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Manufacturing Systems III. Chris Hicks MMM Engineering Email: [email protected] Assessment. End of year examination 2.5 hours duration Answer 4 questions from 6. Manufacturing Systems III. Manufacturing Strategy JIT Manufacturing Manufacturing Planning and control

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Manufacturing systems iii

Manufacturing Systems III

Chris Hicks MMM Engineering

Email: [email protected]


Assessment
Assessment

  • End of year examination

  • 2.5 hours duration

  • Answer 4 questions from 6


Manufacturing systems iii1
Manufacturing Systems III

  • Manufacturing Strategy

  • JIT Manufacturing

  • Manufacturing Planning and control

  • Company classification

  • Modelling & Simulation

  • Queuing theory (CFE)



Reference

  • Hill, T (1986),”Manufacturing Strategy”, MacMillan Education Ltd., London. ISBN 0-333-39477-1


Manufacturing strategy1
Manufacturing Strategy

  • Long term planning

  • Alignment of manufacturing to satisfy market requirements


Significance of manufacturing
Significance of Manufacturing

  • Manufacturing often responsible for majority of capital and recurrent expenditure

  • Long term nature of many manufacturing decisions makes them of strategic importance

  • Manufacturing can have a large impact on competitiveness


Manufacturing strategy2
Manufacturing Strategy

  • Make / buy

  • Process choice

  • Technology

  • Infrastructure, systems, structures & organisation

  • Focus

  • Integration with other functions


Strategy development
Strategy Development

  • Define corporate objectives

  • Determine marketing strategies to meet these objectives

  • Assess order qualifying and order winning criteria for products

  • Establish appropriate processes

  • Provide infrastructure


Identifying market requirements
Identifying Market Requirements

  • Order Qualifying criteria

  • Order winning criteria

  • Order losing criteria


Manufacturing influences
Manufacturing Influences

  • Costs

  • Delivery

  • Quality

  • Demand flexibility

  • Product range

  • Standardisation / customisation


Profile analysis
Profile Analysis

  • Assess match between market requirements and current performance

  • Identify changes required to manufacturing system


Market requirements
Market Requirements

Unimportant

V Imp.

Price

Quality

Delivery

CofOwn

Customisation

Other factors


Current Performance

Unimportant

V Imp.

Price

Quality

Delivery

CofOwn

Customisation

Other factors


Market requirement

Achieved performance

V Imp.

Unimportant

Price

Quality

Delivery

CofOwn

Customisation

Other factors


Process choice
Process Choice

  • Type of process: project, jobbing, batch,line

  • Flexibility

  • Efficiency

  • Robustness wrt product mix / volume

  • Unique / generic technology?

  • Capital employed

  • How do processes help competitiveness?


Manufacturing structure
Manufacturing Structure

  • Layout: functional or cellular?

  • MTS / MTO

  • Flexibility of workforce

  • Organisation, team working etc.

  • Breakdown of costs

  • HRM issues


Products
Products

  • Relative importance, present and future

  • Mix

  • Complexity

    • Product structure

    • Concurrency

    • Standardisation / customisation

  • Contribution


Measures of performance
Measures of performance

  • What are they?

  • Frequency of measurement

  • Comparison with plan.

  • Orientation: product / process / inventory

  • Integration with other functions


Infrastructure
Infrastructure

  • Manufacturing planning & control

  • Sharing information / knowledge

  • CAD / CAM

  • Accounting systems

  • Quality systems

  • Performance measurement


Case studies
Case studies

  • Heavy engineering

    • PIP teams, simplification, value engineering, cellular manufacturing

  • Automotive supplier

    • “world class” but still relatively low productivity compared with Japanese sister company. Why?


“Manufacturing is a business function rather than a technical function. The emphasis should be on supporting the market” Terry Hill (1996)


Just in time manufacturing

Just-in-Time Manufacturing technical function. The emphasis should be on supporting the market” Terry Hill (1996)


References
References technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • APICS (1987),”APICS Dictionary”, American Production and Inventory Control Society, ISBN 0-935406-90-S

  • Vollmann T.E., Berry W.L. & Whybark D.C. (1992),”Manufacturing Planning and Control Systems (3rd Edition)”, Irwin, USA. ISBN 0-256-08808-X

  • Browne J., Harhen J, & Shivnan J. (1988),“Production Management Systems: A CIM Perspective”,Addison-Wesley, UK, ISBN 0-201-17820-6


Just in time manufacturing1
Just-in-Time Manufacturing technical function. The emphasis should be on supporting the market” Terry Hill (1996)

