System Engineering Review Cliffnotes
Written by Edvin Eshagh   

Review system engineering key concepts (source: ISBN 0-13-16326-0)

Elements of a System

  1. Component - I/O, process operation.  Describe sys state via methods or restrictions
    • each comp effects the whole sys
    • each comp depends on at least one other comp.
  2. Attribute - properties that characterize the sys
  3. Relationships - links between components & attributes

System components that alter material, energy or information
  1. Structural comp. - static parts
  2. Operating comp. - perform processing
  3. flow comp. - material, energy, or info being altered

Subsystem - Different hierarchical levels of system

System Environment - everything outside sys boundaries - Note that sys I/O must often pass through boundaries

Sys classifications
  1. Natural sys - came into being naturally - materials are cyclic - no dead ends, no waste, only continual recirculation
  2. Human-made sys- humans intervened sys through components, attributes, or relations
  3. Physical sys - consumes physical space
  4. Conceptual sys - represented by symbols, hypothesis, ideas - software
  5. Static sys - having structure w/o activity - bridge - building - highway
  6. Dynamic sys - combines structure with activity - i.e. school combines building, student, teachers, books, etc.
  7. Closed sys - does NOT significantly interact with environment - Env. provides context - chemical reaction towards equilibrium
  8. Open sys allows info, energy, matter to cross boundary - plants, ecological sys, bus org. - steady state & self regulatory (adaptive

System Engineering - An interdisciplinary collaborative approach to derive, evolve, and verify a life-cycle balanced system solution which satisfies customer expectations and meets public acceptability

Top-down approach - the design process starts with specifying the global system state and assuming that each component has global knowledge of the system, as in a centralized approach.
Useful for building a car with newer design, it is risky, it will take longer to build

Bottom-up approach, the design starts with specifying requirements and capabilities of individual components, and the global behavior is said to emerge - useful to build existing model; it's cheaper, faster, and less risky

Concurrent/simultaneous engineering - systematic approach to creating product design that simultaneously considers all elements of product life-cycle (manufacturing, transportation, maintenance, disposal, etc)

   A  C  Q  U  I  S  I T  I  O  N   P H A S E   |   UTILIZATION PHASE
Conceptual | Detail design |  Production    | Product use, phase-out    \
Design       | Development |  & Construct. |                                      /
      Manufacturing            | Production              \
      Config. design            | Operation               /
                       Product / sys support        | Support &        \
                         config design                  | Maintenance    /
                                              Product/sys retirement                     \
                                              phase-out, & disposal                       /      
Product phases - acquisition & utilization (producer/consumer activities)

Product life-cycle -
  1. Acquisition
      * Need identification
      * Conceptual - preliminary design
      * Detail design & development
      * Production / construction
  2. Utilization
      * Use, support, phase-out, disposal

baseline - Common frame of reference for improving communications and understanding.  It is described through iterative process requirement analysis.
Functional definition of sys serves as baseline for identifying resource requirement ( hardware, software, people, data, etc)

DDP - Design dependent parameters - attributes and/or characteristic inherent in design to be predicted or estimated.  subset of design consideration - i.e. weight, design life, reliability, reproducibility, maintainability

TPM - Technical performance measure - predicted and/or estimated values for design-dependent parameters.  i.e. availability, cost, flexibility, supportability

Operation Requirements (4 out of 7 required)
  1. Mission definition - Identification of primary and alternate missions
  2. Performance & physical parameters - Definition of the operating characteristics/functions (size, weight, range, bits, etc)
  3. Operation deployment or distribution - Identification of quantity of equipment, software, personnel, etc and the expected geographical location to include transportation
  4. Operational life cycle - Anticipated time that the system will be in operational use. How long, by whom?
  5. Utilization requirement - Anticipated usage of sys in env.  (hours, capacity, etc)
  6. Effectiveness factor - Figures Of Merit
    1. cost / system effectiveness
    2. availability
    3. Mean Time Between Maintenance (MTBM)
    4. Maintenance Down Time (MDT)
    5. failure rate
  7. Environment - Definition of the env in which system is expected to operate (temperature, humidity, mountains, etc)

