High transparency when producing with effective MES
According to a survey by Forrester Research from the year 2004 many companies face their most prominent problems in the production area – in the lack of transparency of production, in imprecise demand forecasts and missing communication structures. These are the greatest hurdles to improving production and product quality. In addition, the legal requirements imposed by country and industry must be met. Here, manufacturing execution systems (MES) enter the production and offer specific solutions.
MES provides the necessary transparency about all value-added production processes. Employees are always informed about the current situation, can respond immediately and direct planning towards the existing production conditions. This permits a fast and flexible response to changes in production, and existing process reserves can be tapped into with MES. In this context various aspects play an important part, eg targeted planning and effective control of production taking into account the current production situation at the time, reduction of material stock in production, fast response to faults and changes in production or traceability of all production results including repair loops for individual products with serial numbers.
Successful MES strategy
To achieve high transparency together with exact traceability in production the following strategy should be considered and implemented:
- Identification of components throughout the production ñ from incoming through to outgoing goods including all repair loops and returns. Only components known to the MES can be traced along the production process and through their life cycle.
- Identification and capture of products with mandatory tracing requirement by issuing serial numbers.
MES issues unique serial numbers. Normally machine-readable labels (barcode, data matrix, RFID, etc.) are placed for this purpose on the component to be identified. The label to be used depends on various criteria, eg available space on the component, production conditions etc.
- Unique allocation of work outcome to the product, the production step and the production stage including the materials used with supplier details (batch allocation).
Because the MES knows the serial numbers produced, all relevant production information can be allocated to the product (unique copy). This allows for the easy representation of forward and backward traceability in the system: When were which components fitted at which workstations to which end product (unique copy) bearing which corresponding serial number? Which serial numbers of specific end products were produced with which component batches from which suppliers during which time period?
The fast and safe answers to the above questions provide for many companies today a good protection with regard to legal provisions for quality and product liability. The extent of recall actions in the automotive sector, for example, can be reduced to a necessary minimum. This helps the manufacturer to minimise any potential loss of image.
- Process interlocking for the automatic safeguarding of production processes.
To produce quality rather than achieve quality through testing all working steps must be carried out with the desired results and in the correct sequence. A subsequent step must only be initiated after the previous one has been successfully completed. With interlocking MES safeguards the work outcome and sequences and can interfere directly in the process as soon as there are any irregularities.
MES can also immediately detect if the
wrong material is loaded at a machine and can prevent this specifically by interlocking. A setup error message is sent to the appropriate employees at the same time. This prevents wrong material from being loaded and used in production. Interlocking helps safeguarding the quality of the production process.
- Complete electronic documentation– reporting by product, process and qualification.
At a time of strong competition the production of high quality products is no longer enough. The complete documentation of the production processes and the relevant quality results is equally important ñ related to a specific product with a unique serial number (unique copy). Different directives/standards apply to different industries, eg ISO9000ff (general quality management incl. documentation), VDA 6.1 (VDA quality management based on ISO 9001 etc), ISO/TS16949 (international quality standard for automotive suppliers) or FDA 21CFR Part 11 (complete documentation of production in accordance with the guidelines of the USA Food and Drug Administration).
These directives are aimed at ensuring product and production process quality and documenting it throughout. This helps drastically reduce quality defects resulting in expensive returns processing and recall actions. In case of a claim for damages the manufacturer has the burden of evidence with regard to product liability. MES provides all relevant production data for this purpose and offers suitable defined production and quality reports.
With its Totally Integrated Automation (TIA) concept Siemens offers a continuous product spectrum and automation environment – starting from basic automation via visualisation and process solutions to the standardised MES software solution. What all TIA products have in common is that they can be used in the most diverse industries and have universally configured interfaces to each other.
With its comprehensive functions the Simatic IT solution meets all the MES requirements of different industries (manufacturing industry, process industry, etc) and provides the link between the technical world production and the commercial world of ERP (ERP: Enterprise Resource Planning).
This not only ensures the correct flow of information during operation, but also provides production managers and foremen with practical planning, information and evaluation functions. The MES solution can thus serve as a central information store for the production since it retains all relevant information in electronic form.
A framework approach further enables the simple graphic display and representation of various client production processes. Individual modules combined with a library concept facilitate the efficient and affordable solution for various tasks, eg traceability/genealogy, order management and production control, material flow control throughout the production, machine data and operational data capture (MDE/BDE) or analyses and reporting (quality, KPI, OEE/DTM).
Clients therefore profit from an enormous cross-industry body of knowledge and synergies they can utilise. Qualified Siemens partners use the software solution in particular to solve current production challenges at their global end clients.
Typical MES workflow
Normally the ERP system sends a list with current production orders. Information. eg item with numbers and delivery date or relevant work schedule including item list, will be provided.
The MES accepts these data for the fine planning of the respective orders on the basis of the actual production situation. The availability of resources (machinery, personnel, materials) will be checked. After fine planning, the orders with fixed working steps will be released for production in the MES (eg by the shift foreman). Employees logging in at their workplace receive the up-to-date order inventory and start the corresponding production process. Via easy to understand dialog masks the workers can call up relevant information (eg work instructions in text form or as video sequences in different languages). Via material management MES keeps the stock of goods (buffer, warehouse locations, auxiliary materials) in production low. All work outcome, eg quantities, pass/fail parts or quality/measurement results are automatically reported to the MES or manually by the operator. As soon as an order is complete the completion message is sent by the MES to the ERP system with the compacted relevant information.
The software implements the specifications of the international ISA 95 standard which clearly defines and describes the MES functions. The implementation of this standard implies a greater security of investment for the client, because the suggestions for the collaboration with other systems and applications within manufacturing are indicated at the same time and deviations from an optimal solution integration can be anticipated and prevented.
The consistent use of MES creates better and more timely transparency in production which offers considerable benefits: documented production ñ both product and process related, fast and exact detection and documentation of errors throughout the production line, information on traceability, targeted narrowing of failure causes by selecting the affected batches and products, online evaluation of status, quality and production data (eg OEE, uptime/downtime, downtime analyses, FPY), reduction of capital lockup through production-lead inventory optimisation (intermediate storage, buffers, process materials, etc.).
Conclusion
MES as a modern production management provides all relevant production information in good time to staff and machines. Transparency in production means faster processes, reduced costs and improved quality for the whole production environment.
MES means to know: ‘Where are the goods at which time in which production line with which results during production?”
Dipl.-Ing Sven Kleine-Herzbruch is with Siemens AG Nurnberg, Germany. www.siemens.com/simatic-it
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