Service center struggles with laser question
July 11, 2005
Metalen Verhoestraete, a metal service center in Roeselare, Belgium, needed a laser, but not just any laser would do. Because many of the company's clients had 3- and 4-meter lasers, Metalen sought a laser that had a much longer bed so it would not compete with its customers.
Dirk Debruyne was in a tough spot. He had to make a decision, and he knew it would not be an easy one. He needed a laser cutting machine, but not just any machine would do.
Debruyne is the technical director of commerce for Metalen Verhoestraete, a 100-year-old service center in Roeselare, Belgium. For the first 65 years of the company's history, it bought and sold metal. For the past 35 years, it also has offered value-added services. For cutting and bending the company uses a typical variety of conventional metal fabricating machines, including flame and plasma cutting machines, shears, and press brakes. It also has punching capabilities.
But the company's customers wanted more, and their needs were specific. Many of them demanded laser-cut-quality parts.
Debruyne had to consider his customers' request for laser-cut-quality parts and his company's position in the market. Debruyne's dilemma was that while he needed to purchase a laser to satisfy customer demand, he didn't want to compete against his customers. Many of them had lasers.
"Within a radius of approximately 30 kilometers from here, there are many lasers that can process 3- or 4-meter lengths," Debruyne said. He held his customers off for three years while looking for the right laser for his needs. He specifically looked for a laser with a large capacity so that he could laser-cut items that his customers couldn't handle.
Another important point was whether the laser would provide a stable process throughout its working envelope. The larger a laser table is, the longer the distance the laser beam must travel. Consistent beam quality from one corner of the laser bed to the opposite corner is a key parameter. And, because the nature of his business makes order quantities unpredictable, Debruyne needed a machine that would be able to handle diverse products profitably without regard for the quantity. In other words, programming would have to be fast and easy. Finally, Debruyne focused on a factor crucial to a laser cutting machine's productivity: its beam-on time.
The only thing he really didn't have to worry about was the demand for laser services. Because he waited for three years after his customers initially asked for laser-cut-quality parts, he was confident that demand would support his purchase.
|Although economic growth in Europe has been lackluster in recent years, Metalen Verhoestraete has experienced no shortage of work. Dirk Debruyne, technical director, describes using a laser for fabricating forms, at right, for pouring a concrete foundation for a rail line that will run from Amsterdam to Paris.|
The company chose an LVD Impuls 6020, a laser machine that has two 6-meter-long shuttle tables. Because it handles such large sheets, Debruyne is confident that he doesn't compete against his customers. "We start where the client stops," Debruyne said.
One of Debruyne's chief concerns, consistency in cut quality, is achieved by the machine's beam compensation system. An additional axis, the beam compensation system keeps the laser beam a consistent length, regardless of where the cutting head travels on the cutting table. Maintaining a consistent beam length keeps the focal length constant, which in turn keeps the beam diameter constant. This ensures consistent cutting quality at any location on the shuttle tables.
The machine's gantry, which is constructed from aluminum rather than steel, enhances accuracy across its working envelope. Aluminum's lower density means that the gantry has less mass and, therefore, less inertia than a steel gantry. The low mass of the gantry contributes to the laser head's positioning accuracy despite the abrupt accelerations and decelerations needed to process sheet quickly. The machine's accuracy is ±0.020 mm, and its maximum positioning speed is 76.2 m per minute.
Metalen has found that programming the machine is easy enough and fast enough that it doesn't turn away the smallest of orders, yet it is also capable of handling large runs efficiently.
"One part or 10,000 parts—no problem!" said Debruyne. A library that stores programs for 2,000 parts aids machine efficiency.
The laser's uptime reflects a consistent demand for laser-cut-quality parts. Although the machine started out running eight hours a day, Metalen found itself using the laser more than 12 hours a day within the first month. During its first two years, the machine ran for 9,000 hours, which equates to more than 12 hours a day, including weekends and holidays. Of the 9,000 hours, the machine spent approximately 8,500 hours in actual cutting—in other words, the beam-on rate is nearly 95 percent of the machine's running time.
The laser allows the company to accept work that it previously would have turned away, according to Debruyne. For instance, the laser's speed and ease of programming allowed the company to tackle a 63-ton order for eight unique parts cut from 20-mm-thick material. The order required three of the value-added processes Metalen provides—laser cutting, bending, and punching.
"We received the order on Wednesday at 4:00 p.m., and it was to be ready for shipment by Monday evening," Debruyne said. In a situation like this, ease of programming comes into play. Every extra minute of programming time is one less minute of processing time. Debruyne estimated that the job would require approximately 70 hours of laser work in total. Two to three hours would be required for programming and the rest was processing time.
Finally, the timing of the order called on the laser's ability to run unattended. Working the order into the company's existing work load meant the machine would have to run late into the evening and over the weekend. Without the laser's ability to run unattended, Metalen would have had to turn down the order.
"If your machines can work unattended on weekends, you can accept orders that other companies can't handle or won't handle," Debruyne said.
Metalen Verhoestraete, Wijnendalestraat 189, B-8800, Roeselare, Belgium, 051-22-7200, fax 051-22-0974, www.verhoes traete.be