Metrology Equipment Trend Moving Process Control to Process Knowledge

Manufacturing metrology is migrating from playing a quality control role to becoming an integral part in manufacturing processes.

The current trends occurring in manufacturing metrology are:

  • Tactile measurements migrating to optical measurement
  • Manual measuring systems being replaced by automated solutions
  • Measuring systems being relocated from Quality Room to Production Floor

Tactile to Optical Sensors

Optical measurement offers full-field measurement rather than discrete features and clearer visual representation of measured results providing easier to interpret actionable data thereby allowing rapid problem solving.

Manual to Automated Metrology

Automated metrology solutions allow higher sampling rates to be incorporated, in many cases 100% of parts can be measured, providing high quality data without operator influence resulting in higher level of confidence over manufacturing processes quality.

Quality Room to Production Floor

This trend started more than 20 years with the tactile coordinate measuring machines (CMM), designed for quality control labs, being relocated adjacent to production processes by encapsulating the CMM in a protective enclosure. Today, the next generation of automated metrology system are specifically designed for shop-floor usage, many involving well proven industrial robots, and the incorporation of optical sensors allow significantly increased metrology to be performed with much reduced inspection times.

Statistical Process Control vs. Quality Measurement

The traditional optimization of manufacturing processes based upon statistics assumes that “Quality of the finished product depends on production scattering”. Classical SPC works with a limited number of control features with defined sources of deviation:

  • Short-term stability of the process (“noise”)
  • Long-term trending (e.g. “temperature change”)
  • Specific events (e.g. “material supplier switch”)
  • Control charts showing variance, tolerance limits, process capability indices etc.
  • Output: Warnings based on chosen control features

SPC offers very limited ability to perform root cause analysis of collected data.

Analysis of part quality using complete surface data obtained from automated optical inspection systems, either integrated into the production process or close-by provides real-time visualization of deviations using color plots providing an intuitive understanding of the entire part metrology and detection of local effects.

Further detailed evaluations can be performed as necessary on individual points, features, part sections, G D & T etc.

Quality Measurement provides reliable part qualification with rapid root cause analysis.

Process Optimization

The goal today in manufacturing being to optimize manufacturing processes to assure product quality.

Process Control

+ Quality measurement

+ Root cause analysis

+ Problem fixing

= Process Optimization

Process Optimization always requires Quality Measurements

Point measurements can perform process control only as it supplies an incomplete metrology description of the part even if 100% of parts are measured. To perform Process Optimization a change of philosophy is needed making quality measurements available as fast as possible to improve process knowledge and accelerate process optimization.

The next step in the evolving role of metrology in manufacturing is Digital Assembly whereby Quality Prediction of the full assembly process can be digitally visualized before physical assembly occurs.

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