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Precision Machinery Maker Verifies Innovative Programs

By SME Media Staff

After a century and a quarter of reinventing itself to fulfill market and customer needs, C.G. Bretting Mfg. Co. Inc. (Ashland, WI) is growing through use of multiaxis machine tools and creative machining and programming strategies to produce large, precision machinery and components for global markets. A key contributor to Bretting’s effective use of leading manufacturing technology is NCSimul Machine toolpath program verification software from Spring Technologies Inc. (Boston, MA).

That kind of dynamic energy isn’t expected to prevail at a 125-year-old manufacturer of industrial machinery, especially one founded in 1890 as a sawmill machinery maker. When the number of sawmills began to shrink, Bretting Manufacturing reinvented itself as a producer of equipment and parts for the shipping, mining, and other industries. Then, in 1929 a customer contracted the company to manufacture a paper-converting machine. A typical paper-converting machine transforms huge rolls of raw paper into millions of paper napkins or other products.

Work on the machines prompted Bretting Manufacturing to design and manufacture its own line of paper-converting equipment beginning in the early 1960s. The machines are large, some stretching over 75′ long and 17′ wide (22.9 and 5.2 m). They also are complex, because they simultaneously perform operations such as folding, multicolor printing, embossing, and packaging in addition to trimming the paper to the desired size. Bretting custom-designs and engineers its paper-converting machinery to fit specific customer requirements. The fully automated machines feature computerized controls, touch screen operation, and in-process video monitoring.

Today, fourth-generation members of the Bretting family comprise top management and the fifth generation has joined the workforce at the company. Bretting occupies over 280,000 ft2 (26,022 m2) on the shore of Lake Superior and houses approximately 400 employees and more than 60 pieces of manufacturing equipment. Among the largely homegrown staff are about 100 engineers, 30 customer support personnel, and 45 service representatives who attend to Bretting customers worldwide.

At the start of the 21st century Bretting management further took advantage of its manufacturing expertise by offering contract fabrication, machining, and assembly services to food processing, mining and moldmaking customers throughout the Midwest. Today, Bretting offers a full complement of precision machining equipment and processes for turnkey contract manufacturing. CNC travelling gantry machines provide five-sided machining in one setup with XYZ travels up to 314 × 150 × 49″ (8 × 3.8 × 1.2 m) and 50-taper, 50-hp (37-kW) spindles. Vertical machining centers with XYZ travels up to 240 × 36 × 44″ (6 × 0.9 × 1.1 m) can handle workpieces up to 10,000 lb (4535 kg) with 50-taper, 6000 rpm spindles. Horizontal machining centers feature two-pallet APCs and 10 and 12 pallet changers and full rotational B axis machining. Bretting’s full complement of capabilities includes waterjet, CMM inspection, grinding, and welding and fabricating processes.

Bretting’s processes are capable of meeting the tight tolerances of its machined components. Programmer Ken Lizak cited an example of paper converting machine frames with bore tolerances of 0.0005″ (0.013 mm) that become increasingly difficult to achieve on large parts where the bores may reach 20″ (508 mm) in diameter. Manufacturing engineer Joe Moran said many parts for the gas and oil, logging, and construction industries are “definitely out of the ordinary as far as their tolerances, their size, and features that have to be accessed.” That complexity along with demands for top quality and cost-effectiveness dictate the use of five-axis simultaneous machining for many operations.

Bretting doesn’t produce high volumes of identical parts. “We’re not that type of company,” Moran said. “Ours is more of an R&D situation where it’s always new jobs. It’s a plethora of unproven, brand-new programs, possibly with new, undefined processes. Sometimes we have to be incredibly creative to machine the parts we make.”

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Bretting Mfg uses NCSimul machine toolpath program verification software on its “custom flavor” innovative programs.

To process challenging parts, Bretting often edits a “custom flavor” into its machining programs, Lizak said. But in many cases, according to Lizak the toolpaths’ uniqueness raises uncertainty about the CAM software’s ability to handle them accurately. “Today’s CAD/CAM software is very good,” he said, “but it can’t see everything. We were lacking the ability to verify our actual G and M codes. We needed that capability when we were working with parts that were very close to the limits of a machine’s working envelope or were using specialized tooling arrangements, such as mounting a right-angle head into another right-angle head.”

Seeking a way to assure that its customized machining programs were free of collisions and other problems, Bretting’s staff evaluated different toolpath verification software packages and chose NCSimul Machine software, a comprehensive software tool for simulating, verifying, optimizing and reviewing CNC machining programs. The simulation software’s 3D graphics help eliminate machining crashes while embedded algorithms and process-based know-how enable optimization of cutting conditions and standardization of shop-floor documentation. The software verifies NC programs in three steps: it investigates and corrects coding errors, simulates machining to locate collisions and repair motion errors, and validates the NC program.

NCSimul enables operators to view a simulation of an operation and verify its performance. “Then they can have a better, warm-and fuzzy-feeling about a process that may seem a little bit off the wall,” Moran said. “That’s where NCSimul helps us go above and beyond what the CAD/CAM software can do. It has enabled us to implement innovative, outside-the-box processes. One of the biggest advantages is that there’s less dry run time because the operators can trust what’s being put out. NCSimul really helps with our first runoff.”

Bretting employs NCSimul on three CNC machines: A five-axis machining center, a gantry machining center with a 3+2 rotary head, and a second gantry machining center. The three machines are the ones most used for “off the wall, tight tolerance work,” Moran said.

Initiating the verification process is quick and simple, according to Moran. When part models, fixturing, and tooling are defined in the CAD/CAM program, the information can be directly selected and exported to NCSimul. After adjusting for details such as the position of the part on the table and various clearance aspects, the operator can load the CAD/CAM program and begin verification.

NCSimul also provides accurate estimates of total process run time. The software records factors that often aren’t included in run time calculations, such as rapid feed rates and toolchange times. “You do get a much better sense of when a job is going to be done and off the table,” Moran said. In some cases the software can be an aid to constructing accurate quotes, but the nature of the production scheduling at Bretting means that the software isn’t normally used that way, especially when making parts for the company’s product lines, Lizak said, “Usually it’s ‘okay guys, we have to have this out the door today.’”

It is difficult to quantify savings that can result from incidents that the software prevents from occurring. However, Lizak said, “Use of the software has helped us identify potential collisions between the workpiece and machine, with absolutely zero risk to the machinery. With its abilities to verify some of the tight clearances that we have to deal with, I feel it has paid for itself.”

Moran concluded that the NCSimul software has been a key factor in maintaining Bretting’s manufacturing momentum. “The ability to use creative programming strategies and verify them is providing the next step as far as our company’s desire to set a tone and continue to be an innovator,” he said.

For more information from Spring Technologies, go to www.ncsimul.com, or phone 617-401-2197.

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