Wave size influence on the mechanical characteristics of the corrugated board.

Jurecic, Denis ; Babic, Darko ; Haric, Anita 等

Abstract: Corrugated board samples will be analysed on different devices intended for quality testing and inspection of corrugated board. The goal is to investigate what kind of influence has different wave size on quality of corrugated board. Four types of examination will be carried out:--resistance to breakthrough,--pressure on horizontal surface,--pressure on the corrugated carton edge,--resistance to bursting. The results will then be analyzed.

Key words: Corrugated board, Strength, Delivery side

1. INTRODUCTION

Except mechanical stability, the chemical, biological and thermal stability are also important. If the corrugated board is well studied and processed, it can achieve good packing with the minimal costs. Generally, it is known which properties a particular wave kind must have, but the investigations are always important in order to control the product quality and to determine the possible irregularities which appear in the production. The investigations detect bad gluing of the paper layers in the corrugated board and bad formed or crushed waves. Two kinds of investigations were performed in the work. Resistivity of the corrugated board to dynamic penetration (Puncture Test) is one of the most important tests because it shows how strong direct mechanical blows can the corrugated board accept and not burst (Jurecic& Babic 2007). Breaking of the corrugated board under pressure (Bursting Test) shows how high pressures can the corrugated board bear before bursting.

2. EKSPERIMENTAL

2.1 Resistance of the corrugated board to dynamic penetration--Puncture Test

This is the test in which the corrugated board is tested to direct mechanical blows. It determines the resistance of the corrugated board to tearing and its toughness. The test shows how strong direct mechanical blows can be applied on the corrugated board and that it does not break. It is important if the products sensitive to outer blows are packed in the packaging. The testing was performed on three different samples of the corrugated board, 2K, 2K/3 and 2K/e. For each sample 10 measuring were done for the front side and 10 measuring for the back side of the corrugated board. At the end, the comparison was made from the medium measuring results to see what the quality of a particular sample was. The testing device is called punctometer.

2.2. Breaking of corrugated board under pressure -Bursting Test

Breaking of the corrugated board under pressure is tested on Mullen device. It is important that the corrugated board is previously conditioned. How high pressures can the corrugated board bear before breaking depends on its quality. The greater the bursting pressure is the quality of the board is better.

2.3. Resistance of the horizontal layer of the corrugated board to pressure -Flat Crash Test

In this test the grade of crushing and rigidity of the waves in the corrugated board under pressure is determined. The test is performed to increase the paper quality for the production of waves or for the quality control itself. Testing is performed on the device Crush tester which was designed for testing the deformities of the corrugated board and its components.

2.4. Resistance of the corrugated board edges to pressure--Edge Crush Test

In this test the resistance of the corrugated board in the direction of its waves is determined, i.e. the edge of the corrugated board on the wave peaks. The test is performed on the Crush Tester, the same as the resistance test of the horizontal surface of the board; only, the device is set at another measuring mode.

3. RESULTS AND DISCUSSION

3.1. Puncture test

The front side of the corrugated board sample 2K, after the 10 performed measurements on the front side and after the obtained medium value, shows somewhat lower result than the result of the testing of the back side of the corrugated board. This shows that the back side of the sample 2K has greater resistance to dynamic penetration than the front side of the board. The results obtained on the sample 2K/3 show that the back side of that board is has also greater resistance to penetration than the front side, with somewhat greater measuring differences between the front and the back side of the board than the difference obtained by measuring the sample 2K. The sample 2K/2 shows the smallest difference between the front and the back side of the board, but the back side has greater resistance to dynamic puncture as well. It can be seen from these measurements that the back side of the board has greater resistance than the front side in all three samples (graph 1,2).

