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How can paper packaging manufacturers improve the quality of corrugated boxes?

with the continuous changes of the world economy, the corrugated box industry is also rising in this period. As a low profit industry, corrugated boxes will be cautious at every step. The quality control of corrugated box is a systematic project, which involves all aspects of the production process

source and formulation of standards

every customer will have its own independent inspection standards. At the beginning of receiving the customer's order, we should carefully analyze the customer's standards, and there are often many written descriptions in the customer's standards. Because there are many statements that are not related to the relevant processes, the operators tend to be confused. If we distribute these standards directly to the workshops or departments, these standards will often be shelved and useless

what we need to do at the beginning of receiving the customer's order is to translate some standards into our own enterprise's internal standards, which need to be simple and clear, easy to understand and operate. After the customer standards are broken down one by one, they are distributed to the procurement, technology, production, quality inspection and other links in the order of production, and then each department sets its own workflow and operation scheme in a certain order

base paper is the main raw material of cartons and often the first step of carton quality control

the quality of base paper involves carton compressive strength, bursting strength, edge pressure strength, moisture-proof effect, folding strength, printing effect, die-cutting operation and other aspects, so the purchase quality of base paper is the source of the whole quality control. Customers' standards often provide physical indicators of cartons, paper name and weight requirements, and we need to calculate the relevant physical indicators of paper according to these requirements as the standard of procurement and acceptance

the relationship between corrugated base paper and physical indexes of cartons

corrugated cartons are composed of corrugated base paper at all levels. The Kangshi formula calculates the compressive strength of cartons according to the physical properties of corrugated base paper to see whether it can meet the requirements: you can also choose a certain corrugated base paper according to the pressure resistance requirements of the predetermined corrugated carton

p=px KP -- empty box compressive strength of corrugated box (unit: n) PX -- transverse comprehensive ring compressive strength of corrugated paper base (unit: n/cm)

among them, the calculation formula of the comprehensive ring crush strength of the three-layer corrugated board base paper is:

px= (r1+r2+rmc)/15.2 the calculation formula of the comprehensive ring crush strength of the five-layer corrugated board base paper is:

px= (r1+r2+r3+rmlcl+rm2c2)/15.2rn -- the test force value of the transverse ring crush strength of the face paper (n/0.152m) Rmn -- the test force value of the transverse ring crush strength of the corrugated paper (n/0.152m) C -- the corrugated shrinkage rate.The length ratio of core paper to face paper

(ca=1.532, cc=1.477, cb=1.361)

k the effective value of comprehensive ring pressure in the empty carton compressive strength, and the calculation formula is ka=30.3+0 000522k=c=27.9+02652-k=b:24.6+02352-k five aa=41.7+0.355z-0.000522kjbb=33.2+0 000522k five cc=38.1+0.3452-0.000522kjab=38.2+0335z-0.000522kjac=402+0.355z-0.000522kjrr=35.7+0.325z-0.000522 three a -- three-layer A-shaped box, the value range of three-layer box perimeter:

70cm ~ 200cm five AC five-layer AC corrugated box, the value range of five-layer box perimeter:

70cm ~ 300cm compressive formula can only estimate the annular compressive strength of paper, but in fact, there are many factors that affect the compressive strength of corrugated boxes, It should include the ring compression strength, tensile strength, bursting strength, tightness, water resistance and water absorption of the paper

tensile strength. The tensile strength of corrugated base paper depends on the fiber structure of the base paper and the bonding force between the fibers. The tensile strength not only affects the tensile resistance of a series of problems such as the performance improvement of the base paper is not obvious in the process of use, but also affects the compressive quality of the paper box after forming, which reduces the amount of raw materials and energy consumption. Generally, if the annular compressive strength of the paper is very good, When the crack length and tensile strength are not good, the deformation of the carton during the compression test is often large, and the final deformation is like an accordion. This is because of the texture, structure of the fibers or the poor connecting force between the fibers. When the carton is subjected to the compression test, the fibers at the crimping edge are stressed first, and this loose and weak fiber can not well transmit the force on the carton to the whole carton, but only the passive parts are under pressure, With the local collapse of the edge, the stressed part gradually moves towards the middle of the box, forming an accordion shaped test phenomenon. If the tensile strength is good, this kind of situation will not occur. The carton will bear a lot of pressure with a small amount of deformation. If you add another yard, the carton will collapse from the center of the box surface because the whole cannot bear the pressure

tightness, the tightness of the paper tests the pressure effect of the base paper in the production process. The tightness will affect the firmness between the fibers, and then affect the ring compression strength and tensile strength of the base paper, and ultimately affect the compressive strength of the carton. Due to the insufficient tightness of the paper, it will also affect the moisture absorption of the carton, It makes the carton absorb moisture excessively in the process of use or storage and reduces the compressive strength of the carton itself

bursting strength refers to the maximum uniformly increased pressure that paper or paperboard can withstand on a unit area perpendicular to the surface of the pattern under experimental conditions. The bursting strength reflects the ability of the carton to bear the handling, loading and unloading, impact and tearing forces in the circulation process. More and more cartons are used. Customers have made clear provisions on the bursting strength of cardboard when placing orders. We need to take the customer's standard; To accurately calculate the bursting resistance of base paper, generally speaking The bursting strength of corrugated board is equal to the sum of bursting strength of lining paper, face paper and sandwich paper multiplied by a coefficient of 0.92, which is independent of the bursting strength of corrugated core paper. Based on this relationship, we can deduce the bursting strength of paper according to customer standards, so as to formulate the grade and origin of paper, and formulate corresponding acceptance standards

