pressure angle, the number of teeth, the width of the gear, the helix angle, as well as data for the hob, and the machine generates its own CNC program. “It’s very easy to program such a complicated machine, which can have up to 15 axes,” said Lohmann. Typically, CNC programming is a complex task that requires manually typing in G-code commands or using computer aided machining (CAM) software to create a program.

In addition, newer CNC gear hobbing machines offer more functionality than traditional, single-purpose hobbing equipment. According to Lohmann, EMAG machines come with NC-controlled auxiliary tools, including sensors and tools for deburring and skiving. For example, sensor tools can be set up to orient a blank to a feature such as a keyway or a blind hole. EMAG can equip a machine to load a blank using a gantry loader, orient it using the spindle based on the sensor data, then cut the teeth with the correct angular position to the feature.

Extensive Automation

Today’s CNC machine tools, including gear hobbers, can be set up with complete process automation including part loading and unloading for lights-out operation. Lohmann explained the details of EMAG’s automation features for gear hobbing machines, beyond a gantry loader as mentioned above:

“It’s not just the gantry loader, it’s also the workpiece magazine that plays an important role. Gears usually roll by gravity. We offer very simple chute magazines where the workpieces roll down on multiple rows, so up to six rows are possible. And, accordingly, we have a higher autonomy,” he explained.

An automated solution could build on this six-row chute magazine with a distributor that picks up the workpiece and passes it to the gantry loader, which exchanges the blanks with finished parts in the work area. Finished parts would be deposited on a belt and transferred out of the machine. “This is our standard automation,” said Lohmann. “But for other customer workpieces such as a gear or shaft that does not roll, for example, we may even replace our magazines with a robotic cell made by EMAG for full realization of lights-out capability.”

When it comes to the automation possibilities available with the latest gear manufacturing technology, the sky is the limit.

One key difference between a piece of legacy equipment and new equipment is the service and support offered. Legacy equipment may have reached its end of life for service and parts, or the OEM may no longer even be in business. With new technology from OEMs like EMAG or many others, service and support are key differentiators for buyers. It’s wise to choose an OEM that has a business entity or division located in the same region where you plan to operate the machine. The costs of downtime from waiting for a part or service call from overseas can far outweigh any upfront cost savings when the equipment is purchased.

Many OEMs, such as EMAG, offer a package deal that is solution-focused. Before selling a machine to a customer, EMAG can begin with the drawings of the gear parts an engineer needs, then specify the machine, the hobs, the workholding fixtures and the automation cell to provide a complete solution from the design stage, then integrate it professionally on the shop floor. Procuring a unified solution, rather than a machine on its own, helps customers start making parts and accelerate ROI on the machine.

(Image courtesy of EMAG.)

(Image courtesy of EMAG.)

EMAG’s K 160 Long Bed is an example of the functionality gained when investing in the latest gear hobbing machines.

Features:

  • Machines shafts up to 1000 mm (39.5 inches) long
  • Maximum workpiece weight – for autoloading – is 25 kgs (55 lbs)
  • Capable of Hobbing multiple gears on one shaft
  • Up to four gear or spline sections with up to three different hobs are possible
  • Orientation of the gear to a keyway or pin hole(s) are possible
  • Alignment of up to three gears/splines
  • Automated loading and unloading

Possible Applications:

  • Long shafts for motors and gear boxes of lifting and rigging devices (cranes in manufacturing buildings, freight railway stations and harbors)
  • Rotor shafts for E-Mobility applications
  • Aerospace shafts with multiple gears and alignment requirements
  • Steering pinions for cars and transport vehicles (Hydraulic Power Steering)
  • Gears, pinions and worms for fractional horsepower and worm gearboxes

Ready to replace your old hobber? Request a consultation with EMAG.