tes 1 quality control
Features
what does the product do and does it contain extra features in comparison to other companies?
Total quality management
wide spread training and quality awareness Started in the early 1980s, Deming/Juran philosophy as the focal Training often turned over to HR function • Not enough emphasis on quality control and improvement tools, poor follow-through, no project-by-project implementation strategy • TQM was largely unsuccessful
Performance
will the product do its intended job and if so will it do it better than the competitor?
in statistical control
A process is operating with only chance causes of variation present is said to be
out of control
A process that is operating in the presence of assignable causes of variation is said to be
Lean
A set of methods and tools used to eliminate waste in a process Focuses on elimination of waste • Long cycle times • Long queues - in-process inventory • Inadequate throughput • Rework • Non-value-added work activities Makes use of many of the tools of operations research and industrial engineering helps identify anything not absolutely required to deliver a quality product on time.
Control
Complete all remaining work on project • Provide the process owner with a process control plans • Training documents (if appropriate) should be provided • Methods and metrics for future audits • Transition plan to the new process might include a validation step - develop ongoing process management plans, mistake proof process, monitor and control critical process, and develop out-of-control action plans
Juran
Emphasizes a more strategic and planning oriented approach to quality than does Deming this persons trilogy: planning, control, improvement (these processes are interrelated, control vs breakthrough, and project-by-project improvement)
Improve
Process redesign to reduce bottlenecks • Mistake-proofing • Statistical tools - particularly designed experiments • DOE can be applied to either the physical process or a computer model of the process • pilot test the solution to confirm that it will solve the problem - generate and quantify, evaluate and select final solution, verify and gain approval for final solution
Legal aspects of quality
Product liability exposure
Defective product
Product possessing one or more defects that affect its safe or effective use
Nonconforming product
Products that fail to meet one or more of their specifications product is not necessarily unfit for use
What would motivate a business to compete for the Malcolm Baldridge Award?
The Baldridge framework encourages a systems perspective to reach goals, improve results, and become more competitive. Even if the company doesn't win the award, the process of competing for it gives them a quality advantage. Also, if they do win the award, that is great advertising to gain more business.
External customer
customer that is purchasing product
Attentiveness
customers generally want caring and personalized attention from their service providers. Customers want to feel that their needs and concerns are important and are being carefully addressed.
spec limit
decided by customer/engineer, decided before production, declarative
DFSS goal
design predictive quality into products
Serviceability
how easy is it to repair if it fails?
Responsiveness
how long did it take the service provider to reply to your request for service? How willing to be helpful was the service provider? How promptly was your request handled?
Reliability
how often does this product fail? Does it fail more often than other brands with similar product?
Deming
stressed "continual never-ending improvement" this persons 14 points are about organizational change and it is the role of management to facilitate this
rational subgroup concept
subgroups or samples should be selected so that if assignable causes are present, chance for differences between subgroups will be maximized, while chance for difference due to assignable causes within a subgroup will be minimized.
Concept of strict liability
-responsibility of both manufacturer and seller/distributor -advertising must be supported by valid data
What are chance and assignable causes of variability? What part do they play in the operation and interpretation of a Shewhart control chart?
"Chance" or "common" causes of variability represent the inherent, natural variability of a process - its background noise. Variation resulting from "assignable" or "special" causes represents generally large, unsatisfactory disturbances to the usual process performance. Assignable cause variation can usually be traced, perhaps to a change in material, equipment, or operator method. A Shewhart control chart can be used to monitor a process and to identify occurrences of assignable causes. There is a high probability that an assignable cause has occurred when a plot point is outside the chart's control limits. By promptly identifying these occurrences and acting to permanently remove their causes from the process, we can reduce process variability in the long run.
What are warning limits on a control chart? How can they be used?
Warning limits on control charts are limits that are inside the control limits. When warning limits are used, control limits are referred to as action limits. Warning limits, say at 2-sigma, can be used to increase chart sensitivity and to signal process changes more quickly than the 3-sigma action limits. The Western Electric rule, which addresses this type of shift is to consider a process to be out of control if 2 of 3 plot points are between 2 sigma and 3 sigma of the chart centerline.
Why is it necessary to consider the variability around the target dimension as a measure of quality?
