A well designed packaging system has one objective, to meet predetermined performance levels – No Matter What! However from little hiccups to extended downtime – planned and unplanned, the overall efficiency of packaging lines is vulnerable to many variables. To meet or exceed target output levels, a packaging system needs to be designed to not only work under ideal conditions but take real world situations into account. In this three-part series, Pearson Packaging Systems discusses several key design concepts that help maximize and maintain system throughput.
System level optimization rather than machine level
A system in general can be defined as an interdependent group of functions forming a unified whole. The key term in this definition is interdependent. Even if each component works optimally on its own, all parts together do not automatically form an efficient system, in particular as the complexity increases. Most systems generally revolve around key components, often critical and high value assets that present the most vulnerable links. Good system design ensures that the vulnerability of such key functions is minimized by mitigating any negative effect other components of the system could have on these assets.
High quality, high performance and reliable machines certainly form the foundation of a well-functioning packaging system to reduce any unnecessary downtime. Nevertheless, downtime will occur for a number of reasons, some as simple as a tape roll having to be replaced or a product jam to be cleared. So instead of making Plan A – the machines and other system components fail-proof in an attempt to minimize outages, a well-designed system always incorporates a Plan B – the operational control strategy that ensures that in the end the overall output goal will be met.
Accumulation and buffering
In general, a secondary packaging system’s most critical assets are the case packer and the palletizer. These functions ultimately determine the target output of the line. If either one of these machines goes down or is operating below capacity due to upstream problems, the resulting loss in output cannot be recovered without expending more time such as running the system overtime.
Accumulation and buffering are critical design concepts that help isolate equipment outages, allowing for recovery without negatively impacting the balance of the line. While accumulation enables products to be temporarily stored, buffering allows them to be delivered at a different rate than received.
For example, if problems with corrugate shut down a case erector, a close coupled downstream packer would be directly affected. However, since mean time to repair or in this case the average time to clear a jam can be easily determined, built-in accumulation covering that timeframe could completely avoid any interruption for the packer. Further down the line, a case sealer may need a tape roll to be replaced. If there is enough conveying to allow products exiting the packer to be accumulated and buffered, the case packer can continue producing at its normal rate while the tape roll is being replaced.
When applying buffering principles, equipment upstream and downstream must have excess capacity, which can range from 20-100%. To optimally use the accumulation area in our example above, both the case erector and case sealer must be capable of producing at faster speeds than the packer and palletizer. Photo eyes determine when the accumulation area is full triggering an automatic shut-off of the erector or sealer as well as automatically turning it back on when cases run low.
In the next part of this article series, we will take a closer look at smart conveyors to support accumulation and buffering as well as network communication.
For over sixty years, Pearson Packaging Systems consistently built its reputation as a manufacturer of high-quality, exceptionally reliable and robust packaging machines. Building on our extensive machine-level experience in erecting, packing, sealing and palletizing applications, Pearson took the logical next step into system integration over a decade ago. Just like we approach machine design, we are committed to providing optimally functioning integrated solutions. Pearson’s team of application engineers and system designers work closely with customers to assist in determining needs and requirements as well as to facilitate a thorough understanding of trade-offs to ensure that the entire system achieves its highest potential within any given constraints.
Call us at 1-800-732-7766 to discuss your project.