Segmentation and optimization in the gold spring manufactory

Montblanc: Material flow optimization and reorganization of production control reduces work in progress and throughput times in complex gold pen manufactory

by Frank Derlien, Stefan Friedrich, Oliver Wegener1, Carsten Hense2, Andreas Gillessen, Andreas Kemmner

Following the introduction of electronic planning boards about two years ago, which made production control at Montblanc Goldfedermanufaktur efficient, transparent and clear, the next major challenge was now on the agenda: the reorganization of production with the aim of significantly reducing throughput times and work in progress. In order to achieve this goal

  • the material flow and department layout were completely redesigned and rebuilt,
  • production is reorganized into production segments (production blocks) and
  • production control was expanded to include a Heijunka component for leveling and smoothing daily capacity requirements in relation to fluctuations in incoming orders.

The spring unit production process is very complex. It resembles a factory with flow production. The spring units are manufactured exclusively by hand. The production process consists of up to 35 different work steps, some of which require the highest manual precision. At Montblanc, for example, every single nib is sharpened, set and written by hand.

The very high number of variants and the daily changing bottlenecks in production due to demand are now mastered quickly and efficiently using electronic planning boards. This was a basic prerequisite for the reorganization of the gold spring manufactory that has now been carried out to reduce throughput times and inventories.

1. analysis of the current situation:
As always, the concept was preceded by a detailed analysis of the current situation. Due to the complexity of Montblanc production and the task at hand, a lot of time was deliberately devoted to this phase. This proved to be very successful, as the rough and detailed concept could be developed and approved in a relatively short time. Based on the data analyses carried out and their results, many ideas and solution approaches were quickly verified in terms of their feasibility and potential for improvement and then pursued further or discarded. In addition to detailed analyses of material flow, value stream and layout, the following parameters, among others, were recorded, evaluated and analyzed:

  • Stocks,
  • Consumption,
  • Incoming orders,
  • Capacities,
  • Capacity limits (machines, set-up, employees),
  • “lost” capacities,
  • Days in arrears,
  • Residue quantities,
  • Planning data,
  • Sales plans.

This was based on both historical data and planning data for future periods.

2. material flow optimization and layout planning:
In recent years, Montblanc’s growing departmental structures and new investments had meant that the flow of materials in the department no longer met the requirements for uniform material flows. The challenge was to optimize the material flow of the three production groups within the existing, relatively cramped premises. should be achieved:

  • uniform material flows and loss-free processes,
  • Shortened material transport routes,
  • increased transparency,
  • reduced space requirements and
  • support for the desired production segmentation (production blocks).

Furthermore, some additional constraints had to be taken into account, such as the expansion of the laser technology competence center and the consolidation of all hydraulic presses in a closed room (noise reduction) at the Montblanc headquarters.

As a result, all requirements including of the additional boundary conditions are fulfilled. The new layout is much “tidier” and has also created additional free space.

U-layout:
The actual material flow in the three production groups was designed and implemented in a so-called U-layout. However, the initially favored approach could not be realized in the existing Montblanc premises. When checking its feasibility in the layout planning, it quickly became apparent that the width of this layout was too large to integrate all three production groups into the existing space.

First approach U-Layout
First approach: U-Layout

A material flow in a U layout with a central material supply rail was therefore chosen. This solution requires considerably less space than a “classic” U-layout approach. The realized approach has slightly longer routes for Montblanc employees to other workplaces compared to the first approach. However, it scores points in terms of even shorter material transport routes, greater material transparency with regard to circulating stocks and can supply all workstations centrally below the material supply rail with power, exhaust air, etc.

Selected approach U-Layout
Selected approach U-Layout

Assembly point outgoing goods:
The material flow in the new U-layout begins in Montblanc production at the welding workstation with the welding of an iridium ball. After the production order has been processed at other workstations, the material leaves the department for the first time after the presetting operation. The springs are tumbled (deburred) in the vibratory grinding department. There are a total of three interfaces to external departments during the entire production process (vibratory finishing, rhodium plating, washing). A central “outgoing goods” collection point was created for these outgoing goods. It is centrally located in the immediate vicinity of all three Montblanc production groups and can be reached within a short distance. This collection point is divided into three areas: Each external processing area has its own area from which the employees collect the material independently.

