Melamine Paper MDF lamination Factory Consultancy

MDF Board and Melamine Paper Lamination Solution

Key Terms:

1. Melamine Formaldehyde:
2. urea-formaldehyde;
3. 2nd (Secondary) Melting
4. 2nd (Secondary) Melting Point
5. Low-Density MDF/HDF

In standard MDF, PB, and plywood construction, MF/UF is used as the veneer or wood-fiber adhesive; similar materials bond more readily. Decorative printed paper is therefore commonly impregnated with the same type of resin. MF can remelt at 180 °C under pressure, which is the basis of melamine impregnation.

From a process perspective, melamine-formaldehyde resin needs time to penetrate the paper's fiber mesh; this is the paper's permeability. MF resin in the paper core then hardens according to its curing-time profile. In line design and operation, the front 2 ovens and rear 4 ovens form the classic configuration. Where workshop length is limited, a 2+3 oven configuration may be used, but avoiding melamine overheating or underheating, excessive residual vapor, or an overly brittle paper surface becomes more difficult.

Melamine-formaldehyde resin will remelt at the stated temperature of 180 °C. This is called its 2nd melting point; at this temperature, MF resin from the melamine paper can penetrate the MDF/PB/veneer fiber structure. This property underlies the melamine short-cycle lamination press and door-skin press. After cooling from this 2nd melting point, the melamine paper on MDF solidifies; a higher cooling rate produces greater surface gloss in the melamine crystal. This is why a cooling-hedgehog device is used in high-volume production.

In short cycle lamination press, and also Door skin press, the common factor need to be considered is, hot platen transfer heating to melamine paper melting, also heating the base MDF, pressure will also push melt MF forced running into inner MDF; the only difference for Door skin and MDF lamination is: Door skin need two step treatment to avoid paper crisp, first punch and get loose MDF marked in frame door skin shape, then apply paper and let two parts melt and solid together; while for MDF lamination, only one time is finished.

Here, loose MDF/HDF, mean less density MDF/HDF, in previous, MDF/HDF need special soften by chemical agent then be treated in above mentioned two steps method. And now, tailor made loose MDF/HDF is softer than normal one, easier to get Door skin mold Shape before meet melamine paper, this guarantee the ratio of qualified finishing.

Production Capacity of the Melamine Impregnation Line

Standard 4 ft 2+4 model impregnation line, at 80 gsm paper, 120% pickup, suitable for MDF content, whole line speed at min. 20 m/min, it will be 20 m/min x 60 min x 20 hr /2.44 meter = 10,000 sheet

For 4 ft 3+5 model, the speed is min 25 m/min, it will be 25 m/min x 60 min x 20 hr /2.44 meter = 12,500 sheet.

If the décor printed paper property is good, glue by experienced formula with very good permeability, also 100% of resin add-on, 2+4 can run at speed at 25 m/min, 3+5 can run at speed of 30 m/min.

Above also says, impregnation line speed is subject to paper property, resin properties, and resin add-on requirement. In general, for MDF paper, the resin add-on about 100-120%, for particleboard, it is about 125-135%. These conditions require different operating speeds.

Melamine Short-Cycle Lamination Press

Melting time is a key concept in lamination. On a flat heating profile at 180 °C, melamine resin normally requires 13-18 seconds to melt; the time depends on the resin formulation and the percentages of MF and UF.

Pressing time: during 2nd (secondary) melting, liquid MF resin penetrates the MDF/PB surface under pressure. The required duration depends on pressure in kg/cm², raw-board structure, and surface smoothness; the stated rule is normally 1 second per 1 mm of base-board thickness.

Loading time: plain board is transferred into body of main press for heating and pressing.

Hydraulic station force preparation and action speed, this is also factoring to determine short cycle laminating process. In some design, accumulator is adopted to shorten a little for pressure re-preparation from valley to summit.

Above factors cause the capacity of Short cycle laminating press as 40-50 second per cycle, 1.2 sheets per minutes. Or say basically 70 sheets per hour.

If high speed servo belt conveyor is adopted, and accumulator in hydraulic station, the capacity will increase to 80/90 sheets.

Super capacity of short cycle lamination presses especially refer to more than 100 sheet/hr model, the press cost will greatly be increasing.

For basic short cycle laminating press, 70 pcs x 20 hr = 1400 sheets per day, or say 70-80 sheet per hour.

Door Skin Press

Its principle is short cycle laminating press alike. There are two factors need to be considered:

1. why two steps treatment. Two steps treatment, means, first only thin MDF board in to mold and get door skin mold shape and curing mark. Due to paper and MDF inner expanding ratio is different, if paper and MDF together and even slowly pressing, the paper will still easier getting broke in mold cut-off area. This will be much low ratio of qualified finishing. In real operating, thin MDF is pressing marked, then apply paper again to get door skin. This two-step method also can guarantee door skin surface uniform while not burl reflect on surface.
2. why multi press. Above two steps door skin lamination, one whole cycle needs about 3-5minutes, to increase economic effect, door skin press is designed to be multi daylight. Normally is 5DL, too many DL, the loading position of top DL is out of limits of employee’s hand range.

Capacity calculation: 60 min / 4mins x 5DL x 20 hr = 1500 sheets per day. 70 sheet per hour average.

Impregnation line, short cycle lamination presses matching balance

Short cycle lamination is normally dual side, it needs two pieces of melamine paper for one Melamine MDF finishing. 1400 sheets Melamine board, means 2800 pcs of melamine paper. In real operating, we can say one 4 ft 2+4impregnation line, need 3short cycle laminating press as production matching balance.

For door skin, due to it is one melamine paper needed, so, normally one impregnation line need 6line of door skin press getting matching balanced in production.

Other Heating Considerations

Both impregnation line, short cycle laminating press, door skin gets heating source from thermal oil boiler normally, but due to heating summit duration is long and huge for impregnation line, and shorter in frequency for lamination press. We strongly suggest different boiler for impregnation line. Don’t make same heating boiler supply for both impregnation line and lamination press.

In the coming proposal, we are to guide classic specification for impregnation line, short cycle lamination press and door skin. If high production in jumbo capacity, synchronization laser tracker, high speed loading, accumulator, vacuum un-lifter, 4-sides trimmer, cooling device can also update.