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New system cuts costs of plasma cutting.

A leading New England sheet-metal fabricator--Kleeberg Sheet Metal Inc, South Hadley, MA--has purchased and put into operation a new type of computer-controlled plasma-cutting system that utilizes software for automatic nesting.

According to Richard Kleeberg, president of the 80-employee company, scrap system has reduced the company's scrap rate--the ratio between waste material and salable parts from each sheet--from an average 20 to 25 percent down to an average of 8 to 10 percent.

In addition, the new system has significantly minimized dimension and nesting errors, reduced man-hours per part produced, and increased the productivity of the company's labor, capital, and energy resources, Kleeberg says.

Called the Series CFC 150, the cutting system, designed and built by Cybermation Inc, Cambridge, MA, includes a heavy-duty plasma-cutting machine with a direct numberical control (DNC) unit (Figure 1), a minicomputer with 20-megabyte permanent disk storage, a CRT terminal with keyboard (Fighure 2), and two printers.

Kleeberg Sheet Metal was the third company to install the CFC 150, and the first to use the system for cutting light-gage sheet metal. The company is also the first to control two CFC 150 cutters with one computer.

Based in a 23,000-sq-ft facility, the 26-year-old company serves all of New England with a 10-truck fleet. Products include fittings and duct work for heating, ventilating, and air-conditioning (HVAC) systems, plus tanks, dust collectors, and other fabrications.

The company cuts aluminum, stainless steel, and 3/16" and 10-gage plate. Kleeberge estimates that his company processes about 1-million lb of steel annually. Tandem tables

Each plasma-cutting machine has rack-and-pinion drives for all axes. Two side-loading cutting tables, one on each end of the cutter, provide easy access. While the machine is cutting parts on one table, the operator unloads cut parts from the second table and inserts a new sheet.

Kleeberg Sheet Metal designed, built, and installed the cutter tables and fume ventilation systems for its two CFC 150 cutters. Cybermation Inc can also provide these equipment and services.

Cutting speeds can range from 100 ipm to over 300 ipm in 10- to 26-gage steel.

A controller called the CYB 400-SM governs torch positioning and cutting movements automatically. This DNC unit accepts commands from the system computer over a direct communications link. No punched tapes are involved.

To cut a sheet, the operator positions it on one of the tandem tables, enters the sheet number on the start-cycle button. The operator can interrupt the cycle at any point, and can run the cutter under local, manual control.

The system's computer is a DEC PDP 11/23 minicomputer from Digital Equipment corp, Maynard, MA. Using software designed by Cybermation in cooperation with its customers, the computer accepts the takeoff input from the CRT terminal, automatically adds connector and seam dimensions, and provides storage for data on dozens of jobs.

The computer also performs automatic nesting, determining the optimum parts-layout and cutter-torch paths for each given part number and sheet size. Torch heigh and speed are selected by the computer according to the sheet material and thickness. These data may be stored in memory for the particular job, or may be keyed in by the computer operator.

The two printers are used to generate parts layout plots, labels, lists, and shipping documents (Figure 3). With appropriate software, the computer can also be used for tasks such as estimating and accounting. Training in days

At Kleeberg Sheet Metal, the president's daughter, Lynne Kleeberg, and another employee perform job specification, parts modification, new-parts entry, scheduling, printing, and other functions at the computer terminals.

Training for these two people and the cutter operators was ferformed by Cybermation Inc at their school in Cambridge. According to Lynne Kleeberg, learning to operate the new system took only a couple of days.

On the 12" CRT screen, a series of menus with simple, English-language prompts guide the computer operator through each job. The operator calls up previously run parts from disk memory, or keys in dimensions and other specs for new jobs.

After specifying a part, the operator calls for a parts plot (Figure 3) from one of the printers. The plot shows exactly how the software's nesting routine has nested the parts on the specified sheet. If the operator accidentally keys in erroneous or inconsistent dimensions--for instance, when midifying an old part--these errors show up as squiggly lines on the printed plot. Payback in six months

After installing the first cutter and computer at a cost of $100,000, the company added a second cutting machine costing $60,000. Both cutters are under the control of the single DEC PDP 11/23. Richard Kleeberg estimates that the first system paid for itself within six months, and the second cutter within four months.

"The first machine freed up four to six people for other jobs," says Kleeberg, "but our output has increased considerably. As a result of using the new cutters and their computer controls, we can lay out and cut jobs much faster. The automatic checking built into the software has enabled us to catch almost all human errors, too."

Kleeberg adds that the improvements in job turnaround time and quality are enabling his company to increase market share in New England. "This year we expect to do $6 milion in sales, up from $5 million last year. That's 20 percent

"Before buying the new system, we had six to eight people lined up along a bench, laying the job up by hand, waiting for a shear or other tool," he adds. "The process was much slower then, and human errors caused a considerable waste of man-hours and material. The improvements have been dramatic."

A telling statistic about the new instalation is the employment record at Kleeberg Sheet Metal. "Since putting the first CFC 150 cutter and its computer into operation," says Richard Kleeberg, "our business has increased to where we've had to boost our work force by 25 percent.

"True, the construction business is up, but our market share has been increasing, too.

"We consider this significant from a labor-relations standpoint," he continues. "We have a union shop, and when we announced that we planned to install DNC cutters, some union members expressed fears of being put out on the street by the new automation.

"Quite the opposite has happened, though; we've hired more people rather than laying off. Now nobody's expressing fears or complainst."

For information on fabricated products from Kleeberg Sheet Metal Inc, circle E27.

For full details on computer-controlled DNC plasma-cutting systems from Cybermation Inc, circle E28.
COPYRIGHT 1984 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1984 Gale, Cengage Learning. All rights reserved.

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Author:Quinlan, Joseph C.
Publication:Tooling & Production
Date:May 1, 1984
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