Automation of a Coating Process

[eaglewood]

This would be a nice little interesting project to work on
Just for reference I have done more than a few projects like this
The fact that you haven’t ordered the hoist yet works in you favor. First when you order the hoist you want to use a “No Load Brake Hoist” to get the control you want. Please don’t confuse the load brake with the motor brake they are different.
Next I would not use any of the tank position switches they are expensive to install and a high maintence item that can give you nothing but headaches
I would use a laser measurement system for position feedback. That way when you are setting up the positions you just need to plug a number into the processor and you can adjust it on the fly when necessary.
As for the crane vfd’s I would use Magnetek crane drives. In this case I would use Flux vector drives on both the hoist and the trolley ( Noload brake hoist drive) these at designed for crane duty not just a label put on a standard drive, they do require an encoder on the motor but they will allow you to control the motor speed down to 0 including suspend the load on the motor and yes I have done this many times. Also don’t forget to order the correct braking resister for each drive to give you the needed braking to control the load.
Because the primary control of this system is from the plc I would swap out the pendent controls with a small radio control for those times when the operator or maintence needs to control the crane. That way the operator can have full control and still remain in a safe location. Each station would have a preset position you just need to tell the control what station to go to.
Sa for the hoist position hear again the hook position will be from the encoder feedback on the hoist motor. As not here with cable hoist’s the cable will stretch a little as time and load effect it so I have found I can correct for this by using the first hoist travel limit switch to reset the hoist position every time it is activated the cable drum on the hoist will give you a constant travel distance. You should also use the hoist travel limit to ensure that the hoist id fully raised before the trolley can move.
If this system were setup correctly I can see it running for many years with very little operator interaction
There other things to consider when doing a system like this you need to go over you requirements carefully

A lot of things here I hadn't even considered. Laser measurement systems instead of limit switches? I was concerned about maintaining those switches up on the I-beam, and not looking forward to it. My spiderman days are behind me. Do you have any supplier recommendations?

Using radio control to keep the operators out of harm's way sounds like a must, now that I think about it.

A lot here to consider. And thanks to everyone who commented about safety. I will do a thorough safety assessment.

 

[arpus4KM]

Parky, thanks for all the help. I have not purchased the hoist and trolley yet, so I can order the motors without breaks. Or at least the trolley motor. I'm not sure if it's a good idea to have no break on the hoist motor, though as I mentioned, loads will be light. (Less than 100lbs.)

what he's talking about is that in the Crane world there are multiple standards that need to be used.

All hoists have some form of holding brake, this brake is engaged when nothing is happening and is a failsafe always closed unless energized brake, typically attached to the back of a motor or on the drivetrain itself (older and larger overhead cranes had clamshell or drum style as well).

Then there are dynamic brakes, these would be like a magnetic flux brake used to help slow a load in lieu of physical brake or VFD to slow it.


When it comes to the brakes mentioned previously, they are talking about LOAD brakes, which are attached internally to the drivetrain and act as a centripetal brake of sorts that when spun without a motor driving it, it will push a pad against a disc to keep a load from going into freefall. The difference is that in cranes with VFD and encoder, it isn't a requirement to have a load brake, and the load brake itself can cause problems with VFD encoder operations, so they typically don't have them. The encoder and VFD take care of all slowing and brake engagement, if the VFD lets go the physical brake will close. It's just different types of standards of safety


The standards can go up or down depending on the situation and what is called for, in Melting, 2 load brakes are required for instance.

 

[parky]

Encoders may not be required, depending on the accuracy, a simple star wheel would sufice providing there is little or no slip, use home & end positions to re-calibrate the counts, proximity switches are probably more resistant to corrosive gases or liquids so there is a possibility, however, I do reccomend using positive acting limits for the end overtravel limits.
As I posted, done a few like this, one used a very long hydraulic linear cylinder for the travel, however, on that one it was the tanks that lifted on pneumatics so no hoist. the position limits over the tanks were through beam so outside of the machine & easy to maintain. one other we did use a star wheel & proxy for position, the teeth gave a pulse about every 20mm which was sufficient to get good registration over the tank, again did not use a hoist but a large pneumatic cylinder to lower/raise the component hangers into the tanks (this was an explosion risk area so required zener barriers for the interface for the sensors).

 

[gbradley]

I don't like the idea of Electrical Hoist above water baths.
Air powered hoist seems safer. but more expensive I know.

