DIFFERENCES BETWEEN THE METHODS OF PRODUCING FRP TANK PANEL

SMC (HOT PRESS)

COLD PRESS

HAND LAY

DEFINITION

Hot pressing is a high-pressure, low-strain-rate powder metallurgy process for forming of a powder or powder compact at a temperature high enough to induce sintering and creep processes. This is achieved by the simultaneous application of heat 150'C hot pressure.

Resin is mixed with a catalyst or hardener if working with epoxy, otherwise it will not cure (harden) for days/weeks. Next, the mould is wetted out with the mixture. Additional resin is applied and possibly additional sheets of fibreglass. To finish the process, a weight is applied from the top to press out any excess resin and trapped air. Stops (like coins) are used to maintain the thickness which the weight could otherwise compress beyond the desired limit.

The fibreglass mats are pre-impregnated with chemical, pre-formed to the shape of the panel, and the excessive materials at four corners are trimmed off, placed inside a bottom mould with cavity, attached to the bottom platen of the press, after the desired number of layer of fibreglass mat have been positioned, pre-compounded and measured volume of resin is poured into the bottom mould.

HYDROSTATIC PRESSURE

up to 6 times

non-standardized

non-standardized

DURATION OF PRODUCING A PANEL

5 to 10 MINUTES depending on the panel thickness

7 DAYS depending on the panel thickness

5 to 7 DAYS

CONCLUSION

Using advanced technology. Simpler in term of manufacturing process for the moulder and less potential human error. It has better flexural strength which is more ideally  suited for use as water storage tank.

Ideally for small production run or one-off. The disadvantages are the control in terms of resin mix, and the type of resin used, and ensuring the total removal of air bubble are very dependent on the person who carried out this work. Another deficiency is the dimensional stability may be an issue if the product is de-mould prematurely.

The disadvantaged is the possibility of ultra-violet degradation of the panel.