Haida: Carton reliability analysis (compressive strength, influencing factors, test methods)

Haida: Carton reliability analysis ( compressive strength, influencing factors, test methods )

Carton compressive strength is the most important quality indicator for many commodity packaging requirements. When testing, the corrugated box is placed between the two pressure plates and pressurized to the pressure at which the carton collapses, which is the compressive strength of the carton.

Expressed by KN .

1 , predetermined carton compressive strength
The carton requires a certain degree of compressive strength, because the carton stacked in the lowest layer during the storage and transportation of the packaged goods is subjected to the pressure of the upper carton. In order not to collapse, it must have a suitable compressive strength, and the carton withstand pressure. Strength is calculated using the following formula:

P=KW(n-1)
Where P---- Carton pressure strength, N
W---- Carton weight after loading, N
n---- stacking number
K---- stacking safety factor

The number of stacking layers n is determined from the stacking height H and the individual carton height h , n=H/h
The stacking safety factor is determined according to the number of layers of the stacking code of goods, and the national standard specifies:
Storage period is less than 30d to take K=1.6
Storage period 30d-100d take K=1.65
Storage period is greater than 100d to take K=2.0

2. Calculate the compressive strength of the carton according to the raw materials

    After the carton compressive strength is predetermined, suitable carton board and corrugated paper should be selected to produce corrugated cartons so as to avoid waste caused by blind production;
There are many formulas to calculate the compressive strength of the carton based on the ring pressure strength of the base paper, but the more concise and practical is the kellicutt formula, which is suitable for estimating the compressive strength of the 0201 carton.

3 , determine the carton compressive strength method
Due to various factors in the production process, the compressive strength of the cartons produced with raw materials is not always exactly the same as the estimated results. Therefore, the ultimate method for accurately determining the compressive strength of corrugated cartons is to use carton compression after constant temperature and wet treatment of the cartons. Test machine testing; for small and medium-sized plants without test equipment, a wooden board can be placed on top of the carton, and an equal amount of heavy objects can be stacked on the wooden board.

To roughly determine whether the carton compressive strength meets the requirements;

4. Factors that affect the compressive strength of the carton
1) Raw material quality
The base paper is the decisive factor in determining the compressive strength of the carton, as can be seen from the kellicutt formula. However, the influence of other conditions in the production process of corrugated cardboard can not be ignored, such as the amount of adhesives, impregnation, coating, and composite processing.

2) Moisture
Carton boxes are made of corrugated paperboard with high water content, or stored for a long time in a humid environment, will reduce its compressive strength. Fiber is a kind of strong water absorption. In the rainy season and high humidity in the air, the moisture balance between the moisture in the paperboard and the atmospheric environment is very important.

3) Box type
The box type refers to the type of box and the ratio of the same kind of box, and they have a significant influence on the compressive strength. Some carton boxes are composed of double-layer corrugated paperboards, and their compressive strength is significantly higher than that of single-layer boxes of the same specifications. Under the same conditions, the higher the box, the worse the stability and the lower the compressive strength.

4) Printing and Opening
Printing will reduce the carton compressive strength. Packing products with air permeability requirements to open holes in the box surface, or punching the handle hole in the box side will reduce the strength of the carton, especially the opening area is large, biased to one side, etc., the impact is more obvious.

5) Processing process deviation
In the process of box making, improper pressure lines, deep grooves, and poor bonding, will reduce the compressive strength of the box. Third, the carton dynamic performance test

    For some specific commodity packaging, such as ceramics, glass products, electrical appliances, instruments, etc., we also need to test the cushioning performance of the cartons on the goods, that is, simulation of transport, loading and unloading, vibration, drop and other tests;

1 , drop test
The cartons after the packaged goods are dropped from the prescribed height in an inconsistent manner, and the quality of the packaged goods in the carton after a certain number of times is checked, or the number of drops when the carton is damaged.

2 , slope impact test
Rotate the carton on the trolley, then slide it off the slope of the height and finally hit it. It is similar to the emergency braking situation during transportation.

3 , vibration test
The cartons are placed on a vibratory table after being packaged, so that they are subjected to vibrations in the horizontal and vertical directions, or they are simultaneously subjected to vibration in both directions. After a certain period of time, the goods are inspected or the time elapsed when the cartons of the goods are destroyed.

4 、 Hexagonal drum rotation test
Place the carton in a hexagonal rotary drum equipped with an impact plate, rotate it according to the specified number of rotations and times, and then check the damage of the goods and carton.