What is the meaning of corrugated carton A, B, C, E, and F flute, and what is the difference?
The typical structure of corrugated cardboard consists of a skillful combination of face and corrugated paper. Analyzed from the perspective of structural mechanics, its shape is very scientific and reasonable. The core part of corrugated board is the corrugated flute, so the shape, type, and combination of flutes have a significant influence on the characteristics of corrugated board. The following is a discussion of the essential points of corrugated flute shape.
Types of flute shapes
A corrugated board is structurally characterized by grooves that are pressed into corrugations. The flute is the main body of corrugated paper. Corrugated board is made from face paper and core paper of the same texture, and if the shape of the corrugated is different, the corrugated board has other properties. Nowadays, there are several types of corrugated paper used in various countries around the world: A flute, B flute, C flute, E flute, and F flute. A flute is the thickest, and the F flute is the thinnest. Theoretically, for the same material, the thickness is inversely proportional to the stiffness. A carton, according to the number of layers of corrugated board, can be divided into three-layer, five-layer, and seven-layer boxes, as well as special packages, the strength of the three layers of the weakest, seven layers of the highest, of course, but also with the use of paper materials have a direct relationship.
1）A-type flute
A-type flute is characterized by several grooves per unit length and the highest corrugation. Corrugated boxes made of A flute are suitable for packing lighter items and have greater cushioning power.
2) B flute
The B-type flute is the opposite of the A-type flute, with more grooves per unit length and the lowest corrugations, and its performance is also the opposite of the A-type flute. Corrugated boxes made of B-type flutes are suitable for packing heavier and harder goods and mainly for canned and bottled goods.
3）C-type flute
The number of flutes per unit length and the flute height of the C-type flute are between the A-type flute and the B-type flute. Its performance is close to that of an A-type flute. In recent years, with the rising cost of storage and transportation, the smaller volume of C-type flutes has been paid attention to and has now become the flute type used in Europe and the United States.
Secondly, let’s talk about the characteristics of E-type corrugated for inner packaging and small packaging.
4）E-type flute
The number of flutes of an E-type flute within a length of 30 cm is generally about 95, and the flute height is about 1.1㎜. Compared with A, B, and C-type corrugated cardboard used for outer packaging, the E-type flute has the characteristics of being thinner and more rigid. Therefore, the primary purpose of developing an E-type flute is to make it into folding cartons to increase cushioning. Corrugated boxes made from E-flute have a beautiful appearance and a smooth surface and can be printed in more complex ways, so they are often used for decorative corrugated boxes.
There is also a standard for identifying good and bad corrugated board:
| Flute type | Flute height（mm） | Number of flutes（1pcs/300mm） |
| A | 4.5-5.0 | 34±2 |
| C | 3.5-4.0 | 28±2 |
| B | 2.5-3.0 | 50±2 |
| E | 1.1-2.0 | 96±4 |
In short, no matter which side of the carton, the heavier, the better, so the product protection is also better.
K = A, A = A, A = B, A3A, B3B, B3C used to indicate the paper quality is what it means.
K paper is the best, followed by A B C paper quality decreasing. “#” that seven layers of cardboard (PS: some people also use this symbol to replace the number of numbers; we have to look at the oh, for example, some people write 12 # cardboard, do not think it is 12 7 layer), “3” that three layers of cardboard, also with the “-” said, “=” that five layers of cardboard. So it is A3A, said the cardboard has three layers, the surface is A paper, paper is also A paper, there is a layer in the middle, and so on. Different paper quality has weight standard K=250g A=175g B=150g C=125g Jag=112g. The reason is that the thicker it is, the heavier it is, of course, the better the quality.
