Using quality data appropriately

It is becoming more and more important to supply information from dif-ferent divisions of the company in a clear and well-organized form and to link such information functionally. Exclusive access to quality data is no longer sufficient. When all data can be accessed, quality data can be traced back to their time of origin. Friction losses are minimized since all indi-viduals with the corresponding entitlement can call up the information at any time and at any location. Not only the quality managers but also all other departments, from purchasing and development to servicing person-nel on the customer’s premises, can work using a uniform database. This ensures the necessary flexibility, especially in functional interlinking, without additional costs being incurred.

One example of this is the inclusion of the employee’s “operator’s li-cense” from personnel management. While it was once sufficient to have documentation of “who inspected what”, today it is becoming increasingly important to take into account the requisite inspector qualifications. Inclu-sion of the employee’s “operator’s license” means that it is possible to prevent tests or inspections being carried out by individuals who do not have the necessary qualifications. When validity criteria are taken into consideration it is even possible to check whether the inspector has in-spected a particular article often enough over recent months to continue to retain his qualifications for inspecting this article. If necessary, he may need to requalify.

Classic examples of documenting quality data are the testing and inspec-tion certificates in accordance with EN 10204, such as inspecinspec-tion certificate nos. 3.1 and 3.2, and specific test report nos. 2.1 and 2.2. On the part of the customer there is very often a demand for special certificates with a greater content. The form and nature of these certificates may vary from customer to customer. The relevant agreement is often limited to stipulating that in the case of a complaint, for example, a certificate has to be provided which gives the information desired. In most cases problems arise at the latest in expanding the contents to include relevant data about the corresponding process characteristics. This is not the case when an MES system is in ser-vice. The required documents can then be given a flexible design as far as the contents are concerned and can be adapted to customer requirements.

The inclusion of all quality-related events which affect the product quality represents an expansion of the classic documentation. This in-cludes interconnecting production data and quality data. Faults which

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occur during the product creation process have a great influence on the resulting product quality. The same is true of the characteristic values of process, machine and tool parameters. All in all there are five groups of causes which are responsible for deviations in quality:

 The individual as an operator or inspector;

 The material used as the result of an upstream production process;

 The machine with the elementary influencing factor, the tool;

 The method which decisively determines the interplay of the individual and the machine, and

 The milieu with various environmental influences such as temperature and dust, for example.

One example of the importance of the “tool” as an influencing factor is the risk of voids forming should a specified mold temperature not be reached. Due to the dependence of product quality on the diversity of in-fluencing factors associated with the cause groups mentioned above, the interlinking of all information takes on a great importance. This is made clear by the gapless documentation of part history which is required as part of product liability and which is a constituent part of an MES system.

The part history must include other information in addition to known in-fluencing variables. It must always list all important events which occurred from the time the drawing was prepared to when the tools were scrapped.

Should there be modifications, these must be described and reasons for them given. Possible contents of a part history include:

 The date of sampling and the beginning of deliveries for production purposes;

 Information about tool repairs;

 Information about process optimizations;

 Information about release changes, and

 The use of new materials.

In the case of complex products, such as machines or automobiles, in addition to the historical approach there is also the requirement that events be integrated into the part history following completion of the product. If a safety-related component is replaced, this change must be documented on account of the traceability required in connection with product liability.

To enable the correct response to be made in the case of a damaging event, which person must respond to which events will be stipulated. Should the damaging event occur, progress control of all activities will be required.

These in turn must be integrated into the part history.

8.4 Documented quality 189 Under no circumstances should the changes in quality-related data documented in a part history be considered in isolation. It should instead be remembered that every change can also have various impacts on other de-partments or processes. While there is a risk with monolithic quality assur-ance that these changes will remain undetected or not necessarily automati-cally have an effect on other departments, an MES system ensures that information is forwarded immediately. All corporate departments or divi-sions have direct access to the revised contents or documents. Consequen-tial costs caused by a delayed inclusion of changed and quality-related data are avoided. Any correction of measured values which becomes necessary after the event can have an effect on the inspection decision and thus on the quality status of the corresponding production lot. In such a case the MES system prevents further processing of the rejected lot in all downstream production processes. All lots into which the rejected lot has already been packed will also be rejected and prevented from being shipped. In the worst case, products which have already been shipped may have to be recalled from circulation. To limit the damage and the associated costs the auto-matic functions of an MES system will be required. Since there is collective access to all relevant data a swift and effective reaction is possible.

Impermissible deviations detected during inspection equipment calibra-tion or during machine or tool maintenance can have similar effects. The results documented with this inspection equipment may be based on incor-rectly measured values. In this case as well the production lots in which the inspection equipment was used must be barred or a reworking note issued. In the event that these impermissible deviations cannot be corrected, the item of equipment must be quarantined and thus no longer be available as a resource.

Upon the equipment being barred for use, the MES must check immediately to see whether it has already been planned into future production orders. If no alternative resources are available, replanning will be necessary.

Causes of defects identified even during the course of a complaint inves-tigation can have direct effects on the production in progress or impending.

If the cause of the defect is determined to be an incorrectly assigned DNC program or to maintenance which was not carried out, appropriate action should be initiated without delay. If necessary, the current machine settings and the tools being used should be checked. It is important that the checking process is instigated rapidly and that it should be automated as much as pos-sible so that consequential costs can be avoided. The use of MES’s higher-level escalation management function can also make a contribution here.

Once a complaint is formally opened this function allows an automatic check to be made to see whether the corresponding article is in any sched-uled or current production orders. If the check is positive, the production manager or the planning manager will be informed. If specific defect causes

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are assigned or actions identified, an escalation can be initiated together with automatic notification. Should receipt of the message not be acknowl-edged, other individuals such as deputizers will be informed automatically.

These examples illustrate the effect of changes in quality-related data or of decisions on other corporate departments or processes and reveal the necessity of deploying an MES system as an integration platform for pre-vious island solutions.