The size change-over time influences the number of batches that the machine can deal with in a productive and cost-effective way. The shorter these times, the fewer the minimum batches and, therefore, the overall flexibility of the plant.

The presence of the dresser increases the flexibility of use, allowing very frequent size change-over: change within a short time (a few minutes) is another of the fundamental criteria required by Bonfiglioli to maximise the machine’s productivity.

Notwithstanding the fact that a large batch is always preferable to small batches and those repeated periodically, a quick size change-over responds to just-in-time production needs. The batch numbers also influence the type of tool to be used: a traditional, dressable ceramic form wheel will be preferred for small batches or for testing activities compared to the better performing (and expensive) CBN wheels. It is up to the user to choose the most suitable solution for the form wheels: traditional dressable ceramic (aluminium oxide), dressable CNB or an electroplated CBN wheel are all perfectly suitable options on the G 250 HS.

Particular attention was given to solutions that allow the reduction of workpiece change-over times: The Samputensili G 250 HS can easily interact with any type of automation on the market.

In the presence of a robot, for example, additional activities can be added (such as washing the workpiece, palletising in appropriate containers, measuring, laser marking, etc.). Bonfiglioli measures all the workpieces machined on the G 250 HS, stores the information for maximum traceability and performs a possible feedback of the parameters of the work cycle based on the measured results, correcting the dimensions in the case of worm wheel or launching a request for re-dressing of the form wheel according to the measured deviation.

The G 250 HS grinding machine is equipped with the Siemens Sinumerik 840D numerical control solution line with an integrated operator panel and Samputensili software, characterised by high precision geometric programming and a user-friendly and easy-to-use interface.

The operator can fill in simple tables with the main parameters of the workpiece and have real-time graphical evidence on the shape of the gear toothing. The whole process is guided and allows the operator to correct and modify different values, recall previous programs, etc.

On this specific machine, Bonfiglioli requested software for the management of tooth flank bias. In fact, there is a difference between the theoretical surface of the tooth designed by CAD and the one realised by the grinding process: the software automatically sets off any bias or allows the most advanced users to set a specific one for each tooth flank. The main advantage of this approach lies in the setting off of the inevitable bending that the tooth will undergo during machining, upon the transfer of the torque: providing the best contact surface for the meshing teeth will improve efficiency, noise and power absorption.