How to correctly evaluate whether the carton meets

2022-08-06
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How to correctly evaluate whether the carton meets the standard

with the development and progress of industry, corrugated boxes as packaging materials have been widely used. Due to the low threshold of corrugated box industry, the competition is extremely fierce. Carton users exposed more or less quality problems in the process of using cartons, such as collapse and rupture of cartons after stacking, resulting in many negative effects

therefore, more and more carton users have realized the dual significance of packaging to product protection and product image promotion. Carton users have become more professional and rational in determining product quality standards, such as adding testing instruments to evaluate the key indicators of cartons... Bursting and pressure resistance (or stacking), comprehensively studying whether the packaging is excessive (excess material design), and realizing the optimization contribution of the design of packaging materials in the manufacturing cost of the whole product

however, in the process of product inspection, when carton users evaluate whether the product is qualified, they often have cognitive deviation and misjudge the product test results. The following is a specific analysis and Discussion on how to correctly understand and evaluate the pressure resistance and stacking test of corrugated boxes, and share personal practical experience with carton enterprises and users

whether the carton pressure resistance and stacking tests meet the requirements must be specified in two standards: inspection status standard and physical index standard

analysis of inspection status

the packaging industry usually adopts the following two inspection status of packaging materials:

the temperature and humidity of carton samples are (23 ± 2) ℃, (50 ± 5)% pretreatment for 24h

standard source: sn/t inspection procedures for corrugated boxes for transport packaging of export commodities

the standard atmosphere for testing pulp, paper and paperboard shall be the relative humidity (50 ± 2)% and temperature (23 ± 1) ℃. Generally, the paper shall be pretreated for 4h, the thin paper shall be at least 5 ~ 8 h, and the high volume or other paper shall be at least 48 h or longer

standard source: gb/t standard atmosphere for sample handling and testing of pulp, paper and paperboard

the purpose of setting carton test pretreatment is to make the fiber tissue structure of each sample in a balanced and stable state. This kind of soft touch will not affect the determination of carton mechanical properties due to large differences in test results. The first pretreatment method shall be used for corrugated boxes

discussion on safe pressure resistance and stacking test

concept statement

pressure resistance is the maximum compressive yield value achieved by continuously and uniformly applying pressure to cartons

stacking (standard name - static load stacking) is to apply a constant mass on the carton package within a certain period of time (usually 24h), and whether the deformation and damage of the carton meet the requirements

we can intuitively understand their differences through the time chart of test force value:

calculation of formula

many materials around can be developed and utilized ① safe anti pressure

p... Anti pressure value n

k...... deterioration coefficient (safety compression coefficient)

g...... gross weight of single package kg

h...... stacking height M

h...... carton height m.

storage period is less than 30 days 30 ~ 100 days more than 100 days remarks

deterioration coefficient 1.6 1.65 2 export cartons usually adopt European and American safety compression coefficient 3

note: deterioration coefficient (strength 1, equipment characteristics of well cover pressure testing machine: degree coefficient) k is determined according to the loaded goods and storage conditions

② stacking mass

m0=k* (h/h-1) * m1

m0... Total stacking mass applied to cartons kg

k...... deterioration coefficient (the same as safety compression coefficient)

m1...... gross weight of single package kg

h...... stack height

h...... carton height m.

discussion on relevant issues:

the determination of deterioration coefficient implies that under various storage and transportation conditions, the pressure bearing capacity of cartons can not meet the pressure resistance requirements under standard test conditions (such as high humidity conditions). However, since this coefficient is a safe compression coefficient, its "safety" is to meet the reduction of carton strength under different atmospheric conditions; The strength of handling and storage is weakened; The strength of load stack decreases with time; When the intensity of transportation vibration and impact is weakened and the atmospheric humidity and logistics conditions are changed above, the box will not collapse or swell and deform, and the protective effect on the packaged goods will not be lost

therefore, as long as the carton is designed and manufactured to be qualified (meeting the safety pressure resistance requirements), the pressure resistance tested under non-standard conditions is less than the safety pressure resistance standard, but it is still "safe". We recognize this, We can further understand the test differences of cartons in different states through the following example data:

comparison project

carton model paper matching outer diameter size

mmunderdifferent test states

pressure resistance test value ({ f) pressure resistance required value ({ f)

