April 2008 Edition

CAD/CAM

Breaking the Mold

Lean principles and a CAD program let a manufacturer make aluminum rather than steel molds, saving the customer time and money

J&M Mold, Fairport Harbour, OH, is a precision tool and die maker for the plastic, aluminum, and zinc injection industries. Owner David Martin is a mechanical engineer who said he has been working in the die casting industry since he was 13 years old. He has been using the full suite of VISI Series software from Vero International, Wixom, MI, since he started his operation seven years ago.

Martin taught himself the VISI software package. He began using VISI 3D machining to produce prototype parts from plastic. Within a week, he was generating parts. After three months, he was competent enough to design and build complete tools. Today, he and his staff can build two complex tools per month.

He said that he addresses industry challenges by staying in tune with the latest technologies and new strategies for faster, more efficient mold assembly.

"For instance, we use VISI Flow software to design accurate molds faster, and VISI Machining for cutting steel and high-feed milling," Martin said. "It' s very important that we get the part right the first time. This keeps our customers happy and we enjoy repeat business because of it."

A medical device customer approached J&M Mold about a mold that was designed and built in China that was producing flawed parts. During a two-day period, Martin used VISI Flow to rework the mold gating system.

"Working with the customer and VISI Flow, we found the best gating situation for the part. I moved the gating to where I thought it would be best and used VISI Flow to confirm it," he said. "In addition, by using VISI Mold we increased the mechanical integrity of the part design and strengthened the areas that needed to be stronger compared to the original Chinese designed mold. We designed and built the tool, shipped it, and as a result the mold generated high-quality parts."

Aluminum is Leaner Than Steel

As a student of lean thinking and lean manufacturing, Martin integrates these theories into his use of VISI products.

"It seems that VISI software was designed around lean manufacturing with the constant flow of menu picks – all operations in one software package," he said. "VISI is a CAD system that was designed by people with tool makers in mind."

According to Martin, who has been working with aluminum since he opened his shop, there has been an upsurge in the popularity of designing aluminum molds versus steel ones.

Aluminum tool delivery is at least 50 percent faster, depending on the part design, compared to steel molds

"We use VISI to develop aluminum prototypes and short run production tools. We're able to generate more parts from them," he said.

As a result, aluminum is beginning to replace P20 steel traditionally used to produce molds that are of 20 to 32 Rockwell hardness. Aluminum molds will last for a long time as long as abrasive or corrosive plastics are not injected into them.

"Why build a P20 tool when you can build an aluminum tool that will last through thousands and thousands of shots or short run production?" Martin said. He cautions, however, that part materials and molding processes must be appropriate for aluminum molds.

"You can't inject just any part into an aluminum mold because of details such as thin-walled shut-off designs," he said. "Such parts don't work as well in aluminum because the aluminum isn't as structurally strong as steel."

However, Martin has found a strategy around that.

"We sub-insert steel shut-offs or slides inside the aluminum mold design. We call this hybrid aluminum tooling and VISI is strategic for designing such tools. Critical or small parts of the mold design can be made of steel while the rest of the design is aluminum," Martin said.

Aluminum is less expensive to machine and designing tools in aluminum is less costly for J&M Mold customers. Using VISI, it took Martin two days to machine a steel plate. The same plate, designed and machined in aluminum, took six hours. He said customers are pleasantly surprised when he tells them he can help them save money by using aluminum instead of steel for their mold designs. Aluminum tool delivery is at least 50 percent faster, depending on the part design, compared to steel molds.

"We can generate at least one aluminum tool per week," he said. "There's no room for error, so we use VISI analysis upfront to assure that the design is accurate the first time."

Indispensable Software

Prior to implementing the VISI Series software, Martin downloaded several demonstration versions of popular general purpose CAD packages.

"None of them compared to VISI's user interface," he said. "Unlike the others, VISI is not parametrically driven so you don't have to hunt and peck on tree-driven icons. Instead, VISI offers specific tools for specific tasks. For me, that gives me more control over exactly what I am doing.

"Most of my customers who use SolidWorks tell me they have a lot of trouble with tasks such as blending and meshing components. Using VISI, however, there's no problem or angst over those efforts."

He likes the VISI machining package, too, particularly the rest milling and pencil milling. Martin said that he wouldn't rough out a complex block without those tools.

"The important aspects for machining include ease of use, time to program, run time on the CNC, quality of finish, and price. VISI beats the competition on all those issues," Al Foote, principal at Compass Technologies, an Ohio-based VISI Series distributor, said.

Martin said using VISI for mold analysis is indispensable.

"Customers understand the analyses add value to each project. They realize and accept the cost incurred as a result of running the analysis helps them save time and money that can be incurred when molds that aren't analyzed must be retooled. VISI Flow is as useful to me as the machine used to cut the tool." Vero International

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