Reverse osmosis membrane production
the manufacturing cycle of reverse osmosis filters for water filtration involves some known hitches: -a lot of manual work has to be performed by qualified labors; -required materials fragility makes manual handling a very hard task; -membrane quality depends too much on human factors (skills, fatigue, concentration,…). Solving these problems means achieving high quality standards and costs saving.
a brand new automatic plant has been designed to produce RO membranes, performing with extreme accuracy all required operations: flat-sheet and brine-spacer handling, membrane construction, glue dispensing and final taping. Flat-sheet and brine-spacer are unrolled, cut and folded to form bundles where one layer of brine spacer is inserted in one folded flat-sheet. Each bundle is inserted and glued between two sheets of tricot up to the proper amount: the whole membrane is then rolled accurately and finally closed with coating tape. Manpower is assigned only to loading/unloading tasks: getting tricots and core-tubes ready on the handling equipment and picking of taped membranes. Even materials consumption is taken automatically under control: if a component is coming to an end, an alarm occurs and the operator can quickly replace it with no time loss.
some distinctive features of this solution must be outlined:
– accuracy and smoothness in material handling preserve membranes from damages and scratches;
– quality depends on an accurate and tireless automatic machine;
– manpower is drastically reduced to simple loading and unloading tasks;
– production cycle can be easily adjusted to actual raw material characteristics.
a distinctive feature of our plant is the use of simple equipments to handle membranes: each equipment is initially set up by the operator with one core-tube and one tricot and henceforth this device follow that membrane through all the manufacturing steps. As the plant presents an in-line configuration, both the loading and the unloading of the equipments are located on the one edge, in a logical nearness; a Cartesian robot is responsible for their movements through the various stations of the machine. The first step is the membrane construction table: here a second Cartesian robot unwrap one sheet of the tricot at a time and lay it down on a stainless steel flat surface. In the meanwhile, on the other edge of the machine, flat-sheet is unrolled up to the required length and then bent: between the two layer of the folded flat-sheet the machine insert a layer of brine-spacer. This particular “bundle” is dragged towards the construction station, inserted in its required position between tricot sheets and then glued on them. All these steps are automatically repeated with high accuracy for the expected number of times. The whole membrane is then smoothly rolled with no scratches or damages and transferred to a fully automatic taping station: maximum care is taken to keep constant both tape tension and step. That’s the final phase and membranes are now cylinder-shaped with a diameter max around Ǿ = 200mm. All these operation are regulated by easy-to-change parameters available on the HMI: tuning the machine to fit production requirements it’s child’s play. Moreover changing type of membrane to produce takes just few simple operations on the touchscreen. Finally particular care has also been taken to operator safety, as required by current regulations, without forgetting an easy interaction with plant devices.