Page 34 - Plastics News July 2019

FeAtures

Automation Part 1

Why Cartesian Robots Are the All-Around Choice for Injection

Molding

Jason Cornell
Cartesian robots—also called linear, three-axis, or gantry types are designed specifically for injection molding,
six-axis and collaborative robots definitely have a place in the plastics industry, but are not ideally suited to the
removal of parts from molding machines

his first of three articles on automation for injection Controls
Tmolders explains why Cartesian (linear) robots are
molders’ first choice in a large majority of applications. The topic of terminology leads us perfectly into some
points about robot controllers. From day one, linear robot
“Cartesian, articulated, collaborative; what is the best manufacturers have been refining their control platforms
type of robot for my injection molding application?” I have around the molding process. This has allowed them to
had this question asked of me a few times lately, so I am create control languages and programs that are ideally
providing my thoughts on the subject. Some may say I am suited to injection molders. Users will find terms, graphics
biased because I work for a Cartesian robot manufacturer. and videos that they are familiar and comfortable with
This may be correct; however my almost 25 years of from the molding world.
experience working with robots in the molding industry Machine interfaces
may lend some credence to my bias.
Cartesian robots have clear definitions of industry-
First off, let’s define terminology that will be used throughout standard interfaces between the robot and injection
this article for each robot type: a) Cartesian robots—also
called linear, three-axis, or gantry types., b) Industrial machine. Be it E67, E12, SPI or others, Cartesian robots
used in this industry are all set up to adapt and connect
six-axis robots—also called articulated or articulated-
arm robots abd easily to a molding machine. Articulated robots may not be
as easily connectable to an injection press. There may be
c) Collaborative
robots—also called additional costs required to adapt six-axis robot interfaces
to the molding-machine standards.
cobots. T hese
are typically Speed
articulated types, In the molding world, it is all about minimizing your mold-
so many of the open time and thus reducing overall cycle time. This is
points made here where Cartesian robots really shine. The speeds of these
about six-axis robots are generally known to be superior to six-axis types
robots also apply and dominate collaborative robots. Faster in and out of
to cobots. When I talk about Cartesian, I am referring to the press means more parts are produced per hour, shift or
robots designed specifically for injection molding. Because day. This equates to a faster ROI for the equipment. Also
these robots are industry specific, all their terminology is given that linear robot manufacturers have been working
built around the injection molding machine. this makes it exclusively in the molding industry for years, they have
ideal when a user switches from working on the injection- been able to come up with features designed specifically to
machine controller to working on the robot controller. This reduce the part-removal time. Features such as Wittmann
commonality also makes learning the Cartesian robots Battenfeld’s Smart Removal intuitively move the robot arm
very simple and intuitive. On the flip side, six-axis robots into the mold area prior to the complete mold-open signal,
make up a very small percentage of those used in injection thus reducing take-out time. This is accomplished without
molding applications. This means that the nomenclature the need for additional transducers or other modifications
and terminology used in their controllers and manuals may to the machine.
have little, if anything, to do with molding.

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