I. Core Production Process Overview

The entire production process is a continuous, highly automated operation, which can be summarized into the following core stages:

Raw Material Preparation → Fiber Preparation → Forming & Pre-pressing → Hot Pressing → Cooling & Finishing

II. Detailed Stage-by-Stage Breakdown

1. Raw Material Preparation Stage

  Process Description:

      Wood raw material (e.g., small-diameter wood, branches, wood residues) is fed via a conveyor belt into a Chipper, where it is cut into uniformly sized wood chips.

      The chips pass through a Screening System to remove fine dust and oversized pieces, ensuring only consistent, qualified chips proceed to the next stage.

  Relation to Flatness :

      Uniform chips are the foundation for producing consistent fiber. Chips of varying sizes will soften unevenly and produce fibers of different quality during refining, leading to an uneven mat density later on, which adversely affects flatness and internal bond strength.

2. Fiber Preparation Stage - The "Heart" of the Line

  Process Description:

  （1）  Chip Washing & Pre-heating: Screened chips are fed into a Pre-heating Bin where they are treated with low-pressure steam to soften and increase plasticity, facilitating fiber separation.

  （2） Defibration: The pre-heated chips enter the core of the Defibrator – the Digester. Here, they are rapidly cooked under high-temperature (typically 170-185°C), high-pressure saturated steam, which softens the lignin. The chips are then fed into the Refiner, where they are separated into individual fibers under tremendous mechanical force.

   3.  Resin Blending & Drying:

          Blending: The separated fibers are mixed with precisely metered resin (e.g., Urea-Formaldehyde UF or Isocyanate PMDI), wax, and other additives in the blowline, ensuring uniform coating.

          Drying: The moist fibers enter a Pipeline Dryer, where they contact high-temperature air, reducing the moisture content from ~50% to 8-12% within seconds, resulting in dry, resin-coated fibers.

  Flatness Assurance Point 1: High-Quality Fiber & Precise Resin Blending

      Fiber Quality: The defibrator must produce fibers with good length-to-width ratio, minimal damage, and uniform morphology. Overly fine or broken fibers compromise mat consistency and internal bond, leading to potential deformation.

      Blending Uniformity: Resin must achieve microscopically even distribution on every fiber. Any inconsistency causes localized under- or over-curing, creating internal stress points that can lead to warping when environmental humidity changes.

3. Forming & Pre-pressing Stage - The "Foundation" of Flatness

  Process Description:

      The dry fibers are spread evenly by a Forming Head onto a moving caul plate to form a continuous, fluffy "fiber mat" (or blanket).

      Modern forming heads often use a combination of mechanical and air-forming techniques to ensure a perfectly uniform distribution.

      The formed mat then passes through a Pre-press, which performs an initial compaction. This removes most of the air, increases the mat's strength for transport, and establishes a consistent initial thickness.

  Flatness Assurance Point 2: Uniform, Non-Drop Forming

      This is the first decisive step for achieving high flatness. If the mat is thicker in the middle or thinner on the edges (or vice versa), even the most advanced press will produce a board with density variations, resulting in a wavy or warped surface.

      Advanced forming technology precisely controls fiber distribution, achieving excellent density uniformity across the entire width and length of the mat, eliminating edge drop, and laying the physical groundwork for uniform hot pressing.

4. Hot Pressing Stage - The "Decisive Battle" for Flatness

  Process Description:

      The pre-pressed mat enters the Continuous Press. This is the core and most valuable component of the entire production line.

      The mat passes between two massive, precision-engineered heated steel belts. These belts apply immense pressure (adjustable specific pressure) and high temperature (typically 180-220°C).

      Under the combined action of heat, pressure, and time (controlled by line speed), the resin melts and cures, transforming the loose fiber mat into a solid, dense MDF board.

  Flatness Assurance Point 3: Superior Control of the Continuous Press

      This is the most critical guarantee for high flatness.

  （1）  Uniform Pressure Distribution: Unlike opening presses, continuous presses use an array of dozens of hydraulic cylinders to apply uniform pressure across the entire board area, preventing localized high or low spots.

   （2）  Uniform Temperature Field: Heated platens and multi-zone temperature control ensure the entire board surface is heated evenly, allowing the resin to cure synchronously throughout the board's thickness. This prevents stress buildup due to temperature gradients.

   （3） Precision Steel Belts: The press's upper and lower steel belts possess extremely high flatness, surface finish, and thermal stability. They act as the "mold," directly defining the surface flatness of the board.

