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Automation upgrade specialists Mastercontrols (MCI) and Southern Technical Services (STS) have jointly retrofitted a Gleason 782 gear hobber with a new CNC control system from NUM.

The machine is used by a large aerospace components manufacturer in Chihuahua, Mexico, to produce spur, helical and crown gears with complex profiles.

Prior to the retrofit, the machine’s control system had become increasingly unreliable, resulting in high maintenance overheads and downtime.

The machine’s new NUM CNC software includes the NUMGear package, which features a graphical user interface.

This software also performs all of the functions that previously required an external electronic gearbox, thereby reducing the complexity of the system and the number of parts that require maintenance.

The Gleason 782 gear hobber is regarded as an industrial workhorse, but this particular machine’s control system was showing signs of age.

In this case, the gear hobber had seven CNC axes, which were controlled by an Allen-Bradley 8600 CNC system, and an external electronic gearbox, both of which had become outdated, unreliable and difficult to maintain.

After several months of intermittent operation, the company sought the help of MCI and STS to restore the machine to peak operational condition at a fraction of the cost of a new machine.

MCI and STS ascertained that the gear hobber was in good mechanical condition, but would benefit from new CNC control hardware and software, together with a new operator panel and some associated control modules.

The customer requested that the machine’s existing drives, motors and feedback devices – all of which were serviceable – should be retained and also stipulated that the machine footprint should not be changed.

MCI and STS accommodated this demand by developing a new sub-panel containing the new NUM CNC, power supplies, circuit breakers and contactors; this sub-panel was subsequently mounted inside the machine’s existing control cabinet.

‘Since swap-out time was going to be important, we chose to use NUM breakout boards in the new sub-panel, which made it very easy to connect to the machine’s existing drives, and by using machine I/O [input/output] boards with terminal strips, we were able to land all the existing wiring without any trouble whatsoever,’ said Jeff Petry, president of MCI.

The retrofit package is based entirely on NUM equipment.

As well as the new seven-axis CNC controller, this includes a PC-based operator panel, which features a 15in (38cm) LCD screen with a full membrane keyboard, and a 61-button machine tool builder’s panel with a hand pulse generator.

An industrial mouse was also mounted on the operator panel.

Using the NUMGear package with its user interface, the operator fills in fields on a graphical representation of the part on the human-machine interface (HMI) and selects a hob tool; the program is then generated automatically.

All customer parts and hobs can be saved on the system by part number so that they can be recalled when the part is needed for production again and hob programs can be archived onto an external USB memory device.

The NUMGear package also closely monitors the hob tooling; the operator enters values into the shift data fields displayed on the HMI and the software then handles all hob shifting completely automatically, informing the operator when it is time to check or replace the hob.

This tight control approach enables tooling costs to be kept to a minimum; hobs can be sent out for grinding and recoating many times before they are worn out.

The new CNC control system also performs all of the functions that previously demanded an external electronic gearbox.

After installing the new hardware and verifying the wiring, MCI and STS powered up the machine and immediately started verifying its operation.

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