The desire to maintain the stirring efficiency of ceramic stirrers remains common amongst glass manufacturers worldwide. In spite of today’s modern stirring systems, it is still normal for engineers to remove ceramic stirrers after a relatively short service life and find that they are faced with an eroded form, generally consisting of nothing more than a shaft.
Glass attack is no longer a problem for users of Johnson Matthey’s Advanced Coatings Technology, ACT™. A thin layer of platinum is deposited onto a ceramic stirrer to form an impervious layer, protecting the ceramic from continuous glass erosion. Virtually any form of stirrer can be coated from complex helical and paddle forms to relatively simple pins.
ACT™ coatings will extend the service life of any stirrer considerably (see our service history list for more details). Fewer changes lead to a reduction in downtime.
The coated components do not change in shape while installed. This results in a dramatic improvement in stirring efficiency over time.
The dissolution of ceramic particles into the finished product is eliminated. This is of particular importance to producers of high quality glass compositions.
The coating process is extremely flexible, enabling manufacturers to consider the use of complex forms.
ACT™ coatings can be thickened to provide protection where it is needed most, such as at the glass line. Thinner coatings can be deposited above the glass line to provide protection from condensate.
Stirrers for colouring forehearths:
Banks of ACT™ coated stirrers can be used in colouring forehearths to mix coloured frits into the glass. Uncoated stirrers lose their form relatively quickly and become less efficient at homogenising the glass during each colour change.
This ACT™ stirrer ran next to two uncoated ones for 92 days and 11 colour changes and was in perfect condition on removal.