Inspection To Go

Courtesy of All images: Wilcox Associates

Massive amounts of data can be captured quickly on the shop floor using portable measuring arms equipped with scanning probes. Here, a Romer Infinite 2.0 portable arm measures heavy earthmoving equipment with a Scan Shark V4ix laser scanner capable of capturing 485,400 data points per second.

A look at portable measurement technologies and their applications.

Measuring parts with portable equipment on the shop floor is always faster than using a coordinate measuring machine in a lab. Previously, though, the accuracy of portable measurement tools was not sufficient to make critical manufacturing decisions. Today, portable measurement systems are more accurate and easier to use than their predecessors. Their advanced 3-D measurement capabilities and integration with CAD and enterprise metrology software packages open new opportunities for greater floor-level inspection productivity and manufacturing process optimization.

Portable devices include 6-axis, arm-type universal gages (including hybrid devices); traditional portable arms; laser trackers; and scanning systems. They provide accurate measurements within a range of 15µm to 100µm, depending on the system. While this does not make them suitable for the high-precision lab work done by CMMs, this degree of accuracy is acceptable for many shop floor measurement tasks.

Some portable measurement devices use cross-platform software (such as PC-DMIS Portable) that allow for offline programming. By doing all the programming off the shop floor, the user can take measurements quickly, with minimal loss of machine time.

Speed Matters

Speed is the key issue for shops considering the use of portable measurement devices next to their machines. Using portable devices for making in-process checks or first-piece inspections (if accuracy permits) takes the least amount of time because no time is wasted taking parts to a remote measurement location and waiting for inspection results.

The key to getting fast measurement results from a portable device is preparation. Before measuring a part, end users should know the results they are looking for and the steps required to get them.

For the latest generation of arm-type gages, this means knowing what features to measure, selecting them using a graphic user interface and following the prompts. Users can perform complex evaluations on the shop floor using portable arms equipped with the same software found on CMMs.

This type of software uses a CAD model to generate efficient probe paths and generates as much as 90 percent of a measurement program offline before taking the portable device to the part.

What’s more, if a first-piece CMM inspection program already exists for measuring a part, users can import all or part of the program into the portable software package with minimal changes. This eliminates most of the programming. Measurement involves taking the portable device to the part, orienting the part to the device and performing the measurement.

In a guided inspection routine, the user interface, using the CAD model as a reference, shows the operator where to probe the part and then displays the measurement results. Color-coding (green for good and red for bad) on the CAD model view of the part indicates where it is in or out of tolerance.

This instant feedback is useful for manufacturing and quality departments. Portable device users on the shop floor obtain measurement results immediately, without tying up the CMMs in the quality lab.

Beyond Pass/Fail