Tooling Article



Die Designer Makes Haste, Not Waste

By: Brad Kuvin

Wednesday, June 1, 2011

Henry Ford once said that “most people get ahead during the time that others waste.”

Dilast developed transfer tools to stamp this stainless-steel exhaust assembly, making use of the new Target Driven Deformation feature within Visi die-design software. TDD allowed the firm to quickly overcome formability issues so that within a few hours it could submit the new geometry back to the customer for air-flow testing. Designing the assembly, which required a maximum weld gap of 0.5 mm, Dilast input part geometry from CMM results out of the tooling and reverse-engineered new geometry using the TDD feature to alter form steels.
In that light, consider Tier Two design house Dilast Tool & Die Ltd., in Cambridge, Ontario, Canada, which feeds a steady diet of tooling to the region’s automotive suppliers. The lethal combination of increased stamped-part complexity and shrinking lead times has Dilast president and part owner Gerald Claus searching for antidotes. Lead times for new projects are as short as 14 weeks, Claus says, down from 24 weeks just a few years ago. Also, customers often look for early-hit parts from hard tooling and laser trimmed in as little as 7 weeks. Meanwhile, part tolerances that once averaged ±0.040 in. have shrunk to as tight as 0.010 in., particularly for parts assembled via robotic welding.

The Dilast 15,000-sq.-ft. die-design and build shop employs 18, including three designers. While it can handle tooling to 180 in. long, the firm’s sweet spot is progressive and transfer tooling 72 to 144 in. long.

“We’re 60 percent progressive, 40 percent transfer,” Claus says, noting a significant increase in the amount of transfer dies coming his . This is due to increasing part complexity as well as the desire of stampers to conserve material.

Complex Dies for Stainless Exhausts, Tricky Seat Bracketry

Dilast has carved a nice niche in the automotive supply chain as a specialist in tooling up metalformers to stamp stainless-steel exhaust components. This niche represents about half of the firm’s book of business. It’s number-two market: complex bracketry for seating assemblies.

Regardless of the end product, Dilast’s tooling almost als is designed to form very complex drawn parts that require simulation to verify formability, supported by design software that allows for quick turnaround of iterative designs. Dilast employs Autoform for simulation, which until recently it had been outsourcing. In April it brought simulation inhouse when it leased an Autoform seat, “giving us more control over design changes,” says Claus, “rather than having to wait for our supplier to schedule our work.”

The design program of choice at Dilast: Visi Progress, from Vero.

“Visi is very good at allowing us to quickly change radius sizes, and then reblend and change the shape of the form tools,” says Claus. “Time is the critical success factor now, and the costs can rise quickly as delays pile up. Working with stainless steel, we can’t solve springback issues simply by moving a die face a few degrees. The parts and dies are too complex. That’s where continuous improvements made to each Visi release over the years, with the introduction of new software features, play a key role in our success.”

Among the new features of which Claus speaks is target-driven deformation (TDD), introduced by Vero with Visi Progress V18. Dilast began using Visi in 2003, with V11; it recently reviewed the latest version, V19.

Help with Restrikes, Cam Trims

Target-driven deformation, says Claus, allows him to quickly redesign features to adapt for springback, based on simulation results. “TDD works quite well with Autoform,” says Claus. “If we’re designing a long part with a lot of form features, and the simulation shows we need to redesign to counteract for springback, identified during simulation, we can go back into Visi and quickly remodel features. This can require changing the entire part geometry. Before Vero introduced TDD, this type of complete geometrical redo might take an entire day; now we can get it done in an hour, sometimes less.”

Claus finds himself redrawing draw radii often, particularly when developing tooling for stainless-steel exhaust parts. “We’re frequently changing radii and the shape of the form tools to adjust material flow,” he says. “Parts are so much more complex than they used to be due to tighter engine compartments—there’s less room and we have to fit parts around other parts. Bends are tighter. And, more parts are undergoing robotic welding, so fitup tolerances are tighter.”

To meet these requirements, Claus notes a trend toward more cam trimming in the die, and more restrike stations. “Visi really helps streamline the design process for restrike stations, which are designed precisely to the math model,” he says. “And when developing cam-trim stations, it’s easier to avoid interference problems, and we can see if the parts are nesting properly.”

Target-Driven Deformation in Action

TDD recently saved the day for Claus as he designed tooling to stamp an automotive seat bracket—a saddle-shaped part with a flange. “Remodeling the flange to compensate for springback, without affecting the saddle, posed a significant challenge, he notes. “I had to overbend by 3 deg., which required changing the entire part geometry. Using TDD, I remodeled the part in less than an hour.”

While TDD represents a major enhancement to Visi, according to a software reviewer at Develop3D magazine, Vero also has been hard at work refining the software’s user interface. “New features,” writes Al Dean, “include consolidation of the file/open and file import commands…the user has drag and drop access to (several) formats…Visi 18 also brings on board tools for working with mesh data, which may come from a reverse engineering process or a simulation. It also provides the tools needed to clean up data, such as for hole filling, rationalizing normals, deleting areas of data and sharpening up edges.”

Claus’s experience proves out Dean’s views. “We’re able to complete design drawings more quickly than ever, with new software features such as automatic view preparation and dimensioning,” he says. “With the last couple of software releases, we’ve been able to reduce detailing time by 50 percent. That’s critical in our market where time is the critical success factor.” MF


See also:

Related Enterprise Zones: Other Processes, Software, Tool & Die

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