In the preparation for some upcoming aluminum projects, I wanted to do some experimenting with feeds and speeds on my KRMx02 CNC.
This will also allow me to put my VFD controlled spindel to the test.
Before starting let me first say a few things about working with aluminum.
1. Types of Aluminum
There are different types of aluminum. Some of it is easy to machine while others are not. The kind of aluminum that you can purchase from Homedepot or other home centers, is the worst for machining. They don't label the type, but I think its mostly 3003 or 5052 which is not the best stuff for machining. If you have to machine it use lots of lube.
I try to purchase 6061 when ever possible if, I know I am going to have to machine it. That is what I will be using for these experiments.
Aluminum can stick you your bit as it is machined. If this happens things go south really fast, ruining your bit and your work. To keep this from happening, use some sort of lubrication.
I like using oil concentrations that are designed to mix with water.
Another type that I like using is the Trend brand Tool and Bit Cleaner. It coats both your bit and stock so that the aluminum wont stick. This is what I will be using for these experiments.
You can get some here:
Trend Tool and Bit Cleaner
3. Clearing Chips
You have to clear your chips. If you dont your tool has to work much harder. By clearing your chips, you remove the heat and your tool does not have to work as hard re-cutting the already removed chips. This will keep your tool sharper and give you a better finish on your cut.
There are a couple ways to clear the chips. Air from an air compressor, coolant flood, Vacuum. I try to keep a vacuum handy with a long skinny nozzle to evacuate the chips if they start building up. I tend not to use air as it can blow the chips every where in the shop.
4. Holding the Stock
You have to hold the stock solid. For smaller piece of aluminum, A machine vise is your only option. If you cant firmly hold the stock it will vibrate and your cut will suffer.
5. Spindle Run-out
If you have a spindle or bit with a lot of runout, then the quality of your cuts will suffer. Aluminum is not very forgiving in this area. If the run-out is excessive, you may find you are breaking bits often.
6. Machine Rigidity
Machining aluminum can really push your machine to its limits. While the KRMx02 was built to handle the kinds of loads I will pushing, other machines may not. The harder your machine has to push, the more liklely backlash and slop will be present themselves.
While performing these tests/experiments I will be using the following equipment. Please note that I will add to this list as things progress.