“In the broad sense, an approach to achieving excellence in a manufacturing company based upon the continuing elimination of waste (waste being considered as those things which do not add value to the product). In the narrow sense, JIT refers to the movement of material at the necessary time. The implication is that each operation is closely synchronised with subsequent ones to make that possible”

APICS Dictionary 1987


Just in time
Just-in-Time technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Arose in Toyota, Japan in 1960s

  • Replacing complexity with simplicity

  • A philosophy, a way of thinking

  • A process of continuous improvement

  • Emphasis on minimising inventory

  • Focuses on eliminating waste, that is anything that adds cost without adding value

  • Often a pragmatic choice of techniques is used


Just in time goals
Just-in-Time Goals technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • “Zero” inventories

  • “Zero” defects

    • Traditional Western manufacturers considered Lot Tolerance Per Cent Defective (LTPD) or Acceptable Quality Levels (AQLs)

  • “Zero” disturbances

  • “Zero” set-up time

  • “Zero” lead time


Just in time goals1
Just-in-Time Goals technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • “Zero” transactions

    • Logistical transactions: ordering, execution and confirmation of material movement

    • Balancing transactions: associated with planning that generates logistical transactions - production control, purchasing, scheduling ..

    • Quality transactions: specification, certification etc.

    • Change transactions: engineering changes etc.

  • Routine execution of schedule day in -day out


Benefits of jit
Benefits of JIT technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Reduced costs

  • Waste elimination

  • Inventory reduction

  • Increased flexibility

  • Raw materials / parts reduction

  • Increased quality

  • Increased productivity

  • Reduced space requirements

  • Lower overheads


Just in time1
Just-in-Time technical function. The emphasis should be on supporting the market” Terry Hill (1996)

JIT links four fundamental areas

  • Product design

  • Process design

  • Human / organisational issues

  • Manufacturing planning and control


Vollmann et al 1992 technical function. The emphasis should be on supporting the market” Terry Hill (1996)


Product design
Product Design technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Design for manufacture

  • Design for assembly

  • Design for automation

  • Design to have flat product structure

  • Design to suit cellular manufacturing

  • Achievable and appropriate quality

  • Standard parts

  • Modular design


Process design
Process Design technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Set-up / lot size reduction

  • Include “surge” capacity to deal with variations in product mix and demand

  • Cellular manufacturing

  • Concentrate on low throughput times

  • Quality is part of the process, autonomation, machines with built in capacity to check parts

  • Continuous quality improvement

  • No stock rooms - delivery to line/cell

  • Flexible equipment

  • Standard operations


Human organisational elements
Human / Organisational Elements technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Whole person concept, hiring people, not just their current skills / abilities

  • Continual training / study

  • Continual learning and improvement

  • Workers capabilities and knowledge are as important as equipment and facilities

  • Workers cross trained to take on many tasks: process operation, maintenance, scheduling, problem solving etc.

  • Job rotation / flexibility

  • Life time employment / commitment?


Organisational elements
Organisational Elements technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Little distinction between direct / indirect labour

  • Activity Based Cost (ABC) accounting

  • Visible team performance measurement

  • Communication / information sharing

  • Joint commitment


Jit techniques
JIT Techniques technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Manufacturing techniques

  • Production and material control

  • Inter-company JIT

  • Organisation for change


Manufacturing techniques
Manufacturing Techniques technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Cellular manufacturing

  • Set-up time reduction

  • Pull scheduling

  • Smallest machine concept

  • Fool proofing (Pokayoke)

  • Line stopping (Jikoda)

  • I,U,W shaped material flow

  • Housekeeping


Group technology cellular manufacturing
Group Technology / Cellular Manufacturing technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Improved material flow

  • Reduced queuing time

  • Reduced inventory

  • Improved use of space

  • Improved team work

  • Reduced waste

  • Increased flexibility


Set up time reduction
Set-up Time Reduction technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Single minute exchange of dies (SMED) - all changeovers < 10 mins.

    1. Separate internal set-up from external set-up. Internal set-up must have machine turned off.

    2. Convert as many tasks as possible from being internal to external

    3. Eliminate adjustment processes within set-up

    4. Abolish set-up where feasible

    Shingo, S. (1985),”A Revolution in Manufacturing: the SMED System”, The Productivity Press, USA.


