Journal Archive

Platinum Metals Rev., 1983, 27, (2), 66

Platinum Components Improve Glass Container Manufacture

Advantages Result in Temperature Homogeneity and Constancy of Gob Weight

The glass container industry is continually seeking ways to improve its products, while at the same time striving to reduce its costs and improve its productivity in order to compete with other forms of packaging. For many years platinum has been widely used in the manufacture of optical glass, but a recent paper by Diether Bottger of Eglasstrek of Hochheim in the Federal Republic of Germany (Glass, 1983, 60, (1), 36–37) demonstrates its great usefulness in the production of industrial and household glass.

Efficient glass container manufacture requires the formation of a thermally homogeneous glass gob of constant weight. These two factors are very difficult to achieve and for many years efforts have been made to overcome the production problems. Electrically heated bushings made in platinum or in a rhodium-platinum alloy have been used in the fibre glass industry for more than thirty years, and this concept has now been introduced into the container field in a procedure recently patented by Eglasstrek. By arranging several platinum contact flanges at regular intervals around the platinum cylinder that acts as a connection between the spout and the orifice ring the cylinder can be heated by direct current. This enables the molten glass to be heated to a constant temperature immediately before leaving the orifice ring, which is held against the platinum cylinder by a retaining attachment. The orifice ring may then be rapidly changed at any time.

Further, the conventional plunger is replaced by a platinum coated paddle plunger, as shown in the diagram, while the use of a double plunger of the same type is also possible. In this way a thermally homogeneous gob is produced and the quality of the glass is greatly improved with beneficial results when the glass is blown. The process known as HTG, Homogeneous Temperature of Glass Gobs, is said to be suitable for all types of glass products in container glass, coloured glass, lead crystal and borosilicate glass, the advantages including flawless industrial and household glass and an exceptional constancy of weight. The author concludes that increased production and efficiency can definitely be furthered by the use of platinum components at a number of the most crucial locations.

In the process known as HTG, developed by Eglasstrek, an electrically heated platinum cylinder serves to maintain a constant temperature in the glass gob. The paddle plunger is also coated with platinum

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