New guns improve bottle spraying at United Glass

Citation

(2000), "New guns improve bottle spraying at United Glass", Industrial Lubrication and Tribology, Vol. 52 No. 3. https://doi.org/10.1108/ilt.2000.01852cad.001

New guns improve bottle spraying at United Glass

New guns improve bottle spraying at United Glass

Keywords: Spraying, Lubricants

Miniature automatic spray guns, applying lubricant to bottles on Lehr spray lines at Harlow - one of United Glass' plants in the UK - are helping the company to improve production efficiency, reduce rejects and meet increasingly stringent customer requirements in the manufacture of glass containers. The guns are of a new type developed by Spraying Systems, whose area engineering manager worked closely with UG technical management and the suppliers of the control system to plan the installation and ensure its smooth operation.

The production lines at Harlow work continuously 24 hours a day, seven days a week, and every day some 2.7 million containers are made there. The products are bottles of various designs, supplied to many of the leading names in the drinks industry including Foster's, Bacardi and Budweiser, and it was in response to the fast-changing and individual needs of customers that United Glass reviewed its Lehr spray arrangements.

The use of sprays on these lines is well established. Their function is the application of a finely atomised coating of lubricant (a mineral-based oil mixed with water) to the neck and sides of bottles as they emerge from the Lehr at a temperature of approximately 100°C. Since imperfect coating fails to protect the bottles against scuffing and risk of subsequent breakage, while excessive wax causes problems during labelling, precise atomisation and accurate spraying have always been important (see Plate 1).

New elements here were the need to handle unusually small bottles and the desire to space bottles more closely on the conveyor, with reduced gaps between one bottle and the next and one row and the next. Closer spacing not only increases throughput, it is also more energy efficient (maintaining temperature through the annealing process) and improves the stability of the bottle rows as they are carried along.

Plate 1 A miniature automatic gun, recently developed by Spraying Systems, traversing between rows of bottles on a Lehr line at United Glass. The gun's reach and compact size allow it to deposit a fine spray precisely on target, avoiding the ring section of the bottle

The spray guns used on Lehr lines are of the air atomising type, in which the lubricant liquid is mixed under pressure with compressed air to achieve the fine degree of atomisation required. They are mounted on transverse tracks above the conveyor and programmed to traverse along each successive row of bottles. Previously-available air atomising nozzle assemblies however were too bulky for effective spraying of closely set rows. Moreover, one of UG's customers requires that no lubricant is deposited on the ring section at the top of the bottle; a condition not easy to satisfy with limited access.

Called in by United Glass to advise on these problems, Spraying Systems Limited was able to recommend a new system based on the use of their recently developed miniature automatic spray gun with a 77mm (3 inch) extension bar. The gun carries an external mix miniature flat-fan nozzle.

With this arrangement (at Harlow there are two of these guns on the traversing spray head on each Lehr line) the spray nozzles reach down between the rows of bottles, positioned to deposit a finely atomised spray precisely on target with no overspray of lubricant on parts of the bottle where it is not wanted.

The new spray gun (ref. 1/8JJAU) is available with a choice of spray angles from 25 to 95 degrees. Liquid pressures range from 0.3 bar to 1.5 bar and liquid flow rates from 2.7 l/hr to 12.6 l/hr. An important feature when spraying waxy liquids is that - despite its compact design - it can incorporate an automatic cleanout needle which operates on every on/off cycle. At Harlow, the gun is programmed to stop spraying at the end of a row before spraying the next row in reverse, so the orifice is automatically cleaned each time.

Spraying Systems are represented world wide and have operating companies in a number of countries. Spraying Systems Limited are based at 4 Bourne Mill Industrial Estate, Guildford Road, Farnham, Surrey GU9 9PS, UK. Tel: +44(0)1252 727200; Fax: +44(0)1252 712211.