Basic steps in a traditional set up operation
Basic Steps in a Traditional Set-up Operation technical function. The emphasis should be on supporting the market” Terry Hill (1996)

1. Preparation, after process adjustments, checking of materials and tools (30%).

2. Mounting and removing blades, tools and parts (5%) Generally internal.

3. Measurements, settings and calibration (15%) includes activities such as centring, dimensioning, measuring temperature or pressure etc.

4. Trial runs and adjustments (50%) - SMED

Typical proportion of set-up time given in parenthesis.


Set up analysis
Set-up Analysis technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Video whole set-up operation. Use camera’s time and date functions

  • Ask operators to describe tasks. As group to share opinions about the operation.


Three stages of smed
Three Stages of SMED technical function. The emphasis should be on supporting the market” Terry Hill (1996)

1. Separating internal and external set-up

doing obvious things like preparation and transport while the machine is running can save 30-50%.

2.Converting internal set-up to external set-up

3. Streamlining all aspects of the set-up operation


Separating internal and external set up
Separating Internal and External Set-up technical function. The emphasis should be on supporting the market” Terry Hill (1996)


Andon
ANDON technical function. The emphasis should be on supporting the market” Terry Hill (1996)

A board which shows if any operator on the line has difficulties

  • Red - machine trouble

  • White - end of a production run

  • Blue - defective unit

  • Yellow - set-up required

  • Line-stop - all operators can stop the line to ensure compliance with standards

  • Flexible workers help each other when problems arise


Jit material control
JIT Material Control technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Pull scheduling

  • Line balancing

  • Schedule balance and smoothing (Heijunka)

  • Under capacity scheduling

  • Visible control

  • Material Requirements Planning

  • Small lot & batch sizes


Pull systems
“Pull” Systems technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Work centres only authorised to produce when it has been signalled that there is a need from a user / downstream department

  • No resources kept busy just to increase utlilisation

    Requires:

  • Small lot-sizes

  • Low inventory

  • Fast throughput

  • Guaranteed quality


Pull systems1
Pull Systems technical function. The emphasis should be on supporting the market” Terry Hill (1996)

Implementations vary

  • Visual / audio signal

  • “Chalk” square

  • One / two card Kanban


Material requirements planning jit
Material Requirements Planning / JIT technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Stable Master Production Schedule

  • Flat bills of materials

  • Backflushing

  • Weekly MRP quantities with “call off” , a common approach


Jit purchasing
JIT Purchasing technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • JIT purchasing requires predictable (usually synchronised) demand

  • Single sourcing

  • Supplier quality certification

  • Point of use delivery

  • Family of parts sourcing

  • Frequent deliveries of small quantities

  • Propagate JIT down supply chain, suppliers need flexibility

  • Suppliers part of the process vs. adversarial relationships


Jit purchasing1
JIT Purchasing technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Controls and reduces inventory

  • Reduces space

  • Reduces material handling

  • Reduces waste

  • Reduces obsolescence


Organisation for change
Organisation for Change technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Multi-skilled team working

  • Quality Circles, Total Quality Management

  • Philosophy of joint commitment

  • Visible performance measurement

    • Statistical process control (SPC)

    • Team targets / performance measurement

  • Enforced problem solving

  • Continuous improvement


Total quality management tqm
Total Quality Management (TQM) technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Focus on the customer and their requirements

  • Right first time

  • Competitive benchmarking

  • Minimisation of cost of quality

    • Prevention costs

    • Appraisal costs

    • Internal / external failure costs

    • Cost of exceeding customer requirements

  • Founded on the principle that people want to own problems


Jit flexibility
JIT Flexibility technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Set-up time reduction

  • Small transfer batch sizes

  • Small lot sizes

  • Under capacity scheduling

  • Often labour is the variable resource

  • Smallest machine concept


Reducing uncertainty
Reducing Uncertainty technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Total Preventative Maintenance (TPM) / Total Productive Maintenance

  • 100% quality

  • Quality is part of the process - it can’t be inspected in

  • Stable and uniform schedules

  • Supplier quality certification


Total preventative maintenance tpm
Total Preventative Maintenance (TPM) technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Strategy to prevent equipment and facility downtime

  • Planned schedule of maintenance checks

  • Routine maintenance performed by the operator

  • Maintenance departments train workers, perform maintenance audits and undertake more complicated work


Implementation of jit
Implementation of JIT technical function. The emphasis should be on supporting the market” Terry Hill (1996)


Implementation of jit1
Implementation of JIT technical function. The emphasis should be on supporting the market” Terry Hill (1996)

Method:

