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 empty box compressive strength of the corrugated box ( unit N) Px - the corrugated paper base paper's transverse integrated 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 - The 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+ 02652-0000522K=B : 24.6+ 02352-0000522K Five AA=41.7+ 0.355Z-0.000522KjBB=33.2+0.3052-0.000522K Five cc=38.1+0.3452 to 0.000522KjAB=38.2+0335Z-0.000522KjAc=402+0.355Z-0.000522KjRr=35.7+0.325Z-0.000522 Three A-- three-layer A楞 box, the range of the perimeter of the three-tier box:
70cm to 200cm five AC - five-layer AC tank, the value range of five-layer tank perimeter:
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 customers are using cardboard boxes bursting strength of cardboard to make a clearly defined when placing an order, we need the customer's standard; Zhui to accurately calculate the bursting of the base paper, corrugated cardboard bursting in general. The strength is equal to the sum of the burst strengths of the paper, face paper and sandwich paper multiplied by a factor of 0.92 , regardless of the burst strength of the corrugating 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 quantity of the contents determine the inner dimensions of the carton ( ie, the volume of the carton ) . The size of the inner wall, the thickness of the wall, and the influence of the production process determine the size of the carton ( ie the size of the knife-edge pressure 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.
The inner size (X.) can be represented by Li × BixHi .
Outside diameter (X) with L. XB . xH . Indicated.
The production size (X) is represented by LxBxH .
However, the two long sides and two wide sides of the production floor plan will be different. Following certain principles, we can make certain modifications according to the requirements of our customers.
The formula for calculating the size of the corrugated box Xi = Xmax · Nx ± d (Nx + 1) + K + T Where X i - the inner dimensions of the carton (mm) Xmax - the maximum outer dimensions of the contents.
Nx - The number of items in one direction of the carton.
D--the balance between the contents and the contents and the carton, ie the tolerance coefficient.
K-- Carton size correction coefficient, is a special correction for the special carton design process, you can take a positive value, you can also take a negative value, the general carton without value.
T - The total thickness of the lining or cushioning.
For example: a mosquito-carton carton, the inner box specification is l30130X25mm , the arrangement method is 3 × 2X10 , that is, the carton box is lined with 3 inner boxes, the wide-faced row is 2 inner boxes, the high-level is 10 layers, and a five-layer board is used above and below Cushion, try to calculate the inner size of this mosquito-repellent carton.
Solution: In view of the mosquito coil case has a certain stability, tolerance factor of 1, high tolerance factor is 0, the correction value takes O, a thickness of the upper and lower pads five cardboard 7mm, the dimensions of this carton is calculated as:
Li=Lmax · n+d(n+1)=130X3+1X(3+1)=394B=Bmax · n+d(n+1)=130X2+1X(2+1)=263Hi=Hmax · n+ d(n+1)+T=25X10+7X2=264 means the inner size of the carton is:
LixXBixHi=394X263X264 need to be particularly reminded that in the calculation of such as mosquito-repellent carton, we must consider the impact of the package on the shape of the inner box after the installation of mosquito coils. If the inner box is high after being packed, we must measure the stacking specification and use the measured value to calculate the execution. Which inner diameter. This information must be correctly conveyed to ensure that the design is accurate.
Remarks: This calculation result is the theoretical calculation data. If there is not much practical experience, you must make a sample box to test before you formally make a batch carton to determine the qualified size and avoid the loss of the batch.
With the inner dimensions of the carton, the basic dimensions of the carton production can also be determined. Theoretically speaking, the length and width of each carton are added to the thickness of one carton, and the thickness of two cartons is added to the height to convert the carton into a carton. After the production size is determined, we need to further determine the unfolded drawing of the straight-line production size. In the unfolded drawing, the size of the sticky mouth, the size of the sticky joint, the molding situation, the corresponding situation of the swing cover, etc. must be set. Once it is set up, many difficulties will be encountered in subsequent processes or markets.
There is a key problem in making dimensions through the conversion of the outside diameter size: due to different manufacturers' methods for measuring the outside diameter, such as the method of measuring the outside diameter of the long side, some include lap joint tongues, while others do not include a lap joint. The tongues, and even more, individual carton manufacturers or manufacturers confusing the outside diameter dimensions with the production dimensions, often lead to errors in information transmission, and eventually result in mass loss. Therefore, the business must understand the specific requirements of the customer during the order process, and correctly convey the customer's information to the production and technical departments.
Some cartons are used when it is necessary to ensure that the outer diameter size, such as loading a container or yardstick base, etc. At this time customers often give us the outer diameter of the carton, which is the outer volume of the carton, and at this time we must be able to correctly The path size is converted into a production size. The method is to calculate the length, width, height, and thickness of two walls by backward calculation. Due to the space relationship, detailed description will not be given here.
Some methods in the process of production quality control, no matter how well we prepare to do our work, we will also encounter many or all kinds of problems in the production process. We need to eliminate all the problems that have occurred and take this experience as Prevention, so as not to repeat again next time. Below we discuss some small methods in the production process.
High standards, strict requirements When the narrative standards were established, we mentioned the criteria for customer disaggregation. In fact, in the production process, the customer's standard can not be used directly as a production standard. There is another reason. Because the customer's standard is already the bottom line of acceptance when the carton is delivered, if there are some cases, it will face unqualified treatment. Therefore, we must establish our own production safety standards in production. Taking the compression standard as an example, the customer's standard is 2200N , then the standard in our production process should be 2640N , which is based on successive process steps against the pressure, and the standard of the previous process is even higher. Since we have set a strict safety factor when setting the paper standard, the physical index of the paper should be effectively converted during the production process.
Exclusion Because carton production is a big project of the system, we often encounter many problems in the production process. In the face of some problems, we need to know what causes the problems and then check them one by one until the cause of the problem is eliminated. In the case of unacceptable pressure failure, for example, a certain round of circular die-cutting procedures found that the compressive strength of the carton was unqualified when it was subjected to compressive resistance. First, check the previous process for compressive test records for any problems.
If there is no problem in retrospecting the previous process test record, check the process problem again to see if there is any significant indentation of the paper feed roller on the surface of the paperboard. After the paper feed roller is raised to a certain height, perform the compression test:
Check the front and back of the cardboard for any extra creases or indentations. If so, test this out.
Contrast method We often encounter some very difficult problems in the process of quality control. Sometimes workers are not very understanding in production. We may wish to use the contrast method to see if there is such a situation in the previous process or other units. May wish to change thinking, change the operation to conduct comparative tests.
Everything in the innovation law is not static, and if we encounter problems, we may wish to change our thinking. In the process of quality control, if we stick to conventions, it will often cause some problems to exist for a long time. The existence of problems will always have roots in him. To find the root cause, we may wish to make some changes, but such changes must follow certain principles and blindly change. It will be counterproductive.
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