Seiton System Improvements for subcontracting Parts Warehouse

Current Work place Situation:

This case study concerns the Seiton system for the subcontracting parts warehouse which supplies the assembly department of a particular factory with assembly parts.

The assembly line of this workplace has been substantially updated during the last ten years. In accordance with the demands of customers, the overall mass production system become a mixed production system which an also produce small lots of a number of different products and finally a system which assembles the necessary products in the necessary amounts, within the time necessary with the least possible numbers of unfinished products, and delivers them to the place where they are needed.

In conjunction with these changes, the subcontracting warehouse has become filled with all manner of subcontracting parts. To an outsider, it looks like a warehouse for a large volume production factory, but in reality, the parts often do not deliver and operations are halted reducing the actual time during which the assembly production line is in operation.

The subcontracting parts delivery method and structure – the method of receiving, organizing, storing, maintaining, and withdrawing in the subcontracting parts warehouse was revised more than ten years ago and has not been changed since then. Now is the time to reform the warehouse structure and overcome difficulties

Current Status of Receiving, Organization, Storage and Withdrawal:

B, who is employed at this workplace, described the current status of delivery and withdrawal. He said that when things are delivered, workers know generally where to put them because signs printed with the names of items are hung in each section of the warehouse. There are no clear division lines on the floor, so workers find the general area and leave items in any space available. They are placed in order of delivery. Item tags and forklift slits on pallets are often placed on sides other than the aisle side. When many outside orders are delivered together, pallets are often piled up two or three high.

The warehouse side does not fix storage spaces so that parts can be collected in assembly order, or so that they can be withdrawn easily.

In addition different types of specialized parts cannot be distinguished at a glance.

Item labels are not uniformly attached to the forklift slit side of pallets. Some are placed on top of parts others are hung from any of the four sides of the pallets. As a result when Seiri storage or withdrawal Seiton is done the warehouse workers walk around in circles looking for the item tags.

Accordingly man hours are spent searching for parts and making re-withdrawals from the warehouse, and stock builds up. On the assembly line, one has to wait for parts, man hours are spent processing defects, actual production time is reduced, and production volume drops.

Looking at these problems (waste and loss) from a long term point of view, we can see that there is no set structure in the annual long term assembly schedule for storing specialized parts for certain products and parts used in common, the number of parts to be stored, the number of divisions, the order and their direction.

Once something is fixed, making changes (re-writing) is difficult. They are not arranged to be movable or adaptable.

There is no structure providing for specialized parts to be delivered directly to the assembly line, bypassing the subcontracting parts warehouse.

Delivered subcontracting parts undergo sampling inspection after a certain has piled up. This stops the flow.

The subcontractor transports them in a large truck for large volume small item transportation, so transportation is made in large volume, large lots and is intermittent.

The assembly production lines in the factory have not been changed into a mixed production system for small lots of a large number of products. As a result, stock and unfinished product builds up on the assembly production line and in the subcontracting parts warehouse.