This article by Rudi Bittniok, Foseco, offers an overview of nozzle technologies for iron autopour and steel bottom pour applications.
Looking at steel foundries in particular, lip pouring by teapot ladles or when using bottom pour technologies, a one shot, low alumina nozzle are widespread technologies. Over the years, new long life or quick change solutions have been developed.
Cross-bore and multi life nozzle solutions have been mentioned in previous articles. Now Foseco introduces the company’s new VAPEX* FosFlow nozzle system. Finally, there is news of the newly developed zirconia nozzles, which are used for the production of metal powders for additive manufacturing using 3D printers to create complex steel structures.
ONE-SHOT NOZZLE APPLICATIONS
Those pressed nozzles (fig.2) containing 38 per cent with or without 5 per cent of graphite or up to 80 per cent alumina (no C) are mainly used as one-shot applications using a well block in a bottom pour ladle.
After the ladle is empty and the slag is removed, the nozzle is changed manually which is not an easy job to do, especially when the ladle doesn’t have a well block.
A L0–L3 well block (fig.1) is also recommended when using standard nozzle 1A–3A shape.
Foseco can supply one shot nozzle systems out of their brand names VISO (Isopressed) and VAPEX (extruded).
The Foseco range contains many pressed and cast nozzles but also different kind of nozzles that can be used more than one time. The four products mentioned in this article highlight different possibilities for longer lifetime and/or better pouring.
ZONED NOZZLES
Normally a steel foundry nozzle is a one-shot product. As the market demands improvements, the new zoned nozzle (fig.3) for multiple use has been invented.
Features of zoned nozzles
- High quality refractory material at the top for improved erosion resistance.
- Transition layer to reduce thermal expansion.
- A main layer with good thermal shock resistance.
- Inner layer for insulation purposes.
The nozzle also has a non-stick coating around the closing area.
CROSS-BORE NOZZLES
Invented nearly twelve years ago, the cross-bore nozzle technology has replaced the cheap standard one-shot nozzle in many steel foundries giving the benefit of a compact and controlled pouring stream and double the lifetime.
This is important in the case of high speed pouring with large nozzle diameters, but even for small diameters, the cross-bore nozzle could be a benefit when the pouring cup is small and the operator wants to achieve maximum control of the casting process.
VAPEX FosFlow NOZZLE TECHNOLOGY
Foseco VAPEX FosFlow (fig.4) is a new system that allows for changes in nozzle diameter, even in a full ladle. VAPEX FosFlow alumina graphite nozzles use both carbon and ceramic bond technology. The combination of the two bonding systems provides unique beneficial properties for steel foundry ladle applications.
The system contains a base nozzle which remains in the refractory bottom of the ladle and an interchangeable pouring nozzle with possible different inner diameters. This pouring nozzle can be replaced quickly even within a ladle cycle.
Foseco provides six different VAPEX FosFlow series >40 (mainly for iron autopour runners) 45, 65, 65 extended, 100 and 100 extended for large ladles. The VAPEX FosFlow nozzle should be used in conjunction with VISO monobloc stopper technology that also allows multiple uses of the stopper (figs.6 and 7).
Benefits
- Suitable for multiple use, mainly in steel foundry applications.
- Pouring nozzle can be changed quickly.
- Multi-use of the stopper and nozzle system resulting in labour cost reduction.
- No cooldown of the ladle (energy savings, ladle lining performance).
As previously mentioned, VAPEX FosFlow can also be used in iron autopour applications. Here, the system offers a quick change of the pouring nozzle in the runner without losing time doing excessive refractory work. Especially on high speed moulding such as a DISAmatic, this system can be useful to minimise production downtime.
The pouring nozzle can be changed easily on the side and will be a speedy benefit if the bore is blocked and a fast nozzle change within minutes is called for. However, having spare runners is recommended to ensure an even easier and smoother change of the pouring nozzle in the maintenance area.
VESUVIUS ZIRCONIA NOZZLE OFFERINGS
Additive manufacturing is a future production technology to create complex shapes by using 3D printing technology. For this product range, high purity metal powders are requested.
Those metal powders need to match pure quality properties to gain best production results and they are mostly produced under vacuum melting and then atomised to get a final powder structure with optimised grain size.
Consequently, different furnace producers are offering different technologies to reach the best metal qualities. After melting, the pouring stream should be as small as possible, thus small zirconia nozzles with diameters of 8-14mm as inner bore are state-of-the-art here. Furthermore, zirconia nozzles provide the best properties in terms of thermal stability.
Vesuvius has invested in a fully automated production for zirconia nozzles for steel casting applications in their flagship plant in Skawina (Poland). The company also offers turnkey refractory solutions, starting in the master melting shop where they supply dry vibratory linings for coreless induction furnaces.
Those melting/casting machines are individually produced to match customer demands. A scenario with a pour cup, outer crucible and zirconia nozzle is shown in figs.13a and 13b.
Foseco can supply this full set.
THE FUTURE
Looking at continuous improvements in pouring technologies, time and safety will become more important in the future. The VAPEX FosFlow nozzle system will be an ideal solution to allow a fast and safe change of the pouring nozzle in steel bottom pour ladles as well as autopouring systems for mass iron foundries. Foseco can also offer a full range of products serving the rapid growth in production of metal powders for 3D printing of complex shapes.
CONCLUSION
In recent decades, the production of nozzles for bottom pouring processes has developed simple chamotte products into a highly technical, pure material product that allows better lifetimes and high-tech products that satisfy demands that did not exist five years ago. With a significant investment to create a fully automated zirconia nozzle production line, Vesuvius will play an important role in this market in the future.
ABOUT THE AUTHOR
Rudi Bittniok is an international marketing manager for flow control foundry. With 34 years of experience in the foundry industry and 26 years with the company, Bittniok provides technical and commercial support to local teams worldwide in implementing flow control products into iron and steel foundries. He enjoys the diversity of the products and applications in each foundry and values the learning experience every time he visits a customer. Additionally, he appreciates the internal foundry network.
Contact: Paul Jeffs, UK technical manager, Vesuvius UK Limited – Foseco Foundry Division, Tamworth, Staffordshire B78 3TL UK. Tel: +44 (0) 1827 289999, email: [email protected] web: www.foseco.com
For copies of the figures referenced in this article, refer to the printed version in the August/September 2024 issue of Foundry Trade Journal.
*VAPEX is a Trade Mark of the Vesuvius Group, registered in certain countries, used under licence.