Tube Fabricating: Danner vs Vello
Glass tubes are used in many different industries from medical storage vials, to electric bulb housing, and beyond. Many factories focus exclusively on fabricating glass tubes rather than creating a variety of glass products. Focusing on one specific task can be cost effective because it allows a factory to use equipment just for the creation of tubes and it does not need to stock other glass fabricating equipment.
In the glass fabricating industry, there are two main processes used to create tube glass- the Danner method and the Vello method. Both manufacturing methods are still in use today.
The Danner manufacturing method heats the glass in a furnace until it is soft and pliable, but not fully melted. The flows in a ribbon to a refractory sleeve, which is turned by a blowpipe or rotating hollow shaft. The glass ribbon becomes wrapped around the sleeve creating a smooth layer of glass. The smooth glass travels away from the sleeve and travels through a drawing machine. While this occurs, a blowpipe fills the center of the glass with air, creating the tube shape. The draw machine continues to shape the tube until it takes on the desired properties of the design.
In the Vello manufacturing method, glass travels out of the furnace into a bowl with a hollow mandrel. The glass travels through the air space between the mandrel and bowl, which creates the tube shape and is transported by rollers to a drawing machine that could be over 200 feet away from the furnace. This cools the tube and allows it to travel straight to cutting and processing at the end of the line. In general, the Vello process is better for high production applications, while the Danner process is ideal for precise, small-batch tube orders.