We know that producing the target dimension each and every time is impossible. Because of this, we must set acceptable limits on either side of the target dimension to strive for. These acceptable limits, or specifications/tolerances, are there to capture the variability in the process. We must consider variability and make sure that the variability is small enough to be encompassed by our specification limits, in order to have a non-defective product. If we consider the modern definition of quality, then the quality of a product will increase when the variability decreases, so we should do our best to minimize the variability of a product to increase the quality of it.
ARL performance measure for a control chart
We want a long average run length for processes that have been in statistical control for a long time and we want a short ARL for out-of-control processes to be able to catch these assignable variations/defects earlier
importance of project selection
We want a project to be a potential breakthrough project, some improvement in the process or product should result in financial gain for company. The value opportunity of a project must be clear. When selecting a project, start with low hanging fruit, move on to the key business metrics
Improve tollgate
-Adequate documentation of how the problem solution was obtained -Documentation on alternative solutions that were considered -Complete results of the pilot test, including data displays, analysis, experiments and simulation analyses -Plans to implement the pilot test results on a full-scale basis. This should include dealing with any regulatory requirements (FDA, OSHA legal, for example), personnel concerns (such as additional training requirements), or impact on other business standard practices -Analysis of any risks of implementing the solution, and appropriate risk -management plans.
Define tollgate
-Does the problem statement focus on symptoms, and not on possible causes or solutions? -Are all the key stakeholders identified? -What evidence is there to confirm the value opportunity represented by this project? -Has the scope of the project been verified to ensure that it is neither too small nor too large? -Has a SIPOC diagram or other high-level process map been completed? -Have any obvious barriers or obstacles to successful completion of the project been ignored? -Is the team's action plan for the Measure step of DMAIC reasonable?
Measure tollgate:
-There must be a comprehensive process flow chart or value stream map. All major process steps and activities must be identified, along with suppliers and customers. If appropriate, areas where queues and work-in-process accumulate should be identified and queue lengths, waiting times, and work-in-process levels reported -A list of KPIV's and KPOVs must be provided, along with identification of how the KPOVS related to customer satisfaction or the customers -Measurement systems capability must be documented. -Any assumptions that were made during data collection must be noted. -The team should be able to respond to requests such as "Explain where that data came from and questions such as, "How did you decide what data to collect" "How valid is your measurement system?" and "Did you collect enough data to provide a reason able picture of process performance?"
Analyze tollgate:
-What opportunities are going to be targeted for investigation in the improve? -What data and analysis supports that investigating the targeted opportunities and improving/eliminating them will have the desired outcome on the KPOV's and customer that were the original focus of the project -Are there other opportunities that are not going to be further evaluated? If so, why? -Is the project still on track with respect to time and anticipated outcomes? Are any additional resources required at this time?
Western Electric Rules
1. one or more point plots outside control limits 2. 2/3 consecutive pints beyond 2-sigma warning limits 3. 4/5 consecutive points beyond 1-sigma OR 4. 8 consecutive points on one side of center line
Six sigma
A disciplined and analytical approach to process and product improvement •Involves a five-step process (DMAIC)
Describe a service system you regularly use. What are the CTQ's of the system that are important to you? Choose one of these CTQ's that has had less than desirable performance, in your opinion, and describe how the service system may be able to improve the CTQ performance.
Canvas is a system that most schools utilized for coursework related materials. In my opinion, it is better suited than other systems like D2L or blackboard. The CTQs that are important to me are visibility, appearance, and reliability. Reliability is one characteristic that has yielded less than desirable performance. For example, since Canvas is an online based software, it requires occasional maintenance. When maintenance is provided it will often limit the functions of Canvas entirely. Universities and Canvas alert users of when the set maintenance will be issued usually 2 days prior. This is very inconvenient if you have a homework assignment, quiz, or test due. If maintenance is scheduled and a student or instructor did not know of the maintenance that will shut down the system for hours, student will not be able to access materials or contact instructors until it is too late. A way that could be prevent this from happening is when maintenance is schedule, assignments will not be allowed to be assigned. Visibility is another characteristic that has yielded less than desirable performance. Canvas can be somewhat tedious to deal with as an instructor, especially when trying to uploads files and assignments. Often, files and assignments can be hidden under various tabs. From the student perspective, visibility can be obscured. A way that developers could improve this process is having an easy to use user interface. For example, on Pinterest a user can save a pin to a board and then also to sections of a board. A similar process could be used in Canvas
Apply the Western Electric rules to the control chart presented in Exercise 5.16. Would these rules result in any out-of-control signals?
