Understanding & Diagnosing CMM Error Code Issues

Posted by Tony Tillett on Sep 15, 2017 11:22:55 AM

Understanding & Diagnosing CMM Error Code Issues-1.jpg

Error codes can appear on a CMM display or are reported by the PC interface for many different reasons, such as emergency, communication faults and stop events. These come in the form of error codes on the LCD and there are dozens of them. The lamp on your machine will blink a number of times, depending on the error and then will stop when everything is cleared. Error codes are numeric and depend on the ability to recover without a power restart and the overall severity of an error. Below we will go through the most common groups of errors and how you can use our Status Metrology App to identify and resolve them.

Probing System Errors

You data point gathering can have probe system inaccuracies. These include lobe errors, speed, stylus length, and probe contact pressure. Understanding these errors can be difficult. Most modern electronic probes don't have any index position when installed on your CMM and they can rotate to a new spot, moving the lobe error. Besides, electronic touch probes are switches that can't determine the approached vector. As a result, you can have a hard time identifying probe errors.

While some errors can be cleared by the CMM user, most of them can be influenced by the manufacturer and minimised by our ‘Status Metrology App.’ In order to reduce deflection, the length of the probe should be rigid. Besides, a heavy work piece can accidentally change the geometry of the guideways, so the workpiece shouldn't exceed the specified weight. Specific variation in the temperature of the CMM and the measuring lab can influence errors in your measurements. Similarly, a fingerprint, a smoke particle, a human hair, or a dust particle all add to uncertainty in the measurements.

In addition to everything above, there are errors that appear because of deviation in the guideway of your machine and this can't be influenced by the operator. There are over 20 of these errors and they include rotational errors, translational errors, and perpendicularity errors.

Mechanical Intrinsic Accuracy Errors

The next big group of errors that a CMM can face is intrinsic accuracy; the mechanical accuracy of the machine including squareness, parallelism, and the perpendicularity of the structure. In other words, if the X-axis isn't perpendicular to the Y-axis, a deviation in Y will appear. You can track these errors with the app as well.

Operator Influences

Finally, the CMM operator can provide the greatest errors. For example, if a CMM operator captures data points with different speeds, repeatability errors will appear. With the app, you can see variations in the reported results and eliminate these errors.

Other operator errors appear when you hold the machine. If your CMM is large, it can be difficult to probe while holding the probe bar because you can't hold it as far up as necessary. When you move the probe bar, you place a strain on the structure of your CMM. If your CMM isn't settled, you will get different data points.

One of the key complaints made by CMM operators is that the reports they receive have too much data with vague fault conditions and suggestions. They suffer from a lack of information and professional recommendations to help fix the errors. A report that tells you what to do and what action to take is a great help in many circumstances.

Manufacturers and CMM operators can use our Status Metrology App to identify and fix errors directly on the production floor. The app keeps all your measurement data in one place and helps diagnose calibration errors. It also gives recommendations on what action to take when a fault is detected. Download the app from the iTunes store by clicking here.

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Topics: Tips & Tricks, CMM Software

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