A new device to measure washboarding is born!


About a year ago I was invited at Proflex to act as a speaker at the DFTA in Stuttgart.

I presented the mainly German Flexo audience with some philosophy about corrugating and advice on making good corrugated board for flexo postprint.

Proflex also hosts small booths to give people who are active in flexo the opportunity to show their novelties.

I passed by a combined booth of FAG and Peret, and my left eye fell on a USB device that could correctly measure braille and also creases in FBB (carton blanks produced on folding boxboard). So we started to talk, since I have been searching already for a long while for a device that can accurately measure washboarding. When I want to do corrugator settings optimization I have to depend on subjective assessments about the amount of washboarding. In the past I tested equipment that is used in the quality control of the production of metal parts, but it did not give me a perfect repeatability and the setup just didn’t fit my suitcase.

Objectivity versus subjectivity… What is perfect board? For one person the board is bad, for the other… I wanted to find a device that could give an objective, correct and repeatable measurement of mechanical washboarding.

The existing braille device has an accuracy of 3 microns and makes a topographic image of a surface. I asked Lukas and Philippe, “can you measure washboarding with it?”. As both are no corrugating experts, I went to look for a sheet of corrugated board to explain them what I had in mind.

Lukas was very interested and immediately started to develop ideas in his mind… I talked to my friend Daniel at Bobst and also he was immediately interested I such a device. One year later the CORRCHECK prototype was ready and I could show it to people in the industry.

The CORRCHECK measures washboarding by giving a value which is based on the average distance between the highest point and the lowest point on the surface. This value is based on the average of 5 measurements. A lower value relates to a lower washboarding amount.

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I was impressed by the repeatability of the measurements. The final version will even have a better accuracy than the prototype.

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As the device accuracy is 3 microns, it also measures the roughness of the paper surface. Hence, measuring a sheet of corrugated board with a cheap and rough recycled liner results in a value that would indicate heavy washboarding. My French colleague Hervé pointed out to me that it would usefull to calibrate the device on the medium itself.

Doing more tests with the CORRCHECK prototype, we figured out that the functionality available in one of the other devices was perfect for checking the flute profiles of single faced material.

This made us think further… The device would be ideal to monitor the mechanical wear of corrugator rollers over duration of time. By measuring the single faced material (coming out of the single facer) at the same positions on the web, on regular basis, and storing the dated measurements for later comparison, one can easily monitor the state of the mechanical wear of the corrugator rollers.

Many potential users are enthusiastic about this function.

O, G, N, F and E flute can be measured accurately with this small portable CORRCHECK device.

Last week I talked to a corrugating manager and one of his problems is that scores performed on the corrugator are good until a customer complains because the folding fails on the erecting/filling line. It is very painful and extremely costly to figure this out at the moment the customer has refused and returned your full lorry.

Measure the crease after you’ve replaced the scores, store the values somewhere and after feedback of the customer that the boxes worked perfectly, you can keep these measurements as a guideline. On regular intervals you retake an image when you are running the same box. Based on the saved values you can make for yourself a tolerance of when you need to replace the score line so you never get costly lorries returning back to your company anymore.

As an example you can find below a graph of the measurements of all the combinations of boards of our recently printed swatch book. The measurements reflect nicely the amount of wash boarding that is visible. The results are very logical and are confirming our thoughts: E flute is better than B flute, the higher the grammage the lower the wash boarding, the surface roughness (Brite uncoated versus Lite + coated ) has an influence, etc.

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So about the CORRCHECK…
We expect to finalize the final version by the end of this calendar year. The device is small, USB connected, comes with a practical user interface for Windows, measures accurately and most importantly it fits my suitcase J. More information can be found here http://www.fag.ch/products/pdf/FAG_CORRCHECK_METSA.pdf

Just for the record… Lukas is the guy developing the device, Philippe from FAG is selling it and I’m there for testing in the field.

Did we now solve wash boarding? Not at all! The mechanical wash boarding value is only one small part of the jigsaw puzzle.

Keep up the good board!

I once was at a plant and I observed the older corrugating manager put his hand in a stack of fresh board. He thinks for a second and then decides that the board is too wet and takes actions based on these tactile sensations. I asked him if he is Spiderman. He smiles says ‘Why?’. I say, if you can feel the absolute humidity of board by just putting your hand in a stack then you need to have special sensors in your hand which feed via your nerve system in to your brain.

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