The decision to buy a portable CMM was made because “the stainless and carbon steel products we make kept get bigger and bigger,” said Patrick Comparin, vice president. “In the last few years some power-generation parts have grown by 20 percent.” Some turbine ring castings now weigh 5,000 to 7,000 pounds and have diameters of 10 feet or more. Some recent valve body castings weighed 21,000 pounds and stood six and a half feet high.

As the existing layout facility became too small, it was more economical to take the measuring systems to the castings rather than move the castings, Comparin noted. This jump in size proved to be too much for the inspection and layout facilities at Sivyer.

Sivyer Steel Corp., a large Bettendorf, Iowa, steel foundry, has seen a steady rise in the size of castings its customers needed. Some new jobs were so big they could not be handled by Sivyer’s coordinate measuring machine (CMM). The castings can not even be moved into the layout room.

Meanwhile, management and engineers at the big foundry have worked long and hard to raise the steel foundry industry’s standards in dimensional measuring. At the same time, other customers were asking Sivyer to reverse engineer castings for which no drawings or patterns were available. These three challenges had a common solution: Sivyer purchased a portable CMM

The decision to buy a portable CMM was made because “the stainless and carbon steel products we make kept get bigger and bigger,” said Patrick Comparin, vice president. “In the last few years some power-generation parts have grown by 20 percent.” Some turbine ring castings now weigh 5,000 to 7,000 pounds and have diameters of 10 feet or more. Some recent valve body castings weighed 21,000 pounds and stood six and a half feet high.

As the existing layout facility became too small, it was more economical to take the measuring systems to the castings rather than move the castings, Comparin noted. This jump in size proved to be too much for the inspection and layout facilities at Sivyer.

"By going to portable measurement, we are trying to raise the bar in the steel foundry business as far as quality of castings goes..."

Sivyer Steel Corp., a large Bettendorf, Iowa, steel foundry, has seen a steady rise in the size of castings its customers needed. Some new jobs were so big they could not be handled by Sivyer’s coordinate measuring machine (CMM). The castings can not even be moved into the layout room.

Meanwhile, management and engineers at the big foundry have worked long and hard to raise the steel foundry industry’s standards in dimensional measuring. At the same time, other customers were asking Sivyer to reverse engineer castings for which no drawings or patterns were available. These three challenges had a common solution: Sivyer purchased a portable CMM

The decision to buy a portable CMM was made because “the stainless and carbon steel products we make kept get bigger and bigger,” said Patrick Comparin, vice president. “In the last few years some power-generation parts have grown by 20 percent.” Some turbine ring castings now weigh 5,000 to 7,000 pounds and have diameters of 10 feet or more. Some recent valve body castings weighed 21,000 pounds and stood six and a half feet high.

As the existing layout facility became too small, it was more economical to take the measuring systems to the castings rather than move the castings, Comparin noted. This jump in size proved to be too much for the inspection and layout facilities at Sivyer.

Most of Sivyer Steel’s large work is cast and machined parts for the construction equipment, mining, defense, transportation, valve and power generation industries. An ISO 9002-certified foundry, Sivyer has developed a computer-assisted concept-to-casting process which puts all design and production data into electronic format. This includes everything from the customer’s designs to final verification of as-poured and finishing castings with a CMM and layout machine.

Sivyer bought a ROMER portable CMM, a six-axis articulated measuring arm with a 12-foot diameter measuring envelope. It is equipped with an operator controlled touch probe and linked to a desktop computer.

Icon-based systems represent various geometric elements making it possible to “see” the component without the engineering drawing. The CAD representation of the component is referenced to the part by touching and/or sweeping various datums known as coordinate locators. Dimensional conformance is established in real time.

Benefits of computer-aided dimensional inspection are quickly realized. “The portable CMM paid for itself in less than a year because it greatly improved the overall dimensional verification process efficiency,” said Phil Bruno, technical director. Large complex components with numerous dimensions are checked in a fraction of the time required with traditional CMM layout inspection and engineering drawings. Measuring errors and missed features due to technician fatigue are virtually eliminated. Dimensional layout reports are accurate, complete and have a professional look which impresses customers, the company added.

