Portable contactless caliper

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Today’s Machining World Archive: June Vol. 2, Issue 06

ELECTRONICS, COMPUTERS, VIDEO AND LASERS IN THE QC DEPARTMENT OFFER MORE OPTIONS FOR MEASURING MACHINED PARTS

Measuring completed parts can sometimes pose as much of a challenge as machining them. The many high-tech measurement instruments available today offer superb precision and accuracy, but measuring those parts can still be tricky. “Everyone wants the ‘Holy Grail’ of measurement,” says Mike Knicker, owner of Q-PLUS Labs, Irvine, CA, a full-service measurement and inspection laboratory. “They want one machine that does it all. It doesn’t exist.” The challenge becomes choosing the appropriate instrument or instruments from the many available on the market. The good news is that these electronic devices not only measure your parts but can also collect and record data for you.

Conventional CMM (coordinate measurement machine)

Though it was invented decades ago, the familiar bridge-style coordinate measurement machine still has its place in the QC department, and the technology continues to evolve. This machine uses a touch probe to contact measurement locations. Then, it calculates the length, radius, and other dimensions.

Helmel Engineering, Niagara Falls, NY, offers a range of CMMs. The Checkmaster model fits on a benchtop, offers accuracy in the range of 0.001 inches, and sells for under $14,000. For measuring critical, small parts like those used in medical or aerospace applications, the company’s new MicroGage offers an affordable option for those needing high-precision automatic CMM. With accuracy better than 0.0005 inches, MicroGage pricing starts under $35,000.

Art Whistler, vice president of sales and marketing, says Helmel CMMs are rugged and durable, suitable for the manufacturing environment. Also, Helmel CMMs do not require compressed air, making them simpler to install than brands that rely on air bearings.

Arm-style CMM

A CMM with long, articulated arms can reach and bend to make measurements that are impossible with bridge-style units. “We developed it for people who don’t usually use CMMs,” says Darin Sahler, global public relations manager, FARO Technologies Inc., Lake Mary, FL, a well-known maker of arm-style CMMs.

These compact, lightweight units, such as the FaroGage, can easily travel out on the shop floor or even be mounted on a machine. The FaroGage yields accuracy to 0.001 inches and costs around $14,000.

Hallcraft Machining, Melbourne, FL, uses the FaroGage for repetitive measurements and inspections. “We use it for first-article inspection and reverse engineering,” explains Dave Hall, vice president of the company. It has proven handy for measuring radius, taper, and surface contour.

Video measurement system

Touching a part with a probe isn’t always feasible, especially for flexible or intricate parts. David DeVowe, executive director of quality at QC Inspection Services, suggests using a non-contact CMM for such scenarios. A video measuring system uses a camera to deliver a magnified image to a screen, where the operator can perform measurements.

Mark Arenal, president of Kinemetric Engineering, highlights that video systems range from simple manually operated units to CNC-capable systems that can process measurements automatically.

Kinemetric Engineering offers a range of non-contact measurement systems, including the KineMeasure KM200, a small, general-purpose video measurement system that costs around $16,000.

Laser micrometer and Profile measurement system

For parts with tight tolerances, a laser micrometer might be suitable. Versions use a laser beam to calculate dimensions based on how much light is blocked by the part. The Mitutoyo LSM- bench-model laser scan micrometer measures parts from 0.02 to 2.36 inches with high accuracy.

Profile measurement systems, like those from TESA Scan, are designed for specific parts and can measure various dimensions and features while the part rotates. These systems significantly reduce inspection time.

Hybrid techniques and Laser scanning

Many companies have both CMMs and vision systems. Hybrid systems integrate both technologies for improved measurement capabilities. Kinemetric’s CP8K unit accepts both video and touch probes, enabling the use of multiple measurement methods.

Laser scanning, originally developed for medical uses, captures thousands of points on an object’s surface to create a “point cloud.” This data helps engineers compare scans with CAD models.

The latest measurement technologies can save time and reduce errors when used appropriately. If you're interested in learning more about Non-contact rotary caliper, feel free to contact us.

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