Die Shop Profits from Reengineering

May 1, 2016

Metalformer Atlas Tool Inc., Roseville, MI, not only has focused on developing innovative programs for tooling and part production for all types of stamped sheetmetal parts; it also has evolved into a provider of advanced die build and repair capabilities. Most recently, die reengineering has been its focus—essentially recreating dies, or their CAD data.

Atlas CAD/CAM manager Walt Tadday works with the Tebis BREP software suite to create, adapt, repair and optimize CAD surfaces of stamping dies.
“When a die comes into our shop from overseas with issues or questions,” says Walt Tadday, CAD/CAM manager at Atlas, “we use a high-resolution scanner (an Atos Triple Scan from GOM, with blue-light technology and 16-megapixel cameras) to generate a point cloud. The cloud, output as a mesh model of the die surface, gives us accurate CAD data of the tool that’s sitting there on our shop floor, despite the potentially faulty documentation.”

It’s not just foreign-made dies that benefit from this process. “Our North American customers send us dies that have been in operation for some time and are in need of repair,” Tadday adds. “Scanning enables us to detect whether or not a die is worn in certain areas due to production, or has other surface imperfections. In addition, we can use the data to make spares. When a die has been running continuously, the details will wear. Scanning generates an accurate solid model of a die’s current condition so we can bring it back to its original state.”

Converting Scan Data to High-Quality Surfaces

Scanning the die surfaces, however, is not the be-all end-all. The mass of scanned data must be converted into high-quality surfaces. Here, Atlas relies on BREP (boundary representation) associative surface-technology software from Tebis, designed to support the creation, adaptation, repair and optimization of CAD surfaces.

“The surface created by the mesh data is essentially like the pattern on the surface of a soccer ball—a series of pentagons,” notes Tebis West Coast sales manager Michael Thiessen. “As a result, you can’t generate highly accurate curves. In addition, when you scan an item with sharp corners you may discover some built-in inaccuracies. Scanners, for example, can’t identify sharp corners due to the triangulation of the data. Instead, they approximate with small radii and the Tebis software then creates a sharp corner.”

Adds Tadday: “BREP creates high-quality surfaces and clean curves, and sets them to the desired tolerances. The final product is data that I can open up in any CAD system. In addition, the mesh creates surfaces that can be very ‘heavy’—using many smaller surfaces. This added ‘weight’ can be a problem when generating toolpaths, and especially when trying to put springback or coordination moves back into the tool. A BREP surface, by comparison, is ‘light,’ which makes it easier to do a lot of things, including putting these modifications back into the original tooling.”

Atlas designs and manufactures medium- to large-sized dies used to stamp automotive parts.
Atlas takes the surfaces created by BREP and transfers them into its Unigraphics or Catia systems, followed by the generation of the needed machine-tool programs.

“BREP is integrated with the Tebis CAD and manufacturing software,” Tadday says, “so that the entire process—from working with the initial scan data to CNC program creation—could be handled in Tebis, but we decided to go with our Unigraphics and Catia software because we have been working with them for many years. It’s all seamless because Tebis has excellent conversion into Catia and Unigraphics.”

A Growing Trend

Thiessen notes a trend in the North American tool-and-die landscape toward increased die reengineering. “Die shops are making fewer new builds because so many large customers have chosen to cut costs by having their dies built overseas,” he says. “That, however, doesn’t mean there’s a shortage of work. The demand for reengineering has increased because tools returning from overseas often are missing engineering changes that have been requested. In other instances, changes may have been made in the building process that may, in fact, be beneficial, but are not reflected in the documentation. Also, there may be quality issues that need to be addressed. In situations like these, shops use sophisticated tools to evaluate the current state of the tool and identify the necessary modifications in order to complete the work.”

Tadday adds that “sometimes customers send us dies that not only are worn but actually cracked or even broken. We can import the scan data into Tebis software using the BREP tool to clean up those surfaces and give us an accurate view of what we’re dealing with, so we can quickly make the needed repairs.

“In addition,” he continues, “with some of the older dies the manufacturer may no longer be in business, so the CAD data can be difficult or impossible to get. However, these dies are still in production. Dies in production may need to be repaired or perhaps modified to accommodate changes to the part. This would be an extremely time-consuming process without BREP software.” MF

Article provided by Tebis, Troy, MI: 248/524-0430, www.tebis.com

Industry-Related Terms: CAD, CNC, Die, Mesh, Model, Point, Surface
View Glossary of Metalforming Terms


See also: Tebis America, Inc.

Technologies: Software, Tooling


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