With the continuous changes in the world economy, the corrugated box industry is also getting better and better at this time. Corrugated cartons as low-profit industries will be cautious at every step. The quality control of corrugated boxes is a systematic project, which involves all aspects of the production process.
Standard source and formulation
Each customer will have its own independent inspection standard. At the beginning of receiving the customer's order, we must carefully analyze the customer's standard, and there are often many textual descriptions in the customer's standard. Due to the fact that there are many statements that are not related to related processes, operators often see a fog of confusion. If we directly distribute these standards to the workshops or departments, these standards will often be put on the shelf and useless.
The work that we need to do at the beginning of receiving customer orders is to translate some standards into internal standards of our own companies. These standards need to be simple, clear and easy to understand and operate. After the customer standards are decomposed one by one, they are distributed to each link of procurement, technology, production, and quality inspection in the order of production. Each department then sets its own work flow and operation plan in a certain order.
The base paper is the main raw material of the carton and is often the first step in the quality control of the carton.
The quality of the base paper relates to the compressive strength, burst strength, side pressure strength, moisture proof effect, folding strength, printing effect, and die-cutting operation of the carton, so the quality of the original paper is the source of the entire quality control. The customer's standards often provide the physical specifications of the carton, the name of the paper and the grammage requirements, and we need to calculate the relevant physical indicators of the paper according to these requirements as a standard for procurement and acceptance.
Corrugated paper and carton physical indicators
Corrugated cartons are made of corrugated paper of various layers. The anti-cotton formula calculates the compressive strength of the cartons based on the physical properties of the cardboard base paper to see whether it can meet the requirements: it can also be selected according to the compressive strength requirements of the predetermined corrugated boxes. Corrugated paper base paper.
P = Px · KP - the corrugated box's empty box compressive strength (unit N) Px - corrugated board base paper's transverse composite ring pressure strength (units N / cm).
Among them, the calculation formula for the integrated ring pressure strength of the three-layer corrugated paperboard paper is:
Px=(R1+R2+RmC)/15.2 The calculation formula for the composite ring pressure strength of the five-layer corrugated paper base paper is:
Px=(R1+R2+R3+RmlCl+Rm2C2)/15.2Rn--Test Force Value of Lateral Ring Crush Strength of Face Paper (N/0.152m) Rmn--Test Force Value of Lateral Ring Crush Strength of Nylon Paper (N/ 0.152m)C - Corrugated shrinkage, the ratio of the length of the corrugating medium to the length of the tissue.
(CA=1.532, CC=1.477, CB=1.361)
K——effective value of the integrated ring pressure in the compressive strength of the empty carton. The formula is KA=30.3+0.2752-0.000522K=c=27.9+0 2652 to 0 000522K=B:24.6+0 2352 to 0 000522K. AA=41.7+0.355Z-0.000522K j BB=33.2+0.3052-0.000522K Five cc=38.1+0.3452 to 0.000522K j AB=38.2+0 335Z-0.000522K j Ac=40 2+0.355Z-0.000522K j Rr =35.7+0.325Z-0.000522 Three A--three-layer A box, value range of three-layer box perimeter:
70cm to 200cm five AC - five-layer AC tank, five-layer box perimeter value range:
70cm ~ 300cm compressive formula can only estimate the paper's ring pressure strength, and in fact there are many factors that affect the compressive strength of corrugated boxes, it should include the paper's ring pressure strength, tensile strength, burst strength, tightness, and Paper waterproof and water absorption and so on.
Tensile strength, the tensile strength of corrugated base paper depends on the fiber structure of the base paper, and the bonding strength between the fibers. The tensile strength not only affects the resistance of the base paper in the machine during use, but also affects the tensile strength of the base paper. After the carton is formed, the compressive quality, usually, if the paper's ring crush strength is very good, and the crack length and tensile strength are not good, it will often cause a large deformation of the carton during the compression test, and the final deformation, such as Accordion-like because of the poor texture and structure of the fiber or the poor connection between the fibers. When the carton is subjected to a compression test, the fibers on the edge of the press line are subjected to force, and this loose and weak fiber does not perform well. The force exerted on the carton is conveyed to the entire carton, except that the passive part is under pressure. With the local collapse of the edge, the force part gradually moves toward the middle of the box, and a deformation test is formed like an accordion. If the tensile strength is very good, this will not happen. The carton will be subjected to great pressure under very small deformation. If it is overweighted, the carton will collapse from the center of the box face because the whole cannot withstand the pressure.
