Page 34 - Plastics News September 2019

FEATURES

Automation - Part 3
Cobots: The New Option for Injection Molders

Joe Campbell
Of late plastics processors with increasing frequency have begun adopting a new level of automation, called
collaborative robots, or “cobots.” based on articulated-arm technology that adds a layer of safety, user-pro-
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ake all the versatility of an articulated-arm robot, and ‡ +LJK PL[ ORZ YROXPH 3URGXFW FXVWRPL]DWLRQ VPDOO
Tadd the ability to work safely in proximity to humans lot sizes and on-demand production to reduce
without guarding, and you have a new option for freeing inventory are driving short runs, making setup even
workers from repetitive operations more demanding.
Thirty years In the last 10 years, and with increasing frequency
ago, fully servo- of late, plastics processors have begun adopting a
controlled robots new level of automation, called collaborative robots,
of any kinematic or “cobots.” Generally based on articulated-arm
FRQÀJXUDWLRQ ZHUH technology, these cobots add a layer of safety, user-
rarely deployed in programmability, and mobility to standard six-axis
injection molding robots. To understand the cobots’ attraction, it helps
applications. The to start with a review of what makes articulated-arm
most common URERWV SRSXODU LQ WKH ÀUVW SODFH
approach was to 7KH SRVLWLRQLQJ ÁH[LELOLW\ DQG RYHUDOO ZRUN HQYHORSH
deploy a simple of six-axis robots are keys to their success in injection
three-axis, point- molding. The additional degrees of freedom translate
WR SRLQW &DUWHVLDQ URERW WKDW ZDV PDFKLQH PRXQWHG :LWK into more choices and options in all phases of the
enough Z (vertical) stroke to reach the centerline of the material handling, assembly, and other applications,
platen, these very simple robots quickly extracted parts which translate into real process advantages:
from the mold and delivered them to totes or conveyors. ‡ )OH[LELOLW\ WR H[HFXWH SUH DQG SRVW PROG SURFHVVHV
Twenty years ago, fully servo-controlled Cartesian robots Placing inserts into the mold and moving parts through
became common, providing greater precision and control post-mold processes means complex motions and
of the end-of-arm tools. Fifteen years ago, molders demanding angles and positions.
began applying six-axis robots in increasing numbers. This ‡ 5HGXFHG WRROLQJ FRVWV )RXU D[LV &DUWHVLDQ URERWV
evolution was driven by several technical and business often require complex tooling to make up for their
drivers that continue today: kinematic limitations. The range of motion and
Post-mold processes. Customers are requiring molders to flexibility of six-axis articulated robots simplify
deliver more complete parts and assemblies, and molders tooling and gripper costs and complexity.
are glad to increase their value. Degating, trimming, ‡ Flexibility to load precision inserts. Acquiring and
polishing, decorating, assembly, wrapping and packaging inserting precision inserts is enabled by the positioning
are now common tasks that are perfect candidates for ÁH[LELOLW\ DQG UHSHDWDELOLW\ RI VL[ D[LV URERWV
automation.
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‡ ,PSURYHG VXUIDFH ÀQLVK &XVWRPHUV DUH VHWWLQJ YHU\ GLIÀFXOW WR UHPRYH ZLWKRXW HMHFWRUV EXW WKH GH[WHULW\
KLJK VWDQGDUGV IRU VXUIDFH ÀQLVKHV ZKLFK UHTXLUH of six-axis robots allows parts to be pulled gently out
parts to be handled carefully from the mold to the of the mold.
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‡ 6KRUWHU SURGXFW OLIH F\FOHV 7KH SDFH RI SURGXFW and clamps often interfere with part motions. Six-axis
updates and new introductions requires constant URERWV SURYLGH WKH JUHDWHVW ÁH[LELOLW\ WR QDYLJDWH
change in manufacturing processes. around the mold.

Plastics News September 2019 34