[jwolin]

I have never worked with a 5 axis machine, but am contemplating converting my 3 axis machine to 5. In researching the CAM packages available for 5 axis machines I keep running accross the terms 5 axis continous and 5 axis indexed. I have an intuitve idea of what this might mean, but need some help in clarifying. What specific advantages would continuous have over indexed? Could someone describe a part where this advantage would be obvious? Why isnt all software 5 axis continuous?

[CNCtoday]

With 5-axis continuos you can pretty much do everything with the part and 5-axis index can't do these kind of contour.



No way you can put radius on the edge of the part 5-axis index.

[puzzleman20]

In simplest terms, 5-axis index will aim your B and C axis then remain stationary while you cut a specific location. When you change cutting location, the B and C axis will re-orientate then remain stationary again for that cutting location. It is actually 3-axis cutting using 5 axis' to aim the bit.
In continous 5-axis, the B and C axis' will continously move while cutting to keep the tip of the cutting bit perpendicular to your part. Continous 5-axis takes more skill to program.

[jwolin]

thanks puzzleman, that description really helps. My remaining question has do to with the limitations of 5 axis indexed. Could you describe a part that could not be done with an indexed CAM package. It seems to me that the advantage of countinous over indexed is a speed advantage. If I understand correctly, in theory, repositioning of the B and C axis, then milling, then reposition of B and C axis, then milling, etc... would produce the same net effect as continous motion. It would just be slower. Am i understanding this correctly? Thanks again for the very helpful answers.

[puzzleman20]

Yes, the speed advantage is correct, but with that speed comes more moving parts (wear and tear) and a need for good part crash detection in your software and code editing skills. Off hand I can't think of a type of part that could not be cut with an indexed 5-axis machine. I don't think the loss in speed is really anything to worry about. We have 3 continous 5-axis machines at work and we almost exclusively use them as 5-axis index. We usually run at least two machines continously for an eight hour shift.

[turmite]

Yes, the speed advantage is correct, but with that speed comes more moving parts (wear and tear) and a need for good part crash detection in your software and code editing skills. Off hand I can't think of a type of part that could not be cut with an indexed 5-axis machine. I don't think the loss in speed is really anything to worry about. We have 3 continous 5-axis machines at work and we almost exclusively use them as 5-axis index. We usually run at least two machines continously for an eight hour shift.

puzzleman you mention good part crash detection. Can you give me an idea how this works? Do you have to model your part, the 5 axis head, etc, to be able to know that detection is going to be accurate?

Mike

[diarmaid]

Could you describe a part that could not be done with an indexed CAM package. If I understand correctly, in theory, repositioning of the B and C axis, then milling, then reposition of B and C axis, then milling, etc... would produce the same net effect as continous motion. It would just be slower. Am i understanding this correctly?.

As is often the case I have zero experience of this. However an uneducated guess would be a sphere type surface. The continuous could mill all around the sphere smoothing it down and maintaining a nice rounded surface, but I think maybe the index wouldnt be able to do this, possibly the closest the indexed could get would be a rough sphere which would need to be ground or maybe just sanded smooth at the end.

As I said a completely uneducated guess.

[JerryFlyGuy]

In reality, I don't think there is anything that can't be machined w/ a index that can be done w/ CM [Continuous motion]. Except, when more than the tool tip is used for a cut. If you look at that giff on the second post of this thread you'll see where using CM kills indexing. That part could be done w/ indexing but the nightmare of programing it would The other thing about indexing is [usually at least... I've not found one that doesn't] you need to create plane's and manually tell the CAM how to orientate the head or part to then enable 3 axis movement. A CM CAM will usually do alot of this for you. If you tell it you want to machine perpendicular to the surface.. it will move the tool for you and simplify some of the code generation.

