Well-stocked even with exotic parts

Inventory management: Procuring spare parts correctly

Dr. Götz-Andreas Kemmner, Managing Director of Abels & Kemmner Unternehmensberatung in Herzogenrath

If stocks are not normally distributed, the disposition is like a guessing game. The supplier Stabilus has its non-series material under control with a new software solution.

Problem: long delivery times

For non-series material, Stabilus GmbH, Koblenz, was looking for a solution to improve inventory management based on the SAP system. This is because spare parts and repair materials place different demands on warehouse management than series parts.

Rare parts in stock at the right time: that is the goal
Rare parts in stock at the right time: that is the goal

After a three-month test phase, the company opted for the DISKOVER 4.1 scheduling system. Uwe Mollenhauer, Head of International Logistics, Production Control and Material Planning at Stabilus, explains the advantages: “The system enables us to optimize inventories at the level of agreed delivery readiness for the large number of our non-series materials.” Stabilus GmbH in Koblenz specializes in the hydraulic damping and adjustment of flaps, doors and seats.

The first task was to differentiate the maintenance objects into A, B and C objects. A-objects are very important for achieving production targets. B objects are also of great importance, but they are designed redundantly or have a low degree of utilization. C objects are maintenance objects of subordinate importance.

Two criteria are important for A and B properties: the level of spare parts costs and the assessability of the wear and tear stock. The higher the spare parts costs for a maintenance object, the more advantageous condition-based maintenance is, which largely utilizes the useful life of a part. Many maintenance materials in A, B and even C properties require longer delivery times. This requires reliable planning and a demand forecast based on historical data. In order to derive the correct forecasts for future requirements, the distribution of demand volumes is crucial. The standard MRP procedures in the ERP or PPC systems generally assume a normally distributed stock issue, which is rarely the case in practice.

In most companies, the proportion of normal distributions in outgoing stock is only around 5%. A relatively large proportion of the distributions – around a quarter – cannot be assigned to any theoretical distribution type. For a long time, Stabilus was looking for a solution to plan non-series items that could not be assigned to a distribution type.

Together with the SAP system, the DISKOVER software now determines the optimum scheduling procedures and parameters. The system is characterized above all by its methodical approach in two successive stages: First, the parts are arranged in an article structure according to demand and consumption behavior. The optimum replenishment procedures and parameters are then determined for each item class with regard to stock levels and required delivery readiness. These parameters are then transferred to the leading host system – in this case SAP – or used directly in DISKOVER to determine the order proposals for parts procurement.


The DISKOVER 4.1 scheduling system is an operational management system for optimizing the supply chain from purchasing to delivery. It is characterized by extensive selection mechanisms for daily planning and portfolio analysis. The software also offers distribution-free scheduling procedures. The system can be run as an add-on tool under SAP and all common ERP, PPS and WW systems. (DISKOVER stands for dispositionwith the aid of confidence ranges, taking into account the actual stock issuedistribution).

Picture of Prof. Dr. Andreas Kemmner

Prof. Dr. Andreas Kemmner

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