I I.I - GENERAL ASPECTS

Finishing consists of removing excess parts of sanitaryvvare during casting and the correction of any defects arising from the moulding or handling processes. The main defects that finishing aims to correct are (Fig. 212):

Casting burr: these seams' form along the coupling surfaces of the moulds. An intrinsic defect of the process, it is much more evident when working with plaster moulds on account of the wear that rounds off the edges. It has been calculated that using a resin mould reduces finishing limes by 20-30%;

Functional holes: finishing involves sealing off those apertures used for the actual easting process, yet also involves making other holes that will allow the finished sanitaryware item to be used properly. These holes are made with sharp punches or in the mould directly as part of the casting process (fig. 2 18);

Defects such as air holes, water droplets or unsightly blemishes with other causes. Other defects eliminated include small cracks or deformations.

Bava brida estorna External rim burr

Fig. 212 - Amis of Mnifaryivare item requiring[finishing.

Finishing is generally a two-stage process:

(ireen finishing (i.e. immediately after removal from tin- mould);

White finishing (i.e. with the piece already dried).

finishing may he done manually or by robots or other machines/devices.

Resin moulds are unaffected by wear and therefore ensure that the external dimensions of the unfinished piece remain constant, giving highly reliable piece positioning performance, a must for automation of the process.

Date: 2015-04-20; view: 1577