Inclusion in material ?
Has anybody seen this before? These were anodized and the pattern came thru as a bright grey, rest of the part was the std. dark grey. They were then stripped, top surface was re machined an a cpl parts and re anodized. The pattern came thru again.
Looking at the stripped parts, the pattern can be seen going thru the mtl. It appears to be some sort of inclusion in the bar stock as the pattern repeats thru all the parts.
The parts are oriented in the vises by the saw cuts so the pattern repeats in basically the same spots on the parts.
During the extrusion process, the last portion to go throught the ex.. die folds in on itself. The "slag" is then part of the extrusion. Make sure you use quality material form known sources.
This is my opinion to what has happened.
Talk to your aluminum supplier. I don't remember the terminology, but there is a specific grade of aluminum that has uniform properties throughout, so that anodizing comes out uniform. Typical extruded aluminum, as stated in the previous post, is known to have these anodizing problems. Actually, I think this may have been discussed on PM in the last few months. Do a search, and you may find out what you need to ask your supplier for.
I was told the problem was because it was Kaiser aluminum.
What alloy and to what spec?
"I was told the problem was because it was Kaiser aluminum.", does that mean they are still made at us for beating them twice?
Seems like allot of crap in there. Some mills "process" their own billet, ie they melt the cheapest scrap they can get and cast the billet in house. Good ingot has been smelted, ie melted scrap and fluxes added to remove the crap and the alloying metals added or subtracted to make 6061 or what ever and this of course costs money. The direct to billet may be ok for some things but not everything.
Originally Posted by dfw5914