 

[James Mcquade]

while you did mention a coating process, what is the application?
paint, anodize, other? each has their own rules to follow.
james

 

[GaryS]

A few things here there seems to a bit of confusion about Motor brake / Holding brake and a load brake
Every hoist must have a holding brake to hole the load on a power failure or when the hoist is not in motion. A load brake is located in the hoist gearbox and is designed to not let the hoist freefall.
So when the hoist is in motion in the lower direction the motor must move to drive the hoist down
A note here they are not available or used on hoist over 30 tons. But through experience I have learned that controlled very speed motion on the hoist with a load brake is difficult and I would avoid it in this application.
As I stated before I would use a Magnetek Impulse VG+ drive on both the hoist and trolley
Yes an encoder is required but it’s the best way to do very slow speed control ( I am talking about down to 0 speed ) and this application requires very precise positioning with very low speed control.
I would avoid using a cable reel here, in a very short time they will give you trouble and could cause to drop the load. The best would be a good quality festoon system.

As for the positioning system as I stated before I would use a laser system on trolley and the motor encoder on the hoist
Her is a link to a place to start looking Crane Positioning - Acuity Laser
They are stating accuracies to +-1mm over a range of 500 M that should meet your requirements
I would select ASCII feedback from the laser system through an ASCII I/O module that would eliminate the need for calibration and scaling as the ASCII feedback would be direct position reading back in.
For the hoist position use a high speed quad counter from the hoist vector drive encoder

As for limit switches the only ones you need would be end of travel limits on the trolley for safety encase of a failure of some type.
On the hoist I would use 2 travel limits pos 1 slow down and pos 2 stop pos 1 would also zero the hoist counter so the system always know where the hook is.

Programming is fairly simple and straight forward

And before anybody asks yes I have done this more than a few times over the years
With proper selection of the hardware and design I would expect it to run without any problems for at least 20 years

 

[dploof23]

A lot of things here I hadn't even considered. Laser measurement systems instead of limit switches? I was concerned about maintaining those switches up on the I-beam, and not looking forward to it. My spiderman days are behind me. Do you have any supplier recommendations?

Using radio control to keep the operators out of harm's way sounds like a must, now that I think about it.

A lot here to consider. And thanks to everyone who commented about safety. I will do a thorough safety assessment.

Keyence makes some nice level monitors. I use them here in a pretty harsh environment and have never had any issue. (Knocking on wood.)

I use these:
https://www.keyence.com/products/process/level/

 

[JeffKiper]

Parky, thanks for all the help. I have not purchased the hoist and trolley yet, so I can order the motors without breaks. Or at least the trolley motor. I'm not sure if it's a good idea to have no break on the hoist motor, though as I mentioned, loads will be light. (Less than 100lbs.)

A light load when pulling out of a tank full of parts can jump in force required pretty fast. Just keep that in mind.

 

[parky]

As Gary posted, however, I have seen a system where a brake on the motor used, the feed to hold the brake off was fed via the safety circuit as well as a seperate relay used to feed the power from the PLC so perhaps a normal brake motor could be used.

 

[JeffKiper]

I like the SEW brake motors. You can feed them the brake from a seperate power source. It makes our life easy. If you go with a full blow VFD with torque proving you can use the VFD to control the brake on the motor. Ive done a few hoist applications over the years and its a nice feature.

 

[arpus4KM]

A few things here there seems to a bit of confusion about Motor brake / Holding brake and a load brake
Every hoist must have a holding brake to hole the load on a power failure or when the hoist is not in motion. A load brake is located in the hoist gearbox and is designed to not let the hoist freefall.
So when the hoist is in motion in the lower direction the motor must move to drive the hoist down
A note here they are not available or used on hoist over 30 tons. But through experience I have learned that controlled very speed motion on the hoist with a load brake is difficult and I would avoid it in this application.
As I stated before I would use a Magnetek Impulse VG+ drive on both the hoist and trolley
Yes an encoder is required but it’s the best way to do very slow speed control ( I am talking about down to 0 speed ) and this application requires very precise positioning with very low speed control.
I would avoid using a cable reel here, in a very short time they will give you trouble and could cause to drop the load. The best would be a good quality festoon system.

And before anybody asks yes I have done this more than a few times over the years
With proper selection of the hardware and design I would expect it to run without any problems for at least 20 years

I feel like i'm taking crazy pills, or I'm muted in this thread or something

mentioned this a few posts back, I've installed quite a bit of crane systems over the course of a few years, dealt with all different kinds and currently help another company service an electro dip system with 7 gantry hoists on it and 14 dip tanks all automated. 350 feet of festoon for the end gantry....