   （4）  Programmable Pressure/Temperature Profile: The control system can be precisely programmed with specific pressure and temperature curves throughout the pressing stages (e.g., air removal, curing, final setting). This optimizes the internal stress distribution within the mat, minimizing residual stresses which is core to preventing subsequent warping.

5. Cooling & Finishing Stage - The "Setting & Precision Machining" of Flatness

  Process Description:

   （1）  Cooling: The board exiting the press is very hot (>100°C) and plastic. It must immediately enter a Cooling Star / Turner, where it is evenly and rapidly cooled to below 50°C via forced air convection and turning. This process sets the resin and releases thermal stress.

   （2）  Conditioning: The cooled boards are typically stored in a Conditioning Warehouse for 24-48 hours. This is a vital "stress equilibration" process, allowing internal temperature and moisture to equalize fully and residual stresses to dissipate.

   （3）  Sanding: The conditioned boards enter a Multi-Head Calibrating Sander. They first undergo coarse sanding to remove the pre-cured surface layer and minor thickness variations, followed by fine sanding to achieve a mirror-smooth surface.

  Flatness Assurance Point 4: Stress Relief & Precision Sanding

      Cooling & Conditioning: Without uniform cooling and conditioning, residual internal stresses will slowly release over time due to changes in ambient temperature and humidity, causing the board to warp. This stage is the guarantee of long-term stability.

      Calibrating Sanding: The sander not only provides a perfect surface finish but, more importantly, performs the final thickness calibration and leveling. It eliminates microscopic thickness deviations (±0.1mm or less) that may have occurred during pressing and cooling, thereby finally locking in and enhancing the board's macro-level flatness.

Conclusion: Achieving High Flatness is a Systematic Engineering Feat

The main equipment for this production line can be divided into the following core systems:

I. Raw Material Handling and Preparation System

This system's task is to process raw wood material into qualified, uniform wood chips.

1.  Debarker (Optional)

      Function: If logs are used as raw material, this machine is needed to remove bark. Bark can affect board color and bonding performance and is usually removed.

      Description: Uses a drum or ring-type mechanism to remove bark by friction as logs are tumbled.

2.  Chipper

      Function: To chip wood (logs, branches, board waste, etc.) into uniform, process-ready wood chips.

      Description: Typically a disc chipper equipped with a heavy-duty disc and knives. Its production capacity is directly related to the disc diameter and motor power, making it a key front-end device determining the line's overall output.

3.  Chip Screening and Re-crushing System

     Function: To grade and screen chips, separating acceptable chips, oversize chips, and fines.

      Main Equipment:

          Screening System: A multi-deck vibrating screen that separates chips into oversize, acceptables, and fines.

          Re-crusher: Crushes the oversize chips a second time to convert them into acceptable chips, improving raw material utilization.

4.  Chip Storage Bin

      Function: To store screened, acceptable chips, providing a buffer for continuous, stable production and ensuring uniform feeding to subsequent stages.

II. Fiber Preparation System

This is the "heart" of the production line, responsible for transforming wood chips into qualified, resin-coated dry fibers.

1.  Chip Washing and Pre-heating Unit

      Function: To remove impurities like sand and stones from the chips and pre-soften them with low-pressure steam, improving fiber quality and reducing refiner plate wear.

2.  Defibrator System (Refiner) This is the core of the core.

     Function: To soften chips under high-temperature, high-pressure steam and separate them into fibers via mechanical grinding, while simultaneously blending resin and other additives evenly with the fibers.

      Main Components:

          Pre-heating Digester: Treats chips with saturated steam for thorough softening.

          Defibrator (Refiner): The core equipment, including precision refiner plates. Separates softened wood into fibers under high power drive. Its power and specifications directly determine fiber output and quality.

          Resin Blending System: Uses high-precision metering pumps and nozzles in the blowline to evenly spray resin, wax, and other additives onto the fibers.

          Discharge Valve/Blow Valve: Controls the discharge of fibers from the high-pressure refining chamber to the atmospheric-pressure drying tube.

3.  Fiber Drying System

      Function: To rapidly dry the resin-coated, high-moisture fibers to a suitable moisture content (8-12%).

      Main Equipment:

          Pipeline Dryer: Fibers are conveyed and dried in a suspended state within a high-temperature air duct. Equipped with a hot air furnace, fans, cyclones, etc.

