Fully Automated Production Planning in Mold Manufacturing at Horst Scholz GmbH

Production of precision plastic parts for micro-technology, gear technologies and medical engineering

Horst Scholz Ltd. was established 1997 in Kronach, Germany and is still a family owned and operated business. The company manufactures precision plastic parts for micro-technology, gear technologies and medical engineering and specializes in the high-end performance modeling of plastics for mold making. All plastic molds are manufactured in-house.

The name Horst Scholz is synonymous with outstanding product quality. Quality that is made possible by the use of 75 high-performance injection molding machines plus peripheral equipment.

The initial situation at Horst Scholz Ltd.

In 2017 Horst Scholz was in the process of creating 40 new molds. Their ERP system is Microsoft NAVISION. For lack of a better planning tool, they were forced to plan their processes with the help of Excel, i.e. manual planning and control. The manufacture of tool molds requires that many different types of electrodes first be produced for use in the EDM machines; at the same time a large variety of metal parts must be manufactured before all the various components meet in pre- and final assembly. Hundreds of processes - many of them running parallel - must be planned for the manufacturing of a single mold. Several projects may run concurrently, i.e. many orders are processed using the same machine pool.

With such an array of complex manufacturing processes, including a combination of both external and in-house manufacturing, it is impossible to expect a human brain (even with Excel) to create optimal sequence planning. The consequences for company Horst Scholz:

• The complexity in the planning process increased enormously as the number of tools and external influences increased.  
• Completion dates were imprecise and additional planning reserves had to be included in the schedule. This resulted in longer delivery times.
• The start date/time for subsequent orders was determined based on the planner’s experience and corresponded to a Push Production.
• The non-synchronous production of individual components led to long lead times.  
• Stagnation caused high inventories, especially of semi-finished goods.  
• The main activity of the planner was not the planning, but rather organizing the day by day work.

Horst Scholz GmbH & Co. KG was enjoying steady growth. However, due to the burden of increasingly complex planning for a steadily growing number of orders, the need for process optimization was becoming more and more urgent. Meeting these new demands would require a significant increase in effectiveness and efficiency.

APS Selection

Martin Rebhan and Karl-Herbert Ebert, top managers at Horst Scholz GmbH & Co.KG, contacted Asprova AG in mid-October 2017, described their situation and asked for technical advice. We recommended the following systematic approach in choosing their planning tool:

1. Create an APS specification sheet (mid-November 2017)
2. Target agreement
3. Data analysis (routings, BOM, orders, etc.)
4. Create a prototype using real customer data
5. Prototype presentation and verification of the results (mid-December 2017)

Planning Challenges at Production Planning

The most important requirement for any planning software is its ability to map the “reality” of a factory 100%, that means, taking into account all production properties, processes, process rules/restrictions and planning restrictions. Mapping the rules and restrictions for mold making specific to Horst Scholz Ltd. was one of many challenges, others included: 

• Multi-level finite capacity planning: all individual processes, main resources and sub-resources must be planned at the same time and take into account finite capacities, whereby in several processes a main resource may have several sub-resources, e.g.: the main resource is a machine; sub-resources may be 2 different jigs/tools and the employees  
• Automatic selection of alternative machines: a machine may have, for example, varying capabilities in terms of product dimensions and material properties 
• Process loops (looping): certain materials may visit a resource multiple times and must always be processed in the correct sequence 
• The synchronization of parallel and merging processes  
• Taking into account raw material availability  
• Considering employee availability: shift calendar and holidays 
• Sub-contracting e.g. hardening (pick-up / delivery dates)  
• Automatic process selection e.g. deciding for in-house or outsource production, according to specific criteria

Implementation and Results  

After successful verification of the Horst Scholz-specific prototype, an Asprova license was ordered at the end of 2017.

• A kick-off workshop was held at the beginning of January 2018. An interface was created for the relevant databases.  
• Basic parameterization in the Asprova software.  
• The dispatching rules and planning logic were defined for individual processes, resources, and orders.
• Asprova’s fully automated planning system was up and running approximately 3 weeks after kick-off (parallel phase).  
• At the end of February 2018: go-live of the Asprova fully automated planning system. It is no longer necessary to use Excel in the planning.  
• Since then, stepwise adjustment and improvement of the data structure.

Both the management, Martin Rebhan and Karl-Herbert Ebert, and the (daily) Asprova users and production planners at Horst Scholz are enthusiastic about the new Asprova planning software.

Additional Benefits:  

• Realistic and feasible sequence planning 
• Process synchronization  
• Material availability is considered in the planning  
• It only takes 20 seconds to calculate the manufacturing of 60 molds - 12 months in advance.  
• Visualizes the status of individual orders 12 months in advance using: order GANTT charts, resource GANTT diagrams, sequence production tables, capacity utilization charts.  
• Gives reliable completion dates for individual tool shapes.