Simple Solutions That Work! Issue 13

10 I n the 80's Acetarc casting and bottom pour ladles were made to comply with British standards. These standards were last revised in 1960, so if you wanted a treatment ladle, of any type, motor drive, or anything specific to suit your own particular requirements, you were pretty much in the hands of the ladle manufacturer. The situation is more so today with the standard being left far behind in practical terms, but at least I hope that I can claim that our design decisions are backed up by both decades of experience and feedback from foundries. STEVEN HARKER Technical Director ACETARC ENGINEERING CO. Ltd ARTICLE TAKEAWAYS: • Clear communications between the foundry, the refractory supplier and the ladle manufacturer will lead to best results • Just because it was done like that in the past, doesn’t mean it still has to be done that way • Secondary benefits can be an important consideration during the total working life of a ladle THE USE OF PRE-CAST MONOFORM LINERS (DROP IN LINERS) IN LADLES Back then when it came to standard lip-pour or bottom pouring ladles, it was all laid out what the shell dimensions were for a given capacity, spout size, lining thickness and many other details. Ladle manufacturers didn’t have to design the ladles, they were, well, standard. There was no customization, no adaptation to the design to make it fit in better with your foundry's working practices. However, there was a period in the mid 1980’s when this adherence to standards, that were increasingly less relevant, led to situations when the client found the capacity of a new ladle was not what was expected. Castable refractory concrete linings were becoming popular and the then usual method of using firebrick linings was starting to be superseded. Clarifying and achieving your ladle's working capacity needs is critical to the process. Back then ladles designed in-line with the standards were expected to have a firebrick lining of, say, 1-1/2” (38mm) thick. However, with a castable refractory lining it was more likely to be 3” (75mm) thick for the same capacity ladle. Consequently, the working capacity of the ladles was reduced. This made it more important to clarify all specifications at the ladle design stage, including internal shell dimensions, recommended lining allowance and the working capacity of the molten metal for a given freeboard. Just asking, for example, a 2 t capacity lip-pour ladle was no longer adequate. The British standards are still used as a base guide, but current ladle designs have moved past these standards to reflect both current foundry working practices and advances in refractory technology. Today, the way we see it, if a foundry wants to adjust anything to suit their specific requirements then they can, as long as it is safe to do so. It’s a system that has worked well and today, at the quotation stage, thanks to advances in CAD, the foundry is likely to get an accurate GA drawing with a shaded isometric view, rather than a generic quotation drawing with the dimensions changed. Effectively a picture and not just a 2-D drawing of the ladle. This makes it far easier for everybody to visualize what they are getting.