Pneumatic to servo feed

We have a machine that uses a SLC500 and a Air Cylinder to feed pipe through a cutter to certain lengths. We have talked about converting to a Servo motor for better accuracy. My boss told me they were quoted $25000.00 to do this. I would like to look into seeing what it would take to do this myself. I obviously would have to figure out how to integrate the servo into the PLC program but for now I need to find the correct motor and drive.

I know he told me the company that came and quoted him the cost of the conversion set up equipment and said he would need a motor capable of push 400lb.

Can anyone give any insight on where to go from here as far as motor selection?

I suggest you google for a servo actuator - something with a integrated controller/drive that has simple I/O interface that you can connect to your SLC system. You didn't say how many different lengths you need so that will be important in your consideration. Tolomatic is where I would start.

you could use a endplate with a small motor and a long bolt. this to set where the cylinder should stop. As the motor is not running all the time it can be very small.
accuracy is below 1% (i used to work for a company making copper tubes.