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Cover Story

Flexible manufacturing, another term for agile manufac-turing, is an alternative to part-specific transfer lines formass production. The advantage is a high flexibility ofparts which makes it easier to react to changes in theproduction processes and allows for the manufacturingof several product variants virtually at the same time.Additionally, it raises equipment availability and theinterchangeability of machines.

The following engine manufacturing example (here:cylinder head) illustrates the exponentially increasingdata traffic caused by the flexibility and variety of com-ponents in agile manufacturing, but it also explains howdata traffic still remains controllable. Especially the dif-ferent perceptions of these data provide a deep insightinto machine behavior and help you assess productquality.

Classical engine manufacturing performs the singleoperations by means of a clocked transfer line. Changescaused by new characteristic specifications are hard andtime-consuming to implement. Besides, there are onlyfew product variants that can be produced in the sameproduction line.

Agile manufacturing performs the same operations asthe classical manufacturing, indeed, but the flexibility ismuch higher (see Figure 1). There are several identicalmachines for certain operations and some of them pos-sibly include more than 50 tools. So the same machineperforms several operations. The equipment availabilitycontrols, as needed, which type of machine performswhich operation with the cylinder head. A machine parkis thus able to process different types of cylinders andvariants of a cylinder type.

This highly flexible processing of parts leads to twoessential questions:

1. The question alone as to whether a machine or allmachines of a machine park are capable or suitableseems to be a problem that can hardly be solved.Compared to a transfer line, you cannot produce e.g.50 parts, measure the characteristics and analyzecapability. Indeed, you can produce 50 parts in agilemanufacturing; however, you may only reach a smallfraction of all available operations. Otherwise, thissituation would require a massive effort to performthe respective options 50 times and this effort is notjustifiable for reasons of time and for financial rea-sons.

2. How can you monitor agile manufacturing in orderto ensure that all characteristics are processed cor-rectly at any time?

You may answer these questions due to the right per-ception of the products to be manufactured and therespective process steps. As the conclusion reached inmany projects for the implementation of the Q-DASCAMERA® Concept indicates, there tend to be two per-ceptions of the manufacturing processes. There is

• a product-related and

• a process-related

approach. The product-related approach evaluates thequality of the product and the process-related approachanalyzes the capability of the entire production line andits components (tools, spindles, etc.).

Product-related Approach

The product-related approach (see Figure 2) assesseswhether the processed characteristics meet the requiredspecifications. You cannot only have a closer look at thesingle characteristics but you may combine different ele-ments (characteristics of a component or characteristicsof a type of product) and evaluate them as a separateunit. Test planning, measuring programs and part identi-fication define with which level a characteristic is asso-ciated. The number of levels you should observe

Dr.-Ing. Edgar Dietrich, Stephan SprinkQ-DAS® GmbH & Co. KG

Agile Manufacturing – a (Small) Step in the

Direction of Industry 4.0?

Figure 1: Agile Manufacturing of a cylinder block (diagram)

Figure 2: Hierarchy of products

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Cover Story

depends on the respective situation and must be deter-mined accordingly.

This helps you assess the characteristics and the higherlevels as an own unit.

You just have to use coordinate measuring machines orSPC stations to measure the characteristics and evaluatethe measured values statistically. Corporate guidelinesand process instructions specify the type of evaluationswhich are also referred to as capability analyses. Thesystem shows on each level whether the single charac-teristics are o.k. or n.o.k., i.e. it shows a clear summarygraphic with e.g. smileys ( , , ) You have to definethe criteria for displaying the single smileys individually.

Moreover, the system processes the same types of char-acteristics in an operation over and over again eventhough they belong to different parts or components(e.g. a borehole with defined specifications). You maycombine all comparable characteristics into a virtualcharacteristic. Regarding the virtual characteristic, thisprocedure quickly leads to a data volume sufficient tomake the desired machine capability analysis possible.

Process-related Approach

In terms of the process-related approach (see Figure 3),the people responsible for the manufacturing processare rather interested in the behavior of machines, theirspindles and tools, independent of the characteristicsthat are currently processed. In order to observe thisbehavior, you have to combine the characteristics, too,and create different levels. Here are some examples oflevels.

• Entire machine park

• All machines performing the same operations

• A single machine

• A tool / spindle of a machine

Since you are able to identify the processing of a char-acteristic clearly, you will always know which machineand tool perform which operation on a part. This is therequirement for structuring the data according to the cri-

teria mentioned above. The number of levels specifiedbased on this approach also depends on the desiredallocation of characteristics to the respective levels.

Even the process-related approach measures character-istics, as described above, and evaluates the measure-ment results statistically based on the process levels.You have to define the criteria for displaying a certainsmiley on a certain level individually. In the end you cre-ate a status overview always indicating whether allprocess steps are taken correctly or whether there aresome deviations. In case of problems in a sequence ofoperations, the process responsible will quickly identifythe manufacturing machine and tool concerned. Thedrill-down function shows increasingly more details, i.e.it presents a summary of tools including the respectivestatus display (see Figure 4). You have to define task-specific criteria for displaying a green, yellow or red bar.Additionally, you may show further details about thecharacteristics corresponding to the respective tool,such as charts, statistics, reports, etc.

The process-related summary allows for an ongoinganalysis of production facilities. This analysis helpsdetecting deviations from target conditions or exceededlimit criteria quickly in order to take respective correc-tive action.

Conclusion

The processed product and the manufacturing facilitycan both be provided continuously with these types ofinformation. So they are able to control themselves.Agile manufacturing based on the principles mentionedin this article takes a first step towards the basic idea ofIndustry 4.0.

Figure 3: Hierarchy of the process

Figure 4: Process-related summary including a drill-downfunction