SS 304 sheets milling dry or with fluid coolant mist

[Vincent82]

Hi everybody


The company where I'm working is making since a while contracts that are implicating thin Stainless Steel 304 sheets cutting (0.016’’-0.024’’). Unfortunately, the actual machinery has only been designed to cut non ferrous material (Multicam 5000 series).

Our objective would to be able to cut thin SS 304 sheets laminated on plywood with our Multicam 5000 Series milling machine. The milling needs to be done preferably dry (cannot be made with the traditional flood of coolant), with a ¼’’ mill bit.

At this moment, we have try with MA Ford Tuffcut Xr series (ALTIN coated carbide) with compressed air and mineral oil at feed and speeds advised by them on their web site. It works well, but unfortunately the bit last about 10 minutes (cutting 295'' total).

Off course we will experiment more tools but your help would be really appreciated about these points to increase the tool life:

What is causing this early tool wear abrasion, heat build up or both?

How long would a bit NORMALLY last for dry milling with air stream and mineral oil with EP?

Should I get better bit life (less tool wear) by using a mist of water base coolant ( between 5 and 10 for 1) with a device like Spraymaster http://www.tricocorp.com/products/product.aspx?c=5&p=22
?

Please don't hesitate to provide advises, suggestions, comments, ...

Thanks

[rounsy222]

Most certainly use a mist. SS builds heat FAST and will decrease your tool life dramatically. Flood is best but since not an option mist provides a good replacement because you get coolant on the cutter and air helps dissapates the heat from both the cutter and material. Good luck

[rustamd]

also dont forget that SS easily work hardens.

[HuFlungDung]

304SS will cut nice if you can eliminate the excessive heat buildup in the cutting zone. Because this type of stainless is a poor conductor of heat, the chips get excessively hot, as does the tool edge in contact with it. The high heat facilitates welding of the chip to the tool, called built up edge. When this breaks away, it erodes the tool, and soon the inefficient geometry generates even more heat because it is cutting poorly, and presto, your tool is ruined.

In a special case where you must avoid water flood coolants, you might experiment with a jet of highly compressed CO2 or NO2, directed onto the workpiece in front of the cut.

I noticed an article about this in Modern Machine Shop I believe, where they were attempting this in lathe turning operations.

Precautions against freeze burns on personnel, and possible suffocation hazards need to be guarded against when releasing large volumes of these gases in a confined area.