Check the following: · Any point outside the 3-sigma control limits? NO. (Point #12 is within the lower 3-sigma control limit.) · 2 of 3 beyond 2 sigma of centerline? YES, points #16, 17, and 18. · 4 of 5 at 1 sigma or beyond of centerline? YES, points #5, 6, 7, 8, and 9. · 8 consecutive points on one side of centerline?
Compare and contrast Deming's and Juran's philosophies of quality.
Deming's 14 points and 7 deadly diseases focused on how the responsibility of quality rests with management, since quality improvement requires management action, for the most part. Juran felt the same - that management was responsible for quality, and thus provided a quality management philosophy called the Juran Trilogy, that included planning, control, and improvement. Both emphasized management involvement with quality. Both aim at increasing quality to meet the needs of the customer, and stress that quality is essential to being competitive. However, Juran emphasized a more strategic and planning oriented approach than Deming did. Deming's philosophy emphasized organizational change and statistical quality control, while Juran has a three-pronged strategic approach focusing on planning, control, and improvement.
Analyze
Determine cause-and-effect relationships and root causes, using the data from the Measure step • Sources of variability - common cause versus assignable cause • Tools - brainstorming, control charts, hypothesis testing, confidence intervals, regression models, failure modes and effects analysis, cause and effect diagram, five whys • Discrete event simulation - analyze data to understand reasons for variation and identify potential root causes, determine process capability, throughput, cycle time; formulate, investigate, and verify root cause hypotheses
What is meant by the "cost of quality"?
Generally speaking, the cost of quality are those costs that are associated with producing, identifying, avoiding, or repairing products that do not meet requirements. We could actually call these costs the "cost of POOR quality", because these costs are associated with producing poor quality products, not high-quality products. The costs of quality have different levels of expense. From least expensive to most expensive, they are preventative costs, appraisal costs, internal failure costs, and external failure costs. As non-quality product makes its way through the manufacturing plant, it costs to appraise or inspect it, it costs more to catch the defect at the end of the production line with a failure at final test and inspection, and it costs most if the defective product finds its way to the customer. If the customer discovers the defect instead of the company, now warranty and rework costs are involved. Preventative are the most cost-effective, and include things like proper training and improving processes to make sure quality defects do not happen in the first place.
when and when not to use DMAIC
Has to associated with something specific on a project-by-project basis. There must be breakthrough opportunity and have a clear value opportunity of a project
Durability
How long does this product last?
Why is it difficult to define quality?
It is difficult to define quality because quality is a subjective term for which everyone has their own definition, and in the end, the definition is based on what the CUSTOMER wants.
If a process is in a state of statistical control, does it necessarily follow that all or nearly all of the units of product produced will be within the specification limits?
No. The fact that a process operates in a state of statistical control does not mean that nearly all product meets specifications. It simply means that process behavior (mean and variation) is statistically predictable. We may very well predict that, say, 50% of the product will not meet specification limits! Capability is the term, which refers to the ability to meet product specifications, and a process must be in control in order to calculate capability.
Defect
Nonconformities that are serious enough to significantly affect the safe or effective use of the product
sensitizing rules and pattern recognition in control charts
Normal common variability should occur very randomly, when a pattern or if sensitizing rules are broken this may indicate that there is an assignable cause of variation present in the control chart that may indicate an out-of-control process
Read the attached case study - "Using DMAIC to Improve Nursing Shift-Change Assignments. After reading the case, produce a Problem Statement for the project. The formula for a good problem statement is general problem at hand + current state of the problem + costs to the company because of the problem.
Nursing shift-change took too long, averaging 43 minutes to complete, which cost the unit approximately $5,000 per month.
Measure
Purpose is to evaluate and determine the present state of the process • Identify key process input variables (KPIV) and key process output variables (KPOV) • Data - from historical records, from sampling, from observational studies • Histograms, box plots, Pareto charts, scatter diagrams, stem-and-leaf diagrams may all be useful • In some businesses, the measurement system must be developed • measurement system capability is important - determine what to measure, manage measurement data collection, develop and validate measurement systems, determine sigma performance level
Most of the quality management literature states that without top management leadership, quality improvement will not occur. Do you agree or disagree with this statement? Discuss why.
Quality is everyone's job, but without top management allocating resources and providing vision and alignment, the effort will fail. Top management must treat quality as important and a priority in order to lead others to feel the same.
