Variable speed drives improves the quality of glass ovens.

A leading manufacturer of glass tempering ovens has turned to the Unidrive M family of variable speed drives from Emerson Industrial Automation to greatly improve the quality of its products. Glaston America, (NJ USA), has established a strong reputation for excellence serving both the commercial and residential glass markets. The company´s biggest customer is Cardinal IG, a market leader in the manufacture of residential glass. To ensure its glass tempering ovens meet the demanding requirements of high profile customers, every effort is made by Glaston to maximize quality.

A recent case in point saw the company address the issue of tiny scratches that can occur as a result of the glass being tempered without precise speed control on the oven´s drives. To overcome the challenge, Glaston researched the market for an alternative to its existing drives supplier.

"The solution arrived initially in the shape of Control Techniques' Unidrive SP drive because of the flexibility of programming and option cards for feedback and communications," explains Cliff Matukonis of Glaston America. "However, we soon migrated to the Unidrive M701 as its new features and functionality better suited our needs. The integration of PROFIBUS communications and application modules for increasing the drives' flexibility was also crucial in our decision."

Led by the results of extensive customer-driven market research, and designed specifically for manufacturing automation applications (Emerson Industrial Automation's traditional area of expertise), each Unidrive M model suits specific application needs. For instance, the Unidrive M701 series drives now preferred by Glaston offer benefits specific to sectors such as ovens and heat treatment equipment.

A total of 14 Unidrive M701 drives with SI-PROFIBUS are now deployed in the company´s glass tempering ovens, one for each roll section. Rollers pass glass through various oven sections to be treated and then through a cooling section prior to packaging. Glaston also uses 14 Unimotor HD - highly dynamic brushless servo motors from Control Techniques, one for each drive.

"The main benefit of the Unidrive M701 is the precise speed control we can now exert on the oven rolls which greatly reduces scratches and imperfections on the glass," states Mr. Matukonis. "Furthermore, we now have more capability and flexibility, and found integration to the control system extremely straightforward. The system´s design and interfaces, along with its extensive diagnostics capability, also ensure ease-of-use for the machine´s operator."

The Unidrive M family of drives offer class-leading induction and permanent magnet servo motor performance with real-time Ethernet. Each drive delivers maximum machine throughput through greater control with single and multi-axis network synchronization. On-board real-time Ethernet (IEEE 1588 V2), advanced motion control and high speed I/O for position capture has made it easier than ever for machine builders to create more sophisticated and flexible machines.

"The new line-up of Unidrive M701 with SI-PROFIBUS is now integral to all our new and upgraded installations," said Mr. Matukonis. "The option cards give these drives incredible flexibility. For example, we are able to bring two encoder signals from other motors into a single drive. With minimal programming, we have been able to have the drives follow either of these encoders with smooth ramps between the two different encoder speeds. I could only find this option in significantly more expensive servo solutions.

"As well as this, we are impressed at how the system deals with any issues. If a drive fails, all the parameters are kept on a magnetic card that can easily be used to program the new drive. It was much easier for the maintenance department to simply put in the card and program the new drive.

"Between the Unidrive SP and Unidrive M series, we have to date installed over 100 servo drives at our production facility and we couldn´t be happier with the results we´re seeing."