Step 1: Raw Material Preparation & Chipping

Logs or wood processing residues are fed by a chain plate conveyor into a drum or disc chipper, where they are cut into specified wood chips. The chips then pass through a trommel screen to remove oversized chips and fine dust, while a magnetic separator removes metal contaminants, providing clean and uniform raw material for subsequent fiber preparation.

Step 2: Fiber Preparation

Qualified wood chips enter a preheating bin (digester), where they are softened under high-temperature high-pressure steam. The softened chips are then fed into a refiner, where high-speed rotating plates separate them into wood fibers. The fibers pass through a classifier to select those with appropriate length and fineness – thick boards require longer fibers, so more long fibers must be retained to enhance core layer bonding strength.

Step 3: Gluing & Drying

The separated fibers are metered into a gluing system and mixed with a precise ratio of adhesive (UF, MDI, or melamine-modified glue). The glued wet fibers enter a flash tube dryer, where they are instantly dried to target moisture content (typically 8–12%) by high-speed hot air, while carrying away uncured free formaldehyde. The dried fibers are collected by a cyclone separator, ready for mat forming.

Step 4: Thick Mat Forming (Critical Section)

Dried fibers first accumulate in a gravity metering bin, then are fed into a mechanical + air-flow combination former. The former uses multi-layer repeated spreading to build a thick mat up to 100–250mm in height. During forming, an online density detector continuously monitors the cross-sectional density distribution and automatically adjusts the discharge rate of the forming heads. This ensures that the density deviation from the bottom to the top layer of the mat is controlled within ±3% – the key to preventing delamination and soft core in thick boards.

Step 5: Pre-pressing & Hot Pressing

The loose formed mat first enters a pre-press, where low-pressure compression expels air from the mat and increases its strength for transport. The pre-pressed mat is then fed into a continuous press or a multi-opening batch press. For 20–40mm thick boards, the hot pressing system uses a gradient temperature and pressure curve: low pressure for degassing in the initial stage, high pressure and high temperature in the middle stage to fully cure the core layer, and finally pressure release to relieve internal stress. In a continuous press, precise control of the steel belt opening height and line speed ensures that the core layer reaches the full curing temperature (120–140°C) throughout the entire pressing cycle, eliminating delamination and blistering.

Step 6: Raw Board Cooling & Conditioning

The hot-pressed raw board still has a high temperature (approx. 70–90°C). It enters a cooling star turner for forced air or water cooling. After cooling, the raw boards are transferred to an intermediate conditioning warehouse, where they rest for 48–72 hours under normal temperature and pressure. This conditioning process allows moisture redistribution within the board, continued resin cross-linking, and gradual release of internal stress, significantly improving dimensional stability and machinability.

Step 7: Thickness Sanding

After conditioning, the raw boards enter a wide belt sander, typically configured for double-sided or multi-head sanding. Coarse abrasive belts remove the loose surface layer, while fine belts perform precision thickness calibration. An online thickness gauge continuously measures board thickness and automatically adjusts the sanding head pressure, controlling the finished board thickness tolerance to within ±0.3mm, while achieving a smooth and flat surface.

Step 8: Cutting & Stacking

The sanded boards are cut to customer specifications using cross-cut and side-cut saws, trimming the edges and dividing them into standard-sized panels. Finished boards pass through online inspection (thickness, density, appearance). Qualified boards are then stacked by grade using an automatic stacker, wrapped with stretch film or strapped with packing bands, and stored in the warehouse ready for shipment.

1. Complete core curing  

  Gradient hot-pressing process and multi-zone temperature control ensure core layer reaches full curing condition for 20-40mm boards. Internal bond strength ≥1.2 MPa, no delamination or blistering.

2. Uniform density through thickness  

  Special thick mat forming system combined with online density feedback achieves smooth density transition from surface to core, deviation ≤±3%, preventing edge chipping or soft core during machining.

3. High capacity & low energy  

  Optimized pressing cycle for thick boards (adjustable continuous press line speed) reduces energy consumption per m³ by 12-18% compared to traditional thick board lines.

4. Excellent flatness  

  Large-diameter press rollers/platens with precision thickness control achieve board camber ≤1.5mm/m, ready for precision processing without extra straightening.

5. Flexible configuration  

  The same line can produce both standard MDF (2.5-20mm) and thick MDF (20-40mm) – one machine for multiple applications.

Q1: How long does installation and training take?  

A: Complete plant installation takes about 4-6 months (including civil work guidance), on-site commissioning and trial production 2-3 months, and operator training 4-6 weeks until independent production.

Q2: Can this line produce both thin and thick boards?  

A: Yes. By changing the former metering device and adjusting press parameters, the same line can produce MDF across the full thickness range of 2.5-40mm. However, we recommend customers specify their main thickness range for optimal configuration.

Q3: Are thick MDF boards prone to delamination or blistering?  

A: No. Our line is equipped with a gradient pressure/temperature control system and online density monitoring, plus customized adhesive formulations. Delamination and blistering rate can be controlled below 0.5%.

Q4: Are there special raw material requirements for thick MDF?  

A: Yes. Thick boards require higher fiber quality. We recommend a mix of softwood and hardwood (e.g., pine + poplar), with fibers ≥2.5mm accounting for >60%. We provide raw material optimization advice.

Our contacts:

Whatsapp: +8618769900191  +8615589105786  +8618954906501

Email: osbmdfmachinery@gmail.com