It sounds relatively simple: a new control panel and operator console for a two-axis pouch machine. However, in the case of this retrofit of an Atlas Copco drive and control system running in Polyair's (Toronto, Ontario, Canada) Chicago plant, the upgrade process was anything but simple.

Polyair, a leading manufacturer of protective packaging products and integrated packaging systems, with nine plants in the US and Canada, had experienced problems with the feed-rolls motor and gearbox on the machine—which caused premature failure of those components. The pouch machine is one of several that combine bubble wrap and recycled paper or polyethylene and convert it to padded envelopes in several sizes and colors, such as those sold at retail in office-products stores, or at the local post office.

The cause of the motor problem turned out to be a PLC logic-timing error in the feed cycle, which resulted in a momentary overload of the feed motor during every machine cycle. This required considerable study of the existing program logic and machine timing to locate and correct the problem.

The existing system used Atlas Copco drive and control products, which were obsolete and no longer supported. The machine builder had written special communication drivers to connect a GE Fanuc PLC with a PCM coprocessor module to the drives for downloading part information.

No access was available to the communication program, and the motion controller and PLC program information were no longer up-to-date. In order to replace the Atlas Copco equipment with Bosch Rexroth drives and controls, it was necessary to carefully evaluate the machine functionality and deduce the control and communication requirements from the available information, then reverse-engineer a replacement system solution.

In addition to programming the new controls, the communication program needed to be recreated from scratch, and significant modifications made to the original PLC program. This required an integrator who offered PLC, motion and human/machine interface (HMI) programming capabilities.

Custom Control Solutions Inc., Bartlett, IL, which specializes in integrating drive and control products from Bosch Rexroth's Electric Drives and Controls business unit (although not exclusively), undertook the work. It involved designing and fabricating a control panel containing new drives and a new motion controller, and a new operator console with a color touchscreen HMI. Also included were installation, programming/reprogramming of both the new controls and existing equipment, and startup of the new system.

As work began, it became evident what had been causing the previous problems. For example, Dave Stuber of Custom Control Solutions uncovered a programming timing error, too minute to see visually, that frequently shut down the machine and tore up expensive, hard-to-get and difficult-to-install components. "The heat-sealing bars that were coming together to seal the two webs to form the sides and bottom of the envelope were not adjusting properly relative to the motion of the webs, and occasionally were still closed when the webs were moving again, causing damage," he says.

The operator interface and job-recipe storage system on the machine had used an Epson PC running Windows 3.11. There were over 100 screens in the operator interface system, resulting in a difficult learning curve for new operators. Stuber replaced the existing system with a new color touch-screen HMI with only five operator screens, which were logically laid out, and completely covered the functions required to operate the machine. All operators found the new system much easier to understand and operate. Moreover, the retrofit caused virtually no disruption to normal production or to Polyair maintenance staff.

Polyair, committed to surpassing customer expectations, sought to ensure that the machines were working at full capacity with virtually no machine downtime hiccups.

According to Polyair maintenance manager Jim Boyd, the retrofit produced quantifiable benefits:

• No machine downtime means that Polyair saves about $1,000 per hour.
• New operators can now be trained in half the time, due to the simplified operator interface.
• Polyair saves up to 20 minutes every time it changes over from one envelope size to another.
• Polyair saves as much as 2,000 linear feet of paper and bubble scrap every day.

Other benefits of the project, according to Polyair project manager Gordon Livey, are that Corporate Engineering no longer receives phone calls about failures, and components and support are always available. That translates to peace of mind, Livey says. He also concluded that the success of this project led to other retrofits involving Polyair and Bosch Rexroth.