Application of buffer system to optimize packaging efficiency

In order to meet the challenges of current costs and productivity inherent in pharmaceutical production, packaging efficiency must be maintained. The packaging line must be run at the most appropriate level and condition, minimize downtime, and follow schedule or other requirements as much as possible. The cumulative buffer system provides a clear solution for manufacturers to solve this problem.

The cumulative buffer system is a temporary storage space that allows product flow to continue while blocking or shutting down a part of the packaging line. With this system, if an interruption on the packaging line is resolved within a short time (usually within a few minutes), the product can be automatically returned to the product flow.

The system can be installed in different locations on the packaging line, depending on which operating step is most likely to cause blockages. It is usually installed in front of the labeling machine. Compared to other equipment on the packaging line, it has had more work stoppages in the past few years. Today, most pharmaceutical companies have at least one buffer system on the packaging line.

The cost of installing and using a buffer system is not low, but in most cases, this kind of investment will soon pay off. Since the buffer system separates a single continuous process, the performance of each machine is maximized and the continuity of product flow is promoted. Therefore, although the system does not directly perform packaging operations like the filling machine and capping machine, it also adds value to packaging lines by promoting balanced production and increasing production. Usually, the misunderstanding of the buffer system is that it masks the invalid work of the packaging line, but in fact it is to increase the efficiency.

This article discusses a variety of buffer systems that can be applied and provides recommendations for companies implementing their own buffers to verify whether the buffer system is useful or beneficial. In addition, this article also provides a case study of a successful buffer system analysis at a pharmaceutical factory.

Classification of buffer systems

There are several types of cumulative buffer systems that can be applied, each with different shapes, requirements, performance, advantages, and disadvantages. They depend on the size of the product, its shape and positioning on the packaging line, the speed of the packaging line, and the cumulative requirements. The main categories include: built-in continuous accumulation (bending and stretching belt systems); batch index accumulation (vertical and horizontal); random continuous accumulation (bidirectional countercurrent and rotary).

In addition, the buffer system can be classified according to product flow: a first-in, first-out (FIFO) system ensures that products that enter the queue first leave first. In general, the FIFO system has a small base, and it takes up less space than other buffer configurations. The system can make products countable (ie, batch number and production time) for tracking in the future; in the FILO system, products leave in the same order as they reached the queue. The advanced back-and-out buffering system can be used in a horizontal or vertical manner; most common systems operate in a state-of-the-art random-arrival (FIRO) manner. Usually in the turntable mode, advanced random-arrival (FIRO) buffers do not operate in a bi-directional manner or in a counter-current manner. Of course, the buffer system does not provide countability or sequence of products.

Research on buffer system

To determine whether a buffer system improves efficiency and throughput, whether the investment is economically reasonable, and to evaluate the best capabilities, location, and speed of the system, it is necessary to conduct in-depth research.
The first step in the buffer system study was to identify planned downtime and unplanned downtime. The company must consider the planned downtime, for example, change the tape of the label roll or container sealer, and identify the activity, duration, and cycle of each piece of equipment on the production line.

Unplanned downtime due to machine obstructions or crashes is difficult to predict and therefore difficult to assess. Buffer analysis should provide a full view of the production line and collect historical data on normal conditions and blocking frequency. Guaranteed minimum power can also be used as a basis for identifying the duration and frequency of downtime. For newly purchased equipment, OEMs will provide equipment theory or historical downtime as a reference guide.

Subsequently, the data collected in the field is input into an already-prepared algorithm to generate a cumulative simulation chart of all devices. A comprehensive buffer analysis will enable packers to understand whether the investment in the buffer system is worthwhile. In general, if the downtime of a packaging line is much shorter and the buffer system can adjust this short-term shutdown, the investment in the buffer system is cost-effective. If the downtime of a packaging line is more than 10 minutes or more, the buffer system cannot guarantee the rationality of its investment.

Packaging line case analysis

The following case study describes the process of demand for a cumulative buffer system for a tablet packaging line. The packaging line consists of an automatic push table, a loader, a tampon machine, a metal detector, a capping machine, an electromagnetic induction capper, a cap reinforcement machine, a labeling machine, a weight detector, a case packing machine, and a palletizing machine. The initial condition of the packaging line is as follows: The operating speed is 240 bottles/minute (BPM); in a 420-minute shift, 72,250 bottles are produced; the downtime is unknown. The production speed of this packaging line is 168 bottles/minute (BPM). Even if there is no clear packaging line interruption data, it is easy to see that the downtime is worth noting because of the huge difference between the operating speed and the production speed. Therefore, buffer analysis is necessary.

