Page 36 - Plastics News July 2019

FeAtures

output. With industrial robots, when guarding is a concern, Three-plate & stack molds
many times we simply utilize a conveyor package with To run these popular applications efficiently, robots must
integrated guarding. The guarding would be attached to
the conveyor, and the entire system could quickly and be equipped with two arms to extract the parts and
runners between each set of plates. A single-arm six-axis
easily be rolled away from the press, to use on another
work cell, or simply move away during mold changes. robot would not be ideal for these applications, as it would
dramatically impact the cycle time.
Control cabinets
Support
Because Cartesian robot manufacturers understand that
floor space is at such a premium in a molding shop, they Of course, articulated-arm robot manufacturers have
technical support. The main difference is that their
have almost exclusively moved to mounting the control
cabinets on the robot traverse beam. Six-axis robots personnel may not necessarily know the injection molding
process and equipment. When calling support, it certainly
require a separate control cabinet that will require
additional floor space. must be helpful when supplier personnel understands
common terms related to robot sequencing in molding
Features specific to the injection molding applications—like core pull, screw recovery, air blast,
process cooling time and ejector sequencing.Many issues that arise

Gantry robot manufacturers have been working constantly are related to the molding machine and robot interface.
to help make the molding process more efficient. We Again, gantry robot manufacturers understand how that
now have features such as Soft Torque, which allows the interface functions. This allows them to quickly ascertain
ejectors to push the arm back with assistance from the what the problem may be and whether it is robot- or
robot. The robot monitors the force applied during this machine-related.
motion and applies a counterforce to move the arm back. Robot/ press integration

Find & Pick is a feature for use with robots on older Some Cartesian robot manufacturers allow their robots
hydraulic presses that may have a tendency for their to be integrated with the molding machines. This
clamp position to vary from shot to shot. With this feature, integration allows the robot programs to be accessed
the robot will vary the part-removal position based on and saved directly through the injection press controller.
fluctuations in the clamp position. Six-axis robots don’t Also, remote diagnostics of both the machine and robot
necessarily have features like these that are specific to can easily be accomplished to determine where an issue
the injection molding process. may lie.
Robot layout configurations In conclusion, six-axis and collaborative robots definitely

Cartesian robot manufacturers offer a variety of have a place in the plastics industry, but are not ideally
mounting options to accommodate project needs and suited to the removal of parts from molding machines.
space constraints. Although traditional “operator side” In almost 25 years of working with automation in the
and “rear side” configurations are still popular, we are plastics industry, I have seen only a small number of
seeing more and more varied layouts. Configurations companies utilize six-axis robots to remove parts from
such as “T-Mount,” “Clamp End” and “Reverse Mount” molding machines. Many of those same companies later
are becoming more popular. Floor space becomes an switched back to Cartesian-style takeout robots. More
increasingly hot commodity as more and more companies often than not, I believe it makes sense to use Cartesian
try to figure out ways to squeeze more machines into robots to remove parts and then use the other robot types
their plants. One way to accomplish this is by setting in downstream and offline applications within the factory.
up the robot to release the parts at the clamp end of That being said, do your homework to determine what is
the molding machine. This allows machines to be placed best for your requirements.
closer together. With this setup, it is easy to configure a Jason Cornell has worked in the plastics injection molding industry
gantry-style robot to traverse along the machine to drop for 25 years, specializing in robotics and automation
the parts at the clamp end. On the other hand, this is
almost impossible for a six-axis robot.

Plastics News July 2019 36