          Dry Fiber Storage Bin: Stores dried fibers, acting as a buffer and balancing capacity between preceding and subsequent stages.

III. Forming and Pre-pressing System

This system forms the dry fibers into a "blank" with the initial shape of a mat.

1.  Forming Machine

      Function: To spread dry fibers evenly and steadily onto a moving caul plate, forming a continuous mat with consistent thickness, uniform density, and no edge drop.

     Description: Uses advanced mechanical or air-mechanical composite forming heads, consisting of scanning devices, metering belts, and the forming head itself. It is the first key piece of equipment for achieving high flatness.

2.  Mat Pre-press

     Function: To perform an initial cold pressing of the fluffy mat, removing most of the air, increasing the blank's strength for transport, and establishing the initial thickness.

      Description: Usually a continuous belt pre-press or a single-opening pre-press.

3.  Mat Scale and Metal Detector

      Function: The mat scale checks forming density online and provides feedback to adjust the former. The metal detector identifies and rejects any metal contaminants in the mat to protect the expensive press belts in subsequent stages.

4.  Caul Plate Return System

     Function: After carrying the formed and pre-pressed mat into the press, the empty caul plates are cycled back to the front of the former via an underlying conveyor line.

IV. Hot Pressing and Curing System

This is the most technologically advanced and capital-intensive part of the line, and is the decisive stage for high flatness.

1.  Continuous Press

      Function: To subject the mat to precisely controlled temperature, pressure, and time while it moves continuously, curing the resin and bonding the fibers firmly into a dense board.

     Description: This is the ultimate equipment for achieving high output, high quality, and especially high flatness. 

It consists of the following key components:

         Steel Belts: Precision components with extremely high flatness, surface finish, and heat resistance, acting as the "mold" for the board.

          Heating Platen System: Provides uniform heat, often divided into multiple temperature zones for precise control.

          Hydraulic Pressure System: Comprises dozens or even hundreds of hydraulic cylinders forming a vast pressure array, allowing for precise pressure profile control along the board's length and width.

          Main Frame and Roller System: Supports the enormous pressing force and drives the smooth operation of the steel belts.

V. Finishing and Sanding System

Processes the pressed rough board into a sellable product.

1.  Cooling Star / Turner

       To rapidly and uniformly cool the high-temperature boards exiting the press, setting their shape, releasing thermal stress, and preventing deformation.

2.  Longitudinal and Cross-Cut Saws

      To cut the continuous board strip into preset widths and lengths (e.g., 1220x2440mm).

3.  Stacker

      To automatically stack the sawn boards into neat piles.

4.  Intermediate Storage System (Conditioning Warehouse)

      Allows stacked boards to rest for 24-48 hours, enabling further equilibration of internal stress and moisture content. This is a crucial step for ensuring the board's long-term dimensional stability and preventing subsequent warping.

5.  Sanding Line

     To perform thickness calibration sanding and surface finishing on the boards.

      Main Equipment:

          Multi-Head Calibrating Sander: Typically with 4, 6, or more heads. The first few heads are for calibration and coarse sanding to eliminate thickness deviation; the latter heads are for fine sanding to achieve a high-quality surface finish. This is the final process for achieving the ultimate macro-flatness and perfect surface.

6.  Final Cutting and Packaging System

     To perform final cutting of the sanded boards according to customer requirements, and to carry out automatic film wrapping, strapping, and packaging.

VI. Central Control System

  Function: This is not a standalone machine but the "brain" distributed throughout the entire line.

  Description: Uses a Distributed Control System or large PLC to monitor, record, and automatically adjust the operating parameters (speed, temperature, pressure, metering, etc.) of all equipment in real-time, ensuring the entire production line operates stably and efficiently on the optimal process curve.

Summary: This production line is a complex system where all the above precision equipment work in coordination. From uniform chipping to precise forming, to the ultimate control of the continuous press, and finally through stress relief and precision sanding, every single piece of equipment contributes to achieving the two core objectives: "Daily Production of 900 cubic meters" and "High Flatness".

  Economies of Scale: Large single-line output significantly reduces unit production costs.

  Exceptional Quality: High flatness and stable physical properties meet the demands of high-end furniture, interior decoration, and export markets.

  Economic Operation: High automation reduces labor dependency; the continuous press offers low energy consumption and high material yield.

  Environmental Compliance: Equipped with advanced waste gas and water treatment systems to meet stringent environmental regulations.

  Investment Value: Represents a technologically mature and reliable large-scale modern production line with a solid return on investment.