MLH/OH - Mean Labor Hour / Operation Hour
MOE - Measure Of Effectiveness
MTBM - Mean Time Between Maintenance
MTTR - Mean Time To Repair
MDT - Mean Down Time
COTS - Commercial Off The Shelf
CAD - Computer Aided Design
CAED - Computer Aided Engineering Design
SEMP - System Engineering Management Plan
TEMP - Test Evaluation Plan

Maintenance & Support - developed during conceptual design phase (3 out of 6 required)
  1. Levels of Maintenance - division of function and tasks for each area where maintenance is performed (on site, shop, org.)
  2. Repair policies - non repairable, partially repairable, fully repairable
  3. Organization responsibilities - Because of maintenance responsibility (customer, producer/supplier, third party, combination), which can change through time, decisions effecting org responsibility will effect sys design
  4. Maintenance support element - supply support, test equipment, personnel, etc
  5. Effectiveness requirement - effectiveness factors associated with support capabilities - supply demand rate, probability of spare part availability, probability success given supply
  6. Environment - env as it pertains to maintenance & support (temperature, shock & vibration, noise, etc)

Conceptual design review
review & validation for system operational requirements, maintenance & support concept, specified TPMs, functional analysis & allocation of requirements at the system level.

Formal Design Review
  1. Formalized checklist of proposed system design in respect to specification.  Problem areas discussed & addressed.
  2. Common baseline for all project personnel.  (Opportunity to listen to or explain and justify design approach).  Results in better comm.
  3. Forum for concurrent engineering
  4. Means to solve interface problems & promote compatibility between different elements
  5. Formalized record of what design decisions were mad, and the reason for making them
  6. Promotes a higher probability of mature design.

System design requirement types

Type A - System specification -
  • technical, performance operational & support characteristics for the system as an entity
  • result of feasibility analysis, operational requirements, maintenance & support
  • TPM requirement at the sys level
  • functional design desc of the sys
  • design requirements for the sys
  • allocation of design requirements to the subsystem level
Type B - Development specification
  • technical requirements (quantity & quality) for any new item below the system (subsystem) level where research, design, and development are accomplished (R&D, equipment, assembly, software, facility, etc)
  • Must include the performance, effectiveness, and support characteristics that are required in the evolving of design from the system level and down
Type C - Product specification
  • Same as above, but they are available or can easily be produced
  • technical requirements (quantity & quality) for any new item below the system level that is currently in inventory and can be produced "off the shelf" - may include Commercial Off The Shelf (COTS)
Type D - Process specification
  • Service or process that must be performed on any component of the sys (machine, weld, etc)
  • technical requirements (quantity & quality) associated with a process and/or a service performed on any element of a system or in the accomplishment of some functional requirement.  i.e. manufacturing (machining, bending, welding), logistic process (materials handling, transportation), info handling process
Type E - Material specification
  • technical requirements that pertain to raw materials ( metals, ore, sand), liquids, semi-fabricated, etc.

Design, Review, Evaluation, Feedback
  • Conceptual design review - scheduled towards end of conceptual & before preliminary design.  Review & eval functional baseline
    • Feasibility analysis
    • system operation requirement
    • maintenance & support concept
    • prioritized TPMs
    • SEMP
    • TEMP
  • System design review -  scheduled during preliminary design - oriented towards overall sys configuration, rather than subsystems
    • One or more formal reviews
    • Functional Analysis & allocation of requirements
    • Type B-E
    • trade-off study
  • Equipment/software design review - scheduled during detailed design & development -
    • Type C-E
    • design data defining major subsystem
    • equipment, models, mock-ups, part list, software, etc
    • Predictions
  • Critical design review - schedule after detailed design, and before the final design to production/construction -
    • Design is fixed, & evaluated for adequacy, producabilty, construction
    • Complete design package
    • analyses, trade-off, predictions
    • detailed construction plan
    • detailed maintenance plan
    • retirement & recycle plan

System Design Review Checklist
  • Operation requirements
  • Effectiveness factors
  • Maintenance concept
  • Functional analysis & allocation
  • trade-off study
  • Sys specifications
  • Sys Eng Management plan
  • Design doc
  • Ecological requirements
  • Societal requirements
  • Feasibility
  • conceptual design review
  • critical design review
  • trade-off study

