American Standard for the determination of the edge pressing strength of corrugated boxes

American Standard for the determination of edge crush strength of corrugated boxes (ECT) the main function of the corrugated box Zui is to protect the inner products during transportation and distribution (whether or not the inner products have the original packaging) From the moment the customer puts the product into the carton, the corrugated box begins to perform the "security work", until the end user takes the product out of the carton and puts it on the shelf in the store, its "mission" is completed In the process of transportation, the United States has very strict requirements for the structure and durability of corrugated boxes The unit stacking mode of cartons and the storage status of warehouses are the key components of modern distribution chain The compressive strength of cartons is one of the standards to measure the performance of cartons Customers' requirements for the compressive strength of cartons include the load-bearing capacity, number of layers, forming method, static loading capacity, warehouse environment, loading time, transportation and other distribution conditions The edge pressure strength of paperboard measured by ECT is of great significance to the compressive strength of the paper box It can be used as a part of the quality measurement tool of the paper box enterprise to ensure the performance of the paper box For nearly a century, researchers have developed a variety of correlations, which can reliably estimate the performance of cartons An article published by McKee et al In 1963 has become a groundbreaking academic paper in this field, which contains the formula for calculating the compressive strength of cartons Later, this method was further modified, such as wolf in 1972, Baka et al In 1993 and challas et al In 1994 However, the "simplified McKee equation" is still considered as the Zui best correlation model between the compressive strength of the carton and the parameters of the carton Although the edgewise compressive strength (measured by ECT) is not a * formula for the compressive strength of cartons, it is a significant factor for Zui in estimating the compressive strength of cartons The edge pressure strength is measured by applying pressure to a sample board until the middle part of the sample collapses Carton strength = 5.87 * ect * √ thickness * circumference ect is closely related to the physical properties of the cardboard material, involving the strength of the face paper and the core paper, as well as their bonding quality Therefore, it is different from other methods which have the same properties of board, that is, bursting strength However, the bursting strength of paperboard is only related to the quality of paper Each corrugated board has puncture resistance and edge pressing strength However, the two characteristics play different roles in carton strength Ect determines the loading performance of the paperboard structure, while the puncture resistance determines the strength required by the puncture paperboard Flattening the cardboard will not have a great impact on the puncture strength, because the strength of the paper is basically the same However, if the corrugated type is damaged, it will greatly affect the ECT value At the same time, the compressive strength of cartons in the stacking process will also be reduced The sensitivity to the quality of cardboard and its components makes ect value a good formula to evaluate the quality of cardboard In order to ensure the performance of cartons, it is necessary to ensure a certain ect value in the production process It is a way to check the processing quality of paperboard by selecting any piece of paperboard from the tile line to measure ect In this way, we can know the quality of this batch of paperboard in the whole order, and compare it with the same kind of paperboard in different batches We can also compare ect value with the general value in the industry, and predict the performance of paperboard through ect This constitutes the operation standard and helps to ensure the effective use of cardboard Up to now, ect value measured on the equipment of tile line is mainly for reference of the subsequent process Assuming that all samples are in the same condition before testing, the ECT value may decrease or remain unchanged during other processing The edge pressing strength is affected by many processing procedures: feed roller, pull out belt, printing, line pressing, die cutting, etc When handling and "touching" corrugated board It is possible to damage the structure of paperboard and reduce the strength of paperboard Quantification of ECT values at different points in the production process can help to identify the key areas of cardboard damage and repair the areas In the following example (see the table below), you can find the average ect value of cardboard in an order in different production stages The change of ECT measurement value is closely related to the characteristics of the material itself and the processing procedure In this example, printing and die-cutting are the steps that cause great loss of Zui to ECT value, which shows that these two processes need to be improved In any case, the overall goal is to make the ECT value of the product as close as possible to the value of the just laying off line before leaving the factory When ect value is combined with carton performance, it is necessary to consider where to measure ect value in carton As the corner part of the carton will bear more pressure than the other parts of the carton, the position close to the corner shall be selected as much as possible during the measurement However, all of TAPPI's ect test methods (t811, T838, t839) indicate that the ECT should be measured away from the crimping line In addition, it can be measured at some weak points of the carton For example, the effect of printing process on the performance of cartons can be understood by measuring at printed and unprinted places In a word, if some cartons are selected and the edge pressing strength is measured in different areas, the consistency of the results can be used as one of the indexes of the quality of cartons Note as with all paper test features, ect values are sensitive to the moisture content of the sample Very few carton factories have a test environment that meets the TAPPI standard, and controlling the moisture content of samples and the test environment will help to reduce the degree of numerical deviation If the value deviates seriously, the ECT value has no practical significance In addition to water content and environmental factors, ect values are affected by many factors, such as sample collection and preparation Careful preparation of the samples for testing, especially the parallelism and arrangement of the stressed surfaces, is the key to obtaining accurate and repeatable application results The corrugated part of the carton is under pressure To know the compressive strength of ECT sample corrugated can accurately understand the characteristics of carton materials Of course, even small data biases can have a huge impact For example, the distance between the sample and the pressure line, as well as the height of the sample will have a great impact on the results These and other factors are described in detail in the research articles on ECT, and the importance of careful sampling and testing in ECT projects is emphasized Article 222 of the motor freight classification of the United States stipulates that TAPPI t811 ECT (including all the preconditions and conditions for testing) can be used as the proof of the relevant performance of the paper manufacturer's certificate (BMC) The number of times of wax immersion and re setting required by t811 test may not be as practical as fixing sample edge with clamp (t839), or cutting sample with cutter or planer (T838), or not reinforcing edge However, different test methods lead to different results All ect test methods can be associated with the compressive strength of the carton, however, it should be noted that different methods are associated in different ways McKee's formula is to use a wax treated edge test method Therefore, using the ECT sample data (t811) processed by wax, the compressive strength value of Zui reliable carton can be obtained Other methods may need to use the modified McKee formula When testing the compressive strength of cartons, it is very important to use correlation on the basis of ECT method Although it is necessary to establish a richer test database to correlate with the actual performance of cartons, no matter what test method you choose, the decrease of ECT value can be used as an indicator of the decrease of the compressive strength of cartons in the production process Ect is widely considered to be an important factor affecting the compressive strength and stacking strength of cartons Although the comprehensive evaluation of ECT is rarely mentioned in this paper, it is not difficult to find that many factors in the production process will reduce the compressive strength of cartons The determination of ECT value can help carton enterprises to establish a benchmark for production capacity, provide quality inspection standards, and clarify the processes that need to be improved Additional information about ECT can be obtained from relevant and TAPPI workshops and publications
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