Revimac Stirrers in Vetri Speciali

13 July 2020




One of the most common problems in the glass industry is the Zirconium cord presence down the glass flow, commonly knowns as cat scratches.

This situation is usual with fused cast refractory, which tend to exude especially in the furnace, but also from working ends or forehearths.

This zirconium parts exuding from the refractories are heavier than glass, and sink in the channel bed forming a line, that will cause visible defect on the container if not properly treated.

This phenomenon uses to increase when refractories are close to the end of their campaign-life, and so when the structural integrity of furnace and channels is secure, using stirrer mechanism could help to increase glass quality.

But there are other good reasons to stir the glass, such as to enhance glass temperature homogeneity or when we colour glass in the forehearth; In this case it will be mandatory to install a few lines downstream the frit injection point.


To address the above-mentioned issue Revimac developed its first solution many decades ago by providing to glass factory a mechanism that will stir the molten glass in the equalizing zone.

Recently we update our stirrer design with the new RST20. With this recent evolution, our system is now adopting gear-driven blade to increase longevity and reliability.

We precisely address our effort into provide a solution capable to reduce maintenance operation to the minimum, precisely because of the harsh environment this mechanism is located.

The most common set-up will be by using twin, counter-rotating, over-lapping paddle type stirrers, but many different combinations are available.

It’s possible to choose between solutions with 1, 2, 3, or 4 heads (stirrer) depending on the size of the forehearth channel and the needs of the customer.

This last version have been chose even from Vetri Speciali, in their San Vito al Tagliamento plant where they installed Revimac RST20 stirrer mechanism in 5 lines.

Mechanical structure:

  • Steel frame (portal) to be installed in the equalization zone;
  • Manual hoist winch for lifting and lowering the stirrer heads;
  • Stirrer unit single or double (1+2, 2+1, 2+2) including saddle, air-cooled electric motor, transmission with protective cover, refractory stirrer housing head.
  • Gear driven blade.

Control system

  • Main Cabinet featuring individual inverters with RPM counter and display, power supply, emergency circuit, signal lamps and connecting cables, manual/automatic selector.
  • Local Control Console featuring emergency, alarm, reset, start & stop buttons, local/remote selector, rotation selector and connecting cables.


  • Glass thermal homogeneity.
  • Cord removal.

For coloring forehearth there’s a specific version designed to stir the molten glass with the colorant (frit) to obtain a homogeneous coloration. Stirring station dedicated to glass coloring forehearth are customized in accordance with the pull, the temperature, the glass composition and the kind of coloring is needed to achieve.

Stirrer control unit could be integrated in the forehearth control cabinet.

Refractory stirrer

They can be of various forms and types, the Revimac RST system is compatible with all models in the market.

They can be screw type, or paddle type.

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