A recurring problem at many bakeries is the alarming number of reworked products. A gourmet pretzel operation provides a good example. Processing is relatively simple: preparing dough and ingredients for kneading, extrusion portioning, injecting gourmet filling, twisting, transporting on trays, baking and cooling. Trays transport product from one part of the line to another. With a fast-moving production line, employees could not provide clean trays to the makeup line fast enough to keep up with the portioning equipment. This was a major constraint. Farther down the line, rework occurred in the labeling and packaging areas — rework partially caused because of the haste in collecting and moving trays.
As trays were removed from the ovens, pretzels were detrayed and began their journey to labeling and packaging. The trays, however, had to be manually scraped, cleaned, oiled and returned to the front of the line. Trays piled up. Workers had to move around racks, pick up trays, pile them at their stations and begin cleaning. Then all trays had to be gathered again before they could be moved to oiling. While this was a constraint, cleaning was fast and became faster when required trays did not get back to the front of the line in time. Analysis determined cleaning was not the problem, instead, transport was the real problem. Ironically, the solution was to slow down the tray cleaning operation while improving the flow of the trays.
However, the largest problem on the line was rework at packaging. Nearly 15% of the packages were being rejected and reopened because of poor sealing, labeling or box seals. The processing line was moving too fast for packaging.
Fast is not the same as efficient and effective.
In simple business terms, product processed and ready to ship is the main goal for production management. However, the process of getting “product in the box” may be more wasteful than productive. Moreover, the natural response for more output is faster processing. The difficulty is that faster usually means more mishaps and mistakes. When we put our Lean thinking hat on, more rework, more problems and more waste is not the path toward more “product in the box.”
Resolution to these problems requires first-hand observation to fully appreciate the benefit of slowing down. Consider the packaging process at the gourmet pretzel plant. In this particular part of the plant, the line either sorts, seals, labels or boxes pretzels. These final steps are generically called packaging.
The first “pinch” point is the sealing of the plastic bag. Basically, the wrap-and-seal process frequently gets jammed or produces faulty seals. Furthermore, a maintenance worker simply could not get the wrapper to work consistently. Sometimes the feed was out of sync with the seal mechanism; other times the feeds were not synchronized evenly; sometimes the seal was not secure because of inconsistent time or temperature at the sealing jaws. In short, many packages had to be sent back through the process.
PRODUCT PILED UP.
Flow was almost nonexistent. Rework was at least 15% of all packages in an hour, also occurring inconsistently in bunches compared with one package in every six.
Interestingly, the behavior of maintenance and operators was to speed up when they had pile ups. The old saying that “haste makes waste” was well demonstrated in their behavior. All too often, speeding up is the typical response. The equipment was still out of sync and malfunctioned. Once that occurred, more rework was generated.
Bottlenecks and jams that create rework are an alarm for Lean thinking and significantly contribute to inefficient and ineffective production. Rework is waste: It is nonproductive. It is important that production foremen, mechanics and workers fully understand the principle of flow — product moving continuously at a rhythmic pace. Stopping and starting is the opposite of flow. Ripping open flawed packaging is a waste of time and money.
TAKING 'TAKT' TIME.
How fast and by when the ordered product is pulled through the production process is called “takt time.” This Lean Manufacturing term can be further defined as the maximum time per unit allowed to produce a product in order to meet demand, or how long it takes a product to flow though the line on a good day. On a bad day, there is evidence of flow variance such as jams, rework and other wastes. In the pretzel scenario, considerable effort did not lead directly and rhythmically to “product in the box.”
Fast is not necessarily rhythmic. Fast is neither necessarily productive nor effective. Using the theory of constraints, a Lean thinker realizes that the goal is quality baked products packaged, not packaged product that has to be reworked.
Look at the constraint and change the way you frame the problem. Think, is this flow? If not, stop the process and look at root causes. Often times, equipment that requires synchronization of various moving parts and functions works more smoothly if not run at full speed. Slowing down can be a practical solution for enhancing flow and maintaining steady production. Older equipment is more forgiving if run slightly slower.
Evidence and feedback indicate that many baking and snack managers don’t agree with this point; however, more often than not, slowing production down will put more “product in the box” than speeding up the line. Output must be a measure of quality product ready for shipment. Sure, rework is work, but it is not productive. Take a new approach, and slow down at least a little. You will find more product is efficiently and effectively produced and packaged.
Glen Miller, PhD, is senior Lean consultant for Performance Essentials Inc., Harleysville, PA. For more information on Lean manufacturing visit www.performanceessentials.com.