Hello Guest it is May 19, 2019, 05:14:05 PM

Author Topic: micromachinng surface finish  (Read 2675 times)

0 Members and 1 Guest are viewing this topic.

micromachinng surface finish
« on: April 19, 2010, 06:08:54 PM »
Hi everyone.  New to the forum.

I will be doing some very fine micromachining for which I require a very smooth cut and finish.
Seems there are not that many choices available in my price range. 

Here's an excerpt of an article on the web:

Initially, MACH 3™ was chosen as the control software, and the output was sent to a stepper motor driver controller. Since the computer was running the driver software and CAM software, the commands in MACH 3™ were not occurring in “real-time”, and thus, there was a slight time lag due to the multiple computer processing needs. Figure 4a shows a complex precision part cut using the MACH 3™ software and the resultant stair-stepping on the cutting surface

Link to original paper:
http://www.sefi.be/wp-content/abstracts2009/Otieno.pdf

Can any "gurus" verify the above statement?  Is this indeed an issue for micromachining like in the example above?  Or an issue of not knowing the Mach3 software well enough?

thank you.
Re: micromachinng surface finish
« Reply #1 on: April 19, 2010, 07:55:42 PM »
I would take very little stock in the "paper" as presented.
They claim an 80-150k machine is too expensive for the
"lucrative" micromachining market.If it's lucrative then maybe that machine is cheap.
The home built machine is just another small milling machine copy.No innovation there. ::)
I would find a very solid machine with a very high speed spindle for your micromachining
I'm sure mach 3 would do just fine.
Re: micromachinng surface finish
« Reply #2 on: April 19, 2010, 09:40:04 PM »
There are soooooooo many things wrong with that paper....  Whoever wrote it does not understand what he's working with.  Perhaps most glaring:

"The low-cost machine has been set-up to use 1/4 stepping for a positional accuracy of 0.0000625 inches (about 1.6 microns). It should be noted that in all cases, the accuracy achieved is dependent on other considerations such as manufacture and assembly processes employed. In addition, spindle run-out is responsible for much of the inaccuracy. Typical spindles have inherent run-out in the region of several microns. However, the accuracies are improving. The low-cost spindle which is being used in this application, shown in figure 3 below, has a low run-out; approximately 0.00024 inches (about 6 microns)."

He confuses resolution with accuracy (two TOTALLY different things!), and makes no allowance for the inaccuracy of the leadscrews, and other purely mechanical factors, such as backlash (which is virtually NEVER zero).

Regards,
Ray L.
Regards,
Ray L.

Offline docltf

*
  •  353 353
    • View Profile
Re: micromachinng surface finish
« Reply #3 on: April 19, 2010, 11:25:22 PM »
if you plan on doing work like this, machine control software is the last thing on the list. quality comes from the strength and accuracy
of the working tables and the base they are running on. then you add a top of the line spindle. if you think about it there are people out
there now making the micro cutting bits,and they have been doing it for many years.

bill
Re: micromachinng surface finish
« Reply #4 on: April 20, 2010, 05:07:54 PM »
Thanks for your opinions, everyone.