Lecture 2: Quality Management and Six Sigma: Lean Supply Chain Flashcards
List various names for “lean”
●“Toyota Production System” ►Introduced at Toyota, Japan in 1950s by Taiichi Ohno ●“Lean Manufacturing” ►Term coined by Womack, Jones & Roos in their study on the Automobile industry: “The Machine that Changed the World” ●Just-in-Time (JIT) ●“Stockless Production” ●“Japanese Management” ●“Lean six-sigma”
What is a fundamental lean/JIT approach? Name 3 types of waste (3 Ms) related to Japanese/Toyota Production System?
Fundamental lean approach: Remove waste - all things that do not add value.
●Muda (無駄): An activity that is wasteful and doesn’t add value (e.g. using 3 cars although it was possible to transfer everything in 2 cars)
●Mura (無斑): Unevenness (Using one car overfilled and another car under-filled)
●Muri (無理): Over-burden of resources (using one car with too much resources)
-> goal: no muda, no mura, no muri
Name and explain 7 sources of waste.
●T-I-M-W-O-O-D
►T: Transportation waste: Material movement
►I: Inventory: Work-in-Process Inventory Waste
►M: Motion: Unnecessary motion of producer, worker, or equipment
►W: Wait: Waiting time of Jobs and Resources
►O: Over-processing: doing more work than what is required by customer
►O: Over-production: Producing too early, too much
►D: Defect: Rework, rescheduling, repair
What are lean objectives?
●Produce ►Exactly what is needed (quality) ►Exactly how much is needed (quantity) ►Exactly when it is needed (just-in-time) ►Exactly where it is needed (location) ►At the lowest possible cost
What are the tools for lean production?
●Value Stream Mapping (process focus)
- A graphical way to analyze where value is or is not being added as material flows through a process
●One-piece flow: Leveled Scheduling (Heijunka)
- A schedule that pulls material into final assembly at a
constant rate. Mixed production (ABC,ABC, ABC), not traditional production (AAA,BBB, CCC). Less WIP-inventories means faster throughput. Decreased Inventories: Synchronization of production with sales
●Pull (Kanban)
- An inventory or production control system that uses a
signaling device to regulate flows. Produce only when there is a demand -> Empty container from Process 2 triggers Process 1 -> Possibility to control and reduce WIP-inventories
●Continuous Improvement (Kaizen)
- Japanese philosophy that focuses on continuous improvement. What is possible today is the standard for tomorrow. There is no “finish line”.
●Mistake-proofing (Poka-Yoke)
Examples of Poka-Yoke:
1) Fixtures to ensure that parts can be attached only in the right way;
2) Electronic switches that automatically shut off euqipment if a mistake is made;
3) Checklists to ensure that the right sequence of steps is followed
Quality definition
●Quality of Design
Inherent value of the product in the marketplace
►Is the design of the product according to the customer’s wishes?
●Quality of Conformance
Degree to which the product/service design specifications are met
►Is the product manufactured according to the design?
What are the dimensions of quality of design?
●Performance: Primary product/service characteristics
●Features: Added touches, bells and whistles, secondary characteristics
●Reliability: Consistency of performance over time
●Durability: Useful life
●Serviceability: Resolution of problems and complaints
●Esthetics: Sensory characteristics (sound, feel, look etc.)
●Reputation: Past performance and other intangibles
●Timeliness: Speed, Reliability
●Flexibility: Level of Customer Specifications that can be met
What is the internal and external importance of quality?
●Externally - Satisfy Customers - Reputation of the Company → Long term Strategic objective - Product liability (Health, Safety & Environment)
●Internally
Quality and Productivity are positively correlated
- Decrease of cost: “Less scrap, Less rework”
What kind of costs consist of the total cost of quality?
CONTROL COSTS (unavoidable costs):
1) Prevention costs
e. g. Process/product design, Training, Vendor relations, Supplier development
2) Appraisal costs
e. g. Quality audits, Statistical quality control
FAILURE COSTS (avoidable costs):
1) Internal failure costs
e. g. Yield losses, Rework charges, Replanning
2) External failure costs
e. g. Returns / recalls, (Warranty) repairs, Lost business
What is Statistical Process Control (SPC)? What is the tool for it and what does it show?
Statistical process control (SPC) involves testing a random sample of output from a process to determine whether the process is producing items within a preselected rang
●Basic Assumptions
- In any Production Process there is a “Common Variation” (random variation)
- Production Processes are not always in a “State of Control”
●Tool:
- Control Charts
SPC Charts can be used to detect whether or not a process is “under control”
►Non-random behavior: System is out of Control
►The X-bar chart will not show the difference between Sample 1 and 2
►An R-chart will show the difference
What is process capability and how to measure it?
●Measure of ability to meet specifications
●Process limits:
►Based on normal variation in the process
●Specification limits:
►variation as designed and which is acceptable for customers
●Specifications:
►USL: Upper Specification Limit
►LSL: Lower Specification Limit
●“Good” if Cp > 1; “Bad” if Cp < 1
Cpk shows how well the parts being produced fit into the range specified by the design specifications
› Aim is to have Cpk larger than one
› When two numbers (X-LSL and USL-X) are not close,
indicates mean has shifted
What are the differences between upper/lower specification and control limits?
Control Limits/Specification Limits
Voice of the process/ Voice of the customer
Calculated from Data/ Defined by the customer
Appear on control charts/ Appear on design specification
Apply to subgroups/ Apply to items
Guide for process actions/ Separate good items from bad
What the process is doing/ What we want the process to do
What is a Six Sigma technique?
●Improvement technique introduced within Motorola and GE
►Quality improvement program
►Focus: Objective is to minimize “span” (6s)
→ Result is increased reliability / dependability
Area - diamond, spelling - one misspelled word in a library, time - 6 seconds per century
What is the standard approach for Six Sigma projects?
A standard approach to Six Sigma projects is the DMAIC methodology described below:
- Define (D)
- identify problem, define requirements and set goals - Measure (M)
- gather data, refine problem, measure inputs and outputs - Analyze (A)
- develop problem hypotheses, identify “root cause”, validate hypotheses - Improve (I)
- develop improvement ideas, test, establish solution and measure results - Control (C)
- establish performance standards and deal with any problems
What are the components of Total Quality Management?
●1. Everything is focused on the Customer Service triangle (Strategy, Personnel, System around the customer)
●2. Empowerment ►Everybody has responsibilities → Focus on quality of their own work → Employee commitment is essential ►Everybody has the power to make decisions (within certain guidelines) → Manager is Coach: Stimulate, Give feedback ►Teamwork: Joint decision making → “Self-steering teams” ► Bottom-up suggestions for improvement
●3. Quality at the source ► Prevention → “You can not inspect quality into the product” → Quality control at each process ► Quality control by “process-owner” himself / herself → “Immediate feed-back” → Training is essential ► Supplier-Customer Partnership → Trust → Knowledge in each-other’s production process → No incoming inspection → Joint problem-solving
●4. Ongoing Improvement (Kaizen) ► Target: → “Zero-defects” → “Do it right - On time, the first time, and every time” → Strive for excellence ►There is no finish line! ►Incremental Improvement → As opposed to radical improvement
●5. Management based on facts
►Measure performance
→ See where mistakes are made and prevent them from happening again (e.g. control charts)
