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DMU 100 monoBLOCK~~~~~~~~~~~~and the end of scraping

JHOLLAND1

Titanium
Joined
Oct 8, 2005
Location
western washington state
here is new video release from DMG
emphasis is on configuration versatility---in this case a trunnion type rotary fifth axis

what caught my eye was the uncovered linear tracked guideways used by the
rotary axis

Mori Seiki has a "Business and Capital Collaboration with Germany's GILDEMEISTER AG"
dating to 2009
and when you look at the product offerings of M Seiki, DIXI--which Mori owns
and DMG there appears to be a commonality of linear roller bearing guideways---
and interestingly none of the machine frame makers want to draw attention to this

maybe because they do not make the linear track-- THK and NSK seem to prevail in
the higher priced machines

so ---looking over the literature of THK interesting facts appear--

thk notes that simply rough milling a load bearing surface and then applying
linear guideway will improve accuracy by an immediate 90%
and if you are DIXI, you use tracked rail for load bearing components but
spend 500 hours scraping machine frame and even rail cars to move into
the 2 millionths/inch repeatability the machine promises

THK also notes nonchalantly lithium soap grease should be used as track
lube--and you will reduce way lube consumption by 93%

sure, there is lots of used iron begging for a good scrape--but the message
from new product makers seems clear---rail, rail, and more rail

DMU 100 monoBLOCK - YouTube


jh
 

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I got to tour Makino's plants in Japan and can atest that they also hand scrape the ground surfaces that the tracks sit on and the tops of the trucks. This type of scraping, which is for geometric improvement only (improving flatness, parallelism, ect.) looks kind of funny because they don't scrape the entire surface, they just scrape the high spots to bring them down to the lowest points, or correct very slight error. It looks like a brand new surface that has spots worn out on it already. It functions perfectly fine, but looks odd to a person that is used to seeing completely scraped surfaces on ways that are meant for oiling.

I agree you don't hear any machine manufacturers claiming their bearings are better than the next guy's and I too would suspect they are all using the same bearings from 1 or 2 bearing manufacturers.
 
The future will be interesting..... With new engineering techniques who knows what will happen.... We know linear rails can in no way compete for stiffness that you get with cast iron ways, but with cutting speeds getting higher and higher, machining today is less about taking hogging cuts and more about taking many light cuts...

With light cuts, less stiffness required, linear rails win with their high speed capability...
 
The future will be interesting..... With new engineering techniques who knows what will happen.... We know linear rails can in no way compete for stiffness that you get with cast iron ways, but with cutting speeds getting higher and higher, machining today is less about taking hogging cuts and more about taking many light cuts...

With light cuts, less stiffness required, linear rails win with their high speed capability...

Since the machine is HH equipped, I suppose its apt to include this HH Active Chatter Control video here. Tight feedback loops, active sensing and micropositioning are augmenting the role of ultimate machine rigidity, with the goal of increased dynamic stability.


 
.. We know linear rails can in no way compete for stiffness that you get with cast iron ways,

That's actually a wives tale/carryover from the days of cheap crappy machines being the only ones with linear guides. Most of the builders are using roller guides for their heaviest duty machines nowadays. Titianium specific machines with HSK100 or 125 spindles, 1000ft/lbs of torque, etc, use rollers. Casting design, spindle design, and axis thrust are much more important than the difference between box ways and roller guides.
 








 
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