Inverted Robots and Vanishing Trays Solve Manufacturer’s Space Constraints
- A creative "vanishing tray" design uses pneumatic cylinders to drop empty trays through gravity feed to a lower conveyor, eliminating need for floor space to return trays.
- Inverted robot configuration freed up floor space while allowing easy access for operators during maintenance and product changeovers across 30 SKUs.
- Strategic component placement, including IP67-rated valve manifolds mounted directly on machines and an actuator-mounted vision system, reduced control cabinet size and commissioning costs.
South Coast Robotics is a Fanuc authorized system integrator that found itself tasked with automating packaging line operations for a home-care products manufacturer.
The most intensive manual operation this project focused on involved the tray unloading stations, where small, filled bottles are removed from cardboard trays and loaded in paper blister packaging before the package is conveyed to one of numerous blister pack machines.
After evaluating the project, South Coast Robotics found that there were several constraints that made developing and implementing a successful automation solution a challenge.
First, the facility needed a system with a small footprint, as there was simply no room at the plant to move the blister pack machines.
Next, rapid changeover capabilities were essential to accommodate the home care products manufacturer’s approximately 30 stock keeping units (SKUs).
South Coast Robotics designed a custom rotating pneumatic mechanical gripper that can rotate 360° and make four picks/four places per cycle at a rate of 36 ppm 24/7.
The system also needed to be easy to operate and maintain, and it had to be safe.
And, of course, the manufacturer wanted to reduce labor costs, increase throughput and get a fast ROI on the project.
For this project, South Coast Robotics leveraged the capabilities of its sister companies Coast Pneumatics, an automation products distributor, and South Coast Controls, which designs and builds custom control panels.
Small footprint required innovations
The first design challenge was tray handling. There was simply no floor space available to route empty trays via a conveyor back into the plant for reloading.
In response, a senior South Coast Robotics design engineer created the “vanishing tray” solution. Once the tray is empty of bottles, Festo pneumatic DSNU round cylinders, DFM guided cylinders and ADN compact cylinders hinge down a section of the conveyor the tray is resting on. With this setup, the empty tray simply rolls down the slanted section through gravity feed and onto an exit conveyor located directly below and parallel to the in-feed conveyor.
Cylinders then elevate that section of conveyor, and a full tray moves into the unloading position. The empty tray travels back to the end of the exit conveyor where trays are accumulated and then manually carried back to the fill line.
Reaching the manufacturer’s throughput goal of up to 36 bottles picked and placed per minute, up from the manual rate of 30 ppm, required two infeed conveyors per robot. A full system has four robots and eight infeed conveyors. Two side-by-side in-feed conveyors enabled staggered unloading.
As soon as one tray is emptied and “vanishes,” there is a full tray ready for unloading on the sister conveyor and vice versa.
An upside-down approach to robot placement
South Coast Robotics knew that delta robots had the speed to unload the trays at that rate required, but side-by-side delta robots would be cost prohibitive for the project and did not provide sufficient reach. Though lower-cost six-axis robots could manage the pick rate needed, floor mounting multiple six-axis robots would require too much floor space.
Using inverted robots solved two issues at once — we got the robots off the floor, which saved space, and the inverted robots can be moved out of the way, so that operators and maintenance personnel can perform maintenance activities and product changeovers.
To solve this issue, South Coast Robotics inverted Fanuc LR Mate 200iD six-axis robots. Each system has four inverted robots to meet throughput requirements.
“Using inverted robots solved two issues at once,” said Ray Antalek, director of program management at South Coast Robotics. “We got the robots off the floor, which saved space. And the inverted robots can be easily moved out of the way, so that operators and maintenance personnel can access the blister packing equipment during maintenance activities and product changeovers.”
With this inverted robot design, a robot picks from one tray and, when that tray is empty, the robot moves over and above the adjoining conveyor, which contains a full tray.
Smart vision and safety systems
The equipment designed by South Coast Robotics has all appropriate safety interlocks and guarding. An Allen-Bradley Compact Guardlogix 5380 safety controller operates and coordinates all the activity and ensures that the safety integrity level and performance level metrics used to assess the safety of a system have been met. An Allen-Bradley PanelView 5310 HMI serves as the human-machine interface.
A Keyence VS-L500CX smart camera vision system is mounted on a Festo DGC linear actuator. The vision system verifies that the correct SKU is being loaded and provides guidance data to the robot, which is necessary for precision/high-speed pick-and-place operation.
Mounting the camera on the actuator meant one vision system could do the work of two by being able to be positioned above each conveyor. This design feature reduced component acquisition and commissioning costs.
South Coast Robotics also designed a custom rotating pneumatic mechanical gripper for this project. The gripper can rotate 360° and make four picks/four places per cycle. The gripper’s open and close cycles feature high-speed rotation and pick and place at a rate of 36 ppm 24/7.
Remote I/O enables full digitalization
Another step South Coast Robotics took to maintain the small footprint involved mounting IP67-rated Festo VTUX valve manifolds on the machine. This enabled a reduction in control cabinet size. Mounting the valves closer to the actuators also improved response time and lowered air consumption.
The valves on the modular VTUX are located on one side of the manifold. On the other side, South Coast Robotics specified an EtherNet/IP communication module for the multiprotocol manifolds as well as I/O modules for analog, digital and IO-Link components.
With this setup, the empty tray simply rolls down the slanted section through gravity feed and onto an exit conveyor located directly below and parallel to the in-feed conveyor.
Festo assembled and tested each VTUX manifold prior to shipping it per the South Coast Robotics production schedule. Pre-assembly and testing decreased South Coast Robotics assembly time by about four hours, “a small but vital efficiency gain on a complex project,” said Josh Cantrell, sales engineer for South Coast Robotics.
Valve manifold mounting on the machine also simplified and saved on assembly time. Assemblers ran a single compressed air tube to each manifold and a single EtherNet/IP cable. This allows for the VTUX manifolds to appear under a single IP address, making commissioning using the Festo Automation Suite software simpler and faster than otherwise possible.
Digital communication for every analog, digital and IO-Link sensor, valve and actuator is at backplane speed for high performance. The system features toolless changeovers — an important factor considering the line packages approximately 30 different SKUs.
Results for the home care products manufacturer
“Detailed time studies at our facility confirm we are achieving key objectives of increased throughput, lower labor and fast return on investment,” said Cantrell.
Results from the time studies include:
- A 20% increase in throughout from 30 picked and placed per minute (ppm) manually to 36 ppm using automation
- A 66.7% decrease in labor over three shifts from a total of 27 to 9.
- A two-year return on investment.
Harry Ellis is president of Coast Pneumatics.
