Help me about trouble servo system

[fasagianghanoi]

Dear all, Thank you verybody fisrt I have a trouble with my servo system below : - Servo system have 8 step ; each step is 2mm - I use PLC FX2N-32MR and FX2N-1PG ; Servo amplifier is MR-J2S-400A; Motor servo is HC-KFS43 When I start my machine , Servo runing but the first step (from zero point to fisrt point about 1.8mm ; After that the first point to second point is 2mm . All step later is correct (2mm) I don't kown why ??? Please help me !! Please tell me what way to checking this problem Thanks alot I'm waiting for support from you Lam

[mikeb]

Do you have any backlash in the mechanics. The first position would take it up, then the rest would be ok. I am assuming that the servo returns to the beginning by rotating in the opposite direction. Edited April 16, 2008 by mikeb

[panic mode]

it does sound like backlash, but you can also check program. if backlash is the problem you would see same error every time servo changes direction as long as motion after changing direction is greater than backlash (this means you can measure it). if the amount of movement after changing direction is less than backlash, you probably won't see any position change (you may still see some depending on system, like when load is under tension, travel is on incline etc.)

[fasagianghanoi]

Dear all, Thank you so much . Before this machine is running good . All step is correct . Some time when starting this machine is running correct position but after 1 hour this machine running not correct. But now it is have problem . About backlash I already checked but still not . If you have any support me please send reply me . Thanks alot Lam

[panic mode]

well what else has changed? program? drive parameters? load? inertia? home flag position? home sensor? is the wiring correct? what else is used in the system? any noise sources? is there something else that kicks in when this axis is returning to start position? do you get any faults from the drive? was the system setup correectly in the first place? how many pulses you get per 2mm of travel? what is the speed? where does the position reference come from? is it correct and repeatable? does it have sufficient accuracy? is this problem ONLY WITH THE FIRST move after powerup or every time axis returns to start positon? does this axis change direction? (rotary can go endlessly in one direction). does the drive have enough time to return to start position after all forward moves? ...

[fasagianghanoi]

Dear Mr Panic This fault when machine running about 20 products , 21st product will incorrect So I don't know why ? Worker of this machine said me that the fault depend on temperature. Some time the machine can run correct abour 2 hour but some time this machine runing about 20minutes Please help me Thank so much . Lam

[panic mode]

i'm not sure i can offer much of a help since there is so little to go on. if it is temperature related issue (maybe cold joint etc.) it should be relatively easily confirmed with cold spray and hairdryer (you may try heatgun but be darn carefull). watch what you do with spray as you probably don't want liquid forming on anything with high voltage...