Testing types - see diagram 6.2, p145
  • Type 1 - Evaluation of breadboards, engineering & service tests - Can be system or component level
  • Type 2 - (require 5 out of 9 ) - Formal & detailed test of prototype (pre-production, not fully qualified).  Initial test for operation use, which can include:
    • Performance test - 
    • Environmental qualifications
    • structural test
    • Reliability qualification - determined by MTBF & MTBM
    • Maintenance demonstration - asses MOE, MTBM, MTTR, MDT
    • Support equipment compatibility test
    • Personnel test & eval
    • Technical data verification
    • Software verifications
  • Type 3 - Formal test & verification - After sys qualification & before completion of production phase - Operational test over time (1st life cycle)
  • Type 4 - Continuing test during the operational phase

Preparation for system test & evaluation - before formal eval
  • Selection of test Items - equipment/software configuration
  • Test & Eval procedures - operation & maintenance tasks that follow formal approved procedure
  • Test-site selection - single or multiple site, perhaps under different environmental conditions
  • Test personnel & training  - 1)operators, 2)supporting engr., admin, etc.  operators/maintenance staff should be same skill level as consumer
  • Test facilities & resources - many instances, new design and construction are required, which effect scheduling & duration (test chambers, capital equipment, env control, etc)
  • Test & support equipment - test & support equipment should be procured and available for testing Types 2,3,4.
  • Test supply support - everything needed to support system through its life cycle (materials, data, personnel, spare parts, inventory, etc).

Types of decision making
  • Under Assumed Certainty (p183) - decision based on science and  conceptual simplification of reality.  This does not mean future is known.  i.e. Ohm's law, Newton's law
  • Under Risk (p187) - Anticipated future worth is known only with a degree of assurance.  Decision maker does not suppress the acknowledged ignorance about the future, but makes it explicit by assigning probabilities
    • Aspiration level Criterion  - desired level of achievement (min loss or max profit)
    • Most-Probable Criterion -
    • Expected Value
    • Comparison Criterion  - Based on criteria; ie. if you know only Expected value & probability then use expected value, otherwise, only use probability
  • Under Uncertainty (p188) - When probabilities are not available for assignment to future events,
    • Laplace Criteria - every option has same probability (p=1/n)
    • Maximin Criteria - pessimistic view - Min value for each alternative, and select the max
    • Maximax Criteria - optimistic view - Max value for each alternative, and select max
    • Hurwicz Criteria - max { alpha * max(Eij) + (1-alpha) * min(Eij) }

Direct vs Indirect Experimentation

  • Direct Experimentation - Object/state/event/environment is subject to manipulation and the results are observed.  i.e. move furniture around until the desired orientation is achieved. 
  • Indirect Experimentation (simulation) - Explore the effects of alternating system characteristics without actually producing and testing each candidate system.  Models are used, which can range from schematic diagrams to physical models, analog (p165) or digital models, to Mathematical models.  Useful when knowledge of the system is sketchy; can reduce cost during early stage of development.

Decision Making under risk - decision maker does not suppress acknowledged ignorance about the future, but makes it explicit through the assignment of probabilities

  • Aspiration Level Criterion (p187-8)- Desired level of achievement (profit), or avoidance (loss).  Exists in most personal or professional decision making.
  • Most Probable Future Criterion - Focus on most probable outcome from several that can occur.
  • Expected Value Criterion - Maximize gain or minimize loss. Viewed with caution only when payoff of possible outcomes are disproportionately large.  Weighing all payoffs by their probabilities.

Decision making under uncertainty - inappropriate or impossible to assign probability, or all have same probability.

Total Cost & Optimum/economic procurement quantity to order
TC = CiD + CpD÷Q + ChQ÷2     And Q* = Sqrt( 2 CpD÷Ch)
Where TC = Total Cost, Q* = Optimum economic procurement quantity, Ci = item cost per unit, Cp = procurement cost per procurement, Ch = hodling cost per unit per period, Q= procurement quantity
Example:  If Demand = 10k, cost to order=$50, and holding cost=$1.10, then Q*=953.4 per order

Upper and Lower Control Limits (UCL, LCL) are calculated within 3σ, which yields to 99.865% accuracy.
Control charts for variable - Graphical representation of a mathematical model used to monitor a random variable process to detect changes in a parameter of that process.  Help to distinguish between the existence of a stable pattern of variation and the occurrence of an unstable pattern.

