UMC & Computape

Вторник, 26 февраля 2019 20:02

Software Heads Off Costly Code Rework, Crashes

Programming in the Swan City

Two shops share their stories on CGTech’s Vericut software and the benefits of machine simulation

Forty-five minutes northwest of Minneapolis sits the small town of Monticello, a place of parklands and hiking trails on the banks of the Mississippi River. Thousands of trumpeter swans winter here each year, basking in the relatively warm water discharged from the nearby power plant, while the town’s human residents enjoy fishing, snowmobiling, and a prosperous economy. This is the home of contract CNC programming firm Computape Inc.

Founder Ed Popp was an NC Specialist working for General Electric when he decided to enter the programming business. The year was 1976, a time when most machine tools still had hand cranks and levers. There was no C in CNC back then—automated lathes and mills took instructions from long rolls of paper tape, and programs were created using APT (Automatically Programmed Tool) on time-share computers fed by stacks of punch cards. Despite this, Computape quickly earned a reputation as the go-to place for complex, error-free toolpaths, and the company eventually came to specialize in 5-axis programming of aerospace and defense components such as airfoils, blades, and stringers.

The Next Generation

Fast forward to 1994. That was the year Popp’s son Mike came to work for the family business, having earned his degree in computer programming from the University of Minnesota. Upon hiring his son, Popp decided this would be a good time for another upgrade, the purchase of machine simulation software from a then fledgling company in Irvine, Calif., CGTech. Not many in the industry had heard of CGTech at that time, let alone its flagship product Vericut, yet the Popps are strong believers in technology and knew G-code simulation would allow them to provide better service to their customers.

The company reins have since been passed to Mike Popp, who still has the original user guide for Vericut version 2.0, released the year before he started with Computape. Both Popp and the software have evolved over the years, but one thing remains constant: his high opinion of Vericut. “It’s a must-have product for anyone doing business in CNC manufacturing,” Popp said. “Vericut’s a life saver.”

Computape does its CAD modeling and CNC programming using a variety of software suites, including NX from Siemens PLM Software, Catia V5 from Dassault Systèmes, and VoluMill by Celeritive Technologies. Postprocessing is accomplished via Austin N.C.’s G-Post, with whom Computape is an authorized partner. With high-end tools like these at his disposal, some might question why Computape bothers with code verification. Popp’s reply to those people is they don’t understand the power of Vericut.

“CNC programming is like an artist creating a sculpture,” he explained. “You start with a vision of how you want the material removed, being careful to cut away the right amount at the right time, and end up with a masterpiece. Unlike an artist, however, we have the technology in Vericut to visually refine our cuts before any material is removed.”

Artistry aside, Vericut provides much more than accurate toolpaths and crash avoidance. Most of Computape’s projects are fixed bid, which means Popp must be as efficient as possible if he’s to avoid costly code rework. “I don’t have time to mess around with changes to the program, and neither do my customers. Once I review a project in Vericut, I know it’s good.”

Spreading the Word

So strongly does he believe in Vericut’s capabilities for process improvement—both his and his customers’—that it’s become a permanent part of the Boeing-compliant Digital Product Definition (DPD) procedure at Computape, a process that’s adhered to whether the part is a $50 mounting bracket or a $50,000 airfoil. At the end, Vericut results are delivered to his customer along with the drawing and NC-file package. For those that don’t own Vericut—an increasingly smaller percentage, said Popp—a free viewer is available from the CGTech website.

Vericut is also a great communication tool, Popp pointed out. Tool libraries with speed and feed information are clearly defined in Vericut, as well as machine tool construction and travel limits. This allows for easy collaboration with the customer during process definition and Q&A sessions, providing confidence on both sides of the phone that the delivered product is error free and clear of any tool reach or potential interference problems. “There’s too much time and money involved in making a part these days for something to go wrong,” he said. “The first part has to be good, and with Vericut, it is.”

His competition might think he’s crazy for sharing the technology. After all, most businesses that latch on to a competitive edge like to keep it close to the vest. Not so, Popp. He’s been spreading the good word of toolpath verification almost as long as he’s had it, leading a number of his customers to bring their own verification in-house, sometimes cutting Computape out of the action.

One of these is Ultra Machining Company (UMC), an aerospace and medical machine shop just down the road from Popp. UMC’s first project with Computape was in 2005, but purchased a seat of Vericut one year later after owner Don Tomann saw a demo of the software at an NTMA trade show. UMC had recently bought the company’s first 3-channel Nakamura Super NTX mill-turn center and decided the crash potential was too high. Since that time, UMC has added eight similar machines, and has also established itself in the 5-axis, wire EDM and Swiss-style machining arena. As a result, Vericut toolpath verification is now an internal requirement on most new part programs.

CNC Programmer Mike Triplett can think of several instances where Vericut has saved the day, but said that its original intent of crash prevention is somewhat secondary at this point. “I can’t tell you how many times I’ve said, ‘What you see on the screen isn’t always what you get on the machine.’ The reason is because the CAM system’s simulation uses its own internal calculations, whereas Vericut reads the actual G-code, the same as the machine tool.”

Don Lahr, CNC programmer, agreed. “You can see so much more in Vericut. We can watch everything working together while proving out the G-code, tool projections, and travel limits, while simultaneously checking for collisions. Quite often we’ll review the code in Vericut and identify a particular part feature that doesn’t look right, or a cutting tool that could be programmed more efficiently. It lets you identify these issues before they get out to the machine, and deliver a better product to the shop floor.”

As a certified ISO 13485:2003 and FDA compliant supplier, UMC must adhere to rigid quality requirements. One of these is the need to submit a PPAP (Production Part Approval Process) on any new projects, and adhere to that process thereafter. Gone are the days of taking on a job and continuously tweaking it to improve part profitability and tool life—since there’s only one shot to make it right, it’s important to lead with your best machining foot forward, something Vericut has helped UMC with time and again.

“We have some customers where, once the process is bought off, that’s it. No more changes,” Lahr said. “The AUTO-DIFF feature in Vericut checks for various conditions by comparing the design model against the actual cut stock model. Did we hit all the features? Is there any gouging of the workpiece, or leftover material that shouldn’t be there? Most importantly, did we violate the customer model? If so, what can we do about it?” UMC also uses CGTech’s OptiPath module, which as its name implies looks at toolpaths and optimizes them using pre-defined volume and chipload parameters, speeding up where possible and slowing down when necessary to avoid chatter, broken tools, and bad parts. Together with AUTO-DIFF, UMC can be confident the initial part process is a good one, and there won’t be embarrassing post-PPAP calls to the customer to request a deviation.

As with Computape, UMC also uses the Vericut Reviewer, except in UMC’s case it’s for the company’s internal customers: the machinists and engineers. “Our machinists review the Vericut file when they’re setting up a job,” said Lahr. “It helps them visualize the machining process and identify which tool is cutting each part feature. They can measure the part in Vericut for comparison against the actual workpiece and quickly identify which offsets need adjusting. It really narrows down what steps have to be taken when troubleshooting a problem.”

Looking back over the past nine years, about the only thing Lahr and Triplett would change is the implementation. “We probably should have started on a simpler machine,” Triplett said. “The NTX has two spindles, two turrets, a B-axis milling head and live tooling. There’s just a lot going on at one time. Learning Vericut on a machining center or 2-axis lathe would have given us a better understanding of its capabilities earlier on, and made for fewer sleepless nights. Even so, we got through it just fine. It’s an awesome product.”

Article published in Manufacturing Engineering, November 2015 (Web link)


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