My buddy Dave P. + I will be starting a lil project real soon. We will be making an inconel butterfly plate for a special kind of throttle body.

Had a couple of questions:

1. Any special considerations when TIG welding inconel aside from getting appropriate filler rod? Playing with 625...

2. Can cast pieces of inconel be pressed / hammered / beaten / milled / machined / etc. without causing cracks or structural issues?

3. How does the rate of thermal expansion compare between inconel and cast iron?

Thanks,
-Dave

 

I say you make a barrel or sliding type throttle body

 

Coefficeint of thermal expansion for mild steel 1010 = 7.228

Coefficient of thermal expansion for inconel 625 = 5.5

 

machining inconel is some hard tough ****, just keep it realy cool and your gonna need good shard carbide tooling

 

When you machine Inconel you should use High Speed Steel. Run it at 20 Surface Feed ESPECIALY WHEN DRILLING. I work with this stuff all the time. It is a very abrassive material and it work hardens instantly. BE CAREFULL. You should only use carbide on incolnel if you can't use HSS it just wears down way to fast. If you do use it run it no faster than 100-200 SFM. cast incolnel shold not crack if it is machined or welded.

 

When cutting, use low RPM around 230 and stay under the cut. Don't let it heat treat under the cutter. Lots of coolant, medium pressure. You have to make sure the material is removed before the heat gets to it! Good luck! Also, if you high speed sand or grind inconell, it tends to create small suface cracks, so be careful.

 

Make sure when you hear things like use this RPM for milling that both parties are clear on what type of milling operation and diameter of tool is being discussed carbide tools run about three times faster than tools made of High Speed Steel and cobolt tools run about 15 percent faster than High Speed Steel. Here is A formula for figuring out Speeds(RPM) and Feeds(Inches per minute) for machining.

RPM=(4XSFM)/Dia.

Some common Sfm for HSS are:

4140 steel-80sfm
1000series steels(mild steels)- 100sfm
Aluminum-200-300sfm depending on what type of machining process you use
300 and 400 series Stainless Steels-60-75sfm
Incolnel-20-30 sfm

For Carbide
4140-300+sfm
1000series mild steels-300-400sfm
Aluminum-400-500sfm
300 and 400 series stainless steels-100-180 sfm
Incolnel Try 100 and work you way down to increase tool life( i have never found any speed or feed that worked well with carbide in incolnel it just kills carbide)

For feed rates if you have a power feed available start slow and work your way up
it takes a while to learn what tools will take in a givin setup (due to rigidity or lack thereof) and what the machine can handle.