  • X chart, p330 - Plot over time of sample means taken from a process
    xdoubleBar = (∑ X) ÷ n, R = (∑ R) ÷ n, d2= R÷σ , A2=3÷d2Sqrt(n) , CL=xdoubleBar ± A2R
    Where R = Range
  • R chart, p332 - Plot over time of range taken from a process (usually for <X)
    LCLR=D3R  , UCLR=D4R 

Table 11.2 (p331) - Factors for Construction of X and R Charts


 X chart

 R chart

 sample Size, n









When n>10, then look into S-chart (standard deviation of range).
Statistitions like n≥30, where as Quality Assurance (QA) like to use n≥5

* Application of X and R charts:
Further inquery is needed if one or more values fall outside one set of limits.  If assignable cause to outlier(s) can be found, then the outlier(s) can be disregarded and you can construct a new control limit

Control charts for Attributes -

  • P chart, p335 - a two-value classification(i.e. proportion of failing over predetermined time period). 
    µ=np, σ=Sqrt(np(1-p)), Sp=Sqrt(P(1-P)÷n), Control Limit = P±Sp  
  • C chart, p338 - a discrete classification (i.e. number of arrivals per hour, or number of pixel defects on a TV screen) - it uses sample size of one.
    c=S2c = [∑(np)]÷n , Control Limit = c ± 3Sc

Definition And Explanation Of Reliability
Reliability - Probability that a system will perform in a satisfactory manner for a given period when used under specified operation conditions.  Element of reliability:

  • Probability - quantitative
  • Satisfactory performance - specific criteria to meet (i.e. TPM)
  • Time - completing mission as scheduled (MTBF, MTTF)
  • Operating Conditions - such as environmental factors.  "Experience has indicated that the transportation, handling, and storage modes are sometimes more critical from reliability standpoint than are the conditions experienced during actual system operational use" p371

Failure Rate
lamda = λ = (# of failures) ÷ (total operating hours)
MTBF = 1 ÷ λ

Typical  failure-rate curve
Bathtub curve based on time-dependent failure exhibits the following:
  1. Decreasing failure rate region - Infant mortality period where debugging is occurring
  2. Constant failure rate region - Life period with least maintenance - Exponential failure law applies
  3. Increasing failure rate - System/equipment wearout period, requiring increased maintenance

Series-Parallel component relationship
Series Reliability R = P1 P2 ... Pn
Parallel Reliability R = 1- (1-P1)(1-P2)...(1-Pn)
Series-Parallel  - Solve by simplifying the network

Reliability Models - Functional Flow diagrams (from functional analysis) lead to the development of reliability block diagrams and model that can serve as basis for reliability allocation, prediction, stress strength analysis, and subsequent design analysis and evaluation tasks.

Reliability Allocation - First, system top-level requirements are specified, then the requirements are allocated to subsystem level, unit level, and down to level needed to provide meaningful input to the design.

Components selection and Application - Utilize components that when combined, are capable of meeting the overall reliability requirements for the system.  Design for reliability should consider:

  • Selection of standardized components - known reliabilities, characteristics, and previously qualified.
  • Test and evaluation of all components and materials prior to design acceptance.

