Count shot weight, colour changes and regrind for every bucket, mug and storage box.

Household plastics are sold on weight, shine and colour range. A bucket that runs a few grams light looks the same on the shelf, but a shop owner who weighs it by hand in the back of the store will not reorder. The saving went to the resin and nobody measured it.

Household plastics manufacturing software connects the mould, the resin lot, the colour and the shot weight on every run. The moulding floor, the resin store, the tool room and the packing section all read one job record, so the question of which mould made a batch has one answer. Take one bucket. Trace it from granule to nested stack.

Resin arrives as polypropylene, HDPE or LDPE granules in bags or silos. Masterbatch is added in a measured ratio to give each colour. Regrind from sprues and rejects is blended back at a set share, which the supervisor decides by experience and by the look of the first piece. A mould sits on an injection machine, or a blow moulding line for jugs and bottles. The setter fits the mould, sets temperatures and cycle time, and runs first-off pieces until weight and finish are accepted by the supervisor on duty. Then the run starts.

Production runs through the shift, with shot weight sampled and rejects set aside for regrinding. Colour changes are frequent, sometimes six in a shift on one machine. Purging between them wastes resin. Products are trimmed, sometimes printed or hot stamped with a brand, and nested or packed into bags and cartons by a crew that counts by eye. Wholesalers and retail chains order by colour and size, and dispatches go out on delivery notes, often split across several vehicles and many towns in a single week. Orders repeat.