The three sizes of the carton and their relationship
There are three sizes of corrugated cartons: outer size, manufacturing size and inner size. These three forms are made up of the length, width and height of the carton. Therefore, the specific expression can be divided into foreign width and height, internal length and height, and manufacturing length and height. The outer size is the size of the volume taken from the outside of the corrugated box, which is generally used as the basis for calculating the freight and marking the outside of the carton.
custom boxes in China indicates that the inner size is the distance from surface to surface taken from the inside after the corrugated box is supported and formed. The inner size is determined according to the volume of the contents. Generally, the inner size is slightly larger than the volume of the contents. Manufacturing size is the production process size converted according to the size inside the carton. Generally, order and adjust the line in accordance with the manufacturing size for production operations.
The relationship between external size, internal size and manufacturing size: (Take 0201 carton as an example)
Outer dimension length (width) = inner dimension length (width) + Thickness of corrugated board * Number of layers of corrugated board (2 layers)
Height of external dimension = height of internal dimension + thickness of corrugated board * Number of layers of corrugated board (a total of 4 layers including internal and external shaking caps)
Manufacturing dimension length (width) = internal dimension length (width) + thickness of corrugated board ÷2* the number of layers of corrugated board
High manufacturing size = high internal size + thickness of corrugated board ÷2* the number of layers of corrugated board
There is also a comprehensive size in the national standard, the comprehensive size of the carton is the sum of the length, width and height of the carton. In the above three sizes, the manufacturing size is relatively flexible, according to the thickness of different corrugated cardboard, different molding equipment and different molding process and change at any time, so master the manufacturing size is the first step to control the size of the carton. The same is true of special-shaped cartons, no matter how many layers of corrugated cardboard, the internal size should be added to the total thickness of these corrugated cardboard, is the outer size of the carton.
Precautions for carton size design
Design the size of corrugated box first to carry out the design of the inside size.
Because the inner size is easier to determine, it is the physical measurement of the goods inside or the physical combination of the calculation of the outer size to determine. The discharge of the contents should be as space-saving as possible, and the supporting force factor should be considered reasonably.
From the point of view of mechanics, if the contents share a part of the supporting force, the requirements of the carton compressive index can be appropriately reduced. Therefore, it means the decrease of cost and the gain of profit. If the contents are boxes, consider the direction of the box thread, because the longitudinal thread is better than the transverse thread support.
In the forming process of corrugated box, the corrugated board should be pressed, so that the corrugated board is well bent, and the structure of the corrugated board is damaged by the pressing line, so that the inner paper shrinks and the surface paper extends. The number of its expansion and the thickness of the cardboard and the way the line has a direct relationship. The thicker the cardboard, the larger the expansion value, the wider the press line, the larger the expansion value.
But regardless of the two - line, three - line or five - line molding method of corrugated boxes, the bottom line of the press wheel convex part of the corrugated board pressure into the center of the corrugated board. Therefore, the inner size of the corrugated box is slightly shorter than the distance between the line and the press line when the corrugated box is unfolded. In this way, the shortened dimension is added as a correction value, which is closely related to the thickness of the corrugated board.
The most common carton in order to protect the contents, usually the outer flap to butt sealing. This requires that the size of the rolling cover of the carton must be calculated accurately. There can be no gap after docking, nor can the rolling cover be superimposed. In principle, the theoretical manufacturing size of the swing cap width should be half of the box width manufacturing size. However, because the inner and outer swing covers are on the same pressure line, the inner swing covers have a supporting effect after folding the outer swing covers, and the outer swing covers must have a certain gap at the joint. Therefore, it is very important to calculate the correction of the width manufacturing size of the outer swing cover. This correction is generally half of the thickness of the pressed line board, but different pressing equipment caused by the board surface paper, paper expansion is not the same, so it is best to determine by actual measurement.
In short, in the structure design of corrugated boxes, according to the use of manufacturing equipment and different production processes and the use of different types of corrugated cardboard and the type and nature of the goods inside to determine. Only after mastering all the structure and size related content of the design of corrugated boxes, can we make corrugated boxes to protect goods and beautify goods.
In accordance with the ISO9001 standard design and development requirements, the output of the new product design to be verified. As far as the output product is concerned, there are two methods of verification: one is to measure, verify whether its specifications and dimensions meet the expected requirements of the design; The other is to carry out a physical loading test. The second method is very practical and very simple. The first kind of measurement requires mastering scientific methods, otherwise the measurement results will be biased.
It is described in SN/T0262-93 inspection procedure of corrugated cartons for export commodity transportation package as follows: The carton is supported and formed, and the Angle between adjacent surfaces is 90°. The length and width of the carton are respectively measured at 50mm from the box mouth on the bond tongue with an inner diameter ruler, and the height of the carton is measured by the distance between the bottom of the carton and the inner flap of the top.
But before you can measure it, there is one step that must be done: Close one end of the shake cover, so that the carton support molding, adjacent surface Angle into 90 degrees close to the gauge, the box with pressure plate to make the inner shake cover close, the top of the box outside the shake cover open, the horizontal wooden ruler on the inner shake cover, and then use the inner diameter ruler in the tongue from the box mouth 50mm to measure the distance between the two faces in the direction of the length, width and height of the box. If the carton height is small, you can measure the position between the first and second nails, because the size is more accurate after the two nails are fixed. If the above detection equipment is not available, the carton can be folded and formed during measurement and leaned against the corner to ensure that the Angle between adjacent surfaces of the carton is 90℃.
The author once encountered such a problem in the process of visiting customers. The customer feedback was that the carton molding was not good and the size deviation was large. After visiting, the inspection personnel of the original customer will fold the carton and form it, and measure it directly at the pressure line of the shake cover. There are two errors. First, the carton flat packaging, two of the line crease aggravated, so that the carton is often folded into a diamond shape, folding molding is not correct carton certainly can not guarantee the accuracy of measurement. Second, after the carton is formed, the shaking cover will have a supporting effect on all sides, especially in the press line, the maximum error, in principle, should be in the tongue from the press line 50mm or the first to the second nail distance between the position of the most accurate and reasonable measurement.