Montblanc overcomes the limits of Kanban

by Dr. Götz-Andreas Kemmner

Hamburg (ba). With a new component, the employees of the writing instruments manufacturer Montblanc can also adapt the Kanban control loops to sporadically running articles.

The range of articles at Montblanc places different demands on the dimensioning of the Kanban control loops. Some production areas work with large batch sizes due to the process, while others are characterized by minimal to no set-up times. On the other hand, customer consumption fluctuates between continuously small quantities and individually requested large quantities.

In addition, the consumption behavior of writing instruments includes regular (X-items), irregular (Y-items) and also some sporadic (Z-items) components due to the large and varied range of items. According to the general Kanban theory, sporadically running items are not suitable for Kanban control. However, each article can be controlled independently of its consumption behavior. The only decisive factor for sporadic items is the level of safety stock required for smooth control. However, this has no mathematical-analytical basis in the classic Kanban formulas, including the one used by SAP. However, a safety stock cannot always be defined for X and Y articles either. This is usually set too high, as the stocks in the control loops do not run empty.

These requirements can now be taken into account with the “SAP-ZDK” add-on module for the SAP system. To do this, the control cycle master data must be expanded to include company-specific master data fields. The program takes the planned sales quantities of the end devices from the SOP planning and uses the BOM explosion to determine the monthly values for all kanban-controlled components. These values form the control dip-specific basis for dimensioning, as they are used to determine the basic and safety stock for each component depending on the consumption behavior (XYZ components). The parameters of each individual component and a simulation period of five years are now used to test the number of kanbans that need to be fed into the system. The safety stock is constantly monitored to ensure that the system does not run empty or that no superfluous Kanban containers circulate in the system. The MRP controller receives results such as the number of kanbans required and the difference to the current situation, maximum number of kanban containers in the storage area, minimum, average and maximum stock levels, calculation of the average monthly setup processes. The dimensioning can now be varied by changing the parameters. In this way, improvements in stocks, set-up processes etc. can be weighed up against changes to the parameters.

At Montblanc, rolling sales planning for the required consumption values is used for future-oriented Kanban dimensioning. Kanban has thus become an acting rather than a reacting control system. The frequent lack of regular resizing of the Kanban system leads to wasted resources and disruptions in Kanban control.

Spring units are stored in trays and fitted with the corresponding kanban types.
Spring units are stored in trays and fitted with the corresponding kanban types.

Resizing is now faster and less complicated

It must be possible to re-dimension quickly and easily at regular intervals or as required, for example due to changes in sales forecasts. At Montblanc, the scheduling department is responsible for this. The new module helps to carry out the re-dimensioning of each individual item quickly and easily and to compare the results with the existing control loops or across different versions and decide what needs to be done.

Problem and solution

Previously
Dimensioning
only with the usual Kanban formula. Parameters: Replenishment time per Kanban, average consumption, quantity per Kanban container, safety factor.

Afterwards
Automatic Kanban dimensioning helps to design the Kanban system in SAP in a more differentiated way and to consistently avoid waste. Simplicity, transparency, etc. are reinforced.

Prof. Dr. Andreas Kemmner

Prof. Dr. Andreas Kemmner

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