Special radially compliant tooling in action on a robot deburring system.
The Flexdeburr's floating design improves the production quality and efficiency of automated part-finishing.
SUCCESSFULLY AUTOMATING PART-FINISHING operations hinges on the flexibility and consistency of the deburring tools used because programmed robot paths do not always coincide exactly with part shapes or contours when shops want to use them to remove burrs, residual material on parting lines and flashing on die-cast parts for operational, safety and aesthetic reasons. Such robot limitations combine with part complexity to make it extremely difficult for shops to meet quality goals with automated deburring systems.
However, special flexible deburring tools, such as the Flexdeburr device from ATI Industrial Automation (www.ati-ia.com), can provide radial compliance to accommodate differences between part edges and actual robot tool paths. These tools easily maneuver around protrusions and into small cavities to satisfy nearly 100 percent of all robotic and automated deburring applications. In addition to improving production quality and part-finishing consistency, these tools speed robot programming time, eliminate manual deburring operations and allow shops to apply automated deburring to a wider range of applications than ever thought possible.
"When we first tried the radially compliant Flexdeburr, we were pleasantly surprised how closely it mimics manual finishing operations," says Charlie Young, manager for advanced automation at Hammond/Roto-Finish (www.roto-finish.com), a company that supplies turnkey finishing systems. "The device is forgiving and allows our systems to quickly and easily change directions, which is especially important when training robots." Programmers can program fewer path points because the tool's tip follows deviations between the robot path and part edges, reducing programming time at Hammond/Roto-Finish.
The shop programs robot paths either by mounting a dowel pin that matches the tool's diameter or by mounting a pointed teaching tool into the robot. The pin or the teaching tool are moved manually to a point where they touch a finished part's edge, and the software records that point. After repeating this process along the part's edges, the robot controller uses the recorded points to define a path. The more complex the part, the more programming time is required to achieve an acceptable path. Because cutting forces are adjustable on-the-fly, programmers can increase cutting forces in areas that have large burrs or where more material needs removed.
For Fanuc Robotics (www.fanucrobotics.com), a robotics systems integrator, the Flexdeburr allows it to improve the designs of its automated work cells, and the company says more manufacturers are using the tool to replace or re-evaluate their manual deburring operations. "For years we developed systems that could do almost all of the necessary tasks. But now, we believe we have found the ultimate solution and that it will provide a 35 to 40 percent gain in productivity due to improvements in the deburring process," says Bob Howard, a Fanuc systems integrator.
By automating deburring operations, shops also eliminate health and safety issues associated with using hand-held tools. Robots do not experience carpal tunnel syndrome and "white fingers" (permanent numbness) conditions that are common among workers whose hands are subjected to constant vibrations, high contact forces and the contorted positions that are typically involved in deburring operations that use hand-held tools that are not ergonomically designed. Also, the automated deburring operations result in more consistent finished part quality.
Shops that want to automate deburring processes look for part-to-part consistency, and, according to Aaron Odham, an applications engineer at ATI, manual operations cannot match the repeatability of robotic work cells. However, inconsistency can occur when parts are misaligned in workholding devices. Without proper workpiece alignment, the deburring tip can gouge parts, leave unwanted burrs and, in a worst-case scenario, break and cause downtime.
Flexdeburr's floating motor and spindle arrangement delivers ±0.31 in. of deburring tip radial compliance for consistent performance on irregular part patterns. The tool is designed to maintain a constant finishing force. Its pneumatic motor/spindle mounts on a pivot bearing that is attached to the tool housing. That allows the motor to move with the pivot bearing independently of the housing. A ring of small pneumatic pistons near the front of the tool housing creates a radial-compliance field.
Compliance force can be exerted on the tool in any direction (360 degrees) radially from the tool. Spinning at a constant 40,000 rpm, the Flexdeburr finishes hard-material parts at rates of 1 in. to 3 in. per second and soft material parts at rates of 3 in. to 12 in. per second.
The Flexdeburr also incorporates ATI's force-control system that is designed to provide high stiffness in path directions and low stiffness in contact force directions. This feature reduces chatter, a common problem with robotic deburring. The tool mounts to robots or CNC machines and requires clean, dry, filtered and non-lubricated air. It has two air connections, one at 90 psi spins the cutting file and the other 60-psi one applies radial force.
Weighing in at 2.6 pounds, the tool operates at 41 to 95 degrees F and uses standard tungsten-carbide industrial bits for adapting to changing assembly lines and part requirements. Shops can change bits quickly from one operation to the next.
Shops that work with plastics and magnesium benefit especially from automating their deburring operations with a Flexdeburr, ATI says. The tool's high speed allowed one of ATI's customers to develop a deflashing/deburring process for magnesium parts that helps to eliminate the hazard of fires and excess waste and keeps the flammable magnesium dust that is created when grinding, machining or deburring from igniting.
The use of magnesium for structural parts is increasing because of its relatively light weight and rigidity and, while magnesium parts usually are produced with state-of-the-art casting processes, removing parting lines and flash is a challenge. ATI's Odham says the Flexdeburr meets that challenge.
When removing the flash from plastic parts with automated deburring processes, shops do not have to worry about exposing operators to plastic dust as when the job is done manually.
Flash is typically the result of welding two plastic part halves together. With completed parts secured in work cells, the Flexdeburr removes flash for smooth joints.