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Questions and Answers
What is the term used to describe the 'noise' of the system?
What is the term used to describe the 'noise' of the system?
In the context of Injection Molding, what is the relationship between molecular weight of polymer and?
In the context of Injection Molding, what is the relationship between molecular weight of polymer and?
What is the term used to describe the difference between the measured and true value?
What is the term used to describe the difference between the measured and true value?
In the context of Machining, what is the relationship between depth of cut and?
In the context of Machining, what is the relationship between depth of cut and?
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What is the term used to describe the minimum increment that can be measured?
What is the term used to describe the minimum increment that can be measured?
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What is the term used to describe the ability to tell the same story many times?
What is the term used to describe the ability to tell the same story many times?
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In the context of Injection Molding, what is the relationship between injection pressure and?
In the context of Injection Molding, what is the relationship between injection pressure and?
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What is the term used to describe the ability to tell the truth?
What is the term used to describe the ability to tell the truth?
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In the context of Machining, what is the relationship between tool life and?
In the context of Machining, what is the relationship between tool life and?
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What is the term used to describe the difference between consecutive measurements intended to be identical?
What is the term used to describe the difference between consecutive measurements intended to be identical?
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What is the primary application of the normal distribution in manufacturing?
What is the primary application of the normal distribution in manufacturing?
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What is the mean lifetime of car tires in the example given?
What is the mean lifetime of car tires in the example given?
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What is the definition of the lognormal distribution?
What is the definition of the lognormal distribution?
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What is a source of variation in the manufacturing process?
What is a source of variation in the manufacturing process?
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What is an example of a systematic variation in the manufacturing process?
What is an example of a systematic variation in the manufacturing process?
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What is the purpose of the normal probability density function?
What is the purpose of the normal probability density function?
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What is the standard deviation of the car tire lifetime distribution?
What is the standard deviation of the car tire lifetime distribution?
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What is the primary application of the lognormal distribution?
What is the primary application of the lognormal distribution?
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What is the purpose of the cumulative distribution function (CDF)?
What is the purpose of the cumulative distribution function (CDF)?
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What is an example of a factor that affects process variations?
What is an example of a factor that affects process variations?
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What is the primary objective of measuring variation in a process?
What is the primary objective of measuring variation in a process?
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What is the characteristic of a normal distribution?
What is the characteristic of a normal distribution?
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What is the term for the allowable or permissible limit of variation of a process?
What is the term for the allowable or permissible limit of variation of a process?
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What is the defect rate per million in the car body build variation?
What is the defect rate per million in the car body build variation?
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What is the purpose of understanding the principle of measurement?
What is the purpose of understanding the principle of measurement?
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What is the primary role of customers in variation and quality?
What is the primary role of customers in variation and quality?
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What is the normal distribution also known as?
What is the normal distribution also known as?
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What is the purpose of minimizing variations in processes?
What is the purpose of minimizing variations in processes?
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What is the term for the change in outcome of a process?
What is the term for the change in outcome of a process?
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What is the primary objective of quantifying the variation statistically?
What is the primary objective of quantifying the variation statistically?
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What is the primary source of variation that affects the accuracy of a manufacturing process?
What is the primary source of variation that affects the accuracy of a manufacturing process?
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What is the primary reason for measuring variation in a process?
What is the primary reason for measuring variation in a process?
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Which of the following is a principle of measurement that determines the ability to distinguish between different values?
Which of the following is a principle of measurement that determines the ability to distinguish between different values?
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What is the term used to describe the ability of a product or service to consistently meet customer needs?
What is the term used to describe the ability of a product or service to consistently meet customer needs?
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What is the relationship between the molecular weight of a polymer and its accuracy in injection molding?
What is the relationship between the molecular weight of a polymer and its accuracy in injection molding?
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What is the purpose of understanding the normal distribution in manufacturing?
What is the purpose of understanding the normal distribution in manufacturing?
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What is the primary purpose of understanding the principles of measurement in manufacturing?
What is the primary purpose of understanding the principles of measurement in manufacturing?
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What is the primary objective of customers in variation and quality?
What is the primary objective of customers in variation and quality?
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What is the term used to describe the difference between the measured and true values of a process?
What is the term used to describe the difference between the measured and true values of a process?
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What is the term used to describe the change in outcome of a process?
What is the term used to describe the change in outcome of a process?
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What is the primary objective of quantifying the variation in a process statistically?
What is the primary objective of quantifying the variation in a process statistically?
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What is the purpose of minimizing variations in processes?
What is the purpose of minimizing variations in processes?
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What is the relationship between the depth of cut and surface roughness in machining?
What is the relationship between the depth of cut and surface roughness in machining?
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What is the term used to describe the ability of a process to produce consistent results?
What is the term used to describe the ability of a process to produce consistent results?
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What is the primary role of the normal distribution in manufacturing?
What is the primary role of the normal distribution in manufacturing?
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In manufacturing, the primary application of the normal distribution is to:
In manufacturing, the primary application of the normal distribution is to:
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What is the term used to describe the allowable or permissible limit of variation of a process?
What is the term used to describe the allowable or permissible limit of variation of a process?
