Wet end of corrugated cardboard
Core Definition
The Wet End is the core section for corrugated board forming and bonding, which produces continuous corrugated board base by preheating base paper, forming corrugations, gluing and laminating, with moisture and steam control throughout the process; the Dry End is the finishing and forming final section of the board, which completes slitting & scoring, fixed-length cross cutting and automatic stacking in a dry state to output finished board stacks meeting order specifications. The two realize speed and parameter linkage through the whole line control system, being the two core components of the corrugated board production line, and their equipment precision and process coordination directly determine the board quality, production efficiency and loss rate.
Key Equipment & Functions
|
Name |
Core Function |
| Unwind Stand | Carry roll base paper and realize stable control of unwinding tension |
| Automatic Splicer | Splice base paper without stopping the machine, ensure continuous operation of the production line and avoid shutdown loss |
| Preheater & Moisture Regulator | Steam preheat the base paper, adjust the base paper moisture to 8%-12%, eliminate base paper warpage and improve forming stability |
| Single Facer | Core forming equipment, press the core paper into specified corrugated types (A/B/C/E/F) through upper and lower corrugating rolls |
| Bridge Conveyor | Connect Single Facer and Double Backer, stably convey single-faced corrugated board and control paper conveying tension |
| Glue Applicator | Precisely apply glue to the corrugated peaks of single-faced corrugated board, control the glue amount at 6-10g/m² and ensure bonding uniformity |
| Double Backer | Core laminating and setting equipment, thermally press and laminate liner paper with glued single-faced corrugated board, dry and set through heating plates to ensure firm bonding |
Core Process Flow
Roll base paper unwinding → Automatic Splicer splicing without shutdown → Preheater & Moisture Regulator humidity regulation and preheating → Single Facer core paper corrugation forming → Glue Applicator corrugated peak gluing → Bridge Conveyor stable conveying → Double Backer liner paper + corrugated core paper thermal lamination → Drying and setting → Continuous corrugated board base output
Key Control Points
1.Moisture control: The moisture of the base paper is stabilized at 8%-12% after preheating, excessive moisture is easy to cause board blistering and debonding, and insufficient moisture is easy to cause corrugated brittle fracture and board warpage;
2.Temperature control: The preheating temperature is adjusted according to the base paper grammage (150-180℃), and the hot pressing temperature of the Double Backer is adapted to the board thickness (160-170℃ for three-ply board, 170-180℃ for five-ply/seven-ply board);
3.Glue application control: Precisely control the glue amount and keep the glue viscosity stable (adjust according to ambient temperature, 200-300cP at 25℃), avoid excessive glue overflow and insufficient glue debonding;
4.Temperature control: The preheating temperature is adjusted according to the base paper grammage (150-180℃), and the hot pressing temperature of the Double Backer is adapted to the board thickness (160-170℃ for three-ply board, 170-180℃ for five-ply/seven-ply board);
Dry end of Corrugatd Board
Core Definition
As the back-end process section of the corrugated board production line, it undertakes the continuous dry board base output by the Wet End and completes the finishing processing of the board in a dry state without moisture/steam intervention. Its core function is to process the continuous board into finished board stacks meeting the order's width, length and scoring requirements, being the key link determining the board's dimensional accuracy, appearance quality and stacking efficiency.
| Name | Core Function |
| Slitter Scorer | Core finishing equipment, realize fixed-width slitting of the board through circular knife slitting, press out precise folding lines through scoring wheels to adapt to carton forming needs |
| Cross Cutter | Fixed-length cutting equipment, realize fixed-length cutting of the board at high speed through flying shear cutting with an error controlled within ±1mm |
| Stacker | Finished product collection equipment, divided into gantry type/rotary type, automatically layer and align the cut finished boards to form standard board stacks for easy storage and transportation. |
Core Process Flow
Wet End continuous corrugated board base input → Slitter Scorer fixed-width slitting + precise scoring → Cross Cutter fixed-length high-speed cutting → Defect Remover (Optional) unqualified product removal → Counter & Marking Machine (Optional) counting and marking → Stacker automatic alignment and stacking → Standard finished board stack output.
Key Control Points
1.Accuracy control: Slitting width error ≤±0.5mm, scoring depth adapted to board thickness (avoid scoring too deep to break and too shallow to fold); cross cutting length error ≤±1mm, and the accuracy remains stable at high speed (≥300m/min);
2.Speed synchronization: The speed synchronization error between Dry End and Wet End ≤±0.5% to avoid board stretching and accumulation that cause cutting deviation and board damage;
3.Stacking control: Stack alignment error ≤±5mm, stacking height can be adjusted according to order/storage requirements to avoid stack collapse and board edge damage;
4.Order change efficiency: Support fast order change, slitting knives and scoring wheels can be quickly replaced/adjusted to adapt to the production of multi-variety and small-batch orders.
| Comparison Dimension | Wet End | Dry end |
| Process Position | Front-end forming section, basic board production | Back-end finishing section, finished board processing |
| Core Task | Corrugation forming, gluing laminating, drying setting, output continuous board base | Slitting, scoring, fixed-length cutting, automatic stacking, output finished board stacks |
| Key Influencing Factors | Moisture, temperature, glue viscosity, steam pressure, paper conveying tension | Cutting precision, scoring depth, speed synchronization, stacking alignment |
| Main Quality Risks | Blistering, debonding, corrugation deformation, board warpage, insufficient bonding strength | Dimensional deviation, scoring fracture/wrinkling, cutting burrs, messy stacking |
| Core Control Center | Wet End intelligent control system (linking preheating, gluing, Double Backer parameters) | Dry End intelligent control system (linking slitting, cross cutting, Stacker parameters) |
| Production Line Speed Adaptation | Adapt to high speed, but prone to parameter fluctuations due to base paper and glue characteristics | Stronger high-speed adaptability, precision less affected by speed (high-end equipment) |
Key Coordination Operation Points of Wet End & Dry End
1.Full Speed Synchronization
The whole line realizes real-time speed linkage between Wet End and Dry End through the main frequency conversion control system, with the synchronization error controlled within ±0.5%, avoiding board accumulation in the Dry End caused by excessive board output in the Wet End, or board stretching in the Wet End caused by excessive cutting speed in the Dry End, which leads to corrugation deformation and dimensional deviation.
2. Full Data Linkage
Modern intelligent corrugated lines are equipped with a MES production management system, where data such as board specifications (thickness, width) and production speed of the Wet End are transmitted to the Dry End in real time, and the Dry End automatically adjusts the slitting knife position, scoring depth and cross cutting length to realize unmanned order change, improve production efficiency and reduce manual errors.
3.Full Quality Closed Loop
Wet End quality determines the foundation of Dry End processing: Wet End board warpage and corrugation deformation will directly lead to Dry End cutting deviation and unstraight scoring, so it is necessary to ensure the flatness of the board base through Wet End process optimization;
Dry End data reversely optimize Wet End process: The Dry End's waste removal data (such as the number of debonded and blistered boards) is fed back to the Wet End in real time, and the Wet End control system automatically adjusts preheating temperature, glue amount and other parameters to realize dynamic quality optimization and reduce the defective rate of finished products.
4.Full Operation and Maintenance Coordination
Wet End and Dry End equipment require synchronous inspection and synchronous maintenance, such as the wear of Wet End corrugating rolls and Dry End slitting knives need to be regularly detected, and wearing parts need to be replaced synchronously; the whole line lubrication and electrical system are maintained uniformly to avoid the whole line shutdown caused by single section equipment failure and improve the production line operation rate.