Finding the Right Balance is Key to Better Material Handling Processes

May 6, 2019
As more material handling and manufacturing processes are turned over to robots, it is essential to balance the capabilities of part presentation fixtures, end-of-arm tooling and vision systems to achieve the best possible solution at the lowest possible cost.

“Defining your requirements for speed, accuracy and reach are critical design starting points, ” explains Ben Sagan, business development manager for robotics at Mitsubishi Electric. “The goal is to make these systems as simple as possible, which is the best way to reduce their cost.

Other design factors to consider include how much weight the end-of-arm tooling can carry, how fast it can go and what are the shapes and sizes of the parts it will need to pick up and put down. If parts have similar shapes and sizes, then fixturing can be less expensive. And whether a part is singulated (isolated in its own space) on a conveyor grouped together in a bin or in a bowl feeder will also impact system design and costs.

“The more part sizes and shapes the robot has to deal with, the more complicated the fixture must be. Think of it as a continuum. If your process requires expensive fixtures, then the focus needs to move from the fixture to the tooling to find ways to reduce costs,” adds Sagan.

One technology advance that addresses this issue is the growing application of servo or electric grippers, replacing pneumatic systems that can only either open or close. These new grippers have the ability to adjust force and stroking position, as well as enable the gripper to open or close in variable ways, which allows them to pick up more delicate products. When combined with a force torque sensor to measure how much force is being applied, these grippers can also help identify a weak or faulty part.

New vision systems at lower prices are also assuming some of the responsibilities that end-of-arm tooling used to handle. Pick in pose methods, for example, where the arm is able to pick up parts in a way that allows them to be put down how and where the user wants, enable more flexible approaches to machine tending.

Although robots cannot yet match human dexterity, all of these developments work together to increase their capabilities, reduce costs and make robotic systems more adaptable to a wider range of tasks.

Reliance Tool, which develops machining processes for its customers in the aerospace and defense industries, was able to improve the quality and throughput rates for ceramic bearing production with a robot-assisted machining center. It deploys targeted laser beams to preheat each work piece ahead of the cutting tool, plasticizing the material for faster and more accurate cutting.

The six-axis, vertically articulated Mitsubishi robot contains a manifold that houses the laser head, pyrometer and vacuum lines. The compact robot was mounted to the roof of the twin-spindle Integrex turning center so that it could operate upside down. The robot provides consistent setup and repeatability, reducing setup times and ensuring correct placement of the laser each time the cutting pattern is changed.

By coordinating the movements of the turning center and the robot, Reliance Tool avoids manually repositioning the laser after cutting. This allows silicon nitride ceramics to be machined in one-tenth the time it takes to grind them and at closer dimensional tolerances.

Tools can also be changed on the fly since the setup of the laser is not dependent upon the position of the magazine. “This flexibility can reduce a 30-minute task to 15 seconds,” says Richard Roberts, director of Corporate Development at Reliance Tool. “If we had to manually change tools from a cutting edge to a drill, for example, we would have to stop everything.”

To read more, visit

Companies in this Article