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      08-21-2012, 12:09 PM   #66
bruce.augenstein@comcast.
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Quote:
Originally Posted by swamp2 View Post
Sorry, wrong.

Here is a quote from Addison D. Cole, CEO of Adcole Corporation an inspection machine company, about how improved engine tolerances are greening engines,

"In the last 25 years, crankshaft roundness tolerances have been reduced from eight microns to three microns. The green cars of the future will have high performance, small engines with very low emissions. Consequently, the production tolerances will continue to tighten..."
On the one hand, I genuinely appreciate this informational nugget, as my dated knowledge would've said five or six microns. On the other hand, sub-micron tolerances in this area may well take another 25 years...

Be that as it may, however, even three microns is a far cry from your sub-micron comment, and my original note was about cylinder to cylinder and piston to piston variation - not crankshafts.

In the example I provided, we're looking at 23 microns in terms of combined piston and cylinder variation in the S52, which is enough to drive a couple of trucks from the Submicron Shipping Company through there, side by side.

Here is where hand assembly can make a difference. A clear difference.


Quote:
Originally Posted by swamp2 View Post
.00x mm is in fact x microns...

Also the S52 was now developed what, well over a decade ago? That's a long time from the perspective of precision, tolerances and robotics! The S65 surely has a variety of single digit micron tolerances.
It's possible (in the sense that almost anything is possible), but going from a combined 23 microns to under a micron would be an extraordinary stretch, wouldn't you say?

Quote:
Originally Posted by swamp2 View Post
No factual/first hand knowledge of this but given the level of inspection this would not be too difficult at all. Watch the video posted below. The piston for each cylinder is placed in a specific holding fixture and robotic mover...
On the contrary. It would in fact be difficult (read: expensive). You would have to measure each piston to essentially exactitude, then store it in one of hundreds of buckets, then measure each cylinder to exactitude, then go and retrieve an appropriate piston...

Expensive.

Quote:
Originally Posted by swamp2 View Post
You know the answer, it is ALL driven by volume and cost and their relation. Its very simple.
I am going to take this as just another of your thoughtless comments, as opposed to a deliberate insult.

In point of fact our disagreement is based on the fact that I know it's NOT all about the money.

Mercedes has built those 6.2 liter engines by the thousands, since they've put that engine into just about everything except the Smart Car. There was clearly enough volume there to justify the automated tooling (a good deal more volume than exists with the S65), yet they went with hand assembly - at least as far as fitting pistons goes.

I believe they did this to get better piston to cylinder wall tolerances, with whatever benefit that provides them.

Bruce

PS - By the way, your childlike faith in the M Group's ability to provide sub-micron tolerances in the S65 is touching - but I'll need some proof, please.