Montblanc incoming goods collection points:
After external processing, the material is transported from these departments back to the specially created staging areas (internal/external interface) in the gold nib factory. These staging areas are located directly next to the subsequent work steps, making the material waiting for further processing immediately visible. The staging areas and the central material supply rail thus ensure maximum transparency in the production groups with regard to the material waiting to be processed.

Operations outside the U-layout:
In addition to the last operation, the so-called writing, in which Montblanc ink is used to test whether the nib glides “effortlessly” over the paper and thus meets the high quality requirements, only the polishing operation was not integrated into the U-layout. Integration would have forced a complete encapsulation of the system within the U-layout and thus “blown up” the U-layout. In addition, integration would also have been very cost-intensive. As polishing is the last operation of the second internal segment, the additional transport distances are very short and therefore acceptable for the design.

Material flow
Material flow

3. production segmentation:
The central component for significantly reducing throughput times and work in progress is the reorganization of Montblanc production into manufacturing segments. The new material flow and the new U-layout take this reorganization into account and support it. Compared to the previous workshop-oriented production, production in segments (production blocks) has drastically reduced both throughput times and work in progress.

Structure of block production:
The ideal situation would be to organize the entire Montblanc production in a single segment. In line with this approach, the aim was to keep the number of segments as low as possible and the number of operations per segment as high as possible.

During the Montblanc production process, the nib assemblies have to leave the gold nib manufactory several times for further processing in other departments (vibratory finishing, rhodium plating, washing). Due to this non-resolvable structure, the segment boundaries were defined in a quasi “natural” way: they are always located where the spring units leave spring production (end of segment) or are fed back into spring production (start of segment). Between these “natural” segment boundaries, it was possible to create continuous flow production.

The new Montblanc production structure thus has four internal and three external segments. A production order must run through all operations of a segment (internal or external) within one working day. The ideal lead time for a production order would therefore be 7 working days instead of the previous average of 33 working days.

However, the target for the throughput time is 10 working days: Buffer stocks are required within the segments at sensitive workstations in order to avoid losing capacity at other workstations within the process chain due to machine downtime. Here, Montblanc clearly prioritizes employee utilization and productivity over throughput time and inventory reduction. For the go-live, the buffer stocks for the initial configuration of segment production were even set slightly higher to ensure the smoothest possible start. The buffer stocks are gradually removed from the system during further operation.

The production segmentation clearly limits the circulating stocks in gold nib production. Each production segment only ever contains production orders in the amount of the daily capacity of the production group. The work in progress is therefore calculated from the net throughput time of all segments multiplied by the daily capacity per production group plus the daily capacity per production group. of the buffer stocks. Compared to the previous circulating stocks, between 50% and 65% less material is now required in the process.

Production segments
Production segments

4. heijunka control – leveling incoming orders and capacity requirements:
The 14- and 18-carat Montblanc gold nibs wait in polystyrene trays for their use at the tip of the fountain pen in the final assembly of the writing instruments. However, before they get there, they have undergone a complex, multi-stage, time-consuming and labor-intensive production process.

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

In view of the complexity of production, optimizing employee deployment (capacity utilization) while reducing throughput times and inventories posed a major challenge for production management at Goldfedermanufaktur.

In order to level out and stabilize capacity utilization in gold nib production at Montblanc in the future, fluctuations in incoming orders (fluctuations in demand) must no longer spill over into the three production groups. To prevent this, the current production control system was expanded to include a Heijunka control system.

Heijunka:
The term Heijunka refers to the process of smoothing required capacity requirements. Smoothed production is considered to be the most efficient and cost-effective method of production. The aim here is to

  • Smoothing of the application quantities to be loaded daily,
  • Harmonization of the material flow through more uniform throughput,
  • Avoidance of accumulating fluctuations in demand,
  • Avoidance of high inventories and long throughput times and
  • Avoiding the alignment of capacities with their peak demand.

