QMT Features: July 2016
Portable arm good practice
Insphere explains the basics for using a portable arm to its full potential

Portable measurement arms are a well-established and trusted technology delivering fast and accurate 3D coordinate measurement data in an ever-growing variety of industrial applications. However, some companies have doubts about their capability or are not using their arm to its full potential.

Arms such as Faro, Nikon or Romer arms are highly portable and can be set up in almost any work area and controlled through intuitive software interfaces. They can use contact probes to take measurements, much like a traditional CMM, or they can incorporate a non-contact laser-line scanner to gather detailed information on freeform surfaces. Operators use arms to check components against tolerance requirements, or in some cases to reverse-engineer digital models from a physical sample.

Their flexibility and speed of operation make portable arms a valuable tool, for example they can make it cost-effective to perform in-process checks at key stages of manufacture, rather than depending solely on an ‘all-or-nothing’ inspection of a finished part.

These new opportunities to use data intelligently to improve manufacturing processes can significantly reduce production costs. However, the speed and flexibility of using an arm can mean that good measurement practices are not always followed. Measurement errors can occur, with the potential to disrupt manufacturing processes or allow bad parts to be wrongly accepted – carrying obvious risks of both financial and reputational damage.

Portable arms tend to be used in settings with little or no control of environmental conditions, and by operators who may have their own ways of doing things, potentially affecting results. Processes might not be controlled through adequate work instructions, and results are often recorded in an ad-hoc fashion that can be difficult to review or validate.

Either through staffing changes or through loss of faith in arm datasets, it can be the case that organisations lose confidence in their arms, leading to reduced usage. Portable arms can become wasted assets, resulting in a poor return on their capital investment.

Insphere Ltd offers a one-day course on portable arm good practice that aims to tackle some of these well-known issues.
The course includes:
  • The foundations of good measurement
  • Measurement planning for arms (set up, reach checks, probe selection)
  • Environmental considerations, introducing measurement uncertainty
  • Field checks, operator controls, data collection strategies
  • Work instructions, equipment maintenance and calibration
  • Good practice probing methods and laser line scanning to minimise errors (including practical exercises).
  • Measurement system analysis, how to generate consistent, robust and reliable data
  • A practical gauge repeatability and reproducibility (GR&R) method for the arm
  • Applying sound principles to your own applications in the future.
Whilst the course is primarily classroom based, the inclusion of practical exercises helps to embed learning and ensure that concepts are understood.

Insphere says that the course gives operators far more confidence in using portable arms to generate reliable data. This helps organisations to make greater use of their arms, which of course gives a better return on the investment.
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