Kanban – A systematic approach to Production Planning and in-process inventory management.
Operation: Kanban Seiton operations at an air frame assembly workshop.
Problems: According to a worker, his factory introduced the Toyota Kanban system ten years ago and took as its motto with the minimum of unfinished products, the materials needed, when needed, and in the quantity needed.
Work, however, does not go according to this motto. Deliveries from each process are late, production volume does not increase, and each process has unfinished products.
The problems arise from a combination of defects in the Kanban system, the structure and other systems. This makes everyone feel as though none of the problems can be resolved so nobody tries to do anything.
The woker NT feels that if something is not improved soon, the Kanban system will disappear altogether. He decided to present the problems to his group leader, SA.
Understanding the situation in which Goals are not met:
NT consulted SA and, according to the steps for setting a theme, first looked at the problem from three points of view, and decided to begin work to set a theme which would improve results and set improvement policy.
Obvious problems: preparatory and tool setting operation time has increased, defects have not decreased, and small accidents occur frequently.
1. The desired Kanban cannot be found, and operational directions to the preceding process are delayed
2. Mistaken Kanban are used for urgent products and delivered late, items that are to be split do not flow as split production.
3. Kanban arrive suddenly, necessitating redoing of preparation in the morning or tool setting change in the middle of the day.
4. Kanban are issued in increasing numbers so that the number of times preparation operations and tool-setting changes have to be done increases.
5. Workers are rushed, those are not used to changes have to help, and defects happen at an un-diminishing rate. Small accidents and injuries bring operations to a halt.
Occurring losses: The cost per unit item is high and added value monetary figure is reduced.
The waste, strain, and inconsistencies which appeared in 10 guarantee loss, so next. NT looked into that.
1. It takes time searching and issuing Kanban and there is time spent waiting for production directions. This alone lowers the amount of actual production time (drop in percentage of actual production time).
2. Too much energy is taken up issuing Kanban. There is no leeway for working on other problems, such as defects, breakdown and the length of tool setting time. The cost of processing has not decreased and unfinished products have not decreased.
3. When due to 1 and 3 time taken is more, production takes that much longer, and deliveries are late.
4. When time is spent taking care of defects, breakdowns, and accidents, actual production operation suffers and production drops.
5. Every time workers are rushed, accidents and defects occur. If the above losses were put into monetary figures, it would come to a large amount. In order to get down to improvements as quickly as possible, the causes of loss were investigated.
Causes of loss: The Kanban system is not completely followed, and other improvements are lacking
1. The Kanban are not categorized by part and function, so that they have to be read over every time they are used.
2. When there are changes in the processes and operations, the rack division labels and items labels for the Kanban storage racks (dispatching style) are not rewritten, so they are sometimes used mistakenly. There is a person who is in charge of rewriting the Kanban at the stage in which they are used.
3. Revision of the Kanban constitution based on the estimated number of production per year, and standard production line charts and process planning charts are overdue. It is never clear which process has issued a Kanban and reach one has to be checked out.
4. There is an incomplete system or issuing Kanban based on variances of numbers in operation schedules for a month, a week, or three days, or revisions are overdue.
5. There is an incomplete system for making operations schedules for a week or three days.
6. The labels for the dispatch boards of Kanban from the preceding process and its rules for use are not kept.
7. Improvements to cut defects and breakdowns, guarantee safety, and shorten tool-setting time are overdue. These are reasons why production does not run according to Kanban or delivery dates.