Uncovering the "Black Holes in Production"

Mr Mioru Tominaga once said: "Work shall be what the customer is ready to pay for. Wastage is everything that is obviously not required for the actual productive operation. More than half the work time in [most] manufacturing organisations is wasted." Mr Sakichi Toyoda defined TPS (Toyota Production System) in a very early stage, and today it is often referred to as Lean Manufacturing. All these great men of industry had one basic message: "Eliminate all dominant wastages along the production chain and therefore increase the value to the customer!"

Defined by the Japanese Toyota engineer Mr Taiichi Ohno, the predominant wastages are:

• Wastage through excess production
• Wastage through waiting- and idle times
• Wastage during internal parts transportation
• Wastage during the productive operation
• Wastage through too high stocks/WIP
• Wastage through unnecessary movements, and
• Wastage through errors/mistakes.

As Figure 1 suggests, eliminating these wastages is a good idea if "Lean Manufacturing" is the aim. Today, "Lean Manufacturing" is often referred to as a discipline of process improvement - in close connection to striving for six sigma manufacturing excellence. Available organisational tools include disciplines such as continuous improvement (Kaizen), just-in-time (JIT) production, demand-controlled material movement ("pull"/Kanban) and others.

As important as these organisational methodologies are - the same level of importance must be contributed to the technical management tools available to achieve the best improvement results in practical reality along the shop floor. The Manufacturing Execution System (MES) for the vitally-interlinked key areas of Production, Personnel and Quality plays an increasingly important role in Lean Manufacturing. The MES is the strategic information management platform for identifying and eliminating all dominant causes of wastage, including permanent monitoring of the corresponding process result. Figure 2 shows a typical IT system infrastructure that embeds the MES in co-existence with ERP- and Payroll-systems. Thanks to ERP-systems, the company's business processes become more integrated and efficient. Associated systems on the same level, such as SCM or APS systems, provide further external integration with suppliers, customers and other partners. To complete this overall integration scenario, the manufacturing company management must also understand the strategic relevance of tapping the full improvement potential along their internal value-adding manufacturing operations. In simple terms and in most cases this improvement process simply starts by getting rid of excessive amounts of paper and internal process interfaces that are based on individual "walking, calling and hunting". Implementing a mature and standardised MES means to properly manage the information flow between the company management level and the production environment in both directions. As a result, the first and most important step towards Lean Manufacturing is done: Having achieved information transparency with consistent and extremely honest actual data in real-time, and having reduced paperwork and associated administration cost to the minimum possible!

On management and control level, the Manufacturing Execution System is used within the company's office environment, usually at the same PC workstation (as to be seen in Figure 2) together with the ERP-system by the following interest groups: Company Management: Overview and Evaluation of the company' s KPI's = Key Performance Indicators. (Figure 3: Example for production order-related value stream mapping (VSM))

Production Manager: Overview and Evaluation of Orders, Machines, Workplaces, Material, Staff, Resources (Figure 4: Example for an online-view of a selected machinery environment)

Financial Controller: Evaluation of Utilization, Efficiency, Effectiveness (OEE - Overall Equipment Effectiveness)

(Figure 5: Example for a group-wide OEE-index analysis and machine efficiency report)

Foreman, Supervisor: Overview and Control of day-to-day production- and staff-issues, WIP status/backlog (Figure 6: Example for detailed information of production orders and their operations) QA Manager: Control of quality processes from goods-receipt, via in-production SPC, all the way to goods-issue (Figure 7: Example for current view of process and quality data and detailed QA evaluations) Planner, Scheduler: Production sequencing for groups, machines, workplaces, considering given capacity constraints, material availabilities, order priorities and WIP backlog (Figure 8: Example for short term production sequencing under consideration of chosen strategies and given constraints on the shop floor) HR Manager/Admin: Absence and Presence Management, Performance Monitoring, Flexible Wage Remuneration (Figure 9: Example for effective personnel scheduling)

The Shop Floor Culture

At the shop floor level, the workers or operators indeed play one of the most important roles: They are providing input ("actual data feedback from the shop floor") for the MES - in three different scenarios:

• Feedback from machines/workplaces through their own manual data entry activity at a terminal station
• Operating machines which are fully connected to the MES with status- and/or process indicators, and
• Operating machines, which are connected with simple status/cycle signals, and providing complementary data input at the terminals.

