Like virtually every U.S. manufacturer these days, Ramcon-Fiberlok, a machinery manufacturer for the non-wovens fabric industry, faces tougher competition from rivals and increased demands from customers. So Werner Schmidt, president of the Memphis-based company, looks for every advantage he can get, including in machinery design.

Over the past several years, Schmidt has found increased resistance to the price of Ramcon-Fiberlok's guillotine cross cutter, which costs as much at $55,000. "Pricing is always important in the industry we are serving," Schmidt says. Ramcon-Fiberlok sells a number of machines for the heavy duty felt non-wovens industry, including line slitters, cross-lappers, automatic pad stackers, ovens, coolers, floor apron systems, and dry powder resin applicators.

A key product in this line is the guillotine cross cutter, used in the production of automotive, mattress, and furniture pads. The cross cutter is a large, heavy-duty piece of equipment with 5-in. diameter feed rolls to handle thick, non-woven material. In a typical manufacturing process, the cross-cutter feed rolls grab the non-woven material from an upstream "cooler" or "slitter." The rolls then feed the material to a pre-set length and then execute a cut. Cutting knives have a maximum cutting width of 157 in. and can slice through material as thick as 3 in.

Responding to customer requests, Schmidt began to seek ways to cut costs on the Ramcon-Fiberlok guillotine cross-cutter, and still meet customer requirements. Cutting through non-woven material quickly and accurately (to 1/8 in.) requires power and precision. According to Schmidt, customers have balked at the premium ($5,000 or more) that a servo system can add to the price of Ramcon-Fiberlok's cross cutter. So Schmidt asked Yaskawa, a manufacturer of ac drives and servo systems, if one of the company's less expensive ac drives with a vector motor could be substituted to decrease expense while providing servo-like performance for speed and accuracy.

With the help of Yaskawa Electric America and its distributor Advanced Industry Support (AIS), Schmidt replaced a servo motor and amplifier with a Yaskawa F7 ac drive and induction motor, which trimmed the price of the machine and reduced maintenance without reducing performance quality.

Yaskawa and AIS helped Ramcon-Fiberlok and Schmidt test the drive's speed and accuracy operating in closed-loop flux-vector mode. Using this feature, Ramcon-Fiberlok was able to realize very tight control of the drive that enables the cross cutter to slice material to length with required precision. Closed-loop flux-vector control allows the ac drive to achieve servo-motor-like performance.

Ramcon-Fiberlok also tested the cutter's speed. With the ac drive, the cross cutter can execute up to 22 cuts per minute. The servo system can cut as many as 29 times a minute, but many Ramcon-Fiberlok customers do not need that kind of speed, Schmidt says. Only when the cross cutter is the limiting factor on a production line is the servo-system speed required. "To be quite frank, we have only one such system in operation," Schmidt says.

In addition to the higher initial expense, servo systems have a number of drawbacks in this application when compared with an ac drive-based system. For one thing, servo systems can require longer set-up times compared to the simplified programming of an ac drive.

In general, ac drives also tend to cause less downtime when repairs are needed. Servo systems typically require an outside mechanic for repairs. "With a vector motor and drive, all I need to do is send a new part, or it can be repaired by someone on the shop floor, and they're right back in business," Schmidt says. Additionally, drives typically require less training and spare parts expense.

For Ramcon-Fiberlok's customers, the cross cutter using the Yaskawa F7 ac drive offers lower initial costs, less downtime for setups, is easier for operators to use and program, and is less difficult and less expensive to maintain. Using the drive, as opposed to the servo system, trims about 50% of the setup when programming the machine.

For more information, go to www.aisimem.com (AIS), www.yaskawa.com.