Tightness, tightness of the paper to test the pressure effect of the base paper in the production process, the tightness of the compactness will affect the degree of tightness between the fibers and then affect the ring paper strength and tensile strength of the base paper, and the final shadow II direction The compressive strength of the carton, and because the tightness of the paper is not enough, will also affect the moisture absorption of the carton, making the carton excessive moisture absorption during use or storage process to reduce the compressive strength of the carton itself.
Bursting strength refers to the uniform increase of the maximum pressure perpendicular to the pattern surface that a paper or board can withstand per unit area under experimental conditions. Bursting strength reflects the ability of the carton to withstand handling, handling, impact, and tearing forces in the process of distribution. More and more cartons use customers to specify the burst strength of cardboard when placing orders. We need to accurately calculate the resistance of the base paper to the customer's standard. In general, the corrugated board is resistant to breakage. The strength is equal to the sum of the burst strengths of the inner paper, face paper and sandwich paper multiplied by a factor of 0.92, regardless of the burst strength of the corrugated medium. Based on this relationship, we can roll out the paper's resistance to breaking strength according to the customer's standards, so as to formulate the grade and origin of the paper, and formulate the corresponding acceptance criteria.
The determination of the quality of paper is not determined by a single physical index. The physical properties of paper should be a comprehensive indicator. Sometimes, in order to prevent the cartons from cutting corners and materials, the customers of cartons use high-precision requirements on the basis of the pressure resistance and breakage resistance of the cartons. In contrast, cartons are required to meet customer requirements. Increase the weight of paper to reduce the grade of paper to ensure cost. This kind of requirement of customers has rejected the low-heavy and high-strength corrugated paper. In fact, considering the overall performance, the low-strength and high-strength corrugated base paper is much more stable than the low-grade and high-weight corrugated base paper. Because the stability of the base paper reduces the individual differences in the physical properties of the carton, the safety of the use of the carton is increased, and low-grade, high-weight paper is difficult to achieve this effect. In the compression design, due to the instability of the low-grade primary paper, it is difficult to accurately perform anti-pressure estimation. The physical properties of the carton after the completion of the individual differences are very large, and the poor quality of the doping, in the use or transport of the carton The process will become the first point of damage and thus affect the use of the entire batch of cartons. When this happens, we need to communicate with customers to find a combination of carton prices and paper costs.
The relationship between the size and production size provided by the customer As the outer package of the carton, we should tailor the product according to the size of the contents, and the customer's standard; the carton often provides us with the inner size or contents of the carton, which requires At the beginning of production, we converted the production dimensions that can be directly manipulated in all our processes.
As a packaging container, a corrugated carton has a certain volume and wall thickness, and accordingly has a certain external volume. The size and arrangement of the contents and the number of them determine the internal dimensions of the carton (ie the volume of the carton). The size of the inner wall, the wall thickness and the influence of the production process determine the size of the carton (ie the size of the knife-edge line during the carton making process). The size of the production, the thickness of the wall, and the influence of the production process determine the outer dimensions of the carton (ie, the outer volume of the carton after folding and forming). In theory, the inner size plus the wall thickness is equal to the production size, and the production size plus a wall thickness is equal to the outer size. In fact, regarding the carton size, especially the outer size is a comprehensive analysis of the data, cardboard quality and production process, especially the lap tongue part of the carton will have a certain impact on the outer volume of the carton, the external volume of the tongue to Two wall thicknesses are added on the basis of the production size. The conversion of the three sizes in the carton production process requires a certain amount of experience. If necessary, a sample box is required for further confirmation.