The Fabricator - August 2009

A A Case Study

KO’ing keystrokes

Transformer manufacturer automates folding machine programming

CFIGURE 1 A material handling system takes a completed transformer tank component from Cooper Power Systems’ double-beam, bidirectional folding system. Photo courtesy of Cooper Power Systems.

By Tim Heston, Senior Editor

About 200 feet below a Chicago street sat a metal box, an electrical trans- former that hummed for more than three decades. Because nothing lasts forever, recently Cooper Power Systems was called on to manufacture a new one. Fabricating these enclosures seems simple enough, but in fact it’s a surprisingly precise process, because each enclosure is just a little different.

The people installing the system “couldn’t move the lines that connected to the transformer,” said Adam Popchock, senior advanced manufacturing engineer at the company’s Waukesha, Wis., plant. “We had a limited range to place the product, so we needed to design a transformer to match the space.”

It’s this fact that makes a manufac-

turer of seemingly standard product lines an engineered-to-order manufacturer. Though its sheet metal enclosures for various products look similar, each is unique. Some vary just a fraction of an inch—a hole for a bushing may be 1⁄ 16 inch different from one product to another, for instance. But those fractions of an inch mean the difference between a sold transformer and a very expensive scrapped part.

It’s typical for operators or setup people in fabrication shops to spend time keying in programs on the shop floor, especially in the bending area. But at Cooper, keying in a vast number of programs, even if it entailed pulling up and tweaking programs from part libraries, dragged down productivity. The company offers millions of part variants, and because it’s Cooper’s business to meet the exact need of a customer, the number of variants is forever growing.

Transformers generally have two large sheet metal components: the tank, an enclosure made of heavy-gauge metal that houses the core and coil assembly plus electrical components; and the cabinet housing electrical connections. Tanks generally are formed from sheets 60 by 80 in., 60 by 100 in., or similar sizes, with thicknesses up to 3⁄ 8 in. “When you screw up,” Popchock said, “it’s a big price to pay because you’re scrapping a big piece of steel.”

For this reason, Cooper Power Systems wanted to take strides toward total automated work flow, from the part drawing in AutoDesk Inventor®, through postprocessing, into the laser and turret punching cells, and on to bending. In other words, they wanted as few keystrokes as possible made on the shop floor. In recent months, the company accomplished just that.

A Standard Folding Language

Most tank and cabinet enclosures are processed through a series of lasers or turret punch presses, on to press brakes or folding systems, then welding, finishing, painting, and assembly.

It looks like typical part flow until you consider what the operators are doing, particularly at the double-beam, bidirectional folding machine: No typing and few, if any, mouse clicks are required to form large parts. There’s no designated programmer anywhere, in fact. Cooper not only took folder programming off the shop floor, but also eliminated the need for anyone to program the folding machine at all.

Working with software firm Logic Design Corp. (LDC), Pewaukee, Wis., Cooper engineers employ what’s called Standard Folding Language™, or SFL, code developed by LDC to serve as a kind of conduit between the design file and the machine control. It takes AutoDesk Inventor (IPT) files, unfolds and sizes them based on the machine’s bending tolerance, and then sends that program to a server location. This occurs about four or five hours before the part reaches the double-beam folding machine, which uses a material handling system to move parts to and from the folding area (see Figures 1-4). The SFL file is then downloaded and automatically translated into code the folding machine can understand.

Popchock conceded that it took “only 30 seconds in some cases to make a folding program [at the machine]. But the operator had to visually review it quickly. That’s lost time. We wanted our operators to be forming parts, not programming the machine.”

The technology Cooper employs is significant for two reasons. One, it totally automates bend programming for the folding machine. Cooper has no need for a dedicated folding machine programmer on or off the shop floor. Second, SFL is designed to be ma-chine- and brand-neutral, so it can be used for a folding machine, panel bender, press brake, or other bending technology. SFL code also is a subset of LDC’s Global Edge® software designed to work with the gamut of fabrication technologies. The software unfolds 3-D CAD files, creates flat DXF files, inserts specific weld marks and other elements not included in the original IPT file, and places the DXFs in a server directory for SigmaNEST® software to take and develop a nest for the laser cutting system.