Design for Six Sigma (DFSS)
Taking variability reduction upstream from manufacturing (or operational six sigma) into product design and development
Malcolm Baldridge National Quality Award
Tedious to apply for, a good internal assessment tool. Has a lot of components, the process makes you think through your current quality processes and determine if they are sufficient.
Discuss the rational subgroup concept. What part does it play in control chart analysis?
The concept of a rational subgroup is used to maximize the chance for detecting variation between subgroups. Subgroup samples can be structured to identify process shifts. If it is expected that a process will shift and stay at the new level until a corrective action, then sampling consecutive (or nearly) units maximizes the variability between subgroups and minimizes the variability within a subgroup. This maximizes the probability of detecting a shift.
warning limits
The inner limits, usually at two-sigma
What is meant by a process that is in a state of statistical control?
The statement that a process is in a state of statistical control means that assignable or special causes of variation have been removed; characteristic parameters like the mean, standard deviation, and probability distribution are constant; and process behavior is predictable. One implication is that any improvement in process capability (i.e., in terms of non-conforming product) will require a change in material, equipment, method, etc.
Provide an example from your own experience where excessive variability can result in an unacceptable performance of a product or service.
There is a nail salon that I have a love hate relationship with, the customer service and capabilities of their staff varies greatly. I have learned the names of the staff that provides higher quality of service, I will not get anything done if my nail tech is not there because I know that I cannot depend on the other staff members to do as good of a job. This particular store has a very high variability in quality which can make it a very negative experience if I do not choose to work with one of the staff members in particular.
the role that variability and statistical methods play in controlling and improving quality
Variability will always exist, it is the spread or dispersion of data. High and tight variability means data is close to the mean which limits the variability of the data. The out of control variability factors are the contributors we want to remove to improve quality, these forms of variability are assignable and removeable, not included in expected/in control variability.
DMAIC in the framework of the Six Sigma philosophy
You cannot use sic sigma without DMAIC however you can use DMAIC without six sigma
An important part of a project is to identify the key process input variables (KPIV) and key process output variables (KPOV). Suppose that you are in charge of a hospital emergency room. Discuss the KPIVs and KPOVs for this business. How do they relate to possible customer CTQs?
You should distinguish between input variables and output variables; recognize the relationship between customer CTQs and key output variables; and make sure the identified variables are measurable. While patients leaving and payment are outputs, they aren't necessarily KPOV's because they are not an output that directly relate to a CTQ. KPOVs are things we measure in the output side of the process that will directly impact the CTQs. Sometimes they are even the same thing. An example in this instance of A KPOV is the times that certain steps in the ER process take, like time from arrival to seeing a doctor. The short wait times, or maybe more accurately "wait time" is a good KPOV. We have to look at variables that can be measured in order for them to be of importance to the CTQ. The number of patients leaving is a good KPOV, but we should instead think of it in terms of time, if you say the CTQ is time in and out. So we should say instead the time it takes to finish payment and the time it takes for patients to be discharged. We have to look at variables that can be measured in order for them to be of importance to the CTQ.
DMAIC
a problem solving methodology • Closely related to the Shewhart Cycle • Use this method to solve problems: • Define problems in processes • Measure performance • Analyze causes of problems • Improve processes − remove variations and non-value-added activities • Control processes so problems do not recur
tollgate significance
a project team presents its work to managers and "owners" of the process. In a six‐sigma organization, the tollgate participants also would include the project champion, master black belts, and other black belts not working directly on the project. At a tollgate, a project is reviewed to ensure that it is currently on track; tollgates also provide a continuing opportunity to evaluate whether the team can successfully complete the project on schedule. Many organizations define specific deliverables that must be completed in order to move to the next project step. They are an opportunity to provide direction regarding the use of specific technical tools and other information about the problem. Organizational problems and other barriers to success—and strategies for dealing with them—also often are identified during tollgate reviews. Tollgates are critical to the overall problem‐solving process; it is important that these reviews be conducted very soon after the team completes each step.
