Paper mill machines run as a linked closed loop. The headbox, wire section, press section, dryer section, calender, and reel all work together. Matching parameters at each stage is the basis of stable production.
Headbox operation
Stock feed
Thick stock is diluted in a blending tank to headbox consistency of 0.3 to 1.2%, adjusted by paper grade. Newsprint runs at 0.6 to 0.8%. Electrostatic copy paper runs at 0.3 to 0.5%. A pump sends the stock to the headbox. Stock pressure stays at 0.01 to 0.03 MPa.
The inlet pipe has a rectifier roll. Speed is controlled at 80 to 150 r/min. This keeps stock flow even and free of flocs.
Forming on the wire
The headbox slice opening is adjusted to the paper basis weight. At a basis weight of 100 g/m², the opening is about 0.8 to 1.2 mm. The jet speed from the slice matches the wire speed. Error is ≤0.5 m/min. This prevents the stock jet from hitting the wire and forming holes.
Wire section operation
Drainage
The forming table uses a shake motion. Amplitude is 1.5 to 3 mm. Frequency is 20 to 30 Hz. It breaks up the fiber layer and helps initial drainage.
Vacuum suction boxes are divided into 5 to 7 stages. Vacuum rises from -0.02 MPa in the first stage to -0.05 MPa in the last stage. Each stage removes 15 to 20% of water. Final sheet moisture is about 75 to 80%.
Wire tension control
The wire section line speed is stable at 120 to 600 m/min, adjusted by capacity. Wire drive roll tension is controlled at 15 to 25 kN. This prevents wire slippage or stretching.
Press section operation
Drainage pressure setup
The press section uses 2 to 3 press groups. The first group is a felt press with linear pressure of 150 to 200 kN/m. The second group is a pressure press with linear pressure of 250 to 350 kN/m. After pressing, sheet moisture drops to 55 to 65%.
Press roll speed is synchronized with wire speed. Error is ≤0.3 m/min. Spray water pipes at 0.2 MPa regularly clean fiber buildup from press surfaces.
For headbox, forming wire, press, and dryer section parts, Hansheng Automation can machine custom components from customer drawings, in single pieces or small batches.
Dryer section operation
Heating and drying control
The dryer section has 15 to 30 dryer cylinders. As the sheet passes through, steam pressure rises from 0.4 MPa to 0.7 MPa. Cylinder surface temperature rises from 65°C to 125°C. Final sheet moisture is controlled at 4 to 6%.
Tension between cylinders drops gradually from 0.8 kN/m to 0.3 kN/m. This avoids sheet breakage or shrinkage wrinkles.
Exhaust support
The closed hood exhaust air speed is controlled at 1.2 to 1.5 m/s. It removes moisture in time and keeps dryer cylinder surfaces free of water, so drying efficiency stays stable.
Calender and reel operation
Calendering
The calender uses 3 to 5 sets of steel rolls or paper-filled rolls. Linear pressure is controlled at 200 to 300 kN/m. Roll speed error against the dryer section is ≤0.2 m/min. After calendering, paper smoothness improves by 30 to 50%.
Reeling
Reel tension is controlled at 0.5 to 1.0 kN/m. Core speed decreases linearly as paper roll diameter increases. This keeps the roll tight and prevents collapse.
Automatic air splicing joins the paper sheet. Splice time is controlled at 0.8 to 1.2 s. Paper break rate stays at ≤0.1 breaks per 1,000 tons of paper.
We also provide precision component customization beyond paper mill equipment. We machine yacht precision components, RC car precision components, medical device components, tobacco packaging machinery parts, filling machinery parts, printing machinery parts, and food machinery parts. Hansheng Automation works from customer drawings and delivers one-off or batch parts to the required material, tolerance, and surface finish. Our scope is precision components, not complete machines.
