Description
Core Compression Tester
Paper Cores are generally used for winding sheet material such as paper / plastic film / foil / textiles.
Material is usually wound on the paper cores with a little tension or stretch. The paper cores are expected to withstand the stress caused due to the winding tension of the material they carry.
Depending upon the nature of the material and the effect of the environment (change in moisture and/or temperature), the material may contract / shrink over time. This compounds the effect of the original winding tension on the paper core.
These forces are always acting radially inwards on the paper core, trying to push the walls towards the center.
If the paper core is unable to withstand the original winding tension or the increased stress due to material shrinkage, it will collapse inwards. This can make the material unusable in many cases. Or at least prevent mounting the paper core on the mandrel / chuck of the un-winder.
Sometime the winding tension may not be very high and the shrinkage may also be negligible, but during handling (or mis-handling) the roll may accidentally drop on the floor, causing the shape of the core to change from round to oval. Again chances of material damage and issues with the un-winder.
The strength (resistance to collapsing) of the paper cores depends upon:
- Quality and Quantity of paper
- Quality and Quantity of adhesive
- Manufacturing process
- Moisture content
- Physical size and dimensions
It is very difficult for a user (paper core buyer) to know all the above factors and their influence on the strength of the paper core. It is equally difficult for even a core manufacturer to know the effect of each variable quantitatively.
But by using the Core Compression Tester ( also known as Collapsing Strength Tester or CS Tester ), it is very easy for both the paper core manufacturer and paper core user to differentiate between a good or bad core and adopt a suitable standard of monitoring the quality of the same.
Types of Test :
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Flat Crush Test :
This is the original method, wherein the paper core is pressed between 2 flat plates and the maximum force required to deform the core is recorded.
This method is great if the winding tension and / or material shrinkage is low, and the paper cores are only getting damaged by accidental drops to the floor. Or if the paper core is used as a container, where the product is packed inside the core and not wound on the outer surface. Eg. Submersible pumps are packed inside paper cores and hence Flat Crush is a better test for these cores.
-
Radial Crush Test :
This method was invented by our founder in 1987.
It uses special test fixtures (called as adopters) to hold the paper core between 2 curved adopters while being pressed.
The profile of the adopter is such that it matches the contour of the paper core, supporting 33% of the core’s outer surface from the bottom and 33% from the top. This allows only the remaining 16.5% on either side to bulge and collapse.
This method is seen to better predict the quality of the paper cores.
Studies / Trials conducted by us showed that 2 paper cores having very similar Flat Crush Test values can still give significantly different Radial Crush Test values, and the cores which had a better Radial Crush Test value, did perform better in the real world.
Comparison of Flat Crush Test vs Radial Crush Test
| Description | Flat Crush Test | Radial Crush Test |
| Adopters | Since this test uses only 2 flat plates, only 1 adopter set is needed for all core sizes | Since this test needs adopters profiled as per the outer surface of the paper core, it needs dedicated adopter sets for every different Core ID and Thickness combination. |
| Cost | Flat Crush Test adopters are not expensive.
Since this test uses a single adopter for all sizes, the total cost (of equipment + adopter) is low. |
Radial Crush Test adopters are customized and hence 3 – 5 times costlier than Flat.
And since this test uses multiple adopters (for multiple sizes), the total cost can be much higher depending upon the variety of paper cores you need to test. |
| Suggested for | Paper Cores used as containers or those subjected to low winding tension and low material shrinkage.
Where the damages in field are usually in the form of the paper core changing shape from round to oval. |
Paper Cores used as winding medium or those subjected to high winding tension and / or high material shrinkage.
Where the damages in field are usually in the form of the paper core collapsing inwards (towards its center). |
| Sample Length | 100 mm | 100 mm |
| Results | Lower than Radial Crush Test. | 2-6 times higher than Flat Crush Test. |
Technical Specifications of Core Compression Tester :
- Digital Model with Backlit LCD Display
- Electro-Pneumatic Model (Runs on Compressed Air)
- Auto-stop & Auto-return upon completion of Test.
- Testing Principle : Constant Rate of Loading (Slow and gradual increase of force till collapse)
- Direct force measurement. No Calculations Required.
- Peak hold facility for registration of maximum compression force.
- Auto-Calibration facility for quick, user-friendly calibration.
- Choice of Measurement units : Kgf / Lbf / N (User settable from Menu)
- Maintenance free design.
- Optional facility to capture test data on to the PC directly through the software and generate PDF test & calibration reports.
Models Available :
| Model | P1000 | P1000-XL |
| Capacity | 1000 Kgf (~ 9800N) | |
| Resolution | 1 Kgf (10 N) | |
| Working Range | 5 – 95% of capacity | |
| Suitable for Core Sizes |
3 – 6 inch ID cores (max OD <200 mm) |
3 – 12 inch ID cores (max OD <350 mm) |
| Photo |  |
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Warranty : 12 Months (Ex-Factory)
Included with all models / SKUs : Air Filter + Pressure Regulator.
Not Included (to be ordered extra) :
- Flat Crush Test Adopter. 1 adopter works for all core sizes.
- Radial Crush Test Adopter. To be ordered for every specific OD that needs to be tested.
Utilities Required :
- Power : 230/110 Volts A.C., 50/60 Hz. Clean power.
- Compressed Air @ 6 Bar (87 psi)
- Calibration weights (Total of 100 Kgs, in any combination).
For models with software
- Desktop / Laptop PC (Intel Core i3, 4gb RAM, Win10 OS, 1080p Monitor) or higher.