Reliability Analysis Methods

  • Failure mode, effects, and critical analysis (FMECA) (p394-400)- Helps to identify& investigate potential system weakness.  Can be used "before-the-fact" and "after-the-fact" of system.
    1. Define system requirement
    2. Accomplish functional analysis
    3. Accomplish requirement allocation
    4. Identify failure modes
    5. Determine cause of failure
    6. Determine the effect of failure
    7. Identify failure detection means
    8. Rate failure mode severity
    9. Rate failure mode frequency
    10. Rate failure mode detection probability
    11. Analyze failure mode critically- assign Risk Priority Number (RPN)
      RPN= (severity rating)(frequency rating)(probability of detection rating)
    12. Initiate recommendations for product/process improvement
  • Fault-Tree analysis (FTA) (p400) - Graphical enumeration and analysis of different was in which a particular failure can occur, and the probability of occurrence.
    1. Identify top-level event
    2. Construct a causal hierarch in the form of a fault tree - cause-and-effect
    3. Determine the reliability of top-level event
  • Stress-strength analysis (p400) - Overstress conditions will result in reliability degradation; under stress conditions maybe costly as a result of overdesign.
    1. Determine nominal stresses
    2. Identify factors affecting maximum stress (concentration factors, heat treating, etc)
    3. Identify critical stress components & calculate mean stresses
    4. Determine critical stress distributions for the life of system/component
    5. Take corrective action for components outside safety margin
  • Reliability prediction (p304) - check on design in terms of the system requirement and factors specified through allocation.  Predicted values of R, MTBF, and/or MTTF are compared against the requirement, and areas of incompatibility are evaluated for design improvement.
    • based on analysis of similar equipment
    • based on estimate of Active Element Group (AEG) - Smallest functional building block (i.e. relay, pump, transistor, etc)
    • equipment parts count
    • stress analysis

Reliability Test And Evaluation -
Accomplished under test category Type II and III. 
Determine whether the system under test meets the specified MTBF requirements. 

p419 - answer to Q1,2 on p475
Maintainability vs maintenance
Maintenance - series of actions to be taken to restore or retain a system in effective operational state.
Maintainability - The ability of a product to be maintained - Characteristic of design expressed in terms of maintenance times, frequency, and cost; maintainability must be built into design). 
Maintainability is the counterpart of reliability; it helps minimize extensive and costly maintenance; maximize Cost Effectiveness (CE) over the life-cycle of the system (maximize Figure of merit)
Maintainablity must be considered from conceptual design and in through the system utilization (figure 13.10, p439), because it effect many design elements, such as: component selection, Level of repair, component accessibility, etc which all effect the system CE.
For example:

  1. Probability of item will be restored within a period
  2. probability of maintenance will not be required more than x times in a given period
  3. maintenance cost will not exceed y dollars per designated period

p420, answer to Q3 on p475
Measure of maintainability - measure of maintainability in regards to downtime, personnel labor hours, frequency, cost, support, etc.  General categories:

  • Corrective maintenance - Unscheduled maintenance as a result of failure
  • Preventive maint. - Scheduled maint. to retaina level of performance
  • Adaptive maint. - continuing process of modifying software to be responsive to changing requirements in data or in processing env (but within the original functional structure)
  • Perfective maintenance - Modification of software for enhancing performance, packaging, etc.

Maintenance Elapsed-Time factors - active corrective and preventive maintenance times, administrative and logistics delay times, and total maintenance downtime

Mct = Mean Corrective Maintenance Time = MTTR = Mean Time To Repair
Mpt = Mean Preventive Maintenance Time - actions required to retain system in specified level of performance
M = Mean Active Maintenance = Average elapsed time to perform maintenance
Mmax = Maximum Active Corrective Maintenance - Usually 90th or 95th percentile point
Mct = Median Active Corrective Maintenance Time
Mpt - Meidan Active Preventive Maintenance Time -
LDT = Logistics Delay Time - extended down time due to waiting on spare ports, resources, transit, etc
ADT = Administrative Delay Time - Personnel assignment priority, labor strikes, orgizational constraints, etc
MDT = Maintenance Downtime - Total elapsed time required for repair/restore.  MDT = M + LDT + ADT

Maintenance Labor Hours

  • MLH/OH - Maintenance Labor-Hour per system Operating Hour
  • MLH/cycle - MLH per cycle of system operation
  • MLH/month - MLH per month
  • MLH/MA - MLH per Maintenance Action
    Corrective MLH = (Σ λi)(MLHi)  ÷ Σ λi

MTBM = Mean time between all maintenance actions; greater values are desired.
MTBM = 1 ÷ ( 1÷MTBMunscheduled + 1÷MTBMscheduled )

MTBR = Mean Time Between Replacement - (sometime replacement is not necessary for maintenance)

Answer to Q4 on p475 - MTBM vs MTBF vs MTBR
MTBM - is duration between maintenance that is inclusive of schedule or unschedule maintenance that may or may not require replacement of components
MTBF - is duration between unscheduled maintenance that are due to system/component failures.
MTBR - is duration between replacement of parts that can be part of scheduled or unscheduled maintenance

