Continuous Flat Press is a key equipment in woodworking machinery used in the production of man-made boards (such as particleboard, fiberboard, oriented strand board, etc.). It uses a continuous hot pressing process to press the slabs mixed with wood fibers or scraps and adhesives into high-strength, high-density boards.

1.Working Principle

The core of the continuous flat hot press is to continuously press the slab through high temperature and high pressure. Its working process is as follows:

1.1 Feeding: The slab after paving and forming is sent to the entrance of the hot press through a conveyor belt.

1.2 Preheating and pre-pressing: Before the slab enters the main pressing area, the adhesive is softened by a preheating device and the air is expelled by pre-pressing.

1.3 Main pressing: The slab enters the pressing area composed of multiple layers of hot pressing plates, and is continuously pressed under high temperature (usually 180-250℃) and high pressure (2-5 MPa) to solidify the adhesive and tightly combine the fibers.

1.4 Cooling and board discharge: The pressed board is cooled and shaped in the cooling section, and then cut into standard sizes.

2. Core Structure and Composition

2.1 Hot press plate system: Composed of multiple heating plates, the interior is heated by heat transfer oil or steam to provide uniform temperature.

2.2 Steel belt system: Two circulating steel belts (upper and lower) hold the slabs and run continuously to ensure uniform pressure transmission.

2.3 Hydraulic system: Pressure is applied through hydraulic cylinders, and the pressing force in different areas can be adjusted in sections.

2.4 Control system: PLC or computer control, real-time monitoring of parameters such as temperature, pressure and speed.

2.5 Auxiliary equipment: includes paving machines, pre-pressing machines, cooling sections, sawing systems, etc.

3.Significant Advantages in Energy Consumption 

3.1 Heat Recovery and Efficient Utilization:

  3.1.1 Continuous Operation, Reduced Heat Loss: The press operates continuously, with the mat entering, being pressed, and exiting non-stop. The heated platens remain at operating temperature, eliminating the massive heat loss associated with the frequent opening and closing of multi-opening presses (where significant heat escapes and cold air enters each cycle).

  3.1.2 Advanced Heat Recovery Systems: Modern continuous presses are typically equipped with sophisticated heat recovery systems, capturing energy from:

         （1） Press Exhaust: Steam and VOCs (Volatile Organic Compounds) released during pressing carry substantial heat, which is recovered to preheat fresh air (for drying systems), heat boiler feed water, or supply low-grade heat elsewhere.

          （2）Thermal Oil System: Heat from the return flow of the thermal oil circuit heating the platens can be partially recovered to preheat incoming oil or for other uses.

  3.1.3 High Thermal Oil Heating Efficiency: Continuous presses primarily use high-temperature thermal oil (instead of steam) for platen heating. Thermal oil systems operate at much lower pressures than steam systems, resulting in lower heat losses, higher thermal efficiency, and more precise, stable temperature control, minimizing energy waste from fluctuations.

3.2. Reduced Drive Energy Consumption:

      No Frequent Opening/Closing: Eliminates the significant energy required to operate the large opening/closing cylinders of multi-opening presses.

      Optimized Hydraulic Systems: Pressure control in continuous presses is typically more refined (e.g., zone control). Main pressure cylinders and auxiliary cylinders (e.g., for belt tensioning, steering) are designed for higher efficiency. Variable frequency drives (VFDs) also reduce pump energy consumption.

3.3  Shorter Effective Pressing Cycle (Indirect Savings):

      Continuous pressing technology often allows producing qualified boards at relatively lower temperatures and longer pressing times compared to the high-temperature/short-time cycles of multi-opening presses. Although the nominal pressing time per point might be longer, the continuous nature results in higher overall efficiency. Lower pressing temperatures also inherently reduce energy requirements.

3.4 Reduced Auxiliary Equipment Energy Consumption:

      Stable and continuous production allows supporting systems (drying, resin application, forming) to operate more steadily, avoiding load fluctuations caused by press cycling, optimizing the energy consumption of the entire line.

Compared to multi-opening presses, continuous flat presses typically achieve energy savings of 35%-40% or more for thermal energy, with significant reductions in electrical consumption as well. This drastically lowers the unit energy cost of OSB production.

4. Major Advantages in Production Capacity 

4.1  Continuous Production:

      Fundamental Advantage: This is the root cause of increased capacity. The mat enters continuously, and pressed board exits continuously, eliminating all non-productive time associated with multi-opening presses (loading, closing, pressure build-up, dwell, pressure release, opening, unloading). Production runs truly "24/7" (except for planned maintenance).

      Exceptional Time Utilization: Effective pressing time approaches 100%, whereas multi-opening presses typically have effective pressing times of only 50%-60% (the rest is spent on non-pressing operations).

4.2 High Line Speed:

      Modern OSB continuous presses operate at very high belt speeds, often reaching 1000 mm/s or more (depending on product thickness and process requirements). This translates to a very large amount of board length (or area) passing through the press per unit time.

4.3  Adaptability to Wide Formats and Thickness Range:

      Continuous presses can be designed very wide (e.g., 4ft, 8ft, or wider), producing large-format panels in a single pass, reducing subsequent edge gluing.

      Precise control of pressure and temperature in different press zones enables production of an extremely wide range of thicknesses (e.g., from 6mm to 40mm or thicker). Production efficiency for thick boards is vastly superior to multi-opening presses (which have very long cycles for thick boards).

4.4  High Yield and Stable Quality:

      Superior Density Profile: Continuous presses typically feature multiple press zones (e.g., 20+), each independently and precisely controlling pressure and temperature. This results in a more uniform vertical density profile (VDP), ideal density curves, and better, more consistent physical and mechanical properties.

      Excellent Surface Quality: The steel belt and platens provide very smooth, flat surfaces with precise thickness tolerances.

      Reduced Pre-Cured Layer: Continuous feeding and optimized temperature gradients minimize the formation of a weak pre-cured layer on the board surface caused by early heat exposure, improving product quality and yield. High yield directly translates to higher effective output.

4.5  Automation and High Efficiency:

      Continuous press lines are highly automated, seamlessly integrating with upstream forming and downstream cutting operations. The entire line operates efficiently with low manual dependency, reducing production interruptions or efficiency losses due to human factors.

A modern OSB continuous press line typically has an annual capacity of several hundred thousand cubic meters (e.g., 300,000 m³, 500,000 m³, or higher). This is a level of output completely unattainable for a multi-opening press line occupying the same footprint and manpower. Output per unit time (hourly, daily) increases by orders of magnitude.

Summary Comparison Table

Feature/Benefit	Continuous Flat Press (OSB)	Multi-Opening Press (Traditional)	Advantage of Continuous Press
Production Mode	Continuous	Batch (Cyclic)	No idle time, ~100% effective pressing
Thermal Efficiency	Very High (Efficient recovery, low heat loss)	Low (High opening/closing loss, difficult recovery)	>35-40% Thermal Energy Savings
Heating Medium	Thermal Oil (Efficient, precise temp control)	Steam or Thermal Oil	Higher thermal efficiency, more stable temperature
Production Potential	Very High (High belt speed, wide format, continuous)	Limited (Restricted by cycle time & number of openings)	Annual capacity: Hundreds of thousands m³; Multiples higher
Product Thickness Range	Extremely Wide (Thin to very thick boards)	Restricted (Low efficiency for thick boards)	Massive efficiency gain for thick boards
Quality / Uniformity	Uniform density profile, superior surface, tight tolerances	Relatively lower, potential batch variation	Higher yield, more stable performance
Automation Level	Very High (Fully integrated line)	Relatively Lower	Lower manpower needs, more stable & efficient operation