Famed 19th-century essayist and social critic John Ruskin once said, “Quality is never an accident. It is always the result of intelligent effort.” This statement is perhaps most true in the manufacturing environment. When it comes to injection molding, quality is an absolute expectation—and it takes discipline to achieve. Operating with anything less than precision can lead to sub-par quality that results in downtime, increased scrap, costly waste, performance issues and, ultimately, dissatisfied customers.
What Ruskin likely didn’t anticipate when he uttered those words more than a century ago are the considerable resources that would be available today to truly make the effort to achieve quality more intelligently. Smart sensor technology is one of those resources.
Driving Intelligent Quality into the Operation
Multiple parameters should be regularly monitored and diagnosed during the injection molding process to ensure optimal quality, but those parameters can be difficult to manage. Often, they require ongoing review of gauges, recording of current status and assessing that status versus acceptable targets. Most users still monitor these parameters manually, periodically requiring personnel to capture needed data. This approach is time consuming and vulnerable to human error. And aging equipment—which comprises the vast majority of today’s plant assets—can make the task even more challenging because older machines often lack onboard gauges. Regardless of where the data come from, a manual monitoring approach often doesn’t reveal an equipment issue before it’s already had a negative impact on quality.
Smart, wireless sensors are changing how this type of monitoring is managed. They can be easily deployed to take the place of or augment gauges, and they enable automatic collection of data when and where a plant operation needs them. Data are available in real-time, and accessed on-demand via user-friendly software and apps. Smart sensors can enhance the capabilities of new or aging equipment, extending its value and useful life.
This intelligent quality approach—the new IQ—enables ongoing condition monitoring to identify trends that may indicate a change in the way equipment is performing. Such changes frequently serve as the first warning sign of an impending issue. Recognizing them is integral to taking action to preserve quality performance, such as making equipment adjustments or scheduling maintenance.
Three Ways to Build Your IQ
When an operation is struggling with quality molding of parts, one of two issues is most frequently the culprit. The first is a short shot—a part that isn’t completely formed. The second is a flash—a part that is formed, but is either outside the specified dimensions or contains significant excess material.
These common issues are typically the result of too much or too little pressure in getting the plastic material to the mold cavities, improper temperature for the plastic material or cooling lines, or humidity fluctuations that prevent the raw material from maintaining the proper state. And there’s a wide margin for error: These factors can have an impact on the molding process from the moment the plastic material is delivered to the molding machine until the part is ejected from the mold.
Smart sensors can play a key role in minimizing these issues. Here are three ways you can put them to work in your operation—today—to introduce intelligent quality.
Maintain pressure—Proper hydraulic working pressure is critical to the injection molding process. The two most critical pressures are that of the injection screw that pushes material into the mold and the clamp that holds the mold halves shut. If insufficient pressure prevents molds from closing properly, they can open and make a part vulnerable to flash, leading to inconsistencies throughout a batch.
Smart sensors can be applied to the primary points of pressure loss, detecting the slightest change in the pressure and providing a real-time alert to the user. This intelligence enables the pressure issue to be addressed early, minimizing scrap and rework costs.
Measuring temperature—Some temperatures must remain consistent to ensure optimal product quality for injection molding. Temperature variability most often occurs at three critical points in the production process: at the mold tool area, in the water lines that cool the parts in the mold before ejection, and within the environment of the molding room.
Sensors can be deployed at these precise points throughout the process to give users access to real-time temperature data. Temperatures that fall below or rise above optimal levels can be adjusted before they have an impact on the product.
Assessing humidity—Too high a humidity can add moisture to the raw material, which can transform its properties and prevent it from molding as expected. Humidity can have an impact on raw material in storage containers, as well as process lines, drying equipment and molding machines.
Smart sensor technology is ideal for in-line and ambient humidity monitoring. Its ability to diagnose issues and track conditions over time enables users to assess gradual trends of increasing humidity within a facility, and take the appropriate actions to address changes.
Going Beyond Quality
Although the impact on quality is compelling, it isn’t the only benefit smart sensors can deliver to the injection molding operation. By revealing issues before they escalate, the use of smart sensors can help decrease maintenance costs. These sensors can give users access to data they wouldn’t otherwise have, especially in hard-to-reach or potentially hazardous areas where gauges would be difficult or dangerous to view. And the use of smart sensors can even improve efficiency and increase productivity. How? By eliminating time-consuming, costly manual monitoring processes.
The advantages of smart sensors will only multiply over time. Already, they’re playing a critical role in creating a roadmap for predictive maintenance. And new applications are being created to provide even better intelligence—more sophisticated diagnostics, integration with other internal systems, trend monitoring, live monitoring, and more.
You don’t have to let quality in your injection molding operation be a happy accident. You can make your effort more intelligent by leveraging smart sensors to increase your plant’s IQ.
Dan Davis is a Certified Fluid Power Specialist and Product Sales Manager for SensoControl and diagnostic tools at Parker Hannifin Corp. Contact him at [email protected] or visit www.parker.com/conditionmonitoring.