Term
| Product Quality Control (Inspection) |
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Definition
| Firms used inspectors to visually inspect or measure the finished product to making sure the product conformed to predefined specifications |
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Term
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Definition
| A Statistician who began to focus on controlling processes making quality relevant not only for the finished product but for the processes that produced the product. He recognized industrial processes yield data (steel being cut into metal yields certain measurements - length, width, height). Laid the foundation for process control charts, a modern-day quality tool. |
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Term
| Statistical Quality Control (SQC) |
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Definition
| Shewart's Conepts, differ from product quality control in that they make quality relevant not only for the finished product but also for the process |
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Term
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Definition
-Worked with Shewart to develop first process control chart
-Developed and Taught Statistical Process Control (SPC) techniques to workers for wartime production
-Went to Japan and performed many top to bottom quality operations makeovers.
-Taught continuous improvement for a competitive edge |
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Term
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Definition
1. A high quality process is actually less costly than a low-quality process (Cost of Quality). Substantial saving accrue from elimination of unnecessary labor.
2. Management should play a large role in quality improvement - "continuous improvement of a stable system" |
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Term
| Deming's Definition of Quality |
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Definition
Continuous improvement of a stable system.
- All Systems (administration, production, sales) must be stable in a statistical sense (requires quality measurements be taken on processes throughout the company and monitored over time)
- Continuous improvement of the various systems reduces variation.
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Term
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Definition
| Never-ending process and is driven by knowledge and problem solving. With better technology and understanding of customer expectations, quality can be continuously improved. |
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Term
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Definition
How well the product meets the needs and wants of the customer
Determined by market research, design concepts, and specifications. Market research is aimed at assessing customer needs. A particular design concept must be developed because there are several ways to meet the customer's needs. Design concepts result in a set of specifications for the product. |
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Term
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Definition
Producing a product to meet the design specifications (how well it conforms to the design). It is considered by Operations as a quality product.
For example, and inexpensive pair of shoes will have high quality if they are made according to specifications, and they will have low quality if they do not meet those specifications. |
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Term
| The goal of continuous improvement |
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Definition
| Reduce variability of the product or process. Usually requires collecting data, investigating reasons for abnormal results, and making necessary changes. Those changes make a more consistent product. |
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Term
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Definition
| Today, firms actively engage in continuous improvement training their work teams to use the plan-do-check-act cycle for problem solving. |
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Term
Plan
(Step 1 of Deming Cycle) |
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Definition
| A management team selects a process (procedure, machine or policy) that needs improvement. The team then documents the selected process, usually by analyzing the data, setting quantitative goals for improvement, and discussing various ways to achieve the goals. After assessing the benefits and costs of the alternatives, the team develops a plan with measures for improvement that can be quantified. |
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Term
Do
(2nd Step of the Deming Cycle) |
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Definition
| The team implements the plan and monitors progress. Data is collected continuously to measure the improvements in the process. Any changes in the process are documented, and further revisions are made as needed. |
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Term
Check
(Step 3 of the Deming Cycle) |
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Definition
| The team analyzes the data collected during step 2 to find out hose closely the results correspond to the goals set in the plan. If major shortcomings exist, the team may have to re-evaluate the plan or stop the effort |
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Term
Act
(Step 4 in the Deming Cycle) |
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Definition
| If the results are successful, the team documents the revised process so that it becomes the standard procedure. The team may then instruct other employees in the use of the revised process. |
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Term
Cost of Quality (Umbrella Term) |
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Definition
When a product fails to satisfy the customer, it is considered to be defective. Many companies have spent significant time, effort, and expense on systems, training, and organizational changes to improve the performance and quality of their products and processes. These costs, attributable to poor process performance and quality, can be broken down into four major categories: prevention, appraisal, internal failure, and external failure. |
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Term
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Definition
Associated with preventing defects before they occur.
They include the costs of:
redesigning - the process to remove the causes of poor performance
- the good or service to make it simplet to produce
-training employees in the methods of continuous improvement
-replacing equipment that might cause future quality problems. In order to improve performance, firms have to invest additional time, effort, and money. |
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Term
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Definition
Incurred in assessing the level of performance attained by the firm's processes. Appraisal helps management identify performance problems. As preventive measures improve performance, these costs decreast, because fewer resources are needed for qualtiy and inspection.
