UNIT IV TOOLS AND TECHNIQUES Benchmarking and TQM Implementation Benchmarking needs and benefits, benchmarking process, Quality function deployment (QFD); house of quality, Taguchi quality loss function, Total productive maintenance (TPM); pillars of TPM, Failure Mode Effective Analysis (FMEA); Failure rate, types of FMEA, stages of FMEA, Case studies.
Failure Mode and Effect Analysis Analytical technique (a paper test) that combines the technology and experience of people in identifying foreseeable failure modes of a product or process and planning for its elimination. FMEA can be explained as a group of activities intended to Recognize and evaluate the potential failure of a product or process and its effects. Identify actions that could eliminate or reduce the chance of potential failures. Document the process.
Reliability Is the probability of the product to perform as expected for a certain period of time, under the given operating conditions, and at a given set of product performance characteristics.
Reliability Requirements Based on the definition of the part, assembly, or process under consideration, the reliability of each sub-system and the factors involved in the reliability must be found, and the appropriate relationships for each part, class, or module of the product must be computed.
Periods of failure can conveniently be modeled by an exponential distribution, and the probability of survival of the product or process may be viewed as:
Assume that a product has a constant failure rate of λ = 0.002 per hour. What is the probability that it will survive or be reliable during the first 100 hours of operation ? Thus, there is a 98% chance that the product will survive during the first 100 hours of operation.
Intent of FMEA An Essential Part of Total Quality Management is FMEA! Provides Training Tracks the progress of a project Helps communicating similar problems Uncovers oversights, misjudgments, and errors Calculate the probabilities of failures Determine if product or process failure effects on other aspects.
FMEA Team FMEA methodology is a team effort where the responsible engineer involves who? Assembly Manufacturing Materials Quality Service Supplier Customer
FMEA Documentation- Block Diagram
Stages of FMEA Specifying Possibilities Quantifying Risk Correcting High Risk Causes Re-evaluation of Risk
Specifying Possibilities Functions Possible Failure Modes Root Causes Effects Detection/Prevention
Quantifying Risk Probability of Cause Severity of Effect Effectiveness of Control to Prevent Cause Risk Priority Number
Correcting High Risk Causes Prioritizing Work Detailing Action Assigning Action Responsibility Check Points on Completion
Re-evaluation of Risk Recalculation of Risk Priority Number RPN = (S) * (O) * (D) S = SEVERITY O = OCCURRENCE D = DETECTION RAKING 19
The Design FMEA Document Current Design Controls Detection (D) Risk Priority Number (RPN) Recommended Actions Responsibility and Target Completion Dates Actions Taken
The Process FMEA Document Process Function/Requirements Potential Failure Mode Potential Effect(s) of Failure Severity (S) Classification (CLASS) Potential Cause(s)/Mechanism(s) of Failure Occurrence (O) Current Process Controls
Limitations: FMEA document’s do not fix the identified problem Def. of the action to fix the problem Will not replace the basic problem-solving process.