The inspection process demands exceptional measurement accuracy to remain a dependable and authoritative arbiter of quality. It’s the gate through which a company’s production output must pass and is a guardian of the company’s reputation in the marketplace and a large element of maintaining high customer satisfaction levels. It follows that advances in technology that promote higher standards demand investigation to inform a potential implementation decision. In general, the advent of digital displays has gone a long way towards reducing or even eliminating basic transcription errors and simple human eyesight frailty misreads. But the digital world has much more to offer than merely improved readouts.
Case In Point
Let’s take a look at Mahr’s range of height gauges available and supported here in the UK at Status Metrology. In particular, we can discuss the height measuring and scribing gauge Digimar-814-SR and use its features to explore the argument in favour of digital technology and the benefits it delivers to the inspection process.
Resolution, Precision and Accuracy
Quite often used interchangeably, these attributes do not mean quite the same thing:
- Resolution - level of granularity of an instrument's readings
- Precision - consistently reliable depth of fineness of that instrument's readings
- Accuracy - correctness of results
Digital can never compensate for a poor quality or inaccurate instrument, not for inadequate calibration. However, whilst the internal mechanics of a device may involve a mix of physical, analogue and digital processes, the most obvious and visible application of digital relates to the outputs and how the digital world handles these with exceptional and repeated precision and accuracy. (To help refresh understanding, there is an excellent explanation of these three terms here.)
More Accurate Measurements
Digital keeps track of reference points and performs tedious and repetitive operator measurements with a single keystroke. Importantly, it delivers exceptional accuracy and this Mahr instrument boasts an error limit of 40 µm at a resolution of 0.01 mm. For many production applications, accuracy and repeatability are more important factors than resolution, and digital helps to achieve that.
In extremely high end instruments for those rare applications where pinpoint accuracy is critical, digital can go even further. For example, given that the ambient temperature in the environment impacts very fine measurements, depending on the material of the object being inspected, a digital sensor can automatically measure the temperature and input the relevant data into the machine’s algorithms. We should stress that the Mahr model does not provide this capability as it is not a requirement for its client base. We merely want to illustrate the added flexibility that is possible.
Accurate Transcription & Recording Of Measurements
More commonly, digital not only delivers clarity of readout, with 12mm characters in the case of the Mahr model under discussion, it captures the reading and transmits it to a storage medium, which can be an Excel spreadsheet or any Windows program via keycodes. The transmission mechanisms offered with this model are Opto RS232C, Digimatic, USB cable and wireless. Or good old fashioned pen and paper should the process or scenario warrant. The point being that the instrument’s output will be guaranteed to be accurately recorded into the storage tool of choice across a range of communication medium options.
Faster Throughput & Greater Productivity
Finally, digital promotes a quicker inspection process because it is an enabler for focusing on the correct and smooth operation of the device. The technician is not concerned with observing and recording readings, merely with ensuring that the process runs as it should from start to finish.
Mahr has enjoyed a top drawer reputation for the consistent quality, accuracy, robustness and longevity of its instruments long before digital came of age. That is the truly pivotal component for success. The addition of digital capability has simply increased accuracy overall, both in the instruments themselves and in the inspection process. It builds on the critical elements that already were in place, and enhances them.