Home > News > Content
MDF Medium Density Fiberboard Is Based On Wood Fiber Or Other Plant Fiber As Raw Material, Broken, Fiber Separation
May 15, 2017

 MDF board Medium density fiberboard is made of wood fiber or other plant fiber as raw material, broken, fiber separation, drying urea urea or other suitable adhesive, and then made by hot pressing a man-made sheet. Its density is generally in the range of 500-880 kg / cubic meter, the thickness is generally 5-30 mm

    MDF board Medium density fiberboard is the mid-sixties developed products, in recent years the rapid development of production. Because it has excellent physical and mechanical properties, decorative properties and processing performance.

  Medium density fiberboard production process is the first step in preparation, equipment mainly chipper, belt conveyor, screening machine, bucket elevator, storage silos and so on. The raw material of the MDF is mainly wood fiber raw material, which includes small diameter wood, branch material, firewood material, processing residue, ideal raw material for the coniferous wood 60% ~ 70%, 30% ~ 40% Skin content should not exceed 5%.

   MDF board Preparation of fiber is mainly fiber separation, MDF production process is the core link. The equipment used for the separation of the fiber has a wooden silo (or preheated silo), a small hopper, a hot mill, a paraffin melting and application device, and a sizing metering device.

    MDF board The steps of fiber separation:

A: hot grinding. The qualified wood chips are transported into the wood chips and the chips are softened by cooking and transported to the grinding chamber. After the hot mill compressed wood chips, the moisture content of the wood extrusion of the higher moisture.

B: waxing. The paraffin wax is melted by the steam coil, and the melted paraffin is pumped into the wood chips before the grinding chamber body. After separation into the fiber, the paraffin is distributed evenly on the fiber surface.

C: sizing. Urea-formaldehyde resin through the examination device, the glue pump into the double metering tank, and then into the pump input discharge tube, the fiber sizing, discharge pipe fiber in the high-speed flow state, glue into atomization, even spray in the fiber surface. Glue can be added to the curing agent, formaldehyde capture agent, such as stirring.

3, dry

MDF production process Drying process The main equipment is dry host, drying pipe and cyclone separator, fiber conveyor, dry fiber silo and other components. Hot mill discharge pipe inhalation drying pipe wet fiber, and hot air full contact, the fiber was suspended in the duct by the air flow, the fiber running in the duct 4 to 5 seconds, the rapid evaporation of fiber moisture to meet the requirements Moisture content (8% to 12%).

4, forming

Pavement molding is a very important process in the production process of medium density fiberboard. This process includes slab paving, preloading, pronging, cross section and so on. The requirements of pavement process are: slab density is uniform and stable , Consistent with the thickness of the slab weight per unit area on the control of consistent stability, with a certain degree of density.

5, hot pressing

At present, the domestic production of high-density fiberboard hot pressing process for the intermittent multi-layer hot pressing process, a variety of process factors have an important impact on the performance of MDF.

A: Hot pressing temperature. The choice of hot pressing temperature is mainly based on the type and performance of the board, the type of adhesive and the production efficiency of the press. Selection of temperature depends mainly on the level of raw materials, tree species, fiber moisture content, adhesive properties, slab thickness, heating time, pressure size and equipment conditions comprehensive factors.

B: hot pressing pressure. The hot pressing pressure is changed during the hot pressing process, and the pressure is gradually increased when the pressure is applied to meet the slab thickness requirement, that is, the pressure should be reduced, and the curing of the adhesive, the formation of various binding forces between the fibers, Low pressure section to complete, the pressure of the low pressure section generally take 0.6 ~ 1.3Mpa.

C: hot pressing time. The determination of hot pressing time is mainly related to the properties of the glue and the curing time, fiber quality, slab moisture content, thickness, hot pressing temperature, pressure and other factors. The hot pressing time is generally expressed by the time required for the 1 mm plate thickness.

D: moisture content of slab. In the hot pressing process, the role of moisture in the slab is to increase the fiber plasticity and thermal conductivity, so the appropriate moisture content of the quality of the board is guaranteed, generally controlled at about 10%, if too high will make the table, core density Gradient increase, the core fiber adhesion MDF board between the poor, step-down exhaust, the water vapor is difficult to rule, resulting in the plate bubble, stratification, if too low will make the board soft, pre-curing layer thickness, board strength