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3mm metal shot production

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mrobe

Mechanical
May 30, 2012
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I produce metal shot on a rotary table. I need an efficient way to remove the shot from the table. I've tried air knives and fixed scrapers, but neither work well. Variations in the production surface that occur as it heats/cools have made it difficult to find a consistent method of removing the finished product from the table surface. Any ideas on how I can consistently and efficiently remove the finished material off the table?
 
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Water spray? The water would have a lot more momentum/drag force on the shot is why I suggest it.

What is table material and what is the metal shot composition? Is it likely that you are getting some welding/bonding of the two materials? Do you apply a ceramic/refractory wash to the table to prevent same, and which one? (I'm assuming you're casting the shot on the table surface?)

Could you convert process to a continuous belt, and invert the belt segments to dump the product?

How about small ejector pins to nudge the shot out of (I assume) the recesses?

Hey, here's and idea - maybe a picture or sketch of what you are doing would help others like me not have to make a bunch of assumptions...
 
Water would be ideal, particularly if it could somehow be recirculated. Oxidation on the finished product would be a customer concern. We would also have to get all the water off the table before it reached the pour point.

The table is 1/8th inch steel. It is coated daily with a graphite emmulsion, which serves as a release agent. And the metal shot is produced from high grade zinc.

We considered a continuous belt early on, but that idea was killed by the budget hawks.

The table surface is not machined in any special way. Molten zinc is introduced to the table in droplets as the table rotates passed a pour point. The surface of the metal cools rapidly enough that we can take it off the table within two feet of the pour point.

I've attached a picture of the table. In the picture you can just make out the air knives that force the shot off the table.
 
 http://files.engineering.com/getfile.aspx?folder=9729ff9c-1f05-4bf6-b2c2-ef80e5c1ecbb&file=100_3514.JPG
I had an opportunity to explore the possibility of steel shots manufacture ,(high carbon steel variety and high chrome variety) long ago. I recall,the metal was poured on to a rotating disc,and the metal spilled off as droplets into a quenching tank below. The height of the ladle through which it is poured,the speed of rotation of the table were some of the important factors. Electronic eyes were used to continuously monitor,change in metal height and accordingly alter the speed of table. Perhaps it had a tilting mechanism too,(cannot remember).

I hope this helps you.

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year
 
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