How Delta Robotics Optimize and Streamline Electronics Manufacturing Processes
parallelograms constrains the end effector to only translational motion. That imparts the same degrees of motion as a three- axis cartesian machine but with a much stiffer and lighter structure. An added advantage of this configuration is that the mass of the drive motors is located in the (typically ceiling-mounted) base, so all the robot’s moving parts are passive lightweight structural elements. Some delta robots have additional rotary axes mounted in series at the end effector to provide four, five, or six-axis motion. Overview of delta robot applications Delta robots are widely used in pick-and-place applications for electronics assembly as well as food and pharmaceutical packaging. When a delta robot operates over one or more conveyors or mobile assembly platforms, items are conveyed or otherwise transported into the robot’s working volume. Then a vision system identifies parts’ exact locations and orientations to guide the robot on where and how to grasp or otherwise operate on the part. So, the delta robot may pick up an item and then move it to its required location. Next, it might set the item down in the target place and orientation. For
example, a delta robot may pick electronic components randomly orientated on a conveyor belt and assemble them onto a circuit board presented to the work cell via a second conveyor belt. Multiple delta robots often work simultaneously along a line with two parallel continuously moving conveyor belts for on-the-fly pick- and-place. Centralized control systems coordinate the systems of such installations — with heavy reliance on machine vision to inform robot control routines. Each individual pick and place operation can take just a fraction of a second to complete.
With several delta robots operating at the same time, very rapid assembly and packaging is possible. Delta uses specific to electronics manufacturing Electronics manufacturing relies on delta robots for the transport and handling of printed circuit boards (PCBs) and components, PCB assembly, and device assembly. PCBs are layered with nonconductive substrates and copper layers. Circuit layouts are typically printed on the board with lithography; then the rest
of the copper layer is chemically etched away. Nonconductive solder masks are then applied to prevent solder bridging between closely positioned components and copper traces. PCB assembly involves placing and then soldering through-hole or surface mount technology (SMT) components. Older PCBs only used through- hole components, but this is now uncommon. Through-hole components have leads inserted through holes in the board and are soldered on the opposite side for greater mechanical strength, but this extra process makes them more difficult to assemble. No wonder SMT components now
Figure 3: Shown here is a vision-laden work cell that employs delta robots, SCARA robots, and mobile robots. The delta robot is stainless steel and IP-67 rated. (Image source: KUKA)
Figure 4: This servomotor-driven delta robot moves to 200 cycles per minute in three degrees of freedom (DOFs) plus a rotational axis. A controller can command these robots’ axes with 2-msec response time to synchronize with conveyors and other tasks. In fact, another delta-robot is the Quattro; it has four instead of three parallelograms connecting the base to the end effector to deliver high stiffness and positioning accuracy at high speeds. (Image source: Omron Automation)
Figure 5: Electronics boards ride a conveyor through an assembly work cell. (Image source: Getty Images)
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