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Case study: Improving production line throughput

Oct. 12, 2021
The packaging line could not be run at its design rate, so it was time to inspect and fix any problems.

At times as maintenance practitioners, we have all walked through our facility and stopped at a line to observe the operation. We have found ourselves in this same spot more times than we care to remember. As we stop and observe, the thoughts begin to race through our heads: How can we see more out of this line? What are we missing? I know we can see better throughput, but how?

About the author: Joe Anderson

I found myself asking these questions for the better part of five years in this plant, and found multiple issues upon our inspections. We saw a variety of areas that could be improved, so why is it that we chose to do nothing? Lack of leadership? Lack of maintenance practices?

The reason is simple, we do not ask Why, we just focus on our current situation, and we do not ask how we can improve our situation.

As a maintenance and reliability practitioners we need to understand what we miss when we are around these lines all day. Some people would say that “I know this machine” so I can tell you what is wrong with it. Not true! The truth is we as a team lack the knowledge and unbiased way of thinking that will allow us to solve problems and see sustainability that comes from improvement.

The process

A major source of our losses with our facility were found out to be on the Bosch line, so we decided that this was an area of focus. Our Bosch line creates the 1.5 lb – 3 lb packages that we see in grocery stores across the United States and Canada. The operation is quite simple: Product is transported to a bin tipper and deposited in a hopper, then carried up an incline belt to a transfer conveyor and fed into a scale. The scale then dispenses the product to the bagger and the pillow pack is created.

The problem

The Bosch has a design rate of 80 ppm, but we ran this line at 65 ppm most of the time for various reasons (product quality, product infeed, etc.). This was a natural speed loss of 15 units per every minute we ran this line. That is nine hundred units per hour, or almost 4 million units lost annually.

Another major issue was all the minor stops that existed on this line. We were losing 1,000 units per hour or more than 4.2 million units per year. We also found some major flaws with quality rejects and bad seals.

Another issue we found is a lack of pride in quality work. The line itself was not secured in place, with cords and hoses all over the floor, and the line was completely filthy.

The solution

We found that a major cause of the speed losses were issues caused by the potato hopper. The potato hopper was worn out and causing potatoes to spill on the floor, and also caused some over/underweight issues. By slowing the machine down, it would “run better.” We ordered all the parts and rebuilt the potato hopper assembly, giving us the ability to speed up the line without as many rejects occurring.

When it came to the minor stop issues, we found three major issues that we set out to address. First was that the reject conveyor for the check weigher would jam bags and even miss at times. This would cause the line to back up and they would shut down the filler. What we figured out is that it was not the proper reject conveyor, and its design was flawed. We ordered a different conveyor and installed it, virtually eliminating these jams and misses.

Our second issue to address minor stops was bad seals. The bag would rip open as it traveled downstream and send unpackaged potatoes through the system, causing us to stop the line to clean up the mess. What we found is that the sealing jaws were worn to the point that it could no longer seal. We replaced them as well.

Our third issue came from printer ribbon breaks, which were stopping the machine frequently. We found that the printer cassette was poorly “fixed” and in need of repair as well as a lack of understanding of the printer settings. We ordered the parts to replace the cassette and trained the operators on the proper settings for the printer. Since that time, we have only seen a couple of breaks in printer film.

To help tighten the ship and sustain these gains, we implemented Operator Care activities through Clean, Inspect, and Lubricate (or CIL) practices. We, management included, cleaned the lines, set cleaning standards, and trained everyone on the line to these new standards. We also implemented an auditing process for coach and mentoring employees on the CILs as they are performed to reinforce the good behaviors. This has changed our culture dramatically.

The results

We have seen more and more employee engagement as these practices are implemented. We saw waste on the line drastically reduce as well lowered the total cost per unit. For example, the cost per unit on this line before we started this engagement was hovering around $5.14. The last two months prior to writing this article was hovering around $3.30. This is a dramatic decrease in cost per unit.

Tactics and Practices

This article is part of our monthly Tactics and Practices column. Read more Tactics and Practices.

About the Author: Kevin Moore

This story originally appeared in the October 2021 issue of Plant Services. Subscribe to Plant Services here.

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