Availability and effectiveness measures

  • Inherent availability (Ai) - Probability that when the system used under stated conditions in an ideal support environment (readily available tools, spares, maintenance personnel, etc), will operate satisfactory (excluding preventive/scheduled maintenance, LDT, ADT)
    Ai = MTBF ÷ (MTBF + Mct)
  • Achieved availability (Aa) - Same as Ai, except preventive (scheduled) maintenance is included.
    Aa = MTBM ÷ (MTBM + M)
  • Operational availability (Ao) - Probability that when system used under stated conditions in an actual operational environment, will operate satisfactory
    Ao = MTBM ÷ (MTBM + MDT)

SE = System Effectiveness - ability of a system to do the job for which it was intended

CE = Cost Effectiveness - measure of a system in terms of mission fulfillment (system effectiveness) and total life-cycle cost.  Figure Of Merit (FOM) can include:  (2 of 5)

  • FOM = (system benefit) ÷ (life-cycle cost)
  • FOM = (system capacity) ÷ (life-cycle cost)
  • FOM = (system effectiveness) ÷ (life-cycle cost)
  • FOM = (availability) ÷ (life-cycle cost)
  • FOM = (supportability) ÷ (life-cycle cost)

Component Selection And Application - (4 of 7)

  • Selection of standardized components & materials - minimize different types.
  • Reliable items - select elements with built-in self-test features and level/depth of diagnostics
  • Repairable using common and available standard tools
  • Accessibility - identify and repair/replace easily.  Elements requiring frequent maintenance should be easily accessible
  • Modularized functional-packaging - to easily replace modules incase of failure
  • Avoid short-life components - to eliminate preventive maintenance
  • Labeling & identification of components - to aid technicians to effectively/efficiently complete their task

Maintainability analysis methods
Trade-off analysis between reliability and maintainability, maintainability prediction, RCM, LORA, MTA, TPM

RCM = Reliability Center Maintenance - p449
LORA = Level-Of-Repair Analysis - p450
MTA = Maintenance Tasks Analysis - p456
TPM = Total Productive Maintenance - p464

Definition and explanation of logistics and supportability

  • Logistics associated with initial purchasing and acquisition, production, transportation, distribution, and installation of system.
    Logistics is part of the supply chain process that plans, implements and controls the efficient, effective forward and reverse flow and storage of goods, services, and related information between the point of origin and the point of consumption in order to meet customer requirements
  • Subsequent sustaining maintenance and support of the system throughout its entire life cycle.

Elements of Logisitics and System Support (6 of 10)

  1. Logistics and Maintenance Support Planning - ongoing iterative activities of planning, organization, and management to insure and coordinate the logistics which includes System Engineering Management Plan (SEMP)
  2. Logistics, Maintenance and Support Personnel - personnel needed to unique logistics and system maintenance (from initial provisioning and procurement to production related)
  3. Training and Training Support - Initial and replenishment/replacement of training materials, equipment, facilities, data, documentation for operators and maintenance personnel.
  4. Supply Support - Spares/Repair Parts and Associated Inventories - spares, consumables (liquids, lubricants, fuel, etc), special supplies, software modules, and supporting inventories to maintain prime mission
  5. Computer Resources (Hardware and Software) - computer software, hardware, networks, facilities to support day-today flow of information
  6. Technical Data, Reports, and Documentation - installation and checkout procedures, operating/maintenance instructions, calibration procedures, overhaul instruction. Includes the ongoing iterative process of data collection, analysis, and reporting covering system throughout its life cycle.
  7. Maintenance Support Facilities and Utilities - Generally part of facilities for unique to support of logistics and maintenance, which includes portable buildings, mobile vans, storage buildings, calibration laboratories, etc.
  8. Packaging, Handling, Storage/Warehousing, and Transportation (Distribution) - all materials, equipment, special provisions, containers, and supplies necessary for packaging and preservation, security, storage, handling, transportation, etc. throughout the system life cycle
  9. Test, Measurement, Handling, and Support Equipment - All tools, monitoring/test/calibration/diagnostic equipment, maintenance fixtures and stands
  10. Logistics Information  - resources necessary to ensure that effective and efficient logistics and maintenance information flow throughout the system life cycle.  i.e. communication links to customer, producer (contractor), sub-contractors, suppliers

Measures of logistics and supportability
Over all effectiveness measures of a system, and the degree to which the system is able to accomplish its mission, are those measures  associated with the logistics and maintenance support infrastructure and its availability when needed.  Some factors include:

supply chain factors
Forward flow of activities that involve with the initial acquisition (procurement) of items from various sources of supply, flow of materials through out the production process, transportation and distribution of products from manufacturer to the customer, the sustaining onsite customer service as required, and all related business-oriented processes necessary.