They include the costs to inspect, conduct audits, and in-process tests on the products. |
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Term
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Definition
Result from the defects that are discovered during production of a good or service.
These include:
-Scrap
-Rework
-Repair |
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Term
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Definition
| Incurred if some major aspect of a good or service must be performed again. ex: if the final inspector at an automobile paint shop discovers that the paint on a car has a poor finish, the car may have to be completely resanded and repainted. If the problem is too severe, the product must be scrapped. These mistakes result in lower productivity and delays the delivery of the product |
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Term
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Definition
Arise when a defect is discovered after the customer has received the good or service.
These include:
-Complaints
-Warranty
-Recall |
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Term
| Deming's suggestion for reducing costs |
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Definition
| Improve the process itself, which will reduce the number of defects - should spent less that 2.5% of every dollar on quality |
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Term
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Definition
A frequency distribution that shows the occurance between high and low ranges for a set of data. It looks like a bar chart and is used to answer:
-what kind of pop. do the data represent?
-How spread out are the data?
-Are the data symmetric or skewed?
-are there outliers? |
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Term
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Definition
| Allow us to analyze extremely large data sets by reducing them to a single graph that can show peaks in data, as well as give a visual representation of the statistical significance of the data. |
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Term
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Definition
| Most random variation conforms on a histogram in the shape of normal distribution, also known as a bell curve. 1 st - 68, 2 sd - 95.4 3 sd - 99.73 sd from the mean |
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Term
| Statistical Process Control |
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Definition
| The application of statistical techniques to determine whether a process is producing consistent, uniform products. Uses process data collected in real time and compares current measures to baseline process performance measures. SPC understands that variation occurs in a process |
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Term
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Definition
| 1. to detect the production of defective good/services 2. indicate that the process has changed and the goods/services may deviate from the design specifications unless something is done to correct the situation. 3. Used to inform management of the changes that have been used to improve the process |
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Term
| Examples of Process Changes that can be detected by SPC: |
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Definition
1. A decrease in the average number of complaints per day at a hotel
2. A sudden increase in the proportion of defective shirts or dresses
3. An increase in the time to process a mortgage application |
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Term
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Definition
| to find the cause of any non-random variation and either eliminate it (if it is producing more defects) or sustain it (if it has resulted in process improvement). |
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Term
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Definition
| The natural or inherent variation of a process. The sources for this variation are unidentifiable and unavoidable |
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Term
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Definition
| Any variation causing factors that are abnormal, identifiable, and can be eliminated. Employee mistakes and material defects, or equiptment malfunctions |
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Term
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Definition
| Collect a sample, count the number of units that are good and bad. We then compare the # of bad units and determine whether the process is performing the way it is supposed to perform. |
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Term
| Examples of attribute control charts |
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Definition
| Ex: long term defect of 5% means that the process is in control, but is producing defects. Whereas if the defects change from 5% to 2%, we say the process has improved but is out of control. |
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Term
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Definition
We measure the actual condition of the products. We measure the weight, volume, length, or other variable measurements. Ex: measure each part in a sample for pounds, and chart them with the sample means
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Term
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Definition
1. The problem of sample size: samples should be fairly large, frequently in the range of 50 to 300 observations (parts) & detection of at least one defective unit
2. How frequently to sample - decided on the basis of the production rate and the cost of producing defects in relation to the cost of inspection. A high-volume production process should be sampled frequently
3. The relationship of product specifications to control limits. If the process is in control and yet too many units are outside the specifications, as judged by management, then the process is not capable of meeting product specifications.
Control charts illustrate very clearly the need to match product specifications to the characteristics of the process
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Term
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Definition
Must perform evaluation prior to production process.
