Tin Can Milk Powder Filling Line

Milk powder and similar blends are sensitive to oxygen, which drives oxidation of fats and shortens shelf life. The seamer pulls a vacuum on the headspace and backfills it with nitrogen before closing the can, leaving a residual oxygen content of 3 percent or less. The nitrogen supply has to be clean and dry: the published requirement is a purity above 99.99 percent at 0.4 MPa, with about 10 cubic metres per hour for each seaming unit.

Each dual-head vacuum nitrogen seamer runs at 12 to 14 cans per minute, which is slower than the filling station, so the seamer becomes the constraint. The published line capacity of 12 to 48 cans per minute is therefore achieved by running several seamers in parallel: with three dual-head seamers the line runs at about 36 cans per minute. Adding a fourth raises the ceiling further.

The line handles 300, 307, 401 and 502 cans with a height of 60 to 200 mm, for fill weights under 1,500 g in standard seaming. Changing the moulds on the filling machine and the vacuum nitrogen seamer allows a different can specification to run, so a plant packing more than one size can cover both without a second line.

The line publishes a weight-based tolerance: within plus or minus 1 g for fills between 100 and 500 g, and within plus or minus 2 g for fills of 500 g and above. Filling is done by a dual-head weigher, so the dose is set by the measured weight rather than by a fixed volume, which is what keeps the accuracy stable as powder density changes.

The published configuration runs to about thirty-four stations, from the bag dismantling table, sterilising conveyor and powder handling group through the vacuum feeder, mixer, metal detector and storage hopper, then into can depalletising, unscrambling, turning and degaussing, empty can sterilising, spoon feeding, dual-head filling, can separation, vacuum nitrogen seaming, can cleaning, laser coding, can turning and plastic lid pressing to the cartoning table.

All machines in the line are built in stainless steel with food-hygiene design, and the interior of every product-contact vessel is polished. Structures that are cleaned regularly use quick-release connections, so a shift change or product change is handled with a strip-down and wash rather than a long shutdown. The line follows GMP practice for canning.

A three-phase 380V 50 Hz supply with a line power of 48.33 kW excluding ancillary plant, compressed air at 1.45 m³/min and 6 kg/cm², and nitrogen at above 99.99 percent purity and 0.4 MPa, consuming about 30 m³/h when three seaming units run. Floor drainage and wash-down facilities are also needed for the cleaning regime.