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What is the primary application of understanding the principles of variation in manufacturing?
What is the primary application of understanding the principles of variation in manufacturing?
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What is the purpose of understanding the principle of measurement in manufacturing?
What is the purpose of understanding the principle of measurement in manufacturing?
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What is the fraction of tires that can be expected to wear out within ±4,000 km of the average?
What is the fraction of tires that can be expected to wear out within ±4,000 km of the average?
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What is the term used to describe the ability of a process to differentiate between different values?
What is the term used to describe the ability of a process to differentiate between different values?
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Which of the following is an example of an environmental factor that affects process variations?
Which of the following is an example of an environmental factor that affects process variations?
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What is the defect rate per million in the car body build variation?
What is the defect rate per million in the car body build variation?
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What is the term used to describe the ability of a process to produce consistent results?
What is the term used to describe the ability of a process to produce consistent results?
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Which of the following is a characteristic of a normal distribution?
Which of the following is a characteristic of a normal distribution?
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What is the primary objective of understanding the principle of measurement?
What is the primary objective of understanding the principle of measurement?
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Which of the following is an example of a systematic variation?
Which of the following is an example of a systematic variation?
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What is the purpose of the cumulative distribution function (CDF)?
What is the purpose of the cumulative distribution function (CDF)?
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Which of the following is a consequence of minimizing variations in processes?
Which of the following is a consequence of minimizing variations in processes?
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What is the relationship between the logarithm of x and the normal distribution in a lognormal distribution?
What is the relationship between the logarithm of x and the normal distribution in a lognormal distribution?
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Study Notes
Variation and Quality
- Variation refers to the change in outcome of a process, while quality is the ability of a product or service to consistently meet customer needs.
- Tolerance is the allowable or permissible limit of variation of a process.
Measure of Quality
- Quality is measured by how well a product or service meets customer needs, which should be related to the specifications of the product.
- Quantifying variation statistically is important to understand the measurement of variation from a process.
Normal Distribution
- A normal distribution helps quantify the outcome of a process and understand the measurement of variation from a process.
- It is a probability distribution of the occurrence of data, and naturally occurring phenomena tend to approximate the normal distribution.
- In manufacturing, normal distribution is a means of quality control.
Normal Distribution Examples
- Car tires can be modeled using a normal distribution, with a mean lifetime and standard deviation.
- The normal distribution can be used to calculate the fraction of tires that can be expected to wear out within a certain range.
Other Types of Distributions
- Lognormal distribution: the logarithm of x is distributed normally, used in applications such as metal powder for 3D printing.
- Lognormal distribution is used when the data is not symmetric around the mean.
Process Sensitivity
- Process sensitivity refers to the factors that affect process variations, including process, material, equipment, operator, environment, and measurement.
Factors Affecting Process Variations
- Process: inherent capability, change of settings
- Material: raw material variation, defects
- Equipment: tool wear, equipment maintenance or calibration
- Operator: procedure, distraction, fatigue
- Environment: temperature, humidity, vibration
- Measurement: capability of the tool (resolution), need for calibration
Types of Variation
- Systematic ("special cause") variation: influences of process parameters or external disturbances that can be isolated and possibly predicted or removed.
- Random ("common cause") variation: caused by uncontrollable factors that result in a steady but random distribution of output around the average of the data.
Variation and Quality
- Variation refers to the change in outcome of a process
- Quality is the ability of a product or service to consistently meet customer needs
- Tolerance is the allowable or permissible limit of variation of a process
Measure of Quality
- LEGO bricks: Special Bricks and Classic Bricks demonstrate variation in manufacturing
- Gillette Razors: variation in manufacturing process affects quality
- Car Body Build Variation: 6 standard deviations from the mean result in 3.4 defects per million
What Do We Need to Know?
- Customers' needs and perceived "good quality" should be related to product specifications
- Quantify variation statistically
- Identify factors that cause variations in processes and minimize them as needed
- Monitor variation and maintain process control
Normal Distribution
- Helps quantify the outcome of a process
- Helps understand measurement of variation from process
- Bell curve: probability distribution of the occurrence of data
- Naturally occurring phenomena tend to approximate the normal distribution
- In manufacturing, normal distribution is a means of quality control
Lognormal Distribution
- Logarithm of x is distributed normally
- Example: metal powder for 3D printing (Ti6Al4V) with specification of 15-45 um
Process Sensitivity
- Factors that affect process variations:
- Process: inherent capability, change of settings
- Material: raw material variation, defects
- Equipment: tool wear, equipment maintenance or calibration
- Operator: procedure, distraction, fatigue
- Environment: temperature, humidity, vibration
- Measurement: capability of the tool (resolution), need for calibration
Machine, Tool, and Workpiece
- Factors that affect variation in machining and injection molding processes
Principles of Measurement
- Accuracy: difference between measured and true value
- Repeatability: difference between consecutive measurements intended to be identical
- Resolution: minimum increment that can be measured
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Description
Discover the principles of quality and variation in manufacturing processes, including tolerance and statistical measurement. Learn how to quantify variation and understand the importance of meeting customer needs.