Refers to the ability of the process to meet the design specifications for a good or service. These design specifications are often expressed as a nominal value with a tolerance (allowable variation above or below the nominal value - given in examples)
The process must be capable of providing the results of analyses within these specifications, otherwise it will produce a certain proportion of "defects". |
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Term
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Definition
-Used to determine the ability to produce positive results (within the design specifications)
-If a process is capable of producing acceptable goods or services, the difference between the upper and lower specification, called the tolerance width, must be greater than the variation of the process distribution
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Term
Process Capability Index (Cpk) |
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Definition
-Compares the mean and standard deviation of the process with the mean and design tolerance (specifications) of the product. (It shows how well the parts being produced fit into the range specified by the design limits)
-We take the minimum value of the two because it gives us the worst-case situation
-If the minimum value is greater than or equal to 1.0 we can then say the process is capable
-If the minimum value is less than the cv of 1.0 either the process mean is shifted too close to one of the tolerance limits and is generating defective output, or the process range is too large. |
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Term
Determining Process Capability Steps |
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Definition
The capability of a process to produce outputs within the design tolerances can be determined by the following steps:
1. Collect sample of preproduction output calculate the mean and range of each sample
2. Develop control charts & verify control. If it's not in control, look for causes and eliminate them
3. Calculate the Cpk. If the results are acceptable use the charts to continuously monitor the output of the process. |
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Term
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Definition
A comprehensive and flexible system for achieving, sustaining, and maximizing total business success.
Began as an effort to improve manufacturing processes, then applied by GE to non-manufacturing processes such as sales, hr, customer service, financial services. |
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Term
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Definition
Process: Drop a marble through a funnel mounted 5 inches above a flat surface. Mark this point where the marble comes to rest (perform 50 times)
Common Suggestions: Hold funnel stationary directly above point (yields variation)
Move funnel from previous point to the equal and opposite side (yielded worse results) |
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Term
What we've learned from the funnel experiment: |
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Definition
1. Variation is natural and an inherent part of any process
2. Tampering ( modifying process without understanding how it works) will harm conformance quality |
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Term
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Definition
Dip black paddle into a mixture of good (white) and defective (red) beads. Withdraw paddle at a 30 degree angle so there are exactly 50 beads on the paddle. Count the number of "defects"
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Term
Lessons from Red Bead Experiment:
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Definition
1. Two causes of variation must be considered and differentiated (common and special)
2. The only way to improve conformance quality (and reduce cost) is to reduce variation
3. The only way to remove/reduce variation is to improve the process (continuous improvement of special variation process) |
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Term
Reducing Variation with SPC |
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Definition
1. Collect a sample
a. Acceptance Sampling
b. Process Sampling
2. Use Statistical Process Control (draw the 99.73% charts - both)
3. Identify and reduce common causes and/or special variation causes |
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Term
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Definition
Involves collecting a random sample of purchased parts and deciding if the population (lot) is acceptable
From raw material, we buy the product
Example: we did this with the matches, since we did not make them ourselves.
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Term
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Definition
(Statistical Process Control) involves testing a random sample from any process and deciding if the population is acceptable
If we make the product ourselves: we can test the beginning, middle, end, pieces before the whole to minimize variation |
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Term
Process Control for Attribute Measurement |
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Definition
Acceptability based on a single good/bad criteria
Example: jellybeans - do they look good? (visual quality, weight, looks)
The symbols involved:
x,n,m,p,pbar,Sp,UCL,LCL |
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Term
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Definition
Measure the actual characteristic (weight, length, volume) for a part in a sample.
Examining closer, the range in which these specific measurements vary.
Example: We measure a part in the sample and record the actual weights (9.8 to 10.2 pounds)
Symbols include:
X, Xbar, Xbarbar, n, m, R, Rbar, A2, D3, D4, UCL, LCL
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Term
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Definition
The natural or inherent variation of items made from a process.
Tied to a design specifications (range of acceptable values) by the process capability |
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Term
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Definition
Process does not meet specifications |
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Term
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Definition
Process does not meet specifications |
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Term
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Definition
Process does not meed specifications |
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Term
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Definition
Process meets specifications - centered withing the upper and lower control limits |
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Term
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Definition
Process is better than the specification requires (smaller bell curve) The process becomes increasingly target-oriented with fewer defects. |
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Term
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Definition
1. Determine the needs of the customer (Idea Generation, Feasibility Study, Product Feasible)
2. Design a product that satisfies customer (Design Quality)
3. Develop the processes needed to make the product
4. Make prototype parts to verify process is in control
5. Use design specifications 2 and process data 4 to verify process is capable
All three of these = Final design - process planning
6. Monitor the ongoing process using the SPC (manufacture stage - conformance quality - continuous improvement) |
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