Systems Flashcards
Skibidi
Two aspects of Quality in a Manufactured Product
1) Product Features and 2) Freedom of Deficiencies
What are the product characteristics in Product Features?
- Design Configuration
- Size of Product
- Function and Performance
- Aesthetic appeal
- Ease of use
- Reliability
- Serviceability
What are the product characteristics in Freedom of Deficiencies?
- Absence of defects
- Conformance to specifications
- Components within tolerance
- No missing parts
What is acceptance sampling?
A statistical technique in which a sample drawn from a batch of parts is inspected, and a decision made whether to accept or reject the batch on the basis of the quality of the sample.
What are acceptance sampling applications?
- verifying quality of raw materials
received from a vendor - deciding whether or not to ship a batch of parts or products to a
customer - inspecting parts between steps in a manufacturing sequence
What are the three main objectives of Total Quality Management?
- achieving customer satisfaction
- encouraging involvement of the entire work force
- continuous improvement.
What are the quality control technologies ?
- quality engineering
- quality function deployment
- 100% automated inspection
- on-line inspection
- coordinate measurement
machines for dimensional measurement - noncontact sensors such as machine vision for inspection
What is a Random Process Variations?
Random variations result from intrinsic variability in the process. All processes are characterized by these kinds of variations.
Random variations cannot be avoided; they are caused by factors such as inherent human variability and minor variations in raw materials.
Random variations typically form a normal statistical distribution. This kind of variability continues so long as the
process is operating normally
How about Assignable Process Variations, What’s that? Skibidi
Assignable variations indicate an exception from normal operating conditions. Something has occurred in the process that is not accounted for by random variations.
Reasons for assignable variations include operator mistakes, defective raw materials, tool failures, and equipment malfunctions.
What is meant by the term process capability?
Process capability equals ±3 standard deviations about the mean output value under the assumptions:
(1) the output is normally distributed
(2) steady state operation has been achieved and the process is in statistical control.
What is a control chart?
A control chart is a graphical technique in which statistics computed from measured values of a certain process output characteristic are plotted over time to determine if the process remains
in statistical control.
What does a control chart consists of ?
The chart consists of three horizontal lines that remain constant over time: a center line (CL), a lower control limit (LCL), and an upper control limit (UCL).
The center line is usually set at the nominal design value, and the upper and lower control limits are generally set at ±3
standard deviations of the sample means.
What are the two basic type of control charts?
(1) control charts for variables
(2) control charts for attributes
What does control charts for variables requires?
Measurements of the quality characteristic
of interest.
What does control charts for attributes requires?
A determination of either the fraction of
defects in the sample or the number of defects in the sample
What’s a histogram?
A statistical graph consisting of bars representing different values or ranges
of values.
Length of each bar is proportional to the frequency or relative frequency of
the value or range.
What’s a Pareto chart?
A special form of histogram, in which attribute data are arranged according
to some criteria such as cost or value.
What does a Pareto chart displays?
A graphical display of the tendency for a small proportion of a given population to be more valuable than the much larger majority.
What is a scatter diagram?
An x-y plot of the data taken of two variables of interest.
What is a cause and effect diagram?
A graphical-tabular chart used to list and analyze the potential causes of a given problem
What does a cause and effect diagram also known as?
A fishbone diagram
What does a cause and effect diagram consists of?
A central stem leading to the effect (the problem), with multiple branches coming off the stem listing the various groups of possible causes of the problem.
What is a robust design in Taguchi’s quality engineering?
One in which the function and performance of the product or process are relatively insensitive to variations that are difficult or impossible to control.
What does a robustness means in a product design?
The Product can maintain consistent performance with minimal disturbance due to variations in its operating environment
What does a robustness means in a process design?
The process continues to produce good product in spite of uncontrollable variations in its operating
environment.
What is a ISO 9000?
A set of international standards on quality developed by the International Organization for Standardization (ISO)
What is ISO 9000 not?
It is not a standard for the products or services
If ISO 9000 is not a standard for the products or services, what is it then?
ISO 9000 instead establishes standards for the systems and procedures used by a facility that affect the quality
of the products and services produced by the facility.
What does ISO 9000 includes?
ISO 9000 includes a glossary of quality terms,
guidelines for selecting and using the various standards, models for quality systems, and guidelines for auditing quality systems.
What is inspection?
Activity of examining the product, its components,
subassemblies, or materials out of which it is made, to determine whether they conform to design
specifications.
What are the two basic types of inspection?
1) Inspection for variables and 2) Inspection for attributes
What is inspection for variables ?
One or more quality characteristics of interest are measured using an appropriate measuring instrument or sensor
What is inspection for attributes?
