Cardboard Problem Solving - Frequently Asked Questions

Discussion on Seven Common Paperboard Problems

China's carton industry automation history can be traced back to the 1980s. Prior to the 1970s, carton production equipment was manually operated and production efficiency was low. From the 1980s to the early 1990s, an era of single-plane units was formed. Cardboard produced by one-sided corrugated units has the disadvantages of soft material quality, poor quality, and large waste of base paper. By the mid-1990s, it had developed into an ordinary low-speed corrugated production line. In recent years, it has rapidly developed into high-speed and high-grade production lines. At present, the production methods of “centralized system manufacturing and decentralized system manufacturing” have been implemented in various localities. This has become the pattern of cooperative production of cardboard within the industry. Automated machinery has gradually replaced manual labor and has also accelerated market competition. The carton industry itself is already a small profit industry, and some regions are still desperately engaged in the "price war" in the industry, which has caused the industry's profits to "shrink" to about 5%, and some even less than 5%.

With such fierce and brutal competition in the market, all companies can only tap into the potential of the company itself and reduce various management costs and costs. On the other hand, it is necessary to improve product quality, reduce losses, and enhance employee quality education to reduce Scrap rate and increase the finished product rate as a profit growth point. The quality of human resources varies from company to company, and most companies often experience cardboard quality problems in the production of cardboard, such as paperboard foaming, low board strength, cardboard warping, cardboard wrinkles, see-saw-like, bursting when crimping, edges Misalignment, poor paperboard bonding, insufficient paperboard thickness, high or low cardboard quality, paperboard quality, etc. Paperboard quality problems often make enterprise investors, managers and operators “eat fragrant and can not sleep”, which makes the production and development of the enterprise greatly constrained. How to improve the quality of cardboard production lines and solve the quality problems of paperboard is also the investment of various companies. There are urgent problems that need to be solved by managers, operators and operators.

Explore and solve several common problems with paperboard quality.

â–  Cardboard foaming

There are many reasons for the foaming of cardboard:

The tension of the corrugated paper and the core paper is not enough. Adjust the brakes so that the tension is as strong as possible without pulling the paper.

The temperature is not enough, the base paper contains too much water, the glue is too thick, the speed is too fast; increase the preheating angle of the base paper, raise the temperature, make the surface temperature not lower than 160°C, thin the sizing amount or reduce the speed.

The thickness of the base paper is uneven, and the air suction slot is blistering when the paper is low in gram. The distance between the sizing roller and the lower screed is adjusted.

Corrugated roller and pressure roller wear seriously, replace and rework.

The wind suction is small, the paper suction is unstable, check whether there is debris in the pipeline and the Citroen fan and clean up the debris. Check whether the spring of the graphite ring at both ends of the tooth roller is invalid and the seal is not good. The suction of the external suction machine is The hood is adjusted to the proper position.

â–  Low cardboard strength

Cardboard production often feels that cardboard has low strength, small force, and relatively soft, often causing customer complaints and returns. Cause the above reasons are often due to the following aspects: speed, sizing too much, the humidity of the base paper, glue manufacturing quality problems, low working surface temperature, poor quality of the original paper without sizing, corrugated roller is too long to use more severe wear. Solution: Reduce the speed, adjust the sizing roller, increase the heating area of ​​corrugated paper, increase the wrap angle of the preheated cylinder, and reduce the amount of caustic soda, because if the amount of caustic soda is too high during pulping, the paperboard will easily absorb moisture after bonding. Increase the temperature of the working surface and maintain the working temperature within 160°C-180°C. As far as possible, purchase raw paper with sizing to make pit paper, increase the number of grams of corrugated paper, and the corrugating roller wear must be repaired and replaced.

â–  poor adhesion of cardboard

Commonly there are separation, blistering, false bonding, and weak bonding. The main reason is

Adhesive quality problems, raw and cooked slurry ratios are not consistent, raw slurry is much more, slurry is less, water is more, powder is less, borax is used more, so that the gel is too fast or the cohesion of the adhesive is less, resulting in volatile water after heating Blistered and separated. Less raw slurry, more mature pulp, less water ratio, more powder, less borax, slower gelling and cohesive force of adhesive, poor adhesion, resulting in surface adhesion, insubstantial adhesion is not solid, often called The phenomenon is "false adhesion".

The speed is fast, the temperature is low, the sizing is large, the moisture of the base paper is large or the speed is slow, the temperature is high, the amount of sizing is small, and the base paper has too little moisture. Therefore, it is necessary to adjust the moisture of the base paper, adjust the preheating angle, control the temperature and the production speed, and adjust The right amount of sizing is crucial.

Non-uniform sizing, single-sided paperboard pits are uneven, the sizing roller and pressure roller of the gluing machine are not parallel, the sizing roller and the homogenizer roller are not parallel, the upper and lower sizing rollers and the upper and lower homogenizing rollers are glued, and the surface of the roller is simple. Roughness, squeezing the pulp board is not clean, affecting the adhesive coating evenly.

The parallel and distance between the press roller and the heating plate and the parallel between the pressure roller and the heating plate must be adjusted.

The thickness of the cardboard is not enough

The reason why the thickness of the paperboard is not enough is that the corrugated roll is not properly adjusted and the depth is not yet in the end, and the upper corrugated roller blank screw is opened. The eccentricity adjustment is not in place, the distance between the gluing machine press roller and the sizing roller is not enough, the uneven distance between the heavy press roller and the heating plate, the press roller and the heating plate is too low, the automatic unloading of the gluing machine press roller mechanism is decreased, and the corrugating roller is seriously worn out High enough.

Cardboard warpage

The warpage of cardboard is usually caused by upper and lower bending, longitudinal and longitudinal bending and diagonal warpage. The main cause of cardboard warpage is that the proportion of moisture contained in each layer of paper is different. Differently, when it is cooled and shaped, the cardboard will be bent, the vehicle speed will be slow, the amount of sizing will be small, the surface temperature of the heating plate of the bonding machine will be high, the water content of the surface paper will be less, the angle of preheating of the tissue paper will be too large, and the cardboard will be formed toward the bottom paper. Bending is also called bending. On the contrary, the speed is fast, the amount of sizing is large, the surface temperature of the heating plate of the bonding machine is low, and the moisture content of the surface paper is large. The surface paper is preheated: the wrap angle is small, the upper single cardboard is flat, and the preheating angle is large. , that is, causing the cardboard paper to bend in the direction of the paper, also known as bending, change the direction of the paperboard to the bottom paper bending method, speed up the speed, increase the amount of lower sizing, reduce the number of bonding machine heating plate, to shorten the heating time of the paperboard, reduce face Paper preheating wrap angle, increase the preheating wrap angle of the upper single wavy paper, and treat the paperboard in the direction of the paper surface, slow down the speed, reduce the amount of sizing in the lower layer, increase the amount of sizing in the upper layer, drain and condense the water, and improve the system temperature, Large Angle preheating tissues, reducing the upper preheat wrap angle.

â– Cardboard burst

Causes of paperboard pressure line, high temperature, low base paper moisture, repeat papermaking many times, raw paper fiber is short, raw paper physical properties are poor, paper thickness is not uniform, pit paper is not sizing, processing methods, try to properly increase the speed, reduce The base paper preheats the wrap angle, reduces the system temperature appropriately, and increases the amount of sizing.

(Author: Guo come to Guangdong Zhaoqing Portman Jialong Packaging Machinery Co., Ltd.)

Corrugated Carton, July 2005 issue