In the process management of carton companies, standardization is one of the important tools. It is very important and necessary for carton companies to pay attention to and strengthen process standardization. Process standardization is an important step for carton companies to achieve standardization, and the standardized control of each process link in the carton production process is an important part of process standardization.
How is your factory doing in the assessment of twelve important indicators for corrugated cardboard production line operations?
Adhesive index
The viscosity and solid content of adhesives for corrugated cardboard should be adjusted according to the season.
Usually, at low temperature and low humidity (winter), the viscosity of the adhesive for single corrugated cardboard is 17 to 21 seconds (apply 4 cups, the same below) and the solid content is 17% to 19%; the viscosity of the adhesive for three corrugated cardboard is 40 to 40 seconds. 60s, solid content is 18%~20%.
In high temperature and high humidity (summer), the adhesive viscosity for single-corrugated cardboard is 20-25s and the solid content is 19%-22%; the adhesive for three-corrugated cardboard has a viscosity of 55-90s and a solid content of 21%-25%. %.
In addition, the adhesive pulling length should be ensured (dip a little adhesive with your thumb, bond it with your index finger, and slowly pull the two fingers apart until the distance between the two fingers when the adhesive breaks) is 15 to 20 mm.
base paper index
(1) Moisture content of base paper. The moisture content of the base paper should be 6% to 8%, which is most beneficial to the bonding and corrugated forming effects of corrugated board. The difference in moisture content between the three types of base paper and the left, middle and right sides of each base paper shall not exceed 3%.
(2) base paper production time. The production dates of the three base papers must be similar before they can be used on the machine.
(3) The number of times the base paper can withstand folding. The base paper should be produced in a low-temperature and low-humidity environment. In order to prevent the carton from bursting due to its low folding endurance, the base paper must have a folding endurance of more than 50 times.
(4) base paper strength. The strength of the base paper is determined based on the customer's compression requirements for the corrugated carton used and the production process of the carton. For example, if the compressive strength of a certain box-type carton is required to reach 1500N, through analysis and calculation, if offset printing is used to print the carton, the base paper should be high-strength A grade, the basis weight is 120g/m2, and the ring pressure index is greater than 7N·m/g; if watermarking is used Or for pre-printed cartons, the base paper should be high-strength grade A, with a basis weight of 110g/m2 and a ring pressure index greater than 6N·m/g.
The selection of base paper strength is relatively complex and must be determined after analysis, calculation, and testing based on relevant technologies. once determined, the base paper must not be replaced for this type of box, and the base paper with the specified corresponding strength must be selected during production.
Original paper force adjustment
The original paper force should be adjusted according to the longitudinal bending degree and usage conditions of the corrugated cardboard.
When the corrugated cardboard is bent in the longitudinal direction of a certain base paper, the tension of this base paper should be released. The tension control of the core of the original paper roll and the outside of the roll are different. The tension parameters of the original paper must be reduced at the core to prevent the paper from breaking. Excessive force on the base paper can easily cause quality problems such as paper breaks, longitudinal bending of the corrugated board, and unsatisfactory corrugated molding effects. On the contrary, it can easily cause bubbling and warping of the corrugated board.
Preheat corner wrapping
The surface temperature of the preheating roller must reach above 100°C, and the temperature of the hot plate must reach above 150°C.
The size of the preheating wrap angle is proportional to the contact area of the base paper on the preheating roller and the moisture content of the base paper. During the production process, the preheating wrap angle can be increased or decreased according to the transverse bending degree of the corrugated board. For example, when single-corrugated cardboard and three-corrugated cardboard are bent transversely, in which direction the base paper is bent, the preheating wrapping angle of the base paper will be increased and the preheating wrapping angle of other base papers will be reduced.
Paper stack adjustment
Although stacking paper at the bridge helps evaporate moisture from corrugated cardboard, excessive stacking of paper will cause phenomena such as washboarding and bending of corrugated cardboard. Therefore, the amount of paper stacking must be reasonably controlled based on the board output effect.
Dust removal system
When producing three-corrugated cardboard, the cleanliness of the cardboard should be ensured. Use the dust removal system of the corrugated cardboard production line, use brushes to remove dust, and turn on the air suction device to reduce printing quality problems caused by paper wool in the subsequent printing process.
Steam pressure and hot platen control
Ensure that the minimum vapor pressure is greater than 7kg and the internal temperature of the hot plate reaches 150°C before production can be started. In actual production, the hot pressing plate is reasonably adjusted according to the bending degree of the corrugated cardboard and the speed of the machine.
When the corrugated cardboard bends laterally in the direction of the box board, the latter set of hot press plates should be lifted to ensure that the glue gelatinizes and the internal temperature of the hot press plates is lowered. When producing corrugated cardboard with a longitudinal dimension less than 600mm, the machine speed should be reduced by 30% to 40%, the last set of hot press plate steam pressure devices should be closed or raised, and the hot press plate should be raised at the same time to dissipate heat.
For pre-printed cardboard, in order to achieve no quality problems during production at 150°C, the pre-printed surface paper should use high-temperature resistant varnish. once it is found that the pre-printed surface paper has ink and varnish lamination at this high temperature, the heat-resistant varnish should be removed. The platen temperature is lowered to 130°C for production again.