The part or product is inspected to determine
whether it conforms to the accepted quality standard.
Inspection by attributes can also involve
counting the number of defects in a product.
What are the four steps in a typical inspection procedure?
(1) presentation of the item for examination;
(2) examination of the item for nonconforming feature(s);
(3) deciding whether the item satisfies the defined quality standards;
(4) action, such as accepting or rejecting the item, or sorting the item into the most appropriate quality grade.
What is the Type I error that can occur in inspection?
A Type I error is when an item of good quality is incorrectly classified as being defective. It is a “false alarm.”
What is the Type II error that can occur in inspection?
A Type II error is when an item of poor quality is erroneously classified as being good. It is a “miss.”
How does quality control testing distinguished from inspection?
inspection is used to assess the quality of the product relative to design specifications, testing refers to the assessment of the functional aspects of the product
QC testing is a procedure in which the item being tested is observed during actual operation or under
conditions that might be present during operation.
What are the two types of sampling plans?
1) variables sampling
2) attributes sampling
What’s a variables sampling?
A random sample is taken from the population, and the quality characteristic of interest (e.g., a part
dimension) is measured for each unit in the sample.
What’s a attributes sampling?
A random sample is drawn from the batch, and the units in the sample are classified as acceptable or defective,
depending on the quality criterion being used.
What are the two problems associated with 100% manual inspection?
1) Expense involved.
2) Problem of inspection accuracy.
Why expense involved always a problem in 100% manual inspection?
Instead of dividing the time of inspecting the sample over the number of parts in the production run, the inspection time per piece is applied to every part.
The inspection cost sometimes exceeds the cost of making the part
Why problem of inspection accuracy always a problem in 100% manual inspection?
There are almost always errors associated with 100% inspection (Type I and II errors), especially when human inspectors perform the inspection procedure.
What are the three ways in which an inspection procedure can be automated?
(1) automated presentation of parts by an automatic handling system with a human operator still
performing the examination and decision steps.
(2) automated examination and decision by an
automatic inspection machine, with manual loading (presentation) of parts into the machine.
(3) completely automated inspection system in which parts presentation, examination, and decision are
all performed automatically.
What are the two forms of positive actions in automated inspection?
(1) feedback process control
(2) parts sortation
Explain feedback process control in automated inspection
Data are fed back to the preceding manufacturing process responsible for the quality characteristics being evaluated or gaged in the inspection operation
Explain parts sortation in automated inspection
The parts are sorted according to quality level: acceptable versus unacceptable. There may be more than two levels of quality appropriate for the process (e.g., acceptable, reworkable, and scrap).
Under what circumstances is process monitoring a suitable alternative to actual inspection of the quality characteristic of the part or product?
Assumption of a deterministic cause-and-effect relationship between the process parameter(s) that can be measured and the quality characteristic(s) that must be maintained within tolerance.
What is meant by partially distributed inspection?
Carried out if there is any economy in performing multiple
inspections at a single location, at the same time, preserving at least some of the advantages of distributed inspection.
What is an industrial robot?
An automatically controlled, reprogrammable, multipurpose manipulator programmable in three or more axes, which may be either fixed in place or mobile for use in industrial automation
Production system consists of two major components. What are them?
1) facilities, which consists of the factory, the equipment factory and the way the equipment is organized
2) manufacturing support systems
Which is not the category of manufacturing systems?
Mechanised systems
What are the category of manufacturing systems?
1) Manual work systems
2) Worker-machine systems
3) Automated systems
The five levels of automation defined in the unit are?
1) device level
2) machine level
3) cell or system level
4) plant level
5) enterprise level
Which is not modes of operation of a modern maintenance and repair diagnostics subsystem?
Limping mode, in which the machine or system works on a reduced or changed capacity, which is involved in case of malfunction or failure.
What are the modes of operation of a modern maintenance and repair diagnostics subsystem?
1) Status monitoring mode
2) Failure diagnostics
3) Recommendation of repair procedure
What’s a status monitoring mode?
The status of key sensors and parameters are monitored and recorded.
What is failure diagnostics?
Invoked in case of malfunction or failure
What’s a recommendation of repair procedure?
The subsystem recommends to the repair crew steps that should be taken to affect repairs.
What are interlocks?
Safeguard mechanisms for coordinating the activities of two or more devices and preventing them to interfere with each other.
Distributed Programmable Logic Controllers (PLCs) and Remote Terminal Units (RTU) are associated wit which forms of computer process control?
Distributed Control Systems (DCS) and Supervisory Control and Data Acquisition (SCADA)
What is not a characteristic of a FMS?
Economics of Scale
What are the amongst the characteristics of FMS?
1) High capital investment
2) Static Variety
3) Fixed system controls
