FEATURE u Sensors & Sensing Systems
The fundamentals of thickness measurement
When selecting sensors for measuring thickness, the first step is to choose an appropriate method and measurement technology. The material, surface and thickness of the target play a crucial role in deciding which option is best for the application, says Glenn Wedgbrow, Business Development Manager at Micro-Epsilon UK.
T
here are many reasons that thickness is important. Changes in thickness during production can indicate wear of
components, for example, in extrusion dies or on rolling stands. Monitoring trends can point to early warning signs.
The traditional method of checking thickness
in a production process is often to take a measurement sample from the start of the production run and then again at the end. But what happened in the middle?
Of course if you find it’s out of tolerance,
that’s a lot of scrap to consider. So you might choose to take more readings during the process. If that check is being done manually then that often requires the production line to stop. Anyone will tell you that most process variability will come in start-and-stop phases so keeping a line running is generally key to getting things consistent. Ultimately, checking the product thickness as it is produced ensures that the end customer
Measurement methods
receives the quality of product expected. Thickness measurement is an important step
in production monitoring, quality assurance and machine control. Although thickness measurements can be carried out using contact or non-contact sensors, non-contact measuring methods offer clear advantages in terms of accuracy and measuring speed. This article describes the use of non-contact measurement techniques.
One-sided measurement One-sided thickness measurements are carried out exclusively using non-contact sensors. In this case, only one sensor is used to measure the complete target thickness or part of the target thickness (e.g. glass thickness).
Two-sided measurement Two-sided thickness measurements are performed with at least one sensor pair mounted in one axis to each other. This sensor pair measures synchronously onto the target. The difference between the individual measurement results gives the target thickness.
Profile Thickness measurement 2D/3D laser profile measurement is used for a wide variety of applications, e.g. the completeness of weld seams, the optimum dosage of adhesives, or the correct gap dimensions. For the inspection of adhesive beads and applied sealants, laser profile scanners check the presence and size of adhesive beads.
ThruBeam measurement With the ThruBeam principle, the transmitter of a laser micrometer produces a parallel light curtain that is transmitted via a lens arrangement into the receiving unit. The beam is interrupted if there is an object in the light path. The shadowing generated by this object is recorded by the receiving optical system and output as a geometric value. Parameters such as diameter, gap, height and position can be measured.
22 October 2022 Irish Manufacturing
Technology combination Combining technologies, for example Eddy current and capacitive or Eddy current and ThruBeam allow for single sided measurements to be made. The complementing technologies detect one or other of the material or base surface and when the values are combined produce the required thickness.
www.irish-manufacturing.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42