3-sigma control limit
action limit, probability of type 1 error is 0.0027, hard and fast limit outer limit
probability limit
action limit, type 1 error probability is chosen directly, hard and fast limits ex. 0.001 gives 3.09-sigma control limits outer limit, when the probability of a type 1 error occurring is chosen
Pareto chart
arranged by types of defects organized by frequency from most to least, most frequent does not mean most important. You can apply weights to items to incorporate importance of the effects of these defects or cost can be added to include the costs of the defect
Internal customer
assembly, next person in the process
3-sigma, probability, and warning
choice of control limits
Shewhart control chart
contains • A center line • An upper control limit • A lower control limit A point that plots within the control limits indicates the process is in control • No action is necessary A point that plots outside the control limits is evidence that the process is out of control • Investigation and corrective action are required to find and eliminate assignable cause(s) There is a close connection between control charts and hypothesis testing
control limit
control chart, where data should naturally around mean, calculated from existing data
Critical-to-quality (CTQ)
elements that jointly describe what the user or consumer thinks of as quality. (AKA: What is important to the consumer) may be: 1. Physical 2. Sensory 3. TimeOriented
Six Sigma/DMAIC goal
eliminate defects, reduce variability
Lean goal
eliminate waste, improve cycle time
External failure
fails when the product gets to the customer, most expensive
nonconformity
failure to meet specifications
Internal failure
hasn't been shipped, occurs during production process, has to be reworked or scrapped
Check sheet
helpful finding trends that are time oriented
Appraisal
inspect all products throughout the production process
quality
inversely proportional to variability (modern definition), subjective, customers decide what is high quality to us
Quality control and improvement
involve the set of activities used to ensure that the products and services meet requirements and are improved on a continuous basis
Phase I use of control charts
is a retrospective analysis of process data to construct trial control limits • Charts are effective at detecting large, sustained shifts in process parameters, outliers, measurement errors, data entry errors, etc. • Facilitates identification and removal of assignable causes
Aesthetics
is it pretty, cool to look at?
Conformance to standards
is the product made exactly as the designer intended?
phase II use of control charts
is used to monitor the process • Process is assumed to be reasonably stable • Emphasis is on process monitoring, not on bringing an unruly process into control
Consider a Shewhart control chart that has been designed so that the probability of a point plotting outside the control limits is 0.25 if a failure mode that is considered critical in the process occurs. What is the average run length that will be experienced in detecting this failure? This process has historically been considered out of control. Since this is the case, is the calculated ARL good or bad?
p=0.25 ARL=1/p=1/.25 ARL=4 In this case the calculation for the ARL is good because this process has historically been considered out of control you want the ARL to be lower. It will make it easier to detect whereas processes that have been in control for a long period of time you would want to have a higher ARL.
dimensions of quality
performance, reliability, durability, serviceability, aesthetics, features, perceived quality, conformance
Preventative
quality planning and control, train and use data to prevent quality issues
variability
refers to how spread out a set of data is. Variability gives you a way to describe how much data sets vary and allows you to use statistics to compare your data to other sets of data.
dimensions of quality of service
responsiveness, professionalism, and attentiveness
Perceived quality
specific aspects of a products valued by customer, varies by customer
Quality planning
strategic activity, and it is just as vital to an organization's long-term business success as the product development plan, the financial plan, the marketing plan, and plans for the utilization of human resources. -has to be intentional, strategic -identify customers and their needs, could be internal or external, listen to the VOC, voice of customer
type 1 error
the data point falls outside the control limits, although outside limits indicates out of control it is a false positive because the process is actually in control the limits are not far enough apart
type 2 error
the data point falls within the control limits, although within the limits should indicate a process is in control, this error occurs when the limits are too far apart and the data is within limits but the process is out of control
specifications
the desired measurements for the quality characteristics of the components that make up the product and the desired values for the quality characteristics in the final product -target or nominal values -upper spec limit USL -lower spec limit LSL
link between quality and cost
the later in the process a quality issue is found, the more expensive it is to rework, scrap, or handle legal problems associated with the defect
quality improvement
the reduction of variability in processes and products
Quality assurance
the set of activities that ensures the quality levels of products and services are properly maintained and that supplier and customer quality issues are properly resolved. Based on documentation: -policy -procedure -work instructions/specifications -records
variables
the shape on a scatter diagram determines the relationship between two (blank)
Professionalism
this is the knowledge and skills of the service provider, and relates to the competency of the organization to provide the required services
Define
use project starter for define stage including problem statement, business case, opportunity statement, goal statement, project scope, project plan, and team. The problem statement identifies what problem we are addressing, baseline performance, and what it is costing the company. -Identify and/or validate the business improvement opportunity, define critical customer requirements, document (map process), establish project charter, build team
components of successful six sigma implementation
• Committed leadership • Use of top talent • Supporting infrastructure • Project-by-project improvement