1. Lower inventory levels

2. Identify problems

3. Eliminate problems

4. Improve use of resources

  • Inventory

  • People

  • Capital

  • Space

    5. Go back to step 1


Jit circle
JIT Circle technical function. The emphasis should be on supporting the market” Terry Hill (1996)

Standardisation

Design - focus

TPM

JIT Purchasing

TQM

Visibility

JIT

Set-up

reduction

Pull scheduling

Multi-skill

Workforce

Plant

Layout

Small machines


Jit limitations
JIT Limitations technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Stable regular demand

  • Medium to high volume

  • Requires cultural change

  • Implementation costs


Computer aided production management systems capm

Computer Aided Production Management Systems (CAPM) technical function. The emphasis should be on supporting the market” Terry Hill (1996)


References1
References technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Vollmann T.E., Berry W.L. & Whybark D.C. (1992),”Manufacturing Planning and Control Systems (3rd Edition)”, Irwin, USA. ISBN 0-256-08808-X

    (Earlier editions just as good!)

  • Browne J., Harhen J, & Shivnan J. (1988),“Production Management Systems: A CIM Perspective”,Addison-Wesley, UK, ISBN 0-201-17820-6


Computer aided production management capm systems
Computer Aided Production Management (CAPM) Systems technical function. The emphasis should be on supporting the market” Terry Hill (1996)

“All computer aids supplied to the manager”

  • Specification - ensuring that the manufacturing task has been defined and instructions provided

  • Planning and control - scheduling, adjusting resource usage and priorities, controlling the production activity

  • Recording and reporting the status of production and performance


Computer aided production management capm systems1
Computer Aided Production Management (CAPM) Systems technical function. The emphasis should be on supporting the market” Terry Hill (1996)

Information systems responsible for:

  • Transaction processing - maintaining, updating and making available specifications, instructions and production records

  • Management information - for exercising judgements about the use of resources and customer priorities

  • Automated decision making - producing production decisions using algorithms


Capm systems
CAPM Systems technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Planning

  • Control

  • Performance measurement


Planning modules
Planning Modules technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Master Production Scheduling (MPS) - high level production plan in terms of quantity, timing and priority of planned production

  • Materials Requirements Planning (mrp) / Manufacturing Resources Planning (MRP)

  • Capacity Planning


Control modules
Control Modules technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Inventory control - keeping raw material, work in process (WIP) and finished goods stocks at desired levels

  • Shop floor control (Production Activity Control) - transforming planning decisions into control commands for the production process

  • Vendor measurement - measuring vendors’ performance to contract, covering delivery, quality and price


Material requirements planning mrp
Material Requirements Planning (mrp) technical function. The emphasis should be on supporting the market” Terry Hill (1996)

“Material requirements plannning originated in the 1960s as a computerised approach for planning of materials acquisition for production. These early applications were based upon a bill of materials processor which converted demand for parent items into demand for component parts. This demand was compared with available inventory and scheduled receipts to plan order releases” Browne et al (1986)


Manufacturing resources planning mrp
Manufacturing Resources Planning (MRP) technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • The combination of planning and control modules was termed “closed loop MRP”. With the addition of financial modules an integrated approach to the management of resources was created. This was termed Manufacturing Resources Planning.

  • Material Requirements Planning (mrp / MRPI)

  • Manufacturing Resources Planning (MRP/MRPII)


Material requirements planning
Material Requirements Planning technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Dependant demand

  • Time phased planning

    Inputs

  • Master Production Schedule

  • Bill of Materials

  • Inventory status

    Assumptions

  • Infinite capacity

  • Fixed lead times

  • Fixed and predetermined product structure


Mrp record card
MRP Record Card technical function. The emphasis should be on supporting the market” Terry Hill (1996)


Mrp conventions
MRP Conventions technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • MRP time buckets

  • Scheduled receipts at start of period

  • Projected available balance at end of period

  • Planned order releases at the start of period

  • Planned orders vs. scheduled receipts

  • Number of buckets = planning horizon


Representation of product
Representation of Product technical function. The emphasis should be on supporting the market” Terry Hill (1996)


Linked mrp cards
Linked MRP Cards technical function. The emphasis should be on supporting the market” Terry Hill (1996)


Backwards scheduling
Backwards Scheduling technical function. The emphasis should be on supporting the market” Terry Hill (1996)


Forwards scheduling
Forwards Scheduling technical function. The emphasis should be on supporting the market” Terry Hill (1996)


Mrp domain
MRP Domain technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Steady state systems

