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Interface Robotics to machine tools

Different ways robotics are interfaced to machine tools

What choices do you have on how the robot call is made?

The topics below coming soon

Fixture requirements

Recommended signals to interface for safety

Options to consider for machine tool

Robots can be interfaced in generally two different ways here are the benefits and draw backs.

Robotics interfaced directly into machine tool with machine tool robot interface option from factory

Advantages

  1. More signals given from machine tool to a terminal strip. There is no need to splice into wires to get signals and figure out safety circuit.
  2. Less hardware and costs of additional panel
  3. Cleaner interface

Disadvantages

  1. Can not modify machine tools ladder interface easily unless the builder has their own automation division.
  2. General functionality of the machine tools ladder may not fit the design and require extensive time to figure out how to modify it.
  3. Can't be customized based on customers needs as easily and add additional automation options.
  4. Somtimes costs a lot more and has long lead times.

External PLC installed for robotic communication

Advantages

  1. Fully customized in every way. You can spec out the exact I/O cards and interface the most efficient way.

  2. Integrators do not have to know how to use the machine tools ladder and interface points. They cab edit and make any changes easily.

  3. Integrators do not need to figure out all the logic already written in the machine tool to attempt to design around the current functionally if it exists.

  4. Machine tool builders often have ladder updates and when they install them they could write over the logic you installed. Therefore causing many problems trying to reinstall and track ladder mods within main ladder.

  5. Add manual operation for fixture clamping if robot is down.

Disadvantages

  1. Some machine tool Ladder I/O signals will not be available to tie into since you are limited to what is wired on the machine.

  2. M-codes may be need and may have to be purchased separately. Depending on cell operation and fixture clamping this may or may not be needed.

Summary and important notes: I prefer using the external PLC just for the simple reason of never taking the chance that someone will update the machine tool ladder and make changes. In the majority of machine tool interfaces you will have everything you need to fully automate your work cell. It may take more leg work to figure out where to get the signals and determine exactly what you need.


Robotics interfacing to machine tools

Setting up the Robot call for load/unloading of parts

Robot integration with machine tools is actually very simple. You generally do not need any robot interface from the Machine tool builder if you are adding on your own PLC, although it will make things easier to interface because then you would not have to search through the electrical books to find the signals to tie into. The only thing you may or may not need from the machine tool is some external M-codes (sometimes special order) Depending on if you want the robot to perform the clamping and monitoring or do you want the machine tool to perform these functions. The other signals you will need are End of cycle, NC in operation, Alarm, External feed hold or alarm input and door open or closed. Many of these signals can usually be taken off of the 3 stage signal light, and the door interlock circuit.

The robot load/unload usually is called in one of the following two ways.

First the robot can be called by the end of cycle signal / M30. When a machine hits the M30 in the NC program a signal is output to the robot and the robot looks at various conditions and begins to unload and load new parts. When the robot has completed its operation it will output a cycle start to the machine tool just as if the operator hit the start button himself. The robot load will then be complete. This is the most common setup.

The second way in which the robot cycle is somtimes called is by an M-code. An External M-code can be output and the NC program will wait on that m-code until it receives a completion signal or M code finish as it is sometimes called. Once the robot receives this signal it begins the load/unload process and when it is complete output a M code finish signal back to the machine tool.