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In implementing a Quality Management System (QMS), fundamentals play a key role. These fundamentals in automotive manufacturing are basic quality methods and techniques. During the era of QS-9000, these were a part of the "seven pack." Now, with the introduction of ISO/TS 16949: 2002, these methods are known as the "core tools." Consistent with the customer-focused QMS, core tools are customer-specific requirements.
The automotive customer specifics and customer requirements are the core tools that include: Advanced Product Quality Planning (APQP) and control plan; Production Part Approval Process (PPAP); Measurement System Analysis (MSA); Statistical Process Control (SPC); and Failure Mode and Effects Analysis (FMEA). Two aspects of core tools need to be explored: their alignment and documentation, and their synergy during application.
Aligning core tools
The first aspect of the correct use of core tools is their alignment. View APQP as the "umbrella" core tool that, in its purest form, identifies all elements of new product development from concept to production launch. APQP is formatted in a five-phase process, with each phase containing a defined set of inputs and outputs. The effect of the transition, for most companies, from QS to TS 16949, relative to APQP, is the added requirements for monitoring customer timing and APQP process performance.
A key product of the APQP process is a set of core documentation that is created in a prescribed chronology. These documents are process flow chart and diagram, Process FMEA (PFMEA), with design FMEA as an input, and control plan and work instructions, created in this order. Within the content and context of these documents is the application of core tools.
Alignment begins with the design record. The foundation of effective implementation and a conforming customer-focused TS 16949 QMS is built on an understanding and fulfilling of customer requirements, needs and expectations. From a practical standpoint, if a customer's requirements are documented in the design, and associated specifications and the design record are not maintained as the most recent engineering change level (ECL) released by the customer, how can requirements be met? To meet requirements means knowing what they are. As such, the part number and ECL become the primary point of alignment that must be maintained across all core documents and all APQP activities.
The second critical point of alignment is the identification, control and documentation of special characteristics. The design record is one of the sources used to identify special characteristics. For both pragmatic and conformance reasons, special characteristics-both customer-designated and internally designed-must be identified consistently in all four core documents: process flow diagram, PFMEA, control plan and work instructions. If special characteristics originate in the FMEA as a result of assessment of criticality, they also must be recorded in all core documentation.
Once the process has been defined in the process flow diagram, the sequence of operations, operation descriptions and associated operation numbers must be documented while creating subsequent documents, PFMEA, control plan and work instructions. The process flow diagram is used to document more than just workflow and the sequence of operations. It also should be used to identify where characteristics, principally special characteristics, are created, as well as identify potential sources of variation. The diagram also can help assess redundant or non-synchronous activities.
In developing the Process FMEA, the next document created in the core document set, the process flow diagram, becomes a critical and required input to the analysis. From the process flow diagram, operation descriptions, numbers, controls and special characteristics must migrate consistently to the FMEA. Characteristics that have escalated to special, or internally designated, status as a result of the FMEA activity can trigger an update to the process flow diagram. Additionally, potential sources of variation documented in the process flow chart should be reviewed when causes of failure modes are identified in the FMEA. The power of the analysis is its use as a prevention method to assess potential process failures.
The control plan is next in the order of creation. Once again, the operation descriptions, numbers, process controls and specials characteristics must be recorded consistently with information documented in both the process flow and the FMEA, including any special characteristics created as a result of the FMEA activity. Descriptions of product characteristics must be consistent with the design record and used when documenting specifications and tolerances for product characteristics. Any change in the ECL mandates updating all core documentation.
The last documents to be addressed in the core set of documentation are the work instructions. The operation descriptions, numbers, controls and special characteristics, part number and ECL all must be consistent with information that has been used in the previous core documents discussed.
In the context of auditing, whether it is process monitoring or internal and external QMS audits, the alignment of key process data is necessary to ensure that customer requirements are achieved, prevention is ensured and variation is reduced. These alignments are traceable across documents.
Achieving core tool synergy
After addressing alignment conformity, the investigation of synergy provides an opportunity to add value to documentation so that it becomes dynamic. Synergy begins with the FMEA. The initial task in the analysis is to identify the "Process Function and Requirements." This is the most critical piece of information on the document because if the requirements are not robustly defined, then failure modes cannot be effectively identified. If we fail to define customer requirements, what confidence can we have in our ability to satisfy those requirements? If an organization is conforming to a quality specification that is founded on customer requirements, it is imperative that they understand those requirements.
To ensure a thorough assessment and documentation of potential failure modes "where there's risk," it is necessary to record "noun, verb and measurable." The measurable is a customer's requirements and is derived from the design record, specifications or equivalent statement of a customer's requirements. It is not uncommon to review a PFMEA and find the process function and requirement stated as "Drill Hole-Operation 10." The questions the auditor or reviewer should ask include: What hole, what size and where? What is important to the customer? Is it the hole's location, its depth, its taper?
