March 2008 Edition

SPOTLIGHT: CAD/CAM

Blue Chip Investment

Through the peaks and valleys of business, shop owners found a program to keep the company from folding

Rick Denny and his step-son, Mike Anderson, have gone through some ups and downs since starting Blue Chip Engineering, Inc., Ramsey, MN, in 1994. The majority of Blue Chip's business is doing overflow work for other shops, making their problem parts; work which they have found to be unpredictable and unstable. But, their bumpy road ultimately led them to GibbsCAM from Gibbs and Associates, Moorpark, CA, and from there, continued success.

From their meager beginnings in a rented space just four feet wider than their vertical machining center, within a year, Denny and Andersen built their own rotary axis and gained some flexibility. By 2003, Blue Chip was a success, with 20 employees keeping 10 CNCs busy, including two 5-axis VMCs, a lathe, and a programmable CMM, in its own 4,600 ft² facility.

Then disaster hit the shop when a key medical device customer decided stamping components would be more economical than machining. The loss of the customer nearly put Blue Chip out of business.

Unable to find replacement work, Blue Chip had to lay off half of its staff. That's when Denny and Andersen decided to find more complex work not likely to be lost to a simpler manufacturing process or to offshore competition.

Past Decisions Foster Future Success

Luckily, Blue Chip was prepared to do that type of work. Denny had decades of experience working in shops and both he and Anderson had been introduced to GibbsCAM. With that experience and knowledge, they applied themselves to getting more complex jobs.

In 2000, Blue Chip accepted an engineering project to develop a machining process — including the fixturing, cut direction, cutter sizes, and speeds and feeds — to machine boat propellers.

"Although we had the machine tools and experience," Denny said, "we lacked the software to machine the hydrodynamic surfaces."

"We used a couple of other CAM systems before," Andersen said, "and they worked well for what we had been doing, but we needed something powerful, so we got GibbsCAM."

They used the computer-aided manufacturing software to extract geometry from the CAD model, and made tool offsets and toolpaths. Then, Andersen developed a fixturing method to hold the work piece, not an easy task for propeller machining. The fixturing included the use of GibbsCAM to model and machine three helical clamps to hold the ends of the blades with set screws. For the props, they chose the application's two-curve flow-machining routine, which allows 3D cutting along surface flow lines. This also saves time on the machine and results in a superior surface finish.

"Like the GibbsCAM spiral cutting routine, flow-line machining eliminated the step-overs of lace cutting and the rougher finish these methods leave," Anderson said. "It also made our job faster and easier. The fixturing and toolpaths let us machine both sides of a propeller in a single load at 400 ipm, the fastest the machine would go."

Using castings made for larger props, Blue Chip machined 20 with sufficient precision to eliminate the time and effort of traditional balancing work. Also, depending on the boating application, the process eliminated or reduced hand polishing.

The job went well for Blue Chip and the customer, who added high-speed machining centers, achieved much higher machining speeds, and had an unexpected benefit: it introduced a new product line of machined propellers.

Since the contract was for development of a process for the customer to implement themselves, it did not result in more machining work for Blue Chip, but it prepared the company for its challenge three years later.

"The propeller work forced us to dive into GibbsCAM and learn everything we could; the same way we did with SolidWorks," Andersen said. "We stopped using our previous CAM software and started using GibbsCAM for everything."

Performance Squeeze

Although Blue Chip had only half the number of employees it did at its peak, Denny and Anderson had sufficient confidence in the Gibbs software to try new work outside of its usual line. The company prospected for complex and challenging surface machining opportunities, specifically with engines.

"I used to drag race," Denny said, "and I enjoy squeezing performance from engines. I've always wanted to machine cylinder-head ports. Customizing ports involves complex surfaces and handwork that begs to be eliminated."

Blue Chip had done some machining work for Hi Tech Motorsport, Elk River, MN, a local performance shop, making throttle bodies from raw stock. In 2006, Brian Ebert, a principal of Hi Tech Motorsport, asked Blue Chip to machine ports on Corvette LS1 engine cylinder heads. The re-ported heads, in combination with different Hi Tech manifolds, cams, and throttle bodies, boosts a stock engine from 350 to 550 horsepower.

The parts were identical, and saved nine hours per head, or about 200 hours total

Hi Tech had been customizing the heads through traditional hand grinding of the intake and exhaust ports, which presents problems that machining can solve. With hand grinders, "porting" a head is a 12-hour job, and because it's done manually, there is no consistency from port to port. More challenging is the replication of a successful job — there is no way to make an identical set of heads by hand.

