Originally repairing Fanuc electronics from the mid 1980’s our founder has repaired and retrofitted CNC machine tools fitted with Contraves, Fanuc, GE (General Electric), GEC, Indramat, Mitsubishi, Philips, Siemens and SEM drives and motors. Due to the burgoning prominence of Fanuc within the UK machine tool industry and GEC ceasing Gemdrive controllers. Repair of Fanuc electronics started in the late 80’s with DNC Electronics later emerging from.
The older engineers still active in the CNC machine tools industry; ours have watched the industry and Fanuc evolve design philosophy producing tighter precision at higher speeds and energy efficient.
This article follows Fanuc from 1970’s onwards when it became independent from Fujitsu. Focusing on electronic servo and spindle drives. Starting with the thyristor based DC servo and spindle units.
Fanuc DC velocity control unit and spindle (1977 ~ 1982)
Fanuc DC servo spindle unit. This drive was fun to fix. With 14 * PC-06 hybrids at $90USD each and no way to figure out which was failing – the best route was too replace the lot. Notorius for failing! No longer supported.
N series DC thrysitor velocity control units powered black cap Getty’s Fanuc motors with tacho, resolver and/or encoder for closed loop machine control. No longer supported
M series DC transistor based units drove the YELLOW CAP servo motors. These drives were self contained velocity control units with either tacho or encoder feedback to the CNC. Fanuc introduced the DC dual axis drive with two channels driven by one amplifier. Still support these DC axis drives.
Fanuc AC induction motors+ drives (RED CAP) 1982 ~ 1994
Famously the advent of FANUC’s red cap motors! Signalling the transistion from DC to AC brushless servo and spindle motors allowing lighter, more compact motors and drives due to more efficient control over variable speed. There were three main interface technologies of this era. Namely analogue, digital and later serial control.
Analogue (Analog) interface between Fanuc systems 6, 10, 11, 15, Zero model A and anodised metal framed axis and spindle drives. However as illustrated Fanuc introduced their famous yellow (RAL: RAPE SEED) plastic molded frame. Colour still in use today. However most of the analog drives were anodized metal framed. CNC controls used LSI chips on the masterboards to control the analogue drives.
Start of the Yellow Plastics Frames:
But, not really draw back to the Anodised analog units and an early release of small AC spindle drives were fitted into yellow cases.
Digital AC technology
185 volt / 18 volt
Introduction of Serial AC technology used on AC serial spindle units.
Simplified Fanuc created the ALPHA series mainly 200volt AC for higher end machining with 400vac high voltage for countries requiring different rated machines. BETA was the lower smaller rated servo units for low end machines or for auxillary functions as it could run PWM digital, FSSB fibre optic and I/O link.
