On the inspection of base paper in carton factory

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Talking about the inspection of base paper in carton factory according to the required purchase plan of base paper, the carton factory must inspect the purchased base paper to confirm whether its quantity and quality meet the agreement. The first purpose of the inspection is to prevent the unqualified base paper from entering the factory and minimize the loss caused by the base paper problem in production. The second purpose is to understand the performance of the base paper through inspection and then make a correct choice, so as to minimize the cost and ensure the quality of the finished product

the base paper is inspected according to the following process:

first, verify whether the delivery code sheet is consistent with the purchase plan, and whether the arrival quantity is consistent with the delivery code sheet. The type, quantity, specification and number of pieces of base paper can be confirmed on the spot, and the weight can be weighed by weighing. The deviation must be controlled within ± 3 ‰ (3 ‰), and the deficiency should be deducted

secondly, check whether the label of the roll paper is clear, whether the package is dirty, and whether the base paper is damaged or damp. In case of damage or dampness, deduction shall be made. The specific method is as follows: if the damage or moisture occurs on the side of the rolled paper, count from the outside to the inside to the layer without damage or moisture, for example, there is n=32 layer (there is no damage or moisture from the 33rd layer), then measure the distance d from the 16th layer to the axis, for example, d=0.55m, and then combine the specification l of the rolled paper (unit: m) and the base paper weight g (unit: g/m2) to obtain the weight to be deducted w = G × L × (2 × three point one four × D) × N in kilograms. If the damage or dampness occurs on the end face of the rolled paper, it is generally not allowed to exceed 2 cm, otherwise it will be treated as return

third, check whether there is a significant mark on the end face of the roll joint, whether the roll end face is flush with the shaft core, whether the roll shaft core has a flat core, whether the two end faces of the roll have the same diameter, whether the tightness of the rewinding and the two end faces are the same, whether the binding of the roll meets the standard, whether a batch of rolls have color difference, etc

fourth, check the moisture content of roll paper with a pin moisture meter. Sampling according to GB and GB. The inspection shall be carried out on the two end faces of the rolled paper, three reference points shall be taken evenly, and the insertion depth shall not be less than 0.6cm. Take the average value of the six test points as the moisture content of the roll paper. In the base paper supply contract, the delivery moisture is generally specified, such as (8.0 ± 2.0)%. The moisture content of the tested roll paper is qualified within the range of delivery moisture, otherwise it shall be treated as agreed by both parties, and the excess moisture shall be deducted generally. The specific method is as follows: if the moisture content M1 of the rolled paper exceeds the upper limit Ma of the delivery moisture, and the weight of the rolled paper is w, the weight to be deducted is w × (M1Ma)/Ma; If the moisture content M1 of the rolled paper is lower than the lower limit MB of the delivery moisture, the rolled paper must be put on trial. If it does not affect the normal production and the quality of the finished product, it will be treated as qualified, otherwise it will be returned. It is worth mentioning that the moisture content of the rolled paper is tested when the rolled paper is accepted in the factory, and the on-site follow-up is required when it is used in the workshop, that is, quality tracking. If any problem is found, contact the supplier in a timely manner to solve it

fifth, performance test of base paper. As general carton factories do not have the conditions for constant temperature chamber testing, and the timeliness of inspection should be considered, normal inspection should be adopted. As long as there are no obvious defects on the surface of the rolled paper, samples can be taken from the second layer to test the quantitative, ring pressure strength, bursting strength, crack length, water absorption and other technical indicators according to the methods proposed in relevant national standards. Quantitative inspection mainly works with customers to see whether there is excess or insufficient gram weight; The ring compression strength and bursting strength test are the most critical. The test results are determined by regression analysis (see the article "the influence of moisture content on the strength of corrugated board" for details), and then by referring to the agreement of both parties, we can know whether it is qualified; Testing the crack length is mainly to understand the tensile strength of the base paper, which can be used as the main basis for whether the tile line is applicable; Water absorption determines the adhesive properties of the base paper, printability, and the severity of the impact of atmospheric moisture, and so on. Other aspects, such as tightness, smoothness, folding resistance, flat compression strength, oil permeability, etc., shall be inspected according to specific needs

finally, carefully record the base paper inspection results of each batch, analyze and compare them, retain excellent suppliers (with stable quality, reasonable price and timely supply), and remove unqualified suppliers from the supplier list. The base paper inspection results can be used as an important reference for the configuration of the base paper of the tile line paperboard

here, another method of quantitative test with ring compression strength sample without quantitative sampler is introduced

because the size of the ring compression strength specimen is longitudinal × Transverse = 15.2cm × 1.27cm, which is suitable for the affirmation of PMV and PPD indicators and thermal comfort conditions under the environment. The product of iso7730 ⑴ 994 (E) is 19.304 cm2, and the total area of five ring compression strength samples is 96.52cm2. Therefore, weigh the total mass m of N ring compression strength samples, convert it into the mass of five ring compression strength samples, expand it by 100 times, and then divide it by 0.9652 to obtain the quantitative w of the base paper

for example, if the total mass of 10 ring compression strength samples measured is m = 2.89g, then the quantitative weight of base paper is w = 100m/(2 × 0.9652) = 149.7 g/m2, i.e. 150 g/m2. In addition, if the total mass of 8 ring compression strength samples measured is m = 3.84g, then the quantity of base paper is w = 100m × 5/(8 × 0.9652) = 248.7 g/m2, i.e. 249 g/m2. This test method is particularly suitable for the quantification and strength of small samples. Leffenhauser blown film company in trotsdorf, Germany, will demonstrate the evolution ultra stretch unit test dedicated to this purpose

tips for quantitative inspection of base paper

the quantitative measurement of paper and paperboard (also known as gram weight, g/m2) is the most basic technical index. General enterprises will be equipped with a quantitative sampler, take 10 circular paper samples with an area of 100cm2, weigh them in turn, and calculate the quantitative value through the formula. Now some enterprises directly use the paper knife to take 10 × When the 10cm2 square paper sample is weighed, there will be relatively large errors, which can not guarantee the authority of the test results. It will also meet the performance requirements of high strength, high wear resistance and good size at the same time, causing unnecessary contradictions between paper enterprises and carton enterprises. If there is no special quantitative sampler, it is not a big problem, because many enterprises already have the ring pressure test sampler, which can completely replace the quantitative sampler, and can do both quantitative and ring pressure tests. The specific operation methods are as follows:

equipped with an electronic balance of 110g at the maximum weighing, with an accuracy of 0.01g

cut 8 samples at equal intervals along the longitudinal direction on a paper sample, and the area of each sample is 15.2 × 1.25cm2, the area of 8 samples is 15.2 × 10cm2, 8 samples are weighed together, and the quantitative value is obtained by dividing the weighed value by 1.52 and multiplying by 100. (end)

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