Quality Risk Management Methodology

Anthony Cumberlege

SAPRAA meeting - Randpark golf club, 20 March 2009

Typical quality risk management process

Quality risk management tools

• Some examples of recognized techniques:– Basic QRM facilitation methods (flowcharts, check sheets etc.).– Failure Mode Effects Analysis (FMEA).– Failure Mode, Effects and Criticality Analysis (FMECA).– Fault Tree Analysis (FTA).– Hazard Analysis and Critical Control Points (HACCP).– Hazard Operability Analysis (HAZOP).– Preliminary Hazard Analysis (PHA).– Risk ranking and filtering.– Supporting statistical tools (control charts, histograms etc.).

Basic QRM facilitation methods [1]

• Cause and effect / fishbone / Ishikawa diagrams:– Problem statement on

right-hand side.– General causes (“bones”)

of the problem stem from the horizontal line (“body”).

– More specific causes branch off from the main “bones”. It could also include a 3rd level or more.

– More branches may be exposed using the “5 whys” technique.

• Simple tools to organize data and facilitate decision-making.

Basic QRM facilitation methods [2]

• Check sheets:– Used for repeatedly collecting real-time data in situ.– Blank sheet (template) to record quantitative / qualitative information.– Characteristic is the making of marks (“checks”) to capture data.– For example:

Basic QRM facilitation methods [3]

– Another example:

Basic QRM facilitation methods [4]

– Examples of check sheet types:• Classification: A trait such as a

defect or failure mode must be classified into a category.

• Location: The physical location of a trait is indicated on a picture of a part or item being evaluated.

• Frequency: The presence or absence of a trait or combination of traits is indicated. The number of occurrences can also be indicated.

• Measurement scale: A measurement scale is divided into intervals, and measurements are indicated by checking an appropriate interval.

• Check list: The items to be performed for a task are listed so that, as each is accomplished, it can be indicated as having been completed.

Basic QRM facilitation methods [5]

• Flowcharts:– A chart that represents an algorithm or process

showing the steps as boxes of various kinds and their order by connecting these with arrows.

– Standard symbols are used to represent the individual process steps:

• Start / end rounded rectangles.• Control flow arrows.• Processing steps rectangles.• Inputs / outputs parallelograms.• Conditional test rhombus

(arrows to be labelled).

Basic QRM facilitation methods [6]

• Process mapping:– A visual representation of the

work-flow that transforms a well defined input or set of inputs into a pre-defined set of outputs.

– High-level maps are used to visualize the entire process.

– Detailed maps focus on process sub-steps.

– Are good visual aids to explain an unfamiliar system to an external person.

Basic QRM facilitation methods [7]

– Another example:

Failure mode effects analysis (FMEA) [1]

• Complex processes are broken down into manageable sub-steps in which failure modes are more easily recognized, causes identified and effects listed.

• For each failure mode the severity (S) must be defined, for example:

Failure mode effects analysis (FMEA) [2]

• For each failure mode the probability (P) must be defined, for example:

• For each failure mode the detectability (D) must be defined, for example:

Failure mode effects analysis (FMEA) [3]

• Current event controls must be listed.• The risk priority number (RPN) is calculated for each failure mode:

• The RPN is evaluated against pre-defined criteria, for example:≥ 200 Critical risk, mitigation required.

70-199 Major risk, mitigation required.

<70, S = 10 Critical risk, mitigation required.

<70, S < 10 Acceptable risk.

• If mitigation is required, proposed actions for a risk reduction strategy must be identified and the RPN re-calculated.

• FMEA can be used to prioritize risks and monitor risk control activities. Typically applied to analyze equipment / utilities / manufacturing processes.

• Product / process understanding is critical for FMEA.

DSPRPN

Failure mode, effects and criticality analysis (FMECA) [1]

• Extension of FMEA to include criticality analysis (CA).• The CA ranks potential failure modes on a criticality matrix

according to combined influence of severity and probability.• Severity levels must be classified, for example:

I = Catastrophic.II = Critical.III = Marginal.IV = Minor.

• The failure mode criticality number (Cm) is the portion of the criticality number for the item due to one of its failure modes under a particular severity classification:

β = Conditional probability of failure mode.α = Failure mode ratio.λp = Part failure rate.t = Duration of applicable phase.

)( tC pm

Failure mode, effects and criticality analysis (FMECA) [2]

• The item criticality number (Cr) is defined as the sum of the failure mode criticality numbers (Cm) under a particular severity classification:

n = 1, 2, 3 … j (Total number of failure modes).