My understand.. and from what little use of Tutorial's that I've tried. It's worth noting that I have zero experiance using any code for 5 axis.. Yet

Jerry [I to need a CM 5 axis.. but haven't decided which one I'm gonna buy.. it has to fit in w/ SW and I would prefer a Gold Partner.. that limit's my choices alot! :tired:]

[Dan B]

Although continuous 5-axis has it's advantages, it also has some disadvantages not yet mentioned. With positional you index the machine and cut in the X, Y and Z axis. In doing so, you are using the feedrates available to these linear travels. When doing continuous cutting, you are now dealing with the limitations in either a rotatable head or trunnion table. On slower machines, you will pay a price in speed. We have a new Hermle that rotates so fast is makes your heart skip a beat, so it's not that much of a limitation. However, our older Hermle does run substantially slower if doing continuous.

One big advantage of continuous, if you have higher end software like WorkNC or HyperMill, is the ability to convert a 3-axis path into a 5-axis, to reduce cutter lengths. For example, if you need a 100mm tool length in 3-axis, you can shorten it up to, say, 30mm, and the program will calculate the rotations to prevent the holder from hitting.

Hope this helps,

Dan

[Capgama]

Hi there
check out this link
http://www.sescoi.com/us/worknc/func...deo_mach.html#
I have been using this software for around 15 years and it work great for all types of machining + 5 axis machining.
There is only 1 type of 5 axis cnc and thats 5 axis cnc.
When you say 5 axis continuous, your right because all 5 axis can possible moving all at the same time at the same feed.
now 5 axis indexing is really called 3+2 axis, where as you can not move the +2 axis when cutting, the +2 axis is only for positioning the head and or table.
you can get a lot more work done with 5 axis cnc vers 3+2 because of the programming time.
There are some really good 5 axis programming software out there,the programing is almost almost automatic these days.
plan on paying around $15000 to $25000 per seat for these type of 5 axis programming software.
here are 3 top players in cam development
worknc
tebis
powermill

If you buy anything less make sure it has welding rod in the box (you will need it) 8->
and also a machine repair guy. no joke 8->

btw these cam programs have built in error checking so there no need for a 3rd part software cost. ch ching

[big_mak]

Don't forget Catia and NX

[Dan B]

I spent a lot of time at IMTS looking at the NX Cam Express demo's. I thought this was a very capable package, especially if you are using SolidEdge or NX for your modelling. The 5X programming appeared to be extemely easy.

Dan

[[email protected]]

Indexing will be moved into position then clamped.
Continuous or contouring is positioned at a feed rate to allow for
machining while it is moving.
Indexing usually has only 360 positions.
Contouring usually has 360,000 positions.
Thats everything I know about it.
Regards Walt.

[Dan B]

Indexing usually has only 360 positions.
Contouring usually has 360,000 positions.

I disagree. Indexing has an infinite amount of possibilities. For example:

A0.001C0.001
A0.002C0.001
A0.003C0.001
and so on.

I would have 1000 possibilities before I rotated the A axis 1 degree. Now within that 1 degree I could rotate the C axis too giving 1000 x 1000 possibilities all within 1 degree of rotation in the A and C. A typical trunnion style machine may have a range of 360 degrees in the C and plus or minus 110 degrees in the A. The total amount of possibilities for positions would be way more than 360.

As for continuous, the amount of possibilities should be exactly the same.

Dan

[Geof]

I disagree. Indexing has an infinite amount of possibilities.........Dan

Infinite is a very big number! I think this calculation gives the actual number but it is late and I may be too sleepy

360 degrees available around one axis at a resolution of +/- 0.001 gives 360,000/2 positions available around that axis. The 110 degrees at the same resolution gives 110,000/2 positions around that axis. The total number of rotary positions is these two multiplied; 39600000000/2 if I counted my zeroes correctly. A big number but not infinite. If the rotary resolution is only 0.01 you take two zeroes off the big number.

And then each of these positions can be located at numerous positions in X and Y so the number gets bigger but still not infinite.

