I have three-gear motors (M7 M6 M5) where one gear M7 is set permanently, while the other two need to be operated by M41 and M42. Additionally, I have a PUMA inverter installed on my machine, but I am not familiar with its sensorless vector control VFD or not. Could you please specify the VFD model you are referring to? Also, will I need to change the main motor to achieve full torque RPM of less than 100 rPM without transmission?
fisaasif wrote: ↑Fri Feb 14, 2025 5:04 am
I need to confirm whether the centroid system can be configured to work with all three gear motors through the PLC.
Yes it can control the three gear motors. However, you can only have four gear ranges. In each range you can control the speed of the spindle motor. Depending on the Centroid control, you may need to purchase the add on I/O board.
Marc has previously mentioned he has the necessary PLC code available for sale, or you can have Centroid create it, or do it yourself.
The real question is, do you even need the transmission? Modern sensorless vector control VFDs can generate full motor torque at 0 rpm, and proper VFD rated motors have a wide rpm range (my Baldor motors I use are rated 0-6000 rpm). People normally lock the transmission in a middle gear, and use the VFD and motor to generate the full rpm range of the original machine.
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I use ABB ACS355 series VFDs in my machines along with Baldor IDNM series inverter rated motors. Most people upsize motors 1 or 2 sizes for more low end torque. The benefit of using a sensorless vector drive and inverter motor is that you do not need to use M41/42/43 because you are not using the transmission. The downside is the added expense.
Cheers,
Tom
Confidence is the feeling you have before you fully understand the situation.
I have CDO. It's like OCD, but the letters are where they should be.
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There is also a downside to running in a single gear, in terms of torque.
Yes, a vector-controlled motor can produce nearly 100% torque at low RPM.
But the same motor, running through a 10:1 gear reduction, will produce nearly 1000% torque.
If you really need low-speed torque, then it is worth figuring out how to use your transmission. You don't need to support all 18 gears, but it is very useful to support 2, 3 or 4 gear ranges.
On the machine that Shane Davis retrofitted, we set it up to use four ranges: high, and then reductions of 3.8:1, 14.3:1 and 45.2:1. No vector drive is going to get 4500% torque out of a motor, but this machine gets that in M41.
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cncsnw wrote: ↑Mon Feb 17, 2025 3:16 pm
There is also a downside to running in a single gear, in terms of torque.
Yes, a vector-controlled motor can produce nearly 100% torque at low RPM.
But the same motor, running through a 10:1 gear reduction, will produce nearly 1000% torque.
If you really need low-speed torque, then it is worth figuring out how to use your transmission. You don't need to support all 18 gears, but it is very useful to support 2, 3 or 4 gear ranges.
On the machine that Shane Davis retrofitted, we set it up to use four ranges: high, and then reductions of 3.8:1, 14.3:1 and 45.2:1. No vector drive is going to get 4500% torque out of a motor, but this machine gets that in M41.
Exactly.
Without Transmission you will need a 20-30 kw spindle drive for decent low RPM torque.
Uwe
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Thank you all for your contributions. Based on your input, I have decided to go with gear transmission. I checked both low and high-range RPM settings. At 1200 RPM, I can cut steel with an 80mm face mill at a depth of cut of 1mm, and the machine operates smoothly. The 4000 RPM setting will be used for smaller cutters and finishing passes.
From your advice, I understand that I need to integrate three geared motors to adjust the required RPM, with one gear being stationary while the other two operate to achieve speeds ranging from 1250 to 4000 RPM. Additionally, I will need a PLC program, some I/O boards, and a brake resistor for this setup. Am I correct? Sir, I am looking for advice from a centroid representative.
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