[RCaffin]

Hi all

I can understand that someone who has just spent $1M on a top of the line machining centre to get 1 micron accuracy might feel the need to justify their expenditure. But that should not blind anyone to recent advances in micro-positioning and micro-machining.

In the latest issue of Laser Focus World I see an ad from Aerotech for their FiberAlign series of motorised movements (p8). These have a step size of one nanometre. That is not a typo: not one micrometre, but one nanometer. There are 1000 nm to a um. XYZ configurations are available, along with motors and software. There are also tilt axes. Range - not given, but of the order of a few centimeters at least.

On the next page (p9) there is an article about laser machining. Some German researchers have been using a Trumpf YAG disk laser to machine an ablation depth of 55 um with a surface accuracy of <1 um. Mind you, they also reported that if you get the speed/feed combinations wrong, this can drift out to an ~10 um surface. So what's new about the need for tuning?

Let's face it, one micron is rather 'yesterday'.

Cheers
Roger
ducks for cover ...

[underthetire]

we developed machines in the 70s that would position in nanometers. again positioning and accuracy are not the same thing. just by reading an article somewhere doesnt make it true. do you have any idea whats involved in just temperature control alone? just 1/100 of a degree will completely change size. the lathe im working on now is one micro inch resolution, during laser checking of positional accuracy the bay went from 68deg to 68.5 degrees and the machine grew 15 micro inch. this is a very heavy very high end machine. then you need to measure flatness squareness, pitch and yaw etc. it only takes one of these items to be out 1 micron, and that machine is no longer accurate to 1um.

[RCaffin]

Hi Under

I agree with everything you are saying about thermal expansion etc. Over 1 m it can be hugely significant.

The difference is the realisation that for many applications, a working volume of 100 mm is 'huge'. There are machines and companies which are making parts which are well under 10 mm in their biggest dimension. I have seen parts that are under 1 mm. That makes for a whole new ball game - and the market for this stuff is growing fast.

Cheers
Roger

[Mhoppe]

I hear you RCaffin. Most of the parts we manufacture are in the 0.01mm to <5mm range. On the 350FG in the lab we have held tolerances of ±0.1um and underthetire is correct, in this regime temperature, not to mention tooling, are extremely critical. Who cares if your machine can hold 0.3um form if your tools aren't even round to a micron? That said, both the temperature in the machine enclosure and the measuring area must be known and controlled very precisely. Although it is nice being able to pull your part back in tolerance simply by breathing on it for a few seconds JK. All of our measurement systems are non-contact and most diameters are measured on laser micrometers from either Z-Mike or Keyence. As for the original post, I don't know what your budget is but the highest resolution linear scales of which I am aware are the Laser holographic linear scales used by Moore Nanotech. I am not sure but I believe they are made by Sony. *edit* also, we are disposing of two older precitech lathes in the near future. I am not sure what will happen to them. The laser scales on them are still good. I am not sure if they might be of use to you but I am willing to ask the uppers what the plan is for them. One machine is company owned the other is the property of the DOE. I am sure the DOE machine is off the table but I can probably ask about the other.

[RCaffin]

Hi MHoppe

OK, that's out of my class!

I have a machining volume of about 250x200x200 mm, which I do use, but I can't get down to micron accuracy. I can sometimes (with care) zero to about 5 microns, and certainly to 10 microns, and I can probe to significantly better than that. But the difference between a hot summer and a cold winter - no idea!

Cheers
Roger

[Mhoppe]

Well, to be honest most of the tolerances requested are in the ~3-5um range. Which sounds tight but if you have ever used these machines you would quickly realize that you can hold that without breaking a sweat, especially on the small parts we manufacture. The yield on the 0.1um part was less than 100% lets say and that is not typical. Was an R&D part and the customer only required a few of them. Measuring to that accuracy was more of a pain than machining to it, and it wasn't on all dimensions just a small sinewave feature around a sphere. I am not sure what your equipment is but Id wager holding 5-10um on it is actually more of a feat than holding 2 or 3 on this machine Just don't tell my boss that hehe

[RCaffin]

I am not sure what your equipment is but Id wager holding 5-10um on it is actually more of a feat than holding 2 or 3 on this machine

Probably :-)
In some ways it is massively over-engineered. Instead of roller bearings on aluminium angle on MDF, or even 16 mm rails, the primary X axis uses 40 mm hardened and ground round steel rods with massive linear ball bearings. And that is for a 250 mm travel.
On the other hand, it's a bit hard to knock it out of alignment ...
Suits me.

Cheers
Roger

[underthetire]

I hear you RCaffin. Most of the parts we manufacture are in the 0.01mm to <5mm range. On the 350FG in the lab we have held tolerances of ±0.1um and underthetire is correct, in this regime temperature, not to mention tooling, are extremely critical. Who cares if your machine can hold 0.3um form if your tools aren't even round to a micron? That said, both the temperature in the machine enclosure and the measuring area must be known and controlled very precisely. Although it is nice being able to pull your part back in tolerance simply by breathing on it for a few seconds JK. All of our measurement systems are non-contact and most diameters are measured on laser micrometers from either Z-Mike or Keyence. As for the original post, I don't know what your budget is but the highest resolution linear scales of which I am aware are the Laser holographic linear scales used by Moore Nanotech. I am not sure but I believe they are made by Sony. *edit* also, we are disposing of two older precitech lathes in the near future. I am not sure what will happen to them. The laser scales on them are still good. I am not sure if they might be of use to you but I am willing to ask the uppers what the plan is for them. One machine is company owned the other is the property of the DOE. I am sure the DOE machine is off the table but I can probably ask about the other.

Trust me, the DOE machine will go back to the doe lab, then get sold at auction eventually after I steal parts to keep the other precitechs or Moore's running .

[RCaffin]

I guess if the DOE machine is missing too many parts, it may go for a fairly low price at auction then?


Cheers
Roger

[underthetire]

Usually yes. I've seen stuff go dirt cheap, and garbage go too high.

[Mhoppe]

They are older Precitech Optimum 2000's. I am not sure what they might go for but Precitech no longer supports them. They still do their best to service them whenever they are out doing PM on our other machines. The lathes can still hold a few microns tolerance and are capable of sub 10nm RMS surface finish but they definitely show their age when sitting next to current offerings from either Moore or Precitech. Most in industry that use these type of machines are machining optics. We use them a bit differently. I am not sure what the market for such a machine would be. Ill hang it up here as I don't want to hijack the thread anymore than I have already :banana: <--- the song should embed with this graphic

[crazydiamond]

This guy built a cnc lathe/grinder accurate to 1um...

https://www.youtube.com/watch?v=sFrVdoOhu1Q

[underthetire]

That guy did a nice build. Nice thermally stable granite bed.