glaverty
Member
I have a project where we are going to update some hydraulic presses. Currently there are some old GE 90 Micro and Modicon PLC’s controlling the presses. These will be replaced with GE VersaMax PLC’s.
Current Operation
Currently the operator has to press two buttons to lower the press until it begins pressing the product at which point he can walk away and the press will compress the product to the desired height and then has a dwell of about a minute. After the dwell time is complete the press raises and the operator again presses the product, this is repeated 10 times. After the product is pressed 10 times it is taken out and the cycle is repeated.
New Operation
For the new operation the operator will place the product in the press, hit a button and the press will automatically press the product 10 times. Once this is complete the operator will change out the parts and repeat the process. The press will have a light curtain, touch screen and a PLC.
Question
Obviously you can’t have the PLC control the safety of the Machine, that would defeat the purpose. So the Light Curtain and E-Stop circuits will be completely separate from the PLC control. Here is the thing though, I have been told that in order for a Hydraulic press to be considered safe by OSHA you have to have “redundant” control meaning two PLC’s and dual solenoid valves on all the hydraulics. So if one of the PLC’s fail the machine shuts down.
Has anyone heard of this? Is it true, I haven’t worked on presses before and since we are going to redo this press I prefer to do it right.
The guys telling me this are outside vendors who are hoping to get some work. Whereas I am more interested in learning how it should be and doing it myself. Obviously they don’t want to give me free consulting and I completely understand that but at the same time I don’t want to be paying for stuff that I don’t need.
If anyone knows where I can get some information on what is considered a SAFE setup of a Hydraulic press I would greatly appreciate it.
Thanks.
Current Operation
Currently the operator has to press two buttons to lower the press until it begins pressing the product at which point he can walk away and the press will compress the product to the desired height and then has a dwell of about a minute. After the dwell time is complete the press raises and the operator again presses the product, this is repeated 10 times. After the product is pressed 10 times it is taken out and the cycle is repeated.
New Operation
For the new operation the operator will place the product in the press, hit a button and the press will automatically press the product 10 times. Once this is complete the operator will change out the parts and repeat the process. The press will have a light curtain, touch screen and a PLC.
Question
Obviously you can’t have the PLC control the safety of the Machine, that would defeat the purpose. So the Light Curtain and E-Stop circuits will be completely separate from the PLC control. Here is the thing though, I have been told that in order for a Hydraulic press to be considered safe by OSHA you have to have “redundant” control meaning two PLC’s and dual solenoid valves on all the hydraulics. So if one of the PLC’s fail the machine shuts down.
Has anyone heard of this? Is it true, I haven’t worked on presses before and since we are going to redo this press I prefer to do it right.
The guys telling me this are outside vendors who are hoping to get some work. Whereas I am more interested in learning how it should be and doing it myself. Obviously they don’t want to give me free consulting and I completely understand that but at the same time I don’t want to be paying for stuff that I don’t need.
If anyone knows where I can get some information on what is considered a SAFE setup of a Hydraulic press I would greatly appreciate it.
Thanks.