The quality of corrugated boxes is related to the security 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, a corrugated carton should be sampled before delivery to determine whether its quality meets the requirements for use. The following three checks are usually performed.
First, the appearance of quality 1, print quality: pattern, handwriting printing is clear, the same color, bright and bright; large error of printing position not exceed 7mm, small box does not exceed 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 dimensions tolerance should be maintained in the large box ± 5mm, small box ± 3mm, the appearance of the same size.
4. Folding cover folding times: The corrugated cardboard box cover is opened and folded 180 times and reciprocally folded more than 5 times. The sum of the lengths of the cracks in the surface layer and inner layer of the first and second types of boxes and 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, the carton compressive strength and influencing factors Carton compressive strength is the most important quality indicators for many commodity packaging requirements, the test will be placed on the corrugated box between the two pressure plate, pressurized to the pressure of the carton crushed, that is, the carton Compressive strength, expressed in kN.
1. Predetermined carton pressure strength The carton requires a certain degree of compressive strength, because the cartons stacked in the lowest layer during the storage and transportation of the packaged goods are subjected to the pressure of the upper carton. In order not to collapse, it must have suitable resistance. Pressure strength. The compressive strength of the carton is calculated using the following formula:
P=KW(n-1)
In the P-carton compressive strength, N
W-Carton weight after loading, N
N-stacking number K-stacking safety factor The number of stacking layers n can be obtained from the stacking height H and the individual carton height h:
n=H÷h
The safety factor of stacking is determined according to the number of days of stacking of goods. China provides:
Storage period is less than 30d Take K=1.6
Storage period 30d-100d Take K=1.65
Storage period is greater than 100d Take K=2.0
Taking into account the mode of transport and conditions, the predetermined pressure strength should also be properly revised.
2. Calculate the compressive strength of the carton according to the raw materials After the compressive strength of the carton is scheduled, the appropriate carton board and corrugated paper should be selected to produce the corrugated cardboard to avoid the 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. The method of determining the compressive strength of the carton is affected by various factors in the production process. Finally, the compressive strength of the carton produced with the raw materials is not necessarily the same as the estimated result. The method for accurately determining the compressive strength of the corrugated red box is finally determined. The carton was tested with a press after constant and constant wet processing. For small and medium-sized plants without test equipment, a wood plate can be placed on the carton, and an equal amount of heavy objects can be stacked on the template to roughly determine whether the carton compressive strength meets the requirements.
4. Factors influencing 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 is also not allowed to be ignored, such as the amount of adhesives, impregnation of ramming height, coating, and composite processing.
2) The moisture cartons are made of corrugated cardboard with high water content, or stored in a humid environment for a long time, will reduce the compressive strength of the base. 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) The box-type box type refers to the type of box and the size ratio of the same type of box, and they also 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 aperture printing will reduce the compressive strength of the carton. 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) The deviation of the processing technology will cause the pressure resistance of the box to be reduced when the pressure line is improper during the box making process, the groove is too deep, and the combination is not strong.
Third, the carton dynamic performance test For some specific commodity packaging, such as ceramics, glass products, electrical appliances, instruments, etc., but also to check the carton of the buffer properties of goods, the packaging of the goods after the carton from the height of the fall from the prescribed height, inspection The number of cartons that have been packaged within a certain number of times, or the number of dropped cartons that have been damaged.
2. The bevel impact test rotates the carton on the sled, then slides it off the slant of a certain height and finally hits the sling. It is similar to the emergency braking situation during transportation.
3. Vibratory test After placing the cartons on the vibratory table, the goods are packaged and subjected to horizontal and vertical vibrations or two-way vibrations. After a certain period of time, the goods are inspected or the time when the goods cartons are destroyed.
4. Hexagonal drum rotation experiment The carton was placed in a hexagonal rotary drum equipped with an impact plate, rotated according to the specified number of rotations and times, and then the damage of the goods and carton was examined.
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.