When It Becomes TOO Routine...

[rake60]

We've all worked with "mystery metals" that we've picked up in our travels.
It looks like average (brass, bronze, steel or cast) but it just doesn't cut right.

I had the happen to me at work today.
Simple little pinion gears made from stock that had been ordered in cut to length.
OK, THAT should have raised a flag!

Speeds and feeds set for the standard 4140 alloy, and this stuff is kicking my butt!
Tools are burning up, drill bits are crapping out on me and the 5/16-18 spiral tap is
starting to make squeaking noises at the usual 285 RPM in the tapping head. ???

After completing the 4th piece in a 8 piece order I finally gave the print a closer look.
Oh, that's 4340 steel not 4140...

Even with the information right in front of me it was a mystery metal to me with my
blinders on. After a few little adjustments to speeds and feeds it cut just fine.

I guess my point is there is no perfect answer when cutting metals.
It may not be the material you think it is.
Listen to what it's asking for and it will tell you what it requires...

Rick

 

[Powder keg]

We have 5" shafts out of 4340 with flanges welded onto them that we make at work. Hardstuff!

Wes