You are still spot on though Gary, and yes most hoist applications here in the U.S. that i've dealt with, with VFD used Magnetek (the company I worked for previously was a magnetek dealer). but you can still get any number of other VFD that have specific hoist operation options that do all the brake control and checking internally in the VFD, including AB, Schneider, Yaskawa, and Demag.

To be fair, you don't need to have a separate brake control if you're worried about it, you could just go with something simple like a Harrington that uses a Conical brake/rotor that automatically releases when you energize the motor itself, the hoist brake is integrated into the operation mechanically. it all depends on the application and what you need for control.

 

[eaglewood]

while you did mention a coating process, what is the application?
paint, anodize, other? each has their own rules to follow.
james

Most of the baths are for cleaning and rinsing. The operative bath uses CHEMEON TCP-HF to coat aluminum parts.

 

[eaglewood]

I feel like i'm taking crazy pills, or I'm muted in this thread or something

mentioned this a few posts back, I've installed quite a bit of crane systems over the course of a few years, dealt with all different kinds and currently help another company service an electro dip system with 7 gantry hoists on it and 14 dip tanks all automated. 350 feet of festoon for the end gantry....



You are still spot on though Gary, and yes most hoist applications here in the U.S. that i've dealt with, with VFD used Magnetek (the company I worked for previously was a magnetek dealer). but you can still get any number of other VFD that have specific hoist operation options that do all the brake control and checking internally in the VFD, including AB, Schneider, Yaskawa, and Demag.

To be fair, you don't need to have a separate brake control if you're worried about it, you could just go with something simple like a Harrington that uses a Conical brake/rotor that automatically releases when you energize the motor itself, the hoist brake is integrated into the operation mechanically. it all depends on the application and what you need for control.

A few things here there seems to a bit of confusion about Motor brake / Holding brake and a load brake
Every hoist must have a holding brake to hole the load on a power failure or when the hoist is not in motion. A load brake is located in the hoist gearbox and is designed to not let the hoist freefall.
So when the hoist is in motion in the lower direction the motor must move to drive the hoist down
A note here they are not available or used on hoist over 30 tons. But through experience I have learned that controlled very speed motion on the hoist with a load brake is difficult and I would avoid it in this application.
As I stated before I would use a Magnetek Impulse VG+ drive on both the hoist and trolley
Yes an encoder is required but it’s the best way to do very slow speed control ( I am talking about down to 0 speed ) and this application requires very precise positioning with very low speed control.
I would avoid using a cable reel here, in a very short time they will give you trouble and could cause to drop the load. The best would be a good quality festoon system.

As for the positioning system as I stated before I would use a laser system on trolley and the motor encoder on the hoist
Her is a link to a place to start looking Crane Positioning - Acuity Laser
They are stating accuracies to +-1mm over a range of 500 M that should meet your requirements
I would select ASCII feedback from the laser system through an ASCII I/O module that would eliminate the need for calibration and scaling as the ASCII feedback would be direct position reading back in.
For the hoist position use a high speed quad counter from the hoist vector drive encoder

As for limit switches the only ones you need would be end of travel limits on the trolley for safety encase of a failure of some type.
On the hoist I would use 2 travel limits pos 1 slow down and pos 2 stop pos 1 would also zero the hoist counter so the system always know where the hook is.

Programming is fairly simple and straight forward

And before anybody asks yes I have done this more than a few times over the years
With proper selection of the hardware and design I would expect it to run without any problems for at least 20 years

Thank you very much, Gary, for all this solid information. I'm getting my ducks in a row for ordering components soon.

And thank you as well, Ian. You are definitely not muted.

Gary, the one suggestion I'm not sure I will implement is the ASCII laser distance sensor output and ASCII module. I've never worked with ASCII output but that's not the issue. It's just that everything I can find on ASCII output modules refers to Rockwell and I won't be using a Rockwell PLC.

 

[JeffKiper]

Instead of an ASCII laser distance you can use Ethernet/IP and talk directly to an AB plc.
You can use a ModBus TCP and talk to just about any other PLC.

 

[parky]

Not knowing the actual process/ hardware that exists etc. I think people may be over thinking this, most dipping processes I have come across the tanks are large enough to take the components with spare room all round, if this is the case then why go to to the extremes of hi res encoders or other methods that cost a lot more, difficult for many maintenance staff to faultfind on. sometimes simple is best.
On a side note: the coating process how is the PH controlled I assume this is manual at the moment.