Package inspection quality

Corrugated paper box quality inspection problem

The quality of corrugated boxes is related to the safety protection of the packaged goods and cannot be damaged during the entire storage, transportation and sales process to realize the value of the goods. Therefore, the corrugated cartons must be sampled before delivery to determine if their quality meets the requirements for use. The following three checks are usually performed.

First, appearance quality:

1. Print quality: clear printing of patterns and handwriting, consistent color, bright and bright; large box of printing position error not exceeding 7mm,
Small box no more than 4mm;
2. Closed quality: There are no loopholes around the box, and no gaps or gaps are left after the lids are closed.
3, size tolerances: box diameter and design size tolerances should be maintained in the large box ± 5mm, small box ± 3mm, the overall dimensions are basically the same;
4, Cover folding times: corrugated box flap cover opened, combined with 180 degrees of reciprocating folding more than 5 times, the first and second type of box surface and inner layer,

The total length of cracks in the three types of boxes is not more than 70mm;

In addition, the joint specification is required, the edges are neat, there is no overlap, and no obvious damage or smearing is allowed on the box surface.

Second, carton compressive strength and influencing factors

The carton compressive strength is the most important quality indicator for many commodity packaging requirements. During the test, the corrugated box is placed between two pressure plates and pressurized to the pressure at which the carton collapses, which is the compressive strength of the carton, which is denoted by KN.

1, predetermined carton pressure 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)
In the formula P---- carton compressive 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 test; For small and medium-sized plants without test equipment, a wooden board can be placed on the 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 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 proportion of the box of the same type, 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.

The above-mentioned dynamic experiments are destructive. To improve the resistance to damage of cartons and commodities is to use cushioning liners, partitions or other protective measures when packaging goods. In addition, some packaging cartons also need to be sprayed, weatherproof and other experiments, according to the contractual agreement between the parties.