CNC 3040 and Aluminium Milling - Problems and Blown Fuse

[Dominic-ASP]

First of all, I am a total newbie to CNC machining. I just bought a Chinese 3040 230W engraving CNC machine and have recently been struggling with milling operations on aluminium. I am trying to cut through a 4.3 mm thick aluminium box with a TiN coated carbide 2 flutes 42degree end mill with the following specs:

• Mill Diameter: 3/32" (2.38 mm)
• Shank Diameter: 1/8" (3.175 mm)
• Length of Cut: 1/4" (6.35 mm)

I am trying to cut a profile through the entire thickness of the box. To generate my gcode, I used CamBam with the following parameters:

• Depth Increments: 0.5mm
• Target Depth: -4.5mm
• Cut Feedrate: 125 mm/min
• Plunge Feedrate: 62 mm/min
• Spindle Speed: 6000 rpm
• Tool Diameter: 2.38 mm
• Inside Profile Cut (Rectangular Shape)

I have been trying 4 times to complete the operation but every single time, at some point, I would start hearing a really harsh noise and could see that my spindle speed was gradually slowing down or even see my end mill completely jam in the aluminium. When it happened, I always tried to shut down my controller as fast as I could to prevent further damage to my machine but during my last trial, the fuse blew and had to replace it. I use WD-40 as a lubricant and compressed air to blow the chips away.

Since I was able to cut through softer 1.25 mm thick aluminum plates with the same machine, end mill and parameters, I am wondering what is causing my problems. At a first glace, do my parameters look good? Is my machine powerful enough to complete such operation? Any hints/tips would be greatly appreciated! Thanks a lot!

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[javanree]

Harsh noise indicates vibrations. How did you mount the box to the milling machine?
Also the aluminium of the box might be a totally different sort than the other plate you cut previously.
On my 3040 I've done some aluminium milling, with similar feed, much higher RPM and a slightly smaller depth increment using an HSS 6mm mill.
Also note a TiN mill is not suitable for aluminium, you are better off using uncoated carbide cutters or maybe even HSS given your low power spindle.

[djr76]

are you getting chip welding into the flutes of the cutter? are you using any type of lubrication?

[dno]

I had similar problems cutting plastic at low feeds. Worked out that voltage drops to 20V instead of 24V, which is 20%.. pretty easy to check.

[CNCMAN172]

Your RPMs for a cutter that small in aluminum seem too slow. Normally to cut aluminum with a cutter under 1/8" in diameter you run about 10,000 RPM with a Depth of cut of about .020" Not sure if you spindle can turn that fast.

Russ

[JoshG502]

First of all, I am a total newbie to CNC machining. I just bought a Chinese 3040 230W engraving CNC machine and have recently been struggling with milling operations on aluminium. I am trying to cut through a 4.3 mm thick aluminium box with a TiN coated carbide 2 flutes 42degree end mill with the following specs:

• Mill Diameter: 3/32" (2.38 mm)
• Shank Diameter: 1/8" (3.175 mm)
• Length of Cut: 1/4" (6.35 mm)

I am trying to cut a profile through the entire thickness of the box. To generate my gcode, I used CamBam with the following parameters:

• Depth Increments: 0.5mm
• Target Depth: -4.5mm
• Cut Feedrate: 125 mm/min
• Plunge Feedrate: 62 mm/min
• Spindle Speed: 6000 rpm
• Tool Diameter: 2.38 mm
• Inside Profile Cut (Rectangular Shape)

I have been trying 4 times to complete the operation but every single time, at some point, I would start hearing a really harsh noise and could see that my spindle speed was gradually slowing down or even see my end mill completely jam in the aluminium. When it happened, I always tried to shut down my controller as fast as I could to prevent further damage to my machine but during my last trial, the fuse blew and had to replace it. I use WD-40 as a lubricant and compressed air to blow the chips away.

Since I was able to cut through softer 1.25 mm thick aluminum plates with the same machine, end mill and parameters, I am wondering what is causing my problems. At a first glace, do my parameters look good? Is my machine powerful enough to complete such operation? Any hints/tips would be greatly appreciated! Thanks a lot!

You might be using dull end mills, I had the same exact issue

[awerby]

Usually, harder aluminum cuts better than softer, so I doubt that's the issue. If your parameters worked before, then they should still work, although they may not be ideal. It could be a dull cutter, or stuff stuck to a sharp one. But it could also be that the aluminum of that box is gummier than the stuff you tried to cut before. There are some grades of aluminum that are kept soft so that they bend and deform well. These can be difficult to machine, though.