Supply chain management (SCM) p513 - A process-oriented, integrated approach to procuring, producing, delivering end products and services to customers.  It includes sub-suppliers, suppliers, internal operations, trade customers, and end users.  It covers management of materials, information, and funds flow.

p521 (5 of 8)
Total Logistic Costs (TLC) = (Cost of development of logistics) + (cost of producing logistics elements) + (cost of operational logistics) + (cost of maintenance & support) + (cost of material acquisition or purchasing) + (cost of material processing or handling) + (cost of distribution) + (cost of customer service)

Transport key issues (5 of 6)

  1. Availability of transportation, or probability of appropriate transportation will be available
  2. Reliability of transportation; probability of completing planned mission
  3. Time it takes to transport product
  4. Maintainability of given transportation capability; probability of the applicable transportation capability can be repaired within a specified time and resources, in the event of failure
  5. Cost of transportation; or per one-way trip
  6. Life Cycle Cost (LLC) of a given transportation capability for a designated period of time

Inventory system consideration
Overall inventory requirement for spares and repair parts must be addressed, in addition to evaluating specific demand situation.  Thus, an Economic Order Quantity (EOQ) is needed to avoid too the cost/resource utilization of too much inventory, or the lack of supply for demand

Demanufacturing operations

  1. Reuse is the heighest form of waste reduction with potential to increase the product's end-of-life value.  May or may not require total disassembly.  Easily justified in the case of components with high manufacturing costs, long innovation cycles, and long lifetimes.
  2. Remanufacturing is the refurbishing or partially rebuilding of a product returned.  Requires disassembly efforts that contribute to the demanufacturing cost.   Recycled parts may be used for reproducing either the same or different products.
  3. Recovery from products to obtain raw materials or reusable components is an important means of reducing disposal volume and cost.

Lean Manufacturing principles - Manufacturing processes are generalized into: forming, deforming, removing , process, and material properties modification.

  1. Use Gravity - easier with lighter components with up/down movements, with snap fit in vertical slot openings, and so on
  2. Use fewer parts - Increase in total number of parts means increase in design and manufacturing cost.
  3. Design for eas of fabrication - Eliminate part rejection or tolerance failures during assembly by:
    a) Design parts so that tolerances are compatible with the assembly method employed.
    b) fabrication costs are compatible with targeted product costs. 
  4. Reduce nonstandard parts - use of common and standard parts eliminate the development costs with designing and manufacturing
  5. Add more functionality per part - The goal is to accomplish the functions required with fewer parts, or allocate more functions per part (objective of functional analysis and packaging requirement).

Assembly principles

  1. Employ automatic inserters - Specify parts that can be automatically sequenced and inserted using DIP inserters, a variable center device (VCD), axial part inserters, or selective compliance assembly robot arm (SCARA) insertion robots.  If not, minimize setups and reorientation
  2. Employ "preoriented" parts - avoid parts that can not be preoriented (reels, tubes, matrix arrays) for easy insertion.
  3. Minimize sudden and frequent changes in assembly direction - following a unidirectional assembly sequence, such as design for top-down assembly, is usually the most desirable.
  4. Maximize process compliance by designing with standard parts, standard processes, ease of assembly, etc.  Use processes that are easy to install and maintain (i.e. snap fits instead of fastners)
  5. Maximize accessibility - Designers should provide adequate clearances for disassembly or for accessing the part for maintenance or replacement
  6. Minimize handling by a) design parts for ease of feeding (insertion), and b)design parts so that they are easy to grasp, manipulate or orient
  7. Avoid flexible components because they are generally difficult to handle and assemble.