Design World

  • Home
  • Articles
    • 3D CAD
    • Electronics • electrical
    • Fastening & Joining
    • Factory automation
    • Linear Motion
    • Motion Control
    • Test & Measurement
    • Sensors
  • 3D CAD Models
    • PARTsolutions
    • TraceParts
  • Leadership
    • 2020 Winners
    • 2019 Winners
    • LEAP Awards
  • Resources
    • Subscribe
    • DIGITAL ISSUES
      • EE World Digital Issues
    • Future of Design Engineering
    • LEAP Awards
    • MC² Motion Control Classroom
    • Motion Design Guide Library
    • Podcasts
    • Suppliers
    • Webinars
  • Women in Engineering
  • Ebooks / Tech Tips
  • Videos
  • COVID-19

Machine vision system watches over injection molding process

By Mike Santora | December 19, 2018

Share
Cognex-In-Sight-700-smart-camera-app

A robot removes a part from the mold and presents both sides of the part to a Cognex In-Sight 7000 smart camera located on top of the mold press.

For most businesses, automated quality assurance systems such as machine vision are rarely promoted as competitive advantages, much less as revenue centers. Instead, quality control activities often fall into the same category as risk mitigation, IT security, and maintenance — a necessary expense but not one to be celebrated. MVA Stratford Inc., recently worked with Cognex Preferred Systems Integrator, Radix recently to reduce rework costs and improve its bottom line.

MVA Stratford is one of North America’s leading supplier of plastic injection-molded parts for the automotive and related industries. Anyone that has purchased a new car in the last decade has likely touched one of its products when placing coffee into a cup holder or securing their seat belt.

Last year, MVA Stratford contacted one of their machine vision integrators for help solving short shots on plastic molded injection machines for automotive components. Short shots occur when liquid plastic is injected into a mold but fails to fill the mold for any number of reasons. As a result, the final part is ejected from the mold before it is fully formed. This poses a significant problem for manufacturers who depend on low inventories and just-in-time component suppliers to keep overhead low and profitability high. Under some contracts, a customer can reject an entire shipment and impose financial penalties on the supplier (in addition to the lost revenue) based on a single short shot. As such, contracts become more common, providing 100% quality assurance is becoming a competitive advantage.

In response to concerns about short shots from a leading automotive customer, MVA Stratford called in Sean Lett, vision and automation sales engineer for Radix, for help developing a mold inspection system to identify short shot parts before they ship to the customer.

“MVA Stratford is one of the few plastic injection-molded part suppliers to use robots to unload plastic injection-molded parts from their presses,” explains Lett. “This opens up several advantages for MVA Stratford.” According to Lett, most companies retract holding pins from molds and let parts drop onto conveyors. With this method, a manufacturer can use machine vision to inspect only one side of a part; if the short shot is on the bottom of the part, it is undetectable.

To resolve this issue, a robot removes a part from the mold and presents both sides of the part to a Cognex In-Sight 7000 smart camera located on top of the mold press. Robot unloading also keeps parts from getting stuck in molds. In some cases, a molded part may not fall out of a mold onto the conveyor even when the pins are fully retracted, resulting in unplanned downtime. The machine stops until a technician can clear the mold or fluid polymer is injected into the open mold, causing considerable downtime and cleanup. When carefully positioned to see both the part from the robot and the mold, a machine vision camera can also verify that the mold is empty, eliminating a common point of failure.

Cognex-injection-molding-machine-application-image

Two plastic molds are entirely empty and ready for the next cycle of injection molding.

On the MVA Stratford press line, the In-Sight 7000 smart camera processes images using PatMax geometric pattern location algorithms and other image processing functions. It identifies the edges of a part and confirms that the part outline meets specifications. If the part passes, the In-Sight 7000 sends a “pass” signal to a nearby Yaskawa robot controller, telling the robot to place the part on the conveyor with other good parts. If the part fails, the robot puts the part on a conveyor with scrap parts.

“One of the keys to success for MVA Stratford was taking ownership of these systems,” says Lett. “A part may run this week and not again for four months. And in every case, settings on the mold, press, robot, and vision system change. Trained MVA Stratford technicians can quickly train the In-Sight 7000 to accommodate a new part or switch to a stored program from a previous run. Our training helped make this possible for MVA Stratford.”

The plastic mold inspection upgrade has been so successful that one of MVA Stratford’s largest automotive clients pulled six other plastic injection-molded parts from competitors. DW

Cognex
cognex.com

MOTION DESIGN GUIDES

“motion

“motion

“motion

“motion

“motion

“motion

“motion

“motion

“motion

Enews Sign Up

Motion Control Classroom

Design World Digital Edition

cover

Browse the most current issue of Design World and back issues in an easy to use high quality format. Clip, share and download with the leading design engineering magazine today.

EDABoard the Forum for Electronics

Top global problem solving EE forum covering Microcontrollers, DSP, Networking, Analog and Digital Design, RF, Power Electronics, PCB Routing and much more

EDABoard: Forum for electronics

Sponsored Content

  • Drilling rig OEM benefits from a PLC with edge computing technology: IIoT case study
  • The industry shift to smart electromechanical actuators
  • Commemorating a great entrepreneurial personality – Oskar Lapp at 100 – A pioneer for the future
  • SE motor – uncompromised motion performance
  • With virtual commissioning, commissioning time and prototype waste is reduced
  • Master Bond Supreme 10HT High strength, NASA low outgassing approved epoxy
Engineering Exchange

The Engineering Exchange is a global educational networking community for engineers.

Connect, share, and learn today »

Tweets by @DesignWorld
Design World
  • Advertising
  • About us
  • Contact
  • Manage your Design World Subscription
  • Subscribe
  • Design World Digital Network
  • Engineering White Papers
  • LEAP AWARDS

Copyright © 2021 WTWH Media, LLC. All Rights Reserved. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media. Site Map | Privacy Policy | RSS

Search Design World

  • Home
  • Articles
    • 3D CAD
    • Electronics • electrical
    • Fastening & Joining
    • Factory automation
    • Linear Motion
    • Motion Control
    • Test & Measurement
    • Sensors
  • 3D CAD Models
    • PARTsolutions
    • TraceParts
  • Leadership
    • 2020 Winners
    • 2019 Winners
    • LEAP Awards
  • Resources
    • Subscribe
    • DIGITAL ISSUES
      • EE World Digital Issues
    • Future of Design Engineering
    • LEAP Awards
    • MC² Motion Control Classroom
    • Motion Design Guide Library
    • Podcasts
    • Suppliers
    • Webinars
  • Women in Engineering
  • Ebooks / Tech Tips
  • Videos
  • COVID-19