temperature 18 ℃

humidity 79% temperature (23 ± 2) ℃

humidity (50 ± 5) %

m102 a = a 316*260*235 289342320

m103 a = a 302*244*235 296335305

m106 a = a 502*276*273 321401 296

note: the above test values are average values

we can clearly see from the above table that although the test results under non-standard conditions with high humidity do not meet the requirements of safety and pressure resistance, it cannot be judged that the carton packaging products do not meet the standards. On the contrary, in the case of low humidity, although the test results meet the requirements, they are not qualified in design and manufacturing

how to correctly and effectively evaluate whether the carton anti pressure or stacking test results meet the standards

because the results of anti pressure or stacking test are equivalent, anti pressure analysis can help us better understand

due to the limitations and requirements of test conditions and work efficiency, most manufacturers usually test the pressure resistance of cartons under normal temperature and humidity, and directly evaluate whether the products meet the requirements. In fact, there is a great risk of misjudgment in this way of assessment, which often misleads the assessment of carton suppliers or leads to losses caused by carton packaging collapse

in the case of high humidity in the south, if the pressure resistance strength of the non-standard state test can reach the safe pressure resistance standard, it means that the carton fully meets the requirements, and the design of the carton meets the requirements; If the tested carton strength fails to meet the safety pressure resistance standard, there are still two possibilities:

the carton design and manufacture meet the requirements

the design and manufacture of cartons do not meet the requirements

it should be noted that when the humidity condition in the north is small, the test results of non-standard state are often higher than the safety compression requirements, but it does not mean that the standard is met. Because in the long-distance logistics conditions, especially the sea transportation conditions, the humidity is large, the test results of non-standard state should take this factor into account in the design, otherwise the risk will be difficult to avoid

therefore, it is very important to correctly evaluate the product test results

process and basic methods:

determine the quality index standards for carton safety, pressure resistance and stacking

the above two indexes can be obtained by formula, and the determination of indexes varies depending on the domestic and export sales and storage period. Under special circumstances, if the carton is supported by the contents, the appropriate anti pressure index value can be determined according to the actual situation, and the weight quality index must be determined by the formula

test pretreatment status:

pretreat the carton under the standard test status for 24 h (general carton users can unconditionally go to an authoritative and impartial testing agency for testing) and then retest to make the moisture of the carton reach a dynamic equilibrium state

precautions for sample extraction:

in the trial production stage of new products, the strength of the sample after printing and die-cutting procedures differs from that of non printing and die-cutting by about%, so the status of the sample and batch products should be basically consistent

the sampling of batch products shall comply with the principle of statistical probability. After years of practical experience, six samples shall be selected from three different packages to reduce the risk of misjudgment

result judgment:

if one of the carton force values detected under the standard state is lower than the anti pressure index, the batch of cartons can be judged as unqualified

discussion on improving the efficiency of stacking test: stacking test often takes a long time, and the economic and effective evaluation method is still in the exploratory stage. The following is the experience that our company has discussed and practiced with customers

basic principle:

the safe anti pressure value of the same type of container is equal to the stacking quality value. The minimum anti pressure value of the sample is not less than the safe anti pressure value. Whether the stacking test is qualified can be determined by detecting the average of the anti pressure peaks of 6 containers. We can intuitively understand their relationship through the following figure

process and method:

we first understand the peak pressure resistance deviation of cartons through empirical test data. Under standard atmospheric conditions:

under the conditions of handling, transportation and storage, the maximum and minimum min deviation of the peak pressure resistance of the same double corrugated carton is about 28%, and the deviation of single corrugated carton is about 33%. (individual severely damaged boxes shall be removed)

determine the average value of the standard safety resistance pressure

then the average value of the standard safety resistance pressure of the double corrugated box should generally be 1.15% of the safety resistance pressure (15% higher than the safety resistance value), and the average value of the standard safety resistance pressure of the single corrugated box should be 1.18% of the safety resistance pressure

test the peak pressure resistance of 6 sample cartons under the standard state, and calculate the arithmetic mean of the peak pressure resistance of the sample cartons. However, since the average value of the test configuration is greater than the average value of the standard safety pressure resistance, the batch of cartons is qualified, otherwise it is unqualified

the above methods have strong operability and are of great benefit to improve work efficiency and evaluate stacking test results more effectively. You may wish to try

reprinted from: corrugated box

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