4 factors for successful automation implementation

Introduction‍

Automation within injection molding is no longer a “nice to have” for large organizations working with six figure budgets.  Today every molder, whether a small custom molder or a large global organization, are expected to produce more parts at a lower price point for their customers. The industry wide adoption of automation for part removal has contributed to this demand.

Years ago it was commonplace to either run molds in full automatic mode with parts dropping into a bin (or onto a conveyor) -or- to employ an operator to manually open the gate of an injection molding machine and remove the part(s) from the mold.  In both situations, there are many benefits associated with using a part removal robot to do this work.  Among these are achieving a consistent cycle, improved part handling, maintaining cavity separation, maintaining part orientation, providing mold protection, reducing labor costs, reduced cycle time (in some situations), and many more.

In addition, the capabilities of part removal robots have consistently expanded while their prices have consistently decreased.  This trend has been observed for a period of no less than 20 years.

All that being said, successful implementation of a parts removal robot often hinges on understanding some basic principles that can “get in the way” of success.  Here are four factors to keep in mind when implementing part removal automation.

1^st Factor – Freeing or “Loosening” the Part(s) during Ejection

Quite possibly one of the most important of the 4 factors, part ejection plays a critical role in determining the complexity of your automation project.  In an ideal application you will want your part(s) and, if applicable, runner to eject freely from the mold.  This means that the mold ejector mechanism has been moved such that the part(s) have overcome the high initial resistance to motion and can then be moved with relatively little force.  This does not mean completely ejected.  Ideally, the parts are ejected so they are free from the mold but are still held in position by the core or cavity.

Part removal robots are designed to carry the loads associated with plastic part(s) being molded and the end-of-arm tool needed to grip the part(s).  They are not designed with excess load capacity to perform the function of part ejection.

Free ejection from the mold confirms that there will not be any special consideration made with regards to robot payload selection, programming, or end of arm tool (EOAT) design.  Though standard part removal applications can be implemented quite cost effectively, mold features that prevent free ejection of the part(s) have the potential to significantly add additional engineering cost to your project.

‍2^nd Factor – Positioning the Part(s) after “Freeing”

Once parts are ejected freely it is important to adjust the ejection distance such that the parts will be presented to the robot in the same position every cycle.  This is a key factor.  If parts are ejected too far then they may fall off the mold before the robot EOAT is in position to capture them with a mechanical or vacuum gripper.  If parts are not ejected far enough they may not be free from the mold and therefore may require excess force for removal.

3^rd Factor – Coordinating Robot and IMM Ejector Motion

Some simple part removal applications can be done with minimal coordination of the robot and IMM ejector motions; however, best practice will generally use a “handshake” between the two making use of Euromap 67 IMM Robot Interface Signals and functionality.  For example, the robot can 1) inhibit the IMM from moving the ejectors forward until it is in position to receive the parts, then 2) once the robot has moved into the grip position it can enable the IMM ejectors to move to place the parts at the grip position (where they are free but still in position), then 3) the robot can grip the parts from this position and confirm (using vacuum sensing or switches) that the gripper has successfully obtained the parts, then 4) the robot can permit the ejectors to retract, and 5) the robot can depart the mold area and procedure to release the parts at the programmed release point.

There are an infinite number of ways the robot and IMM can be setup to ensure a safe and reliable part removal sequence.  Attention should be given to ensuring confirmation of motions that, if not confirmed, could result in a costly collision between the robot, parts, and mold.

‍4^th Factor – Stable Process

The previous 3 factors all address part ejection and location, however, producing consistent quality parts is the backbone to any automation process.  In order to achieve this you must have a stable molding process.  The knee jerk reaction to this would be to say, “yes, our process is stable, we are making quality parts now.”  You may make perfect parts, but are you making them in at the same rate as you would be with a robot.  If you are running parts in fully automatic, you might be running a faster cycle than the robot will achieve.  Therefore, when the robot performs the takeout operation you may need to adjust your mold cooling to get good quality parts.  Chances are if you are running in semi-automatic mode with an operator at the gate you do not know how the mold will stabilize when running in automatic with a part removal robot .

You should anticipate the need to make process adjustments to ensure optimum results from implementing a parts removal robot, particularly when transitioning from semi-automatic operator tended machine cycle.   In certain cases it may also be desirable to make changes to the mold to facilitate automation.

Conclusion

There will always be additional factors to consider when reviewing automation for an application, however, these 4 factors will provide a strong baseline on whether or not you will be met with success or struggle when automating.  If you have a current project in mind, hopefully after reading this article you can answer “yes” to each of these factors.  If you cannot, do not be discouraged.  A successful application may still be possible, it will just require additional engineering, design, testing and budget to establish a successful installation.  Hopefully this guide can help pinpoint possible issues and allow you to address them prior to bidding automation for your application.