Additionally, by definition, process controls must be directed at high-severity failure modes or severity in combination with occurrence, or criticality. The severity ranking value is based on the effect of the failure on the customer or customers. Unless identifying and accurately recording the "measurable," or specifications, in this case for the drilled hole, the adequacy of severity rankings risk being inaccurately valued. Consequently, preventive actions may not be identified that result in reduced variation.
If, for example, the FMEA team has not referenced the design record to identify the measurable for the hole, failure modes oversized and undersized may be the only failure modes recorded. Hole location may be more important to the customer than size. However, if it is not identified as a requirement, or a measurable, the team will not correctly assess its severity and the customer's requirements may not be met. The vital synergy here is between the design record and specification, or customer requirements, and the process function and requirements recorded on the FMEA. Again, to meet a customer's requirements, they must be known.
The assessment of occurrence ranking values needs to be consistent with key data, in this case capability and stability data. This is not to imply that such data be used exclusively to rank occurrence but it should be used to assess likelihood. For example, if all occurrence values associated with a single operation step are recorded as ones and twos, it can be reasonably expected the operation will be stable and capable.
To be effective, cause identification needs to effectively use data from the production of like or similar products. For example, are there problem reports in the organization's records associated with failure modes recorded in the FMEA? If so, the team needs to review the root cause identified in the problem reports. This review helps to prevent a recurrence of problems and failure modes. In addition to the data, root-cause analysis tools and their application must be made efficient in areas such as cause and effect diagramming, 5-whys and fault-tree analysis. This allows for the documentation of potential causes of failure.
The transition from QS-9000 to ISO/TS 16949:2002 intensified the importance of the control plan. Process realization process auditing is being conducted using the control plan as the "checklist." It is a critical document in an effective QMS; its merit as a medium for process monitoring and improvement cannot be undervalued.
A more important aspect of the application of SPC than understanding the "math" is an understanding of variation. If the control plan's control method requires charting, does the personnel tasked with charting know how and when to react? There is a requirement for a reaction plan. In meeting it, a work instruction with step-by-step instructions such as "tag the part, call the supervisor, adjust the settings and re-verify" is common and necessary. More necessary, still, is for the operator to know when to react and how to record the cause of the out-of-control condition-whether it is a point-out, a trend or a run.
Measurement devices and instruments used for process control are a part of the control plan that is affected by a core tool methodology. The devices identified for use as a measurement technique are subject to MSA. The application of MSA typically is limited to calibration and Gage Repeatability and Reproducibility (R&R) studies. The lack of scope in the application of this core tool shows a lack of understanding of the distinction between a measuring device and a control. The components of a control include the method, environment, characteristics, product and personnel, including training and competency.
Is it possible to have a calibrated device with acceptable gage R&R study results and have an ineffective control? The answer is yes. The questions become: Does the gage have adequate discrimination? Is it statistically stable over time? Does it have an acceptable level of measurement certainty? These assessments are made using MSA techniques such as bias, linearity, stability and discrimination.
The final core tool is the PPAP. This activity should be a "gathering up" of APQP documentation. If the PPAP package elements are created on the day the PPAP is due, can there be any confidence that the planning was effective? PPAP is a subset of APQP, an output from Phase Four.
The generation of core tool documentation and use of core tools is not solely a conformance issue. The question is not, does the organization have the documentation but rather, are the core tools understood, executed and deployed to ensure that customer requirements are met and variation is reduced? Does the control plan exert an appropriate level of control of the process? Does the FMEA identify and provide for the mitigation of risk? Does the MSA process address devices or controls? Is SPC used to identify and understand sources of variation? Does PPAP reflect the condition of the production process? It is only when these questions are resolved that a manufacturer can move from detection-based quality systems driven by reacting to problems to prevention-based quality systems focused on the reduction of variation. Q
Cathryn E. Girard is chief operating officer of Integritas Business Systems (Lathrup Village, MI). She can be reached at (248) 423-8242 or at firstname.lastname@example.org.
side bar: TECH tIPS
• The automotive customer specifics and customer requirements are the core tools that include: APQP and control plan; PPAP; MSA; SPC; and FMEA.
• The first aspect of the correct use of core tools is their alignment. View APQP as the "umbrella" core tool that identifies all elements of new product development from concept to production launch.
• The investigation of synergy provides an opportunity to add value to documentation. Synergy begins with FMEA. The initial task is to identify the "Process Function and Requirements."