Polishing machines use programmable servo drives

Crevoisier SA of Les Genevez, Switzerland, is a leading manufacturer of production machines for the high-class watch making industry. The company has recently launched the Universal C-5001 lapping and polishing machine and, at its heart, is a Control Techniques 1.5kW Commander SK running a 1.5kW motor, all controlled by a colour touchscreen HMI panel.

Watch makers are increasing their standard of finishing; parts that are so small they can hardly been seen by the naked eye need to be precise to measurements of 1um. All of the individual parts require polishing before a watch is manufactured and the art of polishing is more difficult than it looks.

Crevoisier's research and development project manager for the C-5001 says: "When polishing small parts you need to be confident of the speed. Also important is torque; at a low speed, constant high torque is required to ensure the quality of polishing. The Commander SK has ensured that the high level of precision demanded has been met."

The C-5001 not only had to provide accurately controllable speed, but also be available in a compact tabletop design. The Commander SK was key to achieving these objectives, as its compact frame meant that it could be set inside the C-5001 and the polishing sequence could be programmed directly onto the drive, thereby eliminating the need for a PLC and saving space and money.

Connecting a colour touchscreen HMI panel directly to the drive also allows for the saving of settings relating to specific watch parts or materials, which saves time in the polishing process. The colour HMI screen also makes the machine very attractive, which is a real bonus in a design-focussed industry.

Crevoisier's research and development project manager comments: "In this industry you must bring new products to market regularly, as you need to show the customer that you are ahead of your competitors and listening to the customer's requirements. The C-5001 does this, as it offers a much improved package compared to its predecessor C-501, which did not feature a drive and worked from a belt design with four settings. The new machine can be set to give a speed anywhere between 250 to 3750rpm, is more compact, quieter and easier to use.

"Control Techniques have really helped us in the design of the new machine, the technical support they have provided such as programming the HMI panel has been invaluable. The quality of their products was known to the company and they were able supply the whole package - the drive and HMI panel. This means we only needed to have one contact for help with development, training and support - a real benefit."