The arm is a central element in Sivyer’s implementation of concurrent engineering -- an effort which began in 1993 and is the responsibility of the Preproduction Planning Group. It is here that solid CAD models are created from customers’ data with solid modeling CAD software. The input includes engineering drawings, IGES files, stereolithography files (STL formats) and solid models from a variety of CAD systems. Two of Sivyer’s 10 full-time degreed mechanical and metallurgical engineers work to complete these models. They add casting-specific features such as feed pads, directional solidification tapers, fillets, radii and stock to be machined away.

Comparin noted that buying the portable measurer probably avoided the expenditure of hundreds of thousands of dollars to buy, install and calibrate a big new conventional CMM. Not to mention the year’s time it would have taken to build a special new layout and inspection facility of several thousand square feet. “There would have been no added return attached to this spending,” Comparin added. “It would just have gone into the cost basis. And it still would have been awkward to handle the large pieces we do here.” Even so, he added, Sivyer “almost” bought a new conventional CMM.

“Until the pieces got so big,” Comparin said, “we could somehow always manage to forklift them into place on the bed of the CMM.” But the conventionally designed computer-assisted layout machine can’t handle a piece if any of its dimensions is longer than 8 feet. The layout / inspection room is somewhat small, too, measuring about 20 by 25 feet.

“By going to portable measurement, we are trying to raise the bar in the steel foundry business as far as quality of castings goes,” said Quality Assurance Supervisor David Wright. “A 10-foot diameter turbine casting may be cast as much as half an inch out of round. This is the norm for this industry’s process capability limits. We want to do a better job for our customers.”

Thus a major job for Wright and the arm is verifying the foundry’s process capabilities -- its ability to hold tight tolerances. “The portable CMM has an accuracy of approximately 0.003 inch which eliminates most of the measuring error in determining process capability,” Wright said.

“Measuring helps us find things like out-of-roundness and off-center rough machining,” Wright continued. “This is especially important when two halves of a part are laid up back to back and machined together. We also check patterns and molds as required. Once the error gets into the steel it’s pretty expensive and pretty slow to fix.”

The portable CMM has also given Sivyer new ways to add value to its work. “For some customers we now do the layout work for their machine shops,” Wright said. He is using an optional punch probe for the end of the arm. “This lets us put a dimple in the steel exactly at the right spot, say for starting a machining cut or drilling or boring a locator hole for a reference pin. Otherwise,” he explained, “the measurements for setting up the job at the machine shop have to be made from the casting’s edge. And who knows exactly where the edge of any casting is.”

Sivyer takes the portable CMM into the field to customers’ job sites and machine shops to check on problems and faults. Wright said that even an overseas trip is practical for the 40-pound machine. However, the arm spends most of its time in Sivyer’s Bettendorf foundry but Wright occasionally takes it across the Mississippi to the Riverside Products’ machine shop in Moline, Ill.

Reverse Engineering

One of the reasons Sivyer originally bought the arm in 1996 was for reverse engineering. A construction equipment company asked us if we could generate drawings for some digger teeth where no drawings were available. With the arm, we were able to digitize one of the teeth and capture point cloud data. We ran that through DMIS and IGES and generated the geometry for new patterns with Pro/E. "It worked very very well and  smoothly,” Wright said. “Everybody involved was very impressed.”

“Reverse engineering with the portable CMM is especially good for complex contours and surfaces that are out in the sky somewhere,” Wright added. “These are surfaces you can’t really put a dimension on very well. The arm sends the data back to the CAD system as an overlay.” Comparisons are easily done, visually, right on screen, he noted.

As a result of raising the quality standards and having extended measurement capability, “We are getting more business,” Wright said. “Those 14,000 pound valve bodies were from two new customers. Checking the first one took a day and a half. The next two were done in just a few hours apiece. With our old methods checking each casting might have taken a week or more.” For Sivyer Steel, new measurement techniques are unlocking new business opportunities and helping it meet its customers’ rising expectations.