Short-Span Compression Testing
Why are manufacturers switching to short span compression testing?
Short span compression testing, also known as SCT testing, is one of the newest techniques available to corrugated testing labs. It is currently gaining favor among testers and taking over from some of the more traditional corrugated crush tests and techniques. Dive in to find out more about why manufacturers are making the switch.
What is SCT?
Short span compression testing is often used as a replacement for ECT testing and is a way to predict the compressive strength of corrugated paper.
In SCT, a single piece of liner board or similar medium is inserted into pneumatic clamps that are precisely aligned to produce a sample free length of only 0.70mm. The sample is then axially compressed until it reaches the point of failure, allowing the tester to measure how long the process takes.
Also growing in popularity is S-testing, a new technique developed in 2018. This method closely correlates with Corrugating Medium Test results but is much more time efficient and accurate. Like in SCT, the S-test uses a clamping system that introduces an offset to the free length of the paper sample. This creates an axial compression that reveals an s-shaped crush of failure zone.
Why SCT testing is rising in popularity
This type of testing is rising in uptake among corrugated manufacturers due to a few different factors, including the small instrument footprint and faster testing times. It is a less complex testing procedure than the traditional alternatives and takes less time to prepare – perfect for fast-paced manufacturing businesses.
You can find out more about the various traditional and new testing methods currently gaining popularity in our exclusive report, ‘Your guide to quality corrugated’.
The benefits of SCT
There are lots of ways that SCT outstrips alternative techniques, including the:
- Short amount of preparation time needed for each sample being tested, thanks to its efficient design
- Accuracy of the measurement, ensured by precisely calibrated clamps
- By using a very small sample, SCT offers greater buckling stability and more insight into the load-bearing fiber portion of the paper or board in comparison with traditional test methods, like the ring crush test or linear crush test.
Knowing the value of the SCT makes it possible to back calculate the ring crush test (RCT) values. An approximation of the equation is RCT CD= 120 x SCT CD – 97 but this is specific for each paper machine and should be checked against the manufacturers’ specifications.
SCT and industry standards
When performed correctly, SCT determines the compressive strength of a material to industry standards. The compression strength of paper and board can be tested to meet ISO 9895, DIN 54518 or TAPPI T 826. Short span compression testing has been recognized as a viable alternative to traditional procedures.
Short span compression testing solutions at Industrial Physics
At Industrial Physics, we’re always looking for the next big innovation in testing and have several SCT machines on offer as part of our corrugated testing products.
17-36 Short Span Compression Tester
The 17-36 Short Span Compression Tester measures the compression strength of paper and board. The span (also known as the gap) is set to a distance of between 0.3-0.7mm.
To perform an accurate compression test on such a short distance, it is essential that the clamps and instrument are extremely stable. The 17-36 model incorporates a precision mechanical design to reduce the occurrence of frictional errors.
Enjoy unmatched accuracy and repeatability from a machine that offers automatic clamping for samples and a modern and compact design. It also features a touch screen an intuitive user interface, for easy operations. Check out the 17-36 Short Span Compression Tester.
The 17-38 S-tester model is designed to measure the compressive strength of the flute/medium. A 15mm wide specimen of un-corrugated medium is placed between two clamps, with a span of 4mm between them an offset of 1mm. The offset of 1mm compresses the flute to form an s-shape during the test and the resulting value is the maximum compressive force it can withstand.
With a touch screen, automatic clamping and a compact and modern design, this is an efficient option that offers less time-consuming sample preparation. Find out more about the 17-38 S-Tester by Messmer Büchel.
80-30 automatic sample preparation station
A useful addition to a corrugated testing setup is the 80-30 automatic sample preparation station. This prep station can accurately cut and press five separate specimens simultaneously, saving time and energy. It has a safety enclosure over the cutting blades and eliminates the need for cutting by hand. For the most reliable testing and results, you need quality specimens – and the 80-30 station makes providing them easy.
Help with short span compression testing from Industrial Physics
Whether you’re looking to update your current corrugated testing setup with SCT solutions or you’re planning to integrate S-testing into your line up, Industrial Physics can help. We’ve got almost 100 years of experience working directly with paperboard and corrugated manufacturers across the globe and look forward to sharing our expertise.
If you’d like to know more about SCT and S-testing is helping manufacturers get accurate results with shorter preparation times and how you could enjoy the same, please get in touch to speak to our corrugated specialists.