cutting metal sheeting

[Mark Taylor]

I have a new client who needs a fairly large number of letters cut out of metal - at this moment I don't know exactly what kind of metal, but maybe aluminum or brass - 1/8 to 1/4" thick. Does anyone have any experience with cutting metal they could share. To date we have exclusively cut wood and a few acrylics - I know there are bits for cutting aluminum on the woodworkers supply - but I don't know if they need any special lubrication while cutting...etc. I would appreciate any responses/experiences to help me determine if this would be viable for us.

Thanks
Mark

[Todd Miller]

I have a new client who needs a fairly large number of letters cut out of metal - at this moment I don't know exactly what kind of metal, but maybe aluminum or brass - 1/8 to 1/4" thick. Does anyone have any experience with cutting metal they could share. To date we have exclusively cut wood and a few acrylics - I know there are bits for cutting aluminum on the woodworkers supply - but I don't know if they need any special lubrication while cutting...etc. I would appreciate any responses/experiences to help me determine if this would be viable for us.

Thanks
Mark

Mark,
I have never cut brass, but have cut aluminum. The thing with aluminum is that there is so many different kinds. You really don't know how it is going to react until you cut into it. So this will require test cuts on your part. I would recommend getting with our tooling guy, Eric Shearn, he would know exactly what tools you would want to use.(see info below) I would also recommend a lubricating mister. This will help keep your tooling cool, and reduce meltback of the material onto the tool. Meltback is when the metal being cut is heated, then melts to the tool. Rendering that tool useless. Note: the longer the tool is cutting the material the hotter the tool is going to get which will give you meltback. On the other hand, cutting too fast may break the tool. So finding that fine line is important.

Eric Shearn
eCommerce Manager
Thermwood Corporation
800.533.6901 ask for Eric
email: Eric.Shearn@thermwood.com

Test tips:
Look at the aluminum chips being thrown off of the tool. They should look like a 6 or a 9. Longer curls = too slow: Small chunks = too fast.
Use both climb and conventional cuts when testing.
Mutliple depth passes may be neccesary. Depending on thickness of material and diameter of tooling.
When drilling use a peck cycle.
Always ramp into material.
Use helix style toolpaths. (constantly ramping into the material @ small increments) This greatly depends on spindle and feed speeds.
Spindle speeds and feed speeds - start low 12,000 RPMS @ 50 IPM and work you way up.
Note: When adjusting your spindle and feed speeds, only adjust one or the other at a time. This will help you understand what each change is doing.
Label your test cuts: Take note of both sides Climb and Conventional. Which one cuts better?

It has been a while since I have cut anything like this, but hopefully this will give a better starting point.

[Mark Taylor]

Todd...thanks for your imput!

Question is the lubricating mister you referred to something that would attached to the spindle and produce a constant mist on the tooling or is it something hand held that would be applied - quote "as needed" throughout the cut?

What type of coolant is the mister using - water or water based, or an oil type lubricant? Which presents another whole series of questions regarding amount of lubricant and it's collection?

Mark

[Todd Miller]

Todd...thanks for your imput!

Question is the lubricating mister you referred to something that would attached to the spindle and produce a constant mist on the tooling or is it something hand held that would be applied - quote "as needed" throughout the cut?

What type of coolant is the mister using - water or water based, or an oil type lubricant? Which presents another whole series of questions regarding amount of lubricant and it's collection?

Mark

There are probably more types than I know about. The misters we used were not programmable. We would just turn them on, then start the program, and let it cut. A lot of the aluminum samples we machined were held down by conventional vaccum directly on the 3/4" sealed MDF table or by using Double face tape. So the mist had no place to go, other than into the board. The board would swell and we couldn't use it anymore. Probably not what your looking for. Here is a link to WoodWeb that may give you more insight.

http://www.woodweb.com/knowledge_base/C ... minum.html

I have only used the waterbase lubricant, and it worked fine. Sometimes the cut needed to be flooded, while other times just a light mist. The amount of mist applied, is proprtional to the amount of material being removed. But there are some types of tools that do not require coolant. As stated in the link above, there are some high helix cutters that remove the chip much faster and keep the tool cooler. And this would remove the coolant mister all together.

[Todd Miller]

Here is another link. I googled "calculate chip load"



Note: this site bases its calculations in Feet Per Minute (FPM) feedrates. Thermwood routers uses a Inches Per Minute (IMP) feedrate. FYI

This may give you a good starting point, but the only way to know, is to cut the material yourself.

[Todd Miller]

http://www.whitney-tool.com/html/calcul ... dFeed.html

here is the link..... Sorry about that.

[Zach Froble]

Mark,

Check out this link. I know there are some other companies that have something similar.

http://news.thomasnet.com/fullstory/471875

Zach Froble