Week 2 - Incroduction To Six Sigma Flashcards
Define six sigma
Is a business improvement approach that seeks to find and eliminate causes of defects and errors in manufacturing and service processes by focusing on outputs that are critical to customers and a clear financial return
What is the relationship between six sigma and variation? (2)
• Refers to a measure of average variation (I.e standard deviation)
• Is about a never-ending effort to continuously variation
What is the relationship between six sigma and defects
• Signifies a generic quality level of at most 3.4 deflects per million opportunities
• Defects have an impact on product or service quality and customers’ satisfaction
What are the key factors in six sigma project selection? (5)
• Financial return - measured by minimising costs associated with quality and process performance and impacts on revenues and market share
• Impacts on customers and organisational effectiveness
• Probability of success
• Impact on employees
• Fit to strategy and competitive advantage
7 Tools for six-sigma and quality improvement
• Elementary statistics (mean, mode, various diagrams)
• Measurement methods
• Process control
• Product design and reliability
• Process improvement
• Implementation and teamwork
• Advanced statistics
3 key characteristics of six sigma
• Problem to be solved
• process in which the problem exists
• One or more measures that quantify the gap to be closed and can be used to monitor progress
Different types of problems that are suitable for six sigma (5)
• Conformance problems - are easily described and well specified
• Efficiency problems - wasted resources when delivering what customers want
• Unstructured performance problems
• Product design problems - creating a product that fulfils what customers demand
• Process design problems - processes that cause problems or result in defects
What is DMAIC? (Six sigma methodology)
• Define
• Measure
• Analyse
• Improve
• Control
Explain the define stage in DMAIC (Six sigma methodology) (2)
• Identify what the problem is that we are trying to solve?
• Launch team, Plan project, Plan change, Understand customer needs
Explain the measure stage in DMAIC (Six sigma methodology) (2)
• Identify what data can we collect to understand the problem
• Document the process, collect baseline data, narrow project focus
Explain the analyse stage in DMAIC (Six sigma methodology) (2)
• Analyse the collected data to know where to focus efforts
• Identify root cause, identify and remove wastes
Explain the improve stage in DMAIC (Six sigma methodology) (2)
• Identify what improvements we should be prioritising to improve performance for customers
• Generate, evaluate and optimise solutions then plan and implement
Explain the control stage in DMAIC (Six sigma methodology) (2)
• How can we ensure that improvements are sustained
• Validate project benefits, control the process
What are the different six sigma teams (5)
• Champions - senior level managers who promote and lead the deployment of six sigma
• Master black belts - full time six sigma experts responsible form six sigma strategy, training, mentoring, deployment and results
• Black belts - fully trained six sigma experts with extensive technical training who perform much of the technical analysis required in six sigma projects
• Green belts - functional employees trained in introductory six sigma tools and methodology working part time and assist black belts
• Team members - Individuals from various functional areas who support specific projects
Where does variation come from? (5)
• Machine (equipment)
• Method (process/inspection)
• Material (Raw, consumables etc)
• Man power (people)
• Environment (external effects that are out of control)
What is tolerance? (2)
• Is the acceptable variation by customer
• Ranges from upper specification limit (highest acceptable outcome) and the lower specification limit (lowest possible outcome
What is normal distribution
Is a bell shape distribution of outputs over time
What is standard deviation (σ)?
Related to output variability
What is the mean (μ)?
Average value of outputs over time
Standard deviation for a population equation
Slide 18 of week 2
Standard deviation for a sample equation
Slide 18 of week 2
Define process capability (Cp)
• Measures how well the data might fit between the spec limits (USL, LSL)
• Cares about whether the process would fit if it was centred
Process capability formula (2)
• Cp = (USL-LSL)/6σ
• (USL-LSL) is the voice of the customer and 6σ is the voice of the process
What is accuracy
Is based on the mean value of hitting the centre but not precise (spread out across the target - high variation)
What is precision?
Closely grouped on the target-low variation) but not accurate and is based on the mean of the value being away from the centre
Accuracy vs precision
Companies aim for high precision and high accuracy
Six sigma metrics (3)
• Defect - any mistake or error that is passed on to a customer
• Defects per unit (DPU) - number of defects discovered (in sample) / number of units produced (in sample)
• Defects per million opportunities (DPMO) = DPU x 1000000 / opportunities for error
Six sigma metrics in services (7)
• Cycle time - how long it takes do something
• Throughput time - a measure of lead time or transit time
• Waste - anything not contributing to what customers are willing to pay for
• Cost - the internal cost of process activities
• Revenue - A better quality product can increase revenue
• Customer requirements - what do customers want?
• Customer satisfaction - which is typically the primary measure of success
5 Key tools used in the define stage
• IPO
• SIPOC
• Flow diagram
• CTQ tree
• Project charter