Value-Add through MES Shop Floor Terminals and direct Machine Connectivity Lean Manufacturing means production without wastage. Naturally, a company can only achieve this scenario if wastages are being defined and subsequently detected when they occur or - even better - if they are avoided in the first place. Where does the information input come from? From the shop floor! To be more accurate: From the operator or the supervisor or directly from the machine.

Manual data feedback by a human being has the following disadvantages, and thus, may provide pitfalls along the way towards achieving a wastage-free production environment:

• Unintentionally or not - operators may report wrong data about yield, scrap, scrap reasons, downtimes, downtime reasons, etc
• Unintentionally or not - operators my not report correctly about actual statuses of machines and resources when they occur, but only after considerable delays, due to the fact that the "status event" has been overlooked or has been ignored.

These issues apply for data entry terminals as well as for input that relies on "pencil & paper". However, while "pencil & paper" is certainly not real-time and requires additional staff effort to capture, convey and evaluate data in both directions and to manually feed it back to the ERP system, the MES shop floor terminal adds value to the operator and thus to the organization, as it not only serves as a "data capturing unit", but also as a real-time information provider on the shop floor:

• Operators and foremen can call up production targets and defaults
• They can view the progress status at any given point of time
• BOM's, Drawings and Videos, etc. can be viewed on the spot
• NC-data settings can be managed and tracked
• Production papers can be printed instantly (including barcodes)
• RFID peripherals or scales can be connected
• QA (SPC) checks can be fully integrated at the same terminal, and
• Machine and process data can be taken over in real time through direct machine connectivity.

Synergy through CAQ Integration

A special advantage for the manufacturing company comes from the integration of the production order data management together with the in-process quality check (IPQC) management at the very same MES shop floor terminal. This eliminates the need for maintaining multiple separate "information islands" and excessive numbers of terminal hardware or excessive amounts of paper for control charts and histograms. The most important advantage is, however, the real-time availability of completely integrated and inter-related information within the MES - all information pertaining to Production and Quality is available on mouse click within one integrated information system.

Direct Machine Connectivity

The use of modern PLC-controlled machinery such as SMT placement machines, computer-controlled ovens, CNC works centers, injection molding machines, and others allow a direct take-over of machine- and process-data through an interface. This means, that information about machine statuses, process parameters are instantly available - either online or near-real-time, depending on the connectivity principle. This fact enables the company to immediately react to crucial values or statuses that tend to run out of control limits. Furthermore, direct machine connectivity provides coherent and consistent data with a considerably low margin for error. Wastages are avoided or, at least, detected early. Lean manufacturing at its best practice!

Typical machine interfaces are the well-known RS232 interface or a file transfer via Ethernet Connectivity (TCP/IP). At present, machine connectivity via OPC Technology or comparable communication standards makes inroads everywhere in the manufacturing world, and the development is driven by the so-called OPC-Foundation. In simple terms, OPC can be understood as a "universal translator between many different machine controls that all speak a different language". Therefore, if a machine vendor is able to provide a standardized OPC Communication data set for their machine control, it makes the life easier for the machine user. Since the communication happens via Ethernet (TCP/IP), typical issues such as limited cabling lengths or signal disturbances are eliminated.When it comes to "old" machines with no sophisticated process interfaces, such as at old manual lath bed turning machines or old printing lines, the question is: How can such an old machine be connected to a modern MES? The availability of standardised programmable machine interface modules makes the life easier for everybody. Such a small machine interface consists of multiple terminal inputs on the front side (screwdriver cable clamps) and a data interface such as RS232/485 on the other side for connection of digital or analog signals to the MES shop floor terminal. Such a machine interface can simply be connected to a dynamic cycle counter (or status indicators - relays, dry contacts, and pulses) of any machine in any manufacturing industry. The connection is established via a simple potential-free two-wire-cable that can bridge extremely long distances between the machine and the machine interface. All relevant logical processing rules for the received machine signals are set and maintained in the standard parameter settings of the MES.

Summary

To achieve a Lean Manufacturing Environment, it is necessary to define measurable targets that define "Lean". Specific organisational methodologies must be implemented to achieve these targets. A proper technical information infrastructure needs to be embedded into the manufacturing organization to support these organizational measures. This is where the Manufacturing Execution System (MES) takes effect: It becomes the organizational "backbone" for increased data transparency in order to uncover all systematic causes of wastage and therefore playing a strategically relevant part in eliminating these wastages and striving for Lean Manufacturing. Properly integrated shop floor terminals and machine/process connectivity ensure that the reported data is true, reliable and consistent - to become a useful decision basis for the company management's improvement actions.