• Output is summarized in a criticality matrix for each item:

• FMECA is most often employed in manufacturing processes.• Product / process specifications must be known for FMECA.

n

j

npr tC )(

1

Fault tree analysis (FTA) [1]

• A failure analysis in which an undesired state of a system is analyzed using logic gate symbols (AND / OR etc.) to combine a series of lower-level events, all displayed graphically.

• Sub-systems are considered individually to minimize the tree complexity.

Fault tree analysis (FTA) [2]

• Each tree has only 1 undesired effect (“top event”). Not a “bottom-up” analysis.

• All causes must be considered. Probabilities of occurrence is not essential.

• FTA is very useful to establish root causes and to evaluate how multiple factors contribute to failures. Can be applied to investigate complaints / deviations.

• Good process understanding is required to identify causal factors.

Hazard analysis and critical control points(HACCP)

• A systematic, preventative approach to product safety that addresses physical, chemical and biological hazards as a means of prevention rather than finished product inspection.

• Consists of 7 principles:– Conduct a hazard analysis.– Identify critical control points (CCPs):

• A point, step or procedure at which controls can be applied and a hazard can be prevented, eliminated or reduced to acceptable levels.

– Establish critical limits for each CCP.– Establish CCP monitoring requirements.– Establish corrective actions.– Establish procedures for ensuring the HACCP system is working as intended.– Establish record-keeping procedures.

• Not limited to manufacturing, also applicable to other processes where CCPs can be identified.

• Comprehensive product / process understanding required to identify CCPs.

Hazard operability analysis (HAZOP) [1]

• Methodology which assumes that hazards are caused by deviations from the system design.

• Process flow diagrams are commonly used:– Examined in sections.– A design intention for each section is specified.

• HAZOP Team identifies possible deviations from the design intention, likely causes and consequences.

• The HAZOP Team typically includes:– Designer.– User.– Technical specialist.– Maintainer.

• Parameters are selected which apply to the design intention, for example:– Flow.– Temperature.– Pressure.– Composition.– Level.– Time.

Hazard operability analysis (HAZOP) [2]

• Deviations from the design intention of selected parameters are determined through the application of guide words, including:– No / Not.– More.– Less.– As well as.– Part of.– Reverse.

• Once the causes and effects of any potential hazards have been established:– The system can then be modified to improve its safety.– The modified design must then be subject to another HAZOP, to ensure

that no new hazards have been introduced.• Typically applied to manufacturing processes and evaluation of

safety hazards.• Design information must be available.

Preliminary hazard analysis (PHA) [1]

• A tool for applying prior experience or knowledge of a hazard or failure to identify future hazards.

• It is a semi-quantitative analysis in which:– Hazards are identified.– Probabilities are estimated.– Severities are assigned.– Hazards are ranked according to their probability / severity

relationship.– Possible controls are determined.

• Historical information which may be used to identify hazards could include:– Statistical data.– Audit reports.– Deviation reports.

Preliminary hazard analysis (PHA) [2]

• Hazard severities are assigned, for example:

• Hazard probabilities are assigned, for example:

Preliminary hazard analysis (PHA) [3]

• A matrix is compiled to rank the risks:

• Risk levels may be assigned from the matrix, for example:– High Not acceptable, mitigation required.– Medium Acceptable with further analysis required.– Low Acceptable.

• PHA allows hazard detection in the design phase and early implementation of corrective actions.

• Analysts must be able to predict hazards with little information available.

Risk ranking and filtering [1]

• A quality risk management tool for comparing and prioritizing (ranking) risks.

• Often the need for risk ranking is driven by a disparity between obligations to manage, mitigate, or reduce an array of risks and available resources.

Risk ranking and filtering [2]

• Risk based filter:– Sufficient resources

available to address all risks (above a certain risk score) simultaneously across all organizational units.

• Resource based filter:– Insufficient resources

available and high risk organizational units are prioritized.

• Can be used by regulatory bodies to prioritize inspections.• Useful to compare and manage complex risk portfolios.

Supporting statistical tools

• Statistical tools can support quality risk management by facilitating more reliable decision making:– Enabling effective data assessment.– Aiding in determining the significance of data.

• For example:– Control charts.– Design of experiments (DOE).– Histograms.– Pareto charts.– Process capability analysis.

Thank you