The acceptance criteria for semi-refined paraffin wax NO.58 is GB/7254-1988 and for stearic acid GB9103-88.
The wax mould workshop is kept in a bright and hygienic state with a temperature between 18-25℃. Wax moulds are acquired by pressing moulding materials into the eligible die which usually bears the duration of service, owner and date of retirement on it. Moulding materials are melt by steam vapour in a bucket where solid raw materials are added into the liquid ones at the same time. By agitating the mixture, it turns into a kind of cream paste which is later kept at a temperature from 45-50℃ for later usage.
With an internal pressure of 0.2-0.5mpa, electrothermal liquid wax injecting machine are used to inject the cream paste into the die and thus produce wax moulds. Parting medium such as transformer oil or mineral oil are applied on the inner part of the dir for the easy removal of the wax mould. After being removed from the die, the wax moulds are put into water to be cooled down so that the precise dimensions and surface smoothness are guaranteed. Then the moulds are layed on a smooth floor after being in water for more than 30 minutes. The wax moulds thus acquired may have some defects and must be repaired or further attended. Moulds with big broken corner and seriously rough surface are rejected. The flashes and burrs are trimmed with a special blade. Repair is allowed in small patches of dents provided that the mould quality is assured. After repairing, all the moulds should be rid of wax scraps and other impurities by a special brush and then they are organized in a tray. After inspection, wax moulds with the same steel designation are welded onto the wax bar in a organized way firmly, forming a cluster of wax moulds. The clusters shall be void of any wax scraps and drops and then be put on a specified area. All the wax bars are firm enough and the surface is smooth without wax scraps, holes and flashes.