[[email protected]]

Dan B,
A = 360.000 degrees. That looks like 360,000 to me. I was talking about only one axis at a time. Look at the control and see how many decimal places are indicated.
B = 360.000 degrees. That looks like 360,000 to me.
C = 360.000 degrees. That looks like 360,000 to me.
My point was, contouring table is able to move continously during the cutting cycle. An indexing table usually moves in one degree increments and then is clamped down in that position. When it is clamped down and the control recieves the signal that in fact the axis is clamped, then machining can take place. Yes, I have seen one half degree indexing tables but it is my opinion that of the indexing tables, the one degree table is more common.
Now let us see how many arguments I get from that statement.
And they wonder why I don't post more oftener
Maybe my trouble is I came from a machine tool background where the ways were made out of 2 inch by 5 inch solid steel and the slides rode on tyco way bearings and the lead screws were about 3 to 4 inches in diameter and very precision ground. Plus, you didn't buy every thing on Ebay.
Best I keep my opinon to myself, Mr. Dan B, the floor is yours.
Best Regards, Walt.

[derekj308]

Hi Guys

I haven't seen any mention of 5a continuous (I would of used synchronous, when in Rome...) enabling the tool axis of a ball nose cutter to remain normal to the workpiece surface to maintain constant surface speed of the cutting edge during finishing passes. For me the major advantage of 5a is that it allows me to finish 5 sides of a die or pattern using short tools without taking the workpiece off the table. Faster and better surface finish than if I was using a 3a with long shanks which force me to take tiny passes to avoid chatter.

Cheers

[Dan B]

Hi Walt,

An indexing table usually moves in one degree increments and then is clamped down in that position. When it is clamped down and the control recieves the signal that in fact the axis is clamped, then machining can take place. Yes, I have seen one half degree indexing tables but it is my opinion that of the indexing tables, the one degree table is more common.

We have 3 5-axis machines here, and none of them work like that. The rotations are driven by code to exact values. If I need a rotation of A23.9877C342.7652 then that's what I get. How would you put holes in on the proper angles if you can only index to whole values?

Now let us see how many arguments I get from that statement.
And they wonder why I don't post more oftener

I'm not arguing, just disagreeing. Is that not allowed?

Best I keep my opinon to myself, Mr. Dan B, the floor is yours.

Perhaps what you describe is based off of your experience. But I bring different experience to the discussion. My experience with 5-axis doesn't come from E-bay, but from high speed 5-axis machines from Germany (and a Tri-tech head)

No need to get bent out of shape. I'm just widening your reality.

Dan

[Mike Mattera]

An indexer generally has fixed increments for their moves and in many cases its triggered by an M code. Many horizontals might have B axis tables, but might not have an infinite amount of motion. I've seen some that only move as small as .1° increments. If you can program B30.123° you probably have a live axis and not an indexer.

However that does not automaticaly mean you can do continuious contouring motion. That's really up to the builder and the type of control.

5 axis continious means all axis in motion at once to produce a coordinated machining motion.
The other term of 5 axis indexed is also refered to as 2+3. This means 2 axis pointioning (tilt) of the face to be machined and then 3 axis surface machining. This is how most people use their 5 axis machines.

Mike Mattera

[Capgama]

Hi there
check out this link
http://www.sescoi.com/us/worknc/func...deo_mach.html#
I have been using this software for around 15 years and it work great for all types of machining + 5 axis machining.
There is only 1 type of 5 axis cnc and thats 5 axis cnc.
When you say 5 axis continuous, your right because all 5 axis can possible moving all at the same time at the same feed.
now 5 axis indexing is really called 3+2 axis, where as you can not move the +2 axis when cutting, the +2 axis is only for positioning the head and or table.
you can get a lot more work done with 5 axis cnc vers 3+2 because of the programming time.
There are some really good 5 axis programming software out there,the programing is almost almost automatic these days.
plan on paying around $15000 to $25000 per seat for these type of 5 axis programming software.
here are 3 top players in cam development
worknc
tebis
powermill

If you buy anything less make sure it has welding rod in the box (you will need it) 8->
and also a machine repair guy. no joke 8->

btw these cam programs have built in error checking so there no need for a 3rd part software cost. ch ching

well said Mike :banana: o and btw most 5a can only move 259deg not 360deg or maybe you got some kind of alien technology j/k