  • Low levels of uncertainty

  • Shallow / medium or deep product structure

  • Stable demand

  • Predominantly make to stock

  • Manufacturing orientation


Mrp parameters
MRP Parameters technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Planning horizon

  • Size of time bucket

  • Lot sizing rules

  • Regeneration vs.. net change


Validity of mrp assumptions
Validity of MRP Assumptions technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Infinite capacity vs. capacity planning

  • Fixed lead times / varying load

  • “Lead times are a result of the schedule”

  • Integration of planning levels requires feasibility at high and low levels


Typical control parameters
Typical Control Parameters technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Safety stock

  • Safety lead time

  • Yield

  • Order quantity category

  • Min/max order levels

  • Max. days supply

  • Min. days between orders


Lot sizing
Lot sizing technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Lot-for-lot

  • Economic Order Quantity (EOQ)

  • Complex optimisation algorithms


Uncertainties in mrp
Uncertainties in MRP technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Environmental uncertainty

    • Customer orders

    • Suppliers

  • System uncertainty

    • Product quality

    • Scrap / rework

    • Process times

    • Design changes

  • MRP nervousness / instability


Dealing with uncertainty in mrp
Dealing with uncertainty in MRP technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Safety stocks

  • Safety lead times

  • Safety due date

  • Hedging

  • Over-planning

  • Yield factors


Appropriate approaches
Appropriate approaches technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Timing uncertainty: safety lead time

  • Quantity uncertainty: safety stock


Mrp nervousness
MRP Nervousness technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Significant changes in plans due to minor changes in high level plans

  • Frequent changes in plans make the MRP system lose crdibility


Causes of nervousness
Causes of Nervousness technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Demand uncertainty

  • Product structure characteristics

  • Incorrect lot-sizing rules


Nervousness solutions
Nervousness: Solutions technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Stable MPS

  • Carefully change any parameter changes

  • Use different lot sizing rules at the high and low levels of the product structure


Mrp problems
MRP Problems technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Quality of the model

  • Bill of materials structure

  • Non-material activities

  • Validity of the assumptions

  • Lack of 2 way time analysis

  • Quality of data

  • Regeneration / computational effort

  • Poor visibility

  • Operational aspects


How to implement mrp
How to implement MRP technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Get accurate data

  • Make sure you have accurate data

  • Have good procedures to make sure that the data is always accurate

  • Remember approximately 75% of MRP implementations fail

  • Unsuccessful MRP costs nearly the same as successful MRP


Capacity planning

Capacity Planning technical function. The emphasis should be on supporting the market” Terry Hill (1996)


References2
References technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Vollmann T.E., Berry W.L. & Whybark D.C. (1992),”Manufacturing Planning and Control Systems (3rd Edition)”, Irwin, USA. ISBN 0-256-08808-X

  • Plossl G.W. & Wight O.W. (1973), “Capacity Planning and Control”, Production and Inventory Management, 3rd quarter 1973 pp31-67


Capacity planning1

Capacity Planning technical function. The emphasis should be on supporting the market” Terry Hill (1996)

“The function of establishing, measuring and adjusting limits or levels of capacity.

Capacity planning in this context is the process of determining how much labour and machine resources are required to accomplish the tasks of production.

Open shop orders and planned orders in the MRP system are input to CRP which “translates” these into hours of work, by work centre, by time period”

APICS Dictionary 1987


Capacity planning2
Capacity Planning technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Plossl bath tub

  • Lead-time = queuing time + set-up time + processing time + transfer time

  • Queuing time is dependant upon the level of backlog in the system

  • Three reasons why queues go out of control

    • Inadequate capacity

    • Erratic input

    • Inflated lead time estimates


Plossl bath tub
Plossl Bath Tub technical function. The emphasis should be on supporting the market” Terry Hill (1996)


Lead time syndrome
Lead-time Syndrome technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Vicious circle which can occur when queuing conditions change

  • Increased demand may increase backlog

  • Increased backlog increases demand

  • If the planned lead times are changed, more orders are likely to arrive to meet requirements during the increased lead time.

  • This further inflates lead times etc. etc.


