Successful robotic deburring is really a matter of choices.

Author:Odham, Aaron
Position::Automation
 
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Robotic deburring and surface-finishing applications continue to grow in number as lean manufacturing techniques demand more from less. Automated surface finishing is a process that can be widely used in the manufacturing technology industry for a variety of applications ranging from aerospace to automotive to ship industry? Coupled with increased healthcare costs associated with maintaining dangerous manual deburring systems, these robotic deburring systems have a huge monetary savings potential if executed correctly.

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One key to a successful robotic deburring system is the ability of the system to adapt to ever-changing part tolerances and burr sizes. Utilizing active or passive force control tools such as those from ATI Industrial Automation in the system will greatly increase a robotic deburring application's chance for success.

In the most generic sense, successful deburring or surface finishing requires a consistent end result regardless of the starting conditions. For deburring and deflashing, success will require: a) completely removing the unwanted burr/parting line, b) leaving the surface free of chatter and scallops, c) not removing too much parent material. Of the three requirements, leaving the surface free of chatter and scallops is the most difficult for human operators. Completely removing the burr/parting line and not removing too much parent material are the most difficult for robots. Humans are wired for change and very easily adapt to changing conditions, but are not very consistent. Robots, conversely, are wired for consistency, but cannot easily adapt to changing conditions unless given "prompts" to change based on feedback from an ATI Six-Axis Force Torque Sensor or using adaptive (compliant) tooling such as AYl's Versafinish or Flexdeburr.

Active force control tools provide prompts to the robot to actively (in real time) change its program trajectory as defined by a controlled-correction routine. These changes can adjust the path speed and adjust the cutting forces. These types of systems are typically more expensive than passive devices, but offer more accuracy and repeatability.

Passive force control tools adapt to the changing part or unwanted burr independent of the robot, but are not as precise or accurate.

Let's examine the pros and cons of both systems, as well as provide general areas of concerns for robotic deburring.

Deburring, finishing art

Much like a master jeweler refines his technique over years of experience to cleave a perfect diamond and produce a brilliant, radiant gem, so must a master finisher rely on experience to remove the right amount of material and produce a beautiful "gem." Applying too much force and in the wrong direction to a diamond results in a useless shattered diamond. Applying too much force in the wrong direction to a part yields useless scrap material--or worse, rework.

To achieve a perfectly deburred or finished part, an operator must constantly adjust the amount of force, location and direction of force, and the speed at which this force is applied to a workpiece as that workpiece constantly changes. The learning curve for this type of work is very steep and filled with costly mistakes. Unfortunately, once the operator has mastered this art, he may be burned out and no longer wish to continue this dirty, dangerous, and degrading job and so the cycle continues with the next new operator.

During the learning process, an operator uses his senses to continually adjust (in real time) his process to achieve an acceptable result. Whether he remembers and applies the same techniques he used Friday afternoon the following Monday morning is a different story. Although we are the most dynamic machines on earth and can adjust to an ever-changing environment, we are not repeatable and lack the physical stamina to achieve the consistent end results demanded in most deburring or surface-finishing applications today.

And now the science

Deburring, grinding, and surface finishing are basically quite simple. For a given material (assuming the material composition and characteristic doesn't change during the process) and given media (assuming the abrasiveness doesn't change), the end result is dependent only upon the media's surface speed, the contact pressure of the media (contact force divided by contact area), and the rate at which the media is presented to the workpiece...

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