it is not a single physical index that determines the quality of paper. The physical performance of paper should be a comprehensive index. Sometimes cartons are equipped with alarm devices and devices to stop burning by force in the rain. In order to prevent carton enterprises from cutting corners, customers not only put forward requirements for the compression resistance and burst resistance indicators of cartons, but also put forward too high weight requirements for the matching of base paper. In order to meet the requirements of customers, carton enterprises can only increase the weight of paper and reduce the grade of paper to ensure the cost. This requirement of customers has turned away the corrugated base paper with low gram weight and high strength. In fact, from the perspective of comprehensive performance, the corrugated base paper with low gram weight and high strength is much more stable than the corrugated base paper with low-grade and high gram weight. Moreover, because the stability of the base paper reduces the differences between individual physical properties of the carton and increases the safety of carton use, it is difficult for low-grade and high gram weight paper to achieve this effect. In the compression design, due to the instability of low-grade base paper, it is difficult to accurately estimate the compression resistance. The physical properties of individual cartons vary greatly after completion, and the adulterated inferior products will become the first damage point in the use or transportation of cartons, thus affecting the use of the whole batch of cartons. In this case, we need to communicate with customers to find a combination of carton price and paper cost

the relationship between the size provided by the customer and the production size. As the outer packaging of the product, we should tailor the carton according to the size of the contents, and the customer's standard; Products often provide us with the inner size or contents of cartons, which requires us to convert them into production sizes that we can directly operate in all processes at the beginning of production

as a kind of packaging container, corrugated box has a certain volume and wall thickness, and correspondingly has a certain external volume. The size, arrangement and quantity of the contents determine the internal size of the carton (that is, the volume of the carton). The inner size, wall thickness and production process determine the production size of the carton (that is, the knife edge pressing size in the process of carton production). The external dimension of the carton (i.e. the external volume of the carton after folding and forming) is determined by the influence of manufacturing size, wall thickness and production process. Theoretically, the inner dimension plus wall thickness equals the manufacturing dimension, and the manufacturing dimension plus wall thickness equals the outer dimension. In fact, the size of the carton, especially the external size, is a comprehensive analysis of the data. The quality of the cardboard and the production process, especially the overlapping tongue of the carton, will have a certain impact on the external volume of the carton. The external volume of the tongue should be added two wall thicknesses on the basis of the manufacturing size. The conversion of the three sizes in the manufacturing process of the carton requires a certain basis of experience. If necessary, sample boxes need to be made for further confirmation

internal dimension (X.), which can be expressed by Li bixhi

the external dimension diameter (x) is L. XB。 xH。 Indicates

production dimension (x) is represented by lxbxh

however, the two long faces and two wide faces in the production size plan will be different from those of doors and windows. Following certain principles, we can make certain modifications according to the requirements of customers

calculation formula of the inner dimension of corrugated box xi=xmax NX D (nx+1) + k+t, where Xi -- the inner dimension of the box (mm) xmax -- the maximum outer dimension of the contents

nx-- the arrangement number of the contents in a certain direction of the carton

d-- the gap allowance between the contents and between the contents and the carton, that is, the tolerance coefficient

k-- the correction coefficient of the inner dimension of the carton is a special correction for the design process of special cartons, which can be taken as positive or negative value. Generally, cartons do not need to take value

t-- total thickness of lining or buffer

for example, for a mosquito repellent incense carton, the inner box specification is l30130x25mm, and the arrangement is 3 2x10, that is, three inner boxes are arranged on the long side of the carton, two inner boxes are arranged on the wide side, 10 layers are placed high, and a five layer board is used as a liner at the top and bottom. Try to calculate the inner size of the mosquito repellent incense carton

solution: in view of the stability of the mosquito repellent incense inner box, the tolerance coefficient is taken as 1, the high tolerance coefficient is 0, the correction value is taken as O, and the thickness of five layers of paperboard is 7mm, Calculate the inner dimension of this carton 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, that is, the inner dimension of this carton is:

lixxbixhi=394x263x264. It should be specially reminded that when calculating mosquito repellent incense cartons, we must consider the volume of the inner box after the mosquito repellent incense is packed.If the inner box is medium high after being installed, the stacking specification must be measured, Use the measured value to calculate which inner diameter to perform. This information must be conveyed correctly to ensure the accuracy of the design

note: this calculation result is theoretical calculation data. If there is little practical experience, sample boxes must be made for trial assembly before formal production of batch cartons to determine the qualified size and avoid batch loss

with the inner size of the carton, the basic size of the carton can be determined. Theoretically, the length and width of the carton are added with one cardboard thickness, and the height is added with two cardboard thickness, which is converted into the manufacturing size of the carton. After the production size is determined, we need to further determine the expansion drawing of the production size of the straight line. In the expansion drawing, we need to set the size of the glued joint, the size of the glued joint lap, the molding condition, the corresponding condition of the swing cover, etc. if these conditions cannot be set one by one, we will encounter many difficulties in the next process or market

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