Laser Technology

Measuring complex parts

By Meghan Boyer

A laser scanner helps save time for Defiance Metal Products

July/August 2011 - A fabrication company with a diverse range of parts requires varied methods to measure and inspect them. Defiance Metal Products Inc., Defiance, Ohio, uses touch probe systems for some shapes but found a laser scanner works well for the complex contoured parts the company also creates.

In operation since 1939, Defiance is a full-service sheet metal fabrication company that manufactures a variety of weldments and assemblies. The company creates parts using multiple fabricating processes, including stamping, forming, welding and CNC work, for multiple industries, such as trucking, commercial vehicles, military vehicles and more. Defiance operates facilities in Ohio, Arkansas, Pennsylvania and Texas with more than 720,000 sq. ft. of manufacturing space. 

“Because a lot of our stamping is really hard to inspect with a touch-probe CMM—a lot of complex contours and surfaces—it just doesn’t lend itself for touch inspection,” says Mike Hoshock, layout tech with Defiance. 

The complexity of some of the stampings meant that touch-probe measuring was not always the best option, so the company in 2008 purchased from Faro Technologies Inc., Lake Mary, Fla., a Faro Laser ScanArm with Faro’s CAM2 Measure X software and PolyWorks, says Hoshock. “We bought the laser scanner to do surface comparisons versus CAD, and we also saw a need for reverse engineering,” he says. The company first purchased the Platinum arm and shortly afterward decided to look into the laser scanner technology because of the range of parts it produces. Defiance previously used a FaroArm Silver without a laser scanner option.

Complex parts
A hard touch probe is beneficial for measuring more square or rectangular parts with holes, slots and prismatic features, says James Kerker, account manager with Faro. A probing arm is more accurate than a laser scanner, so companies requiring tight tolerances and highly accurate measurements on machined features use them, he says. Free-form shapes, such as a stamping tool or a car door, are not line-point applications. Such parts usually have more open tolerances and are a good fit for laser scanning.

“The parts they are making at Defiance with stamping and free-form geometry, you can call those organic shapes,” says Luke Yoder, regional sales manager at Faro. “If you look at the inside of a car, the instrument panel has a lot of free-form shapes. That is really where the laser scanner is highly beneficial.” 

A laser scanner uses light to “probe” objects by projecting a laser line onto a part and uses a camera to find the location of the laser line. Each point on the laser line appears at different places in the camera’s view, a technique known as triangulation.

“It’s almost like using a spray can, if you will, to paint,” says Yoder. “[Hoshock] is capturing thousands of points, tens of thousands of points, over the whole surface of the part, and he is able to look to see how that full point cloud over the manufactured part compares back to the 3-D CAD model. It gives him a lot more information to make decisions for the manufacturing process.”

Time savings
The Faro Laser ScanArm is used for inspection, part-to-CAD comparison, rapid prototyping, reverse engineering and 3-D modeling. The laser can scan up to 19,200 points per second. Faro’s latest introduction, the Faro Edge ScanArm, has a wider laser stripe that increases scan coverage to more than 45,000 points per second. It also has an integrated personal measurement assistant, a built-in touchscreen, an on-board operating system and a seven-axis configuration.

Using its Faro Laser ScanArm, Defiance is able to hard-probe measure or laser scan sections for larger volumes of data without adding or removing attachments or cables or importing data from another CMM. Among the greatest benefits the company has seen since implementing the arm is time savings, notes Hoshock. Employees have less downtime because they do not have to wait for a program to be written or run like they would for a traditional CMM. A program that took workers more than 15 minutes to run on the CMM can be accomplished in less than five minutes using the ScanArm.

“With the more complex stamping, it’s very difficult to check with a probe or it’s very, very time consuming, where I can get a lot more data in a lot less time either using the laser scanner or even using the probing function on the Faro arm itself,” says Hoshock. “You can gather a lot more information in a lot less time.”

When developing a part, Hoshock works with CMM operators to rough it in using the Faro arm and get the key dimensions. The team then will go back with the CMM program and do a more-detailed inspection. “We see a lot of time savings with the programming of the more complicated parts,” he says. “It may take quite awhile to program them on the CMM. With the Faro arm, I can build a routine fairly quickly.”

Without a Faro Laser ScanArm, workers would have to take a part from its station to the fixed CMM, measure it and then feed the data back, says Kerker. “That might take two or three hours to do that,” he says. “Now he can go out and get real-time data. From that information, they can make a live change on the fly.”

Another advantage of working with the ScanArm is being able to measure large parts, notes Hoshock. Defiance manufactures parts that range from roughly 6 in. cubed to parts that measure 6 ft. to 8 ft. long and 2 ft. to 3 ft. wide. “We run a wide diversity of part sizes,” says Hoshock. “We have got some huge weldments that have details welded on in certain locations, and the parts are just too big to fit on the CMM.” Defiance’s largest CMM provides roughly 3.5 ft. by 5 ft. of working range.

The Faro Laser ScanArm enables workers to bring the measurement tool to the part instead of bringing it into the CMM lab. “I’ve got a magnetic mount that I can use, so if I have enough room, I can actually fix the arm to the part and work it that way,” says Hoshock.

Defiance’s ongoing relationship with Faro is beneficial because Hoshock continually learns new information about the company’s ScanArm. “We are constantly having meetings to make ourselves better and getting better through peer learning,” he notes. <p>
Kerker, Defiance’s regional representative, helps keep the company informed. “The relationship started in about 2002 when they purchased their first FaroArm,” he notes. “Defiance is definitely a growing customer of ours.” FFJ

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  • Defiance Metal Products Inc.

    Defiance, Ohio

    phone: 419/784-5332

    fax: 419/782-0148

  • Faro Technologies Inc.

    Lake Mary, Fla.

    phone: 800/736-0234

    fax: 407/333-9911


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