Simple Solutions That Work! Issue 13

24 Exhibit A: 4-Month-Old Lining Stated: They Cleaned It Every Day. Exhibit B: Furnace Lining 3 Years Old Cleaned Properly Exhibit C: New Furnace Lining I posted a sheet at the charge door of the furnace and when the operator cleaned it each shift, they noted the time and signed that it had been cleaned. Since I looked at them daily, I knew by looking at the time it was last cleaned what the furnace should look like when I inspected. What I observed needed to match the timeline of when it was last cleaned, or I would hold the person accountable and resolve that before the furnace could get out of hand. Following these procedures religiously lead to no major furnace repair issues. Here are three examples of everything I have been discussing. Exhibit A: The manager took what he was being told by his team as accurate. I called the manager and he walked up to the furnace and opened the door; what he saw made him speechless. This is why a “World Class Melt Shop” has a manager that checks the furnace daily to confirm that processes are being followed. In Exhibit B and C , you can see the effects of proper maintenance after 3 years as compared to new. You are probably saying there is no way we can do this, and this is crazy to work this hard on the metal and furnaces. Well... we did it where I came from and 30 years later, we were still pressed hard to make sure this was done every shift. Why you say? The proof is in the bottom line. Every year we had very low, unrealistic scrap rates to most, but to us it was normal to look at numbers like that monthly/yearly. With all this being said, aluminum foundries should rethink the direction they are heading (what is not working) and bring back the melt furnace tenders and melt shop managers. Additional Ways of Preventing Defects and Providing “World Class Metal” is Filtering Your Metal. WHY SHOULD I FILTER MY ALUMINUM? Whether you are a die caster, permanent mold or sand foundry the question is always going to come up… Should I filter the metal, degas or both? So let's put this to bed right now. If you are a foundry and are trying to obtain a specific gravity of, lets say, 2.62, chances are you are going to degas to get you there (depending upon the alloy). If your customer's specifications demand it, then you had better degas. If your machining end is experiencing hard spots then you need to filter. If your cut castings are showing signs of porosity you may not have to degas. Let me explain. If your dies are vented correctly then well dispersed hydrogen will go out the vents in the die when the die cast machine slams shut. However, if you have inclusions in your metal you may trap hydrogen in a particular area of the part and that is your porosity issue, not the hydrogen. In some rare cases where you are in a very high, humid area, then you could end up with a large amount of hydrogen in the metal that filtration may not take care of. If you are casting above 1300 degrees F. (which as a die caster you should never do) you can be absorbing more hydrogen into the metal. If, as a foundry, you are above 1400 degrees F, then you are acting like a wick and really pulling the hydrogen into the metal. There are several other reasons hydrogen and inclusions can be finding their way into your castings. If you tap metal into a transfer ladle, then pour it into a holding furnace, and then ladle it into the shot hole, you have just committed three very turbulent acts with the molten aluminum. These molten metal pours will pick up more inclusions, and trap more air and hydrogen in the aluminum. This might cause you to have to degas and filter. I have seen companies actually raise the temperature of the metal to get better fluidity into the die on hard to cast parts. If they just tried filtration first, they may not have had to raise the temperature as much, or at all.