3.2. Bursting Test

After 10 measurements on the front side of the board and the obtained medium value, and after 10 measurements on the back side of the board and the obtained medium value, it can be seen on the sample 2K that the front side of the board has greater resistance to bursting under pressure than the back side of that board. The back side showed somewhat lower result. On the sample 2K/3, after all the measurements and the calculated medium value, it can be seen that the front side of the board has better resistance to bursting than the back side. The sample 2K/e shows the same property, which means that the front side of the board has greater resistance to bursting under pressure. In this case the difference among the resistance of the front side and the resistance of the back side is very small. The investigation shows that the front side of the board had better results in all three samples, which means that it had greater resistance to bursting under pressure than the back side of the board (graph 3,4). When comparing the three medium values for the front side for all three kinds of the investigated corrugated board it can be seen that the greatest pressure to cause bursting was necessary for the sample with the greatest wave, the sample 2K. This was the best achieved result, which means that the sample 2K has the greatest resistance to bursting under pressure and such corrugated boards can be used for heavier and stronger packaging.

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3.3. Flat Crash Test

After the performed measurements of the horizontal surface of the corrugated board resistance to pressure, the following results were obtained. The sample with the greatest wave 2K, after 10 measurements and the obtained medium value for the front side of the board, shows lower result than the back side of the board after as many measurements and the obtained medium value. This shows that greater pressure was necessary for the back side of the board, in order to crush the waves, which means that the back side of the board has greater resistance. The sample 2K/3 shows that the back side has also higher resistance under pressure to the horizontal surface than the front side of the board which can be seen in the obtained measuring results. The difference between the front and the back side of the board is somewhat greater than in the sample 2K. The board sample with the smallest 2K/e wave shows other results. The medium value obtained after 10 measurements shows that the front side of that board has greater resistance under pressure to horizontal surface. The back side of the board has somewhat minor result. From these results it can be seen that only on the sample 2K/e, the sample with the smallest wave, the front side of the board has greater resistance under pressure to the horizontal surface. In other two samples the back side of the board has greater resistance.

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When comparing the medium values for the front sides of all the three tested samples (graph 5, 6) we can see that the greatest pressure on the horizontal surface of the corrugated board can be applied to the sample 2K/e. This sample has the smallest waves and it needed the greatest possible pressure to perform the crushing and the deformation of the waves. This property is essential for corrugated board packaging during the storage.

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3.4. Edge Crush Test

After the 10 performed measurements for each sample of the corrugated board and the calculated medium values, the test results are the following ones (graph 7); the corrugated board with the smallest waves, 2K/e achieved the best results in this investigation. This means that this kind of waves needed the greatest pressure to undergo to crushing and bending. The greater pressure achieved means the better quality of the material. The sample 2K/3 which has somewhat smaller waves had more inferior result. Lower pressure was necessary to cause crushing in the corrugated board. Even smaller pressure was necessary to cause the crushing and bending in the sample 2K. This kind of the corrugated board has the greatest waves and shows the weakest resistance to the bending on its edge. The performed investigation on these three samples showed that the smaller the waves are, the greater number of them exists in one meter and the more resistance they have when the pressure is applied on their edges on the peaks of the waves.

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4. CONCLUSION

The investigations showed that the waves in the corrugated board have different resistance to pressure. The greatest wave (sample 2K) which has the smallest waves in the length of one meter shows the best results at dynamic investigations and Mullen. This shows how the greatest waves soften the dynamic loadings which act on the board surface the best among all. It can be seen that the greatest wave has the greatest strength to pressure. Because of such properties it is the best thing to use such waves for cushioning and packing of products which are sensitive to blows during the transport. The smallest wave (sample 2K/e) which has the greater number of waves in the length of one meter has opposite results from the sample with the greatest wave (sample 2K). There where the sample 2K achieved the best results, the sample 2K/eachieved the worst ones. So the corrugated board with the smallest wave has the best resistance to loading the horizontal substrate and the board edge and it is the weakest one to the direct mechanical blows and the surface pressure. Because of such properties this board is the most suitable for packing the heavy objects which can make the waves even by their weight and which are not sensitive to blows.

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