Capacity control
Capacity Control technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Input-output control: ensure that the demand never exceeds capacity

  • In MTO, backlogs act as buffers against workload variations. In this case it’s a trade off between maintaining resource utilisation and minimising lead-times and inventory


Capacity planning approaches
Capacity Planning Approaches technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Infinite loading: assume infinite capacity, disregarding capacity constraints

  • Finite loading: work to capacity constraints


Infinite loading
Infinite Loading technical function. The emphasis should be on supporting the market” Terry Hill (1996)

Backlog


Finite loading
Finite Loading technical function. The emphasis should be on supporting the market” Terry Hill (1996)


Infinite loading1
Infinite Loading technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Easier - less computation required

  • Identifies and measures scheduled over and under loads

  • Shows how much capacity is required to meet the plan (finite loading does not)


Finite loading1
Finite Loading technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Capacity of each resource specified in terms of “standard” and “maximum” capacity

  • Jobs loaded onto each work centre in priority order

  • When resources are “full”, jobs are rescheduled

  • Horizontal vs. vertical loading

  • The only way to revise a finite loading schedule is to start from scratch, rearranging jobs in a new priority sequence


Capacity planning3
Capacity Planning technical function. The emphasis should be on supporting the market” Terry Hill (1996)

“A prerequisite to having an effective capacity planning system is to have an effective priority planning system.

If the due dates, or lead times are incorrect, the schedule, the priorities and the projection of when the load will hit the resources will be fiction. The system will not work”

Plossl & Wight 1973


5 levels of capacity planning
5 Levels of Capacity Planning technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Resource planning: highly aggregated, longest term level of capacity planning

  • Rough-cut capacity planning: uses MPS data

  • Capacity Requirements Planning (CRP)

  • Finite loading

  • Input / output control


Rough cut capacity planning
Rough-cut Capacity Planning technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Capacity Planning Using Overall Factors (CPOF) calculates the overall direct labour requirements for the MPS and identifies load based upon historic data

  • Capacity Bills, uses BOM and planning data

  • Resource profiles, same as capacity bills, but time phased

  • See Vollmann et al for details


Capacity requirements planning
Capacity Requirements Planning technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • CRP utilises MRP information such as lot sizing and inventory data

  • Shop floor control provides information of the current status of items: only the capacity required to complete items is considered

  • CRP is based upon the infinite loading approach


Company classification

Company Classification technical function. The emphasis should be on supporting the market” Terry Hill (1996)


References3
References technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Woodward J. (1965), “Industrial Organisation: Theory and Practice”, Oxford University Press, England

  • New C.C. (1976), “Managing Manufacturing Operations”, British Institute of Management, Report No. 35.

  • Barber K.D. & Hollier R.H. (1986),”The Effects of Computer Aided Production Management Systems on Defined Company Types”, Int. J. Prod. Res. 24(2) pp311-327


References4
References technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Barber K.D. & Hollier R.H. (1986),”The Use of Numerical Taxonomy to Classify Companies According to Production Control Complexity”, Int. J. Prod. Res. 24(1) pp203-22


Company Classification technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Classification groups “like” items together

  • Dependent upon classification variables

  • Enables similarities and differences between companies to be identified

  • Identify appropriate planning & control method

  • Identify appropriate technology


Classification Approaches technical function. The emphasis should be on supporting the market” Terry Hill (1996)

General company classification

  • Joan Woodward (1965) used Ministry of Labour categories for investigating organisational structure issues

  • Sector based classification commonly used by financial institutions (e.g. FT classification)

  • DTI - SMEs

    Classification of manufacturing

  • Mode of production e.g. Burbidge (1971), volume of production jobbing, batch, flow

  • Goldratt (1980) VAT analysis based upon pattern of material flow

  • Production control complexity New (1976), Barber & Hollier (1986)


Colin new classification
Colin New Classification technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Survey of 186 companies to investigate manufacturing management practice

    Five classification areas:

  • Market - customer environment

    Relationship between cumulative lead time and delivery lead time e.g. make to stock or

    make to order

  • Product range and rate of product innovation

  • Product complexity - number of components per product, depth of product structure

  • Organisation of manufacturing system, functional vs. group layout

  • Cost structure of products


Market customer environment
Market / Customer Environment technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Make to stock v/s make to order

  • Marucheck & McClelland (1986)

    Continuum from pure ETO - pure MTS

  • Positioning of company usually a strategic issue

  • Effects competitive factors - customisation vs. lead time and cost

  • Position effects inventory

  • Hicks (1994) Business process based description


Product complexity
Product Complexity technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Depth of product structure

    effects co-ordination of assembly processes (phasing), uncertainties, lead times etc.

  • Number of components in product

  • Source of components (make / buy)

  • Standardisation / modular design vs. pure ETO

  • Concurrent engineering also increases control complexity


