When did fanuc switch to AC servos?
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    Default When did fanuc switch to AC servos?

    Just curious, Seems like mid to late 80's? I still see some old yellow cap servos out there. Did they switch all at once? Are they or I guess were they fairly reliable? Seems amazing that there are still some running 30 years later...

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    AC analog was introduced in the early 80's. I've got some service documentation dated 1982 on them. My oldest AC digital documentation is 1987 and it is revision 5 so imagine a couple years earlier than that.

    DC must have still been available for a few years as I recall a working on a 1985 Kira machining center still having yellow cap DC motors (though it could have been an old stock machine).

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    Silly question, but what is the difference between the analog & digital systems? I mean fundamentally, I know the difference between analog/digital signals but hows that work in a servo motor/amplifier system?

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    Quote Originally Posted by Jashley73 View Post
    Silly question, but what is the difference between the analog & digital systems?
    Well, when Fanuc went to digital, they solve the pesky problem of their motors working with drives made by other companies...

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    Quote Originally Posted by pmtool View Post
    Seems amazing that there are still some running 30 years later...
    I have 3 machines with yellow caps. One did ferrous parts for Boeing (supplier on Boeing field) 2 shifts a day, 6 days a week from 1982 until about 2007. It had an indexer on one end of the table with a quick change pallet and pallet system on the other end of the table. One side was loaded while the other side was cutting. It made the same simple parts it's entire life. In 2007 a "rebuilt" Fanuc main board put the machine down long term. That board was bad from Fanuc. I have what I believe is the entire repair and maintenance history for the machine. There isn't a servo or servo drive repair in there.

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    I had a Mazak with Gettys Fanuc servos from 1980. Ran like a top.

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    Quote Originally Posted by Jashley73 View Post
    Silly question, but what is the difference between the analog & digital systems? I mean fundamentally, I know the difference between analog/digital signals but hows that work in a servo motor/amplifier system?
    On the analog drives, the tuning was still performed by adjusting pots on the drive board. The digital drives are tuned by servo parameters stored on the CNC. At power up, the parameters are downloaded to the drives.

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    My 88 mori mv40b with fanuc 10m has digital spindle control and red cap servos

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    Quote Originally Posted by Vancbiker View Post
    On the analog drives, the tuning was still performed by adjusting pots on the drive board. The digital drives are tuned by servo parameters stored on the CNC. At power up, the parameters are downloaded to the drives.
    Ok, so the difference is at the CNC-to-amplifier level then. The motors work like any other AC servo motor I suppose?

    I know some of the older Fanuc red-cap (AC) motors had large encoders the size of the motor frame, as where modern Fanuc encoders are much smaller in size than the motor frame. Are these the older AC/Analog motors by chance? Or older incremental-encoders style? Or is that no indication of the system type, but just older designs?

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    Quote Originally Posted by Jashley73 View Post
    Ok, so the difference is at the CNC-to-amplifier level then. The motors work like any other AC servo motor I suppose?
    yes.

    Quote Originally Posted by Jashley73 View Post
    I know some of the older Fanuc red-cap (AC) motors had large encoders the size of the motor frame, as where modern Fanuc encoders are much smaller in size than the motor frame. Are these the older AC/Analog motors by chance? Or older incremental-encoders style? Or is that no indication of the system type, but just older designs?
    DC motors use incremental 3 channel (A, B, and Z) encoders. Older AC motors (with either analog or digital drives) use a 3 channel encoder for position and a 4 bit binary "gray code" signal for commutation position information. Those are the larger bodied black or red encoders and would be incremental on analog drives and incremental or absolute on digital drives. Later AC motors with digital drives use a serial encoder. They are smaller and communication is by a serial data stream instead of the pulse train of the older 3 channel style.
    Last edited by Vancbiker; 02-14-2016 at 11:36 PM. Reason: fixed quotes

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