Problems with milling steel

Pmedic828

Pmedic828

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I am fairly new to machining - i picked up some scrap bar to practice on. The
place where i purchased it from said that it could be cold rolled. When
milling, it seems to leave a less than desirable finish to it. I am using HSS
end mills and even though i take off about 0.005 to 0.010, it won't cut very
well. I have tried to change mills, but both were new out of the pack. It
seems that if i mill it slow, the metal has the appearance of melting with globs
along the cut line. If i mill fast, it seems not to cut.
I am thinking about purchasing an indexable end mill, but others say that it
will chip when it starts cutting? Can anyone take the time to explain why this
is happening.
From others on this site, i see that they bore holes thru 1/2 steel and i can't
cut anything.

Another question, what do you cut stainless steel with? If i wanted to turn 1
inch square bar to round flatten 1 inch on both sides to make a tenon, and bore
a 1/2 inch hole in it, what should i use to do this.
 
We need more info. What mill you have, what the setup is, how ridged it is, what size endmill, what rpm. how deap of cut. A pic of the metal would help. Scrapyard metal could be eny thing.
 
+1 to what kd4gij wrote. FYI - "cold rolled" doesn't really help you much on the type of metal it is. That term is just telling you how the metal was processed.

Pictures of what's going on is a great help too. Especially with "mystery metal".

-Ron
 
More info definitely- but quick response is you need to try quite a few metals, in quite a few ways when you are new, just to determine when the problem is you, the metal you are attempting to machine, the machine, or what combination of the above.

You could drive yourself nuts to find out it is that type of steel. They do exist. Try aluminum first. Of course as I'm saying that, I remember that their are gummy aluminum alloys too hah hah.

If you are spinning the tool too quickly, it may stop cutting.

Ignore the "chip load" column. And don't worry too much about which steel right now. Just ball park. Down lower are aluminum etc.

http://www.mastercuttool.com/endmillspeeds.php



We are happy to help you, but afterward, try something else you have lying around as well.


Bernie
 
Like folks have said, more info about your setup is needed. Pictures speak a thousand words too... -And we can help you.

As for stainless, let's get past the initial question about "normal" steel first. Stainless is surprisingly tough stuff that I do well with now on the lathe (after a couple years of screwing it up) and I have some glitches when milling it -because I don't have a frequent need too. I'll share what I've learned about milling stainless -but it's minimal information. Honestly, I look forward to hearing other folk's responses on it.

Ray
 
What brand of HSS end mills are you using? Are they 2 or 3 or 4 flutes?

If they are elcheapo brand, that could be your problem.

Are the flutes on the end mill changing color as you try to cut?

Are you using any kind of cutting oil or fluid? Or just dry?
 
The problem could be with the end mills you are using. I found that small end mills, especially the ones that are capable of drilling, do not have good chip clearance on the end. RPM, feed and depth of cut did not seem to matter. The problem went away when a 1/2" end mill was used. The end mills are 4 flute.

Bill
 
I know when I was making a drive shaft I used a steel rod I got from a scrapper, and since I didnt have a key cutter I took it to my biddy at his machine shop. He has 6 mills, 4 are HUGE, and when he tried to cut a key slot in this the metal just deformed and the cutter broke. He then informed me this was a very hard heat treated rod of steel, like the stuff they make impact chisels out of. He grabbed me a hunk of "normal" cold rolled rod and it was done in seconds.
From the type of "almost melting looking blobs" it may be really hard steel.
 
Pmedic828 said:
I am fairly new to machining - i picked up some scrap bar to practice on. The
place where i purchased it from said that it could be cold rolled. When
milling, it seems to leave a less than desirable finish to it. I am using HSS
end mills and even though i take off about 0.005 to 0.010, it won't cut very
well. I have tried to change mills, but both were new out of the pack. It
seems that if i mill it slow, the metal has the appearance of melting with globs
along the cut line. If i mill fast, it seems not to cut.
I am thinking about purchasing an indexable end mill, but others say that it
will chip when it starts cutting? Can anyone take the time to explain why this
is happening.
From others on this site, i see that they bore holes thru 1/2 steel and i can't
cut anything.

Another question, what do you cut stainless steel with? If i wanted to turn 1
inch square bar to round flatten 1 inch on both sides to make a tenon, and bore
a 1/2 inch hole in it, what should i use to do this.
Click to expand...


If the endmill is not coated then you "speed" and "feed" or "depth of cut" is to high if metal is sticking/gaulding. If it is coated endmill then please state the coating and "rpm" and feed/IPM at which you are use currently.

The use of metric is acceptable.

All indexable inserts will chip. There is no way around it. The coating on indexable inserts is what gives the tool life including HSS. You mention SS steel and I would use aluminum oxide or uncoated.

I'd shy why away from bore holes with a endmill. Even if it is a center cut. It's better to drill the hole and come back with a endmill and perform a helicle move or circle interpolate at full depth if CNC.

edit:
You'll find out later in life that material composition and form means little from the supplier unless specified.
 
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