The buffer analysis first looks at the packaging line for a shift, asks the operator and analyzes useful data. The observations are as follows: The focus of the packaging line is to make the filling equipment operate in the best condition; the only equipment with a predetermined interruption on the packaging line is the labeling machine; the unscheduled interruption before the labeling machine is the smallest; the labeling machine has three Different interruptions: change labelling machine roll (predetermined), feeder box is blocked (unscheduled) and replacement of the back coil (predetermined); the packing machine has an unscheduled interruption: filling the product in the system Blocking; the stacker has an unscheduled outage: the robotic arm has not received the product.

Based on the above information, the analyst predicts that the optimal buffer level is somewhere before the labeler, so that whenever the labeler breaks, the primary packaging line (from the labeler to the cap reinforcement) Can continue to operate. To verify this idea, the analyst created a cumulative simulation chart for each device on the packaging line and used historical data and information obtained from the original equipment manufacturer.

Figure 1 shows a boxer cumulative simulation chart. There was only one unscheduled interruption (product jam in the filling system), which lasted for 3 minutes and the average time between failures was 150 minutes. The horizontal axis represents all shift times (from start to finish) in minutes, and the vertical axis represents the cumulative product quantity delivered to the cartoner.

Until the first break (the first vertex), the flow is stable, so the product delivered to the cartoner does not accumulate. Obvious rising slopes indicate that the product delivered to the cartoner is being accumulated, which also indicates the first downtime of the equipment (3 minutes). The downward slope after the apex indicates that the break has been resolved and the boxing machine is working again.

The apex also shows that the maximum data accumulated by the product at the time of the interruption was 700 bottles. For this particular case packer, the range of speeds varies from 200 bottles/minute to a maximum speed of 240 bottles/minute. Assuming a gap of 40 bottles/minute, it takes 17.5 minutes for the packer to consume the accumulated product and return to a stable state. The boxer cumulative simulation chart shows that the maximum buffering capacity required is 700 bottles when the packer is operating at a rate of 200 bottles per minute.

Figure 2 is a labelling machine cumulative simulation chart and depicts three different interruptions: scheduled labeler roll change (black line), an unscheduled feeder box block (red purple line) and scheduled Discharge tape reel replacement (blue-green line). It also shows the number of cumulative products input to the labeling machine due to these interruptions.

Figure 3 shows the buffer accumulation simulation before the labeler. It also includes equipment information for the secondary packaging line – the labeler, the case packer and the stacker. Integrating related equipment into a chart also allows analysts to simulate the buffering requirements before a certain point. The figure shows that the required maximum buffering capacity is 1000 bottles. At a running speed of 200 bottles/minute, the buffer zone has the ability to absorb all products accumulated due to the interruption.

Figure 4 shows how the buffered product accumulates at a non-optimal speed. At a rate of 235 bottles/minute, there is a dynamic speed interval between 235 bottles/minute and 240 bottles/minute. This difference of only 5 bottles/minute means that the buffer does not have the ability to consume the product accumulated during the downtime between two failures. After accumulating more than 1,000 bottles, it can be seen that the cumulative level has never returned to zero but has grown over time.

To verify the correctness of the results, the analyst calculated the theoretical throughput of the packaging line at 235 bottles per minute. Figure 4 shows that the downtime for the packaging line is approximately 127 minutes. The total output of the packaging line is 293 minutes of total operation time (420 minutes in a shift minus 127 minutes of downtime) multiplied by 235 bottles/minute. The total output (68,855 bottles) divided by the total time (430 minutes) equals 160 bottles/minute, very close to the actual production capacity of 168 bottles/minute.

Based on the results of this buffering study, the analyst put forward several suggestions for the manufacturer: position the buffer in front of the labeler; set a buffer with a buffer capacity of 1000 bottles; reduce the speed of the packaging line to 210 Bottle/minute. Following the above recommendations, the expected benefits of the packaging line are as follows: Conservatively estimate that 20% of the production capacity can be increased from 168 bottles/minute to 200 bottles/minute; as the speed of operation is increased by 32 bottles/minute, 13760 bottles can be packaged for each shift. (32 x 430).

Earnings and ROI

Assume that the packager invests about $100,000 in the buffer system and sees returns in six months. Case studies show that the use of a buffer system is a cost-effective method for optimizing pharmaceutical packaging. Bypassing the interruption will ensure continuous production flow and prevent loss of product and quality. At the same time, with a compact design and structure, the system also optimizes the use of space.

Determining whether a cumulative buffer system can provide a correct solution, or whether there are serious design or equipment defects that can cause production problems, is essential for in-depth buffer research. Manufacturers should collaborate with knowledgeable material handling system integrators to produce buffering equipment that fits the needs of specific users, and they must have good scalability to accommodate new product packaging needs.

Reprinted from: Logistics Network