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View Full Version : Face milling left to right v right to left ?



TR
10-07-2011, 02:01 AM
Is there a difference when one face mills right to left over left to right using a right hand face mill ?
For example, using some mild steel should I only
1) face left to right
2) right to left
3) both ways

?

macona
10-07-2011, 02:14 AM
Nope. Just depends where you want the chips to fly.

Jaakko Fagerlund
10-07-2011, 03:56 AM
And on a manual or CNC machine? On CNC I would advice going always climb-milling and the direction depends from which side of the workpiece you go.

...and you can always go front-to-back and vice versa ;)

jugs
10-07-2011, 04:00 AM
As macona http://www.freesmileys.org/smileys/smiley-happy088.gif (http://www.freesmileys.org/smileys.php)

Now slightly OT :)

3) both ways

But that made me think about climb milling-

In std/conventinal milling, the teeth are trying to push the work away & everything is pushed into compression removing any slack in system,no problems.

In climb milling the teeth are trying to pull the work in :eek: putting ever thing in tension so any slack in (lead screw/thrust bearings/slides) will allow the work to jump forward (expect expensive tool smashups :mad: ).

Climb milling gives a high rate of stock removal with reduced power/wear on feed system BUT the machine needs to be big, powerful, & have NO backlash (ball-screws & hydraulic feeds are normally used).

See - http://www.youtube.com/watch?v=bZ1ftacIqaE

DATo
10-07-2011, 04:09 AM
Not sure what you mean by "face mill". My understanding of that exact term has more to do with using a largER multiple tooth cutter extending horizontally from the spindle of a horizontal milling machine. In this context macona would be absolutely correct.

But, if you are talking about facing the end of a workpiece using the side of a regular, clockwise cutting end mill then yes, there is a difference. If the dynamics of the machining are such that the cutter is moving left to right across the edge of a workpiece you are doing what is called "conventional milling" but if you are moving right to left it is called "climb milling". Now, particularly with steel, you never want to climb mill on a roughing (or deep) cut because the cutter may have a tendency to pull itself forward at a rate which is faster than the feed rate you have set and may result in a broken cutter. Climb milling is much more forgiving when cutting aluminum and I often do it but not with steel, cast iron ect.

As implied above, conventional milling is more effective, and safer, when removing larger amounts of material but this action will generally leave a poor finish on the workpiece; conversely, a climb cut will generally leave a much better finish. On any material, even steel, one may save a few thousandths for a finish cut using the climb side of the cutter.

Davo J
10-07-2011, 04:30 AM
You need to face from left to right so the job ends up turning out right, LOL

Seriously though, you will find one way leaves a better finish than the other because of the head tramming. Even though you think the tram is spot on, one way always leaves a better finish.
Also not having the face mill hanging over the edge to much on the in feed side will stop most of the hammering on the machine, it just needs to be 1-2mm over the edge.
So if you had a 40mm wide piece of flat bar and the face mill was 80mm, instead of having the face mill lined up to be in the centre of the job, it would be off set so the in feed side would be 2mm over the edge on the in feed and 38mm on the out feed side.

Dave
Edit,
If you are facing with multiple passes on a piece, do as said above and don't climb mill. Climb milling is when you can see the direction of the cutter will pull the material in.

PixMan
10-07-2011, 07:10 AM
When using a common right-hand cutter, I usually do face milling from right to left (meaning cutter starts out on the right side of the work) because that means I'm milling against the solid jaw of the vise.

bborr01
10-07-2011, 08:47 AM
When using a common right-hand cutter, I usually do face milling from right to left (meaning cutter starts out on the right side of the work) because that means I'm milling against the solid jaw of the vise.

Me too, but mostly because it throws the chips toward the back of the machine and away from me.

It can be a slight problem though if there is a lot of slop in the knee and you are using a large cutter. You can get chatter from the knee lifting.

Brian

strokersix
10-07-2011, 12:44 PM
In addition to above comments: For a relatively flexible knee mill or round column I believe that you will have better finish/less chatter if the cutting forces tend to pull the cutter toward you (throw chips rearward). Pulling the cutter toward you will tend to lift the face mill off the work due to machine deflection. Pushing the cutter rearward (throwing chips forward) will tend to cause the face mill to dig in due to machine deflection.

bob308
10-07-2011, 04:14 PM
if you are using a real face mill in a horizontal mill you cut down so you are pushing the work against the table. never up where you are trying to lift the work.

if in a vertical mill you cut against the solid jaw of the vise. if no vise you cut towards the column the mill is more ridget that way.

Jaakko Fagerlund
10-07-2011, 04:50 PM
Seriously though, you will find one way leaves a better finish than the other because of the head tramming. Even though you think the tram is spot on, one way always leaves a better finish.
If the head is in tram, the head is in tram and it doesn't affect the surface finish whether milling from right to left or vice versa. What affects is if the cut is climb milling or conventional milling.

PixMan
10-07-2011, 04:56 PM
if you are using a real face mill in a horizontal mill you cut down so you are pushing the work against the table. never up where you are trying to lift the work.

if in a vertical mill you cut against the solid jaw of the vise. if no vise you cut towards the column the mill is more rigid that way.

+1

Exactly what I was trying to say earlier.

Just the same, I've never used a machine so poorly-constructed or in such poor condition that it made much difference. I've never had a knee, table or vise lift up on me. Under weak vise clamping conditions, I've (very rarely) had parts lift out of a vise, but never during face mill operations. I mill with face mills all the time, and as long as the hot chips are flying away from me, I'm happier.