The analyses of the incoming order data carried out at the start of the project showed very high fluctuations in the daily Montblanc incoming order quantities within the production groups: from up to seven times the daily capacity limit to no incoming orders at all over several days. If an overall analysis was carried out across all three production groups, the periods with no incoming orders at all were significantly reduced. This made it clear that, in addition to leveling incoming orders and capacity utilization within the production groups, the Heijunka control system would essentially also have to be used for balancing between the production groups.

Clocking:
Each Montblanc production group has its own Heijunka board. This is populated with the daily incoming orders by production control. The basis for the daily scheduling of production orders in the production groups from the Heijunka board is the weekly employee scheduling. It is used to determine the daily available capacity in the form of “number of employees” and “number of machinable spring units” per production group. The number of spring units that can be processed represents the cycle at which production order quantities must be loaded daily from the Heijunka board to the first operation of the production groups.

The production groups follow this “cycle” (number of spring units to be processed daily) from production segment to production segment. With a throughput time of one working day, the quantities are “clocked on” from segment to segment. The buffer stocks are of course taken into account. Each production group organizes the organization of work within the segments and the staffing of the corresponding workstations for itself. The following aspects in particular must be taken into account in the management by the Montblanc production groups:

  • Not every spring unit passes through the same workstations.
  • Each work step has very different processing times in some cases.
  • Only a few jobs can be filled at any one time, as the ratio of jobs to employees is approximately 3:1.
  • Despite very high employee qualifications, not every employee can process all work processes or all work processes at the same speed.

Throughput times and work in progress are documented and historicized daily for each production group, each production segment and each individual workstation and evaluated in monthly reports.

Leveling between the Montblanc production groups:
If there are no more orders on the Heijunka board or if the Heijunka board is overflowing with orders, the leveling within the production group is no longer sufficient. If this is the case, a comparison must be made between the three production groups.

Each Montblanc production group manufactures a different product range. As a result, the production orders cannot be exchanged between the groups at will. There is only one product group that can be produced in all three production groups. This product group is a volume model with regular consumption behavior and thus facilitates the balance between the groups. Compensation is always necessary if incoming orders are so low that “lost” capacity must be expected in a group. In this case, orders of the volume model are transferred from the Heijunka board of one production group to the other production group. However, it can also happen that a Heijunka board “overflows” due to a large number of incoming orders. If the order backlog in the Heijunka board exceeds five working days, production orders are transferred to the other two production groups.

If it is not possible to balance production orders between the groups, it is still possible to transfer Montblanc employees from one production group to another production group. In this way, capacity limits can be variably balanced between the production groups.

Visualization in the electronic Heijunkaboard:
The Heijunkaboard for levelling and smoothing the production segments was implemented within the existing electronic planning boards in gold spring production. All the necessary calculation mechanisms are performed automatically by the electronic system. Instead of manual boards, the information is displayed on large flat screens distributed throughout the gold nib production area. In this way, it was possible to combine visual management with efficient operation.

High level of acceptance among Montblanc employees
The block production and the optimized control mechanisms were taken up by the employees with great motivation. Employees were already working with the new system before the official go-live. The originally planned ramp-up phase was therefore drastically shortened.

Stefan Friedrich, Deputy Director of Montblanc Goldfeder Manufaktur
Stefan Friedrich, Deputy Director of Montblanc Goldfeder Manufaktur

5. practical probation:

The new layout, the new material flow, production in segments and the Heijunka control system have now proven their worth at Montblanc Goldfedermanufaktur. The new gold nib manufactory has thus become another key design element of Montblanc’s lean strategy.

Sample planning board incl. Heijunka
Sample planning board incl. Heijunka

1 Frank Derlien is head of spring production, Stefan Friedrich is deputy head of spring production and Oliver Wegener is head of production control for spring production at Montblanc Simplo GmbH, Hamburg
2 Carsten Hense is Head of Production at Montblanc Simplo GmbH, Hamburg

Further information on this topic can be found here:

  • [intlink id=”5471″ type=”post”]Highly efficient note management: Heijunka boards in the final assembly of writing instruments at Montblanc[/intlink]
Image rights: © Montblanc Simplo GmbH
Prof. Dr. Andreas Kemmner

Prof. Dr. Andreas Kemmner

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