"Machining ports is difficult because of the compound angles, the required length of cutters, and the tight space," Denny said. "The tool has to go deep inside without hitting sidewalls or the tool holder, machine at depth without chatter, and then retract without gouging or shanking, which is the hardest part. GibbsCAM lets us add multiple 3D lines for the cutter to follow as it retracts from the cut."

"I didn't know how to drive the tool without hitting everything on the way in or out," Denny said about his first experiences with machining the head, "but Gibbs' tech support gave me the answer. Support was one of the reasons we chose Gibbs when we got the prop job seven years ago."

Making the Automation Move

Hi Tech Motorsport hand-ported one intake, one exhaust, and one combustion chamber, then molded parts from the chambers, had them digitized with a laser scanner, and translated the data into surfaces. Blue Chip imported these into SolidWorks to build a solid CAD model of a cylinder head. It opened the file in GibbsCAM, where it used both solids and surfaces for machining, and the rest of the cylinder head for positioning.

The plan was to use the GibbsCAM Advanced CS module for programming.

"It's all we need if we're are not doing 5-axis simultaneous," Denny said. "We don't have the 5-axis module, so I decided to clamp the part at the different angles, machine a patch surface, rotate to another angle, machine a patch, and so forth. This minimized chatter, since both the tilt and rotary axes are clamped during machining."

A feature of the CAM software offsets the toolpath from the surface, and — using toolpath geometry, points, and lines — drives the cutter. Combined with surface flow machining, it worked well for Denny. He used the software's Transform Toolpath function and copied all the toolpaths to the individual four points he created for each cylinder, to produce identical toolpaths for every port. The job required only five programs to machine the intake, exhaust, and combustion chambers.

It would not have been as easy, had he not relied on the Gouge Checking feature of GibbsCAM, which he said eliminated a lot of scrap, and the feature that Blue Chip considers the best: interactive visualization.

"We rely on the Cut Part Rendering function for everything," Andersen said. "We have the confidence to know that if it looks right and doesn't gouge in simulation, it's going to be right and won't gouge on the machine. There are rare exceptions, so we're cautious, but confident, at the machine."

"We can look down the port and see if you're going to shank the cutter," Denny said. "The Form Tool function shows the shape of the cutter, which protrudes about 4.5" from the holder, starting with a 1/2" diameter shank, tapering to 3/8" diameter, and ending with a 1/2" ball.

"I could rotate to an angle, pick a surface patch, then drive the cutter into the port, and then out. That's all I needed. I visually created the toolpath, rotating my coordinate system about the vertical or horizontal axes, to get a clear path without collisions. I had few numbers to enter because I moved the cutter visually. The visual feedback is powerful, useful, and intuitive. On the first try, I could get to an angle where the tool wouldn't gouge or shank. With Cut Part Rendering I confirmed what I programmed. My first part was good."

A newer feature, Flash CPR, shows a translucent part model, in registration with the rendered cut part; useful in executing the job.

"I can look interactively at the part from any angle," Denny said. "I looked at the ports from the side to check surfaces, from the ends to check for gouging on side walls, and from every direction to make sure the cutter wasn't hitting anything as it went into the heads and retracted. For this porting job, it was indispensable."

Andersen and Denny also discovered a function in this feature which let them check their work.

"We display the rendered cut part on the part model and then toggle the cut part on and off," Andersen said. "By watching for apparent motion each time the overlay appears, you can find the most hidden errors or deviations from the part surface. If nothing appears to move, the part's good."

The cylinder heads were machined on a 5-axis VMC, using the rotary axis for positioning. After seeing and testing the first pair of heads, Hi Tech Motorsport awarded Blue Chip the job of porting 22 heads, which Blue Chip delivered within two weeks. The parts were identical, and saved nine hours per head, or about 200 hours total.

"Hi Tech was as pleased as we were," Denny said.

The Insurance of Difficult Work

To eliminate high- and low-volume work cycles, Denny and Andersen seek more OEM work. As they work toward that goal, they continue diversification across industries, taking on the difficult work as insurance against alternative manufacturing methods and foreign competition.

They have found work in medical instrument and orthopedic implant manufacturing, gained a foothold in automotive and motorcycle part manufacturing, are doing some rapid-prototype machining, added an artist who provides sculpture machining work to their list of customers, and have made aerospace manufacturing the largest portion of their business, with a solid, long-term defense contract.

Denny and Andersen said that GibbsCAM and other technology helped Blue Chip survive through diversification, some difficult work, some fun projects, and shifting from one industry to another as some projects end and others ramps up.

"If we hadn't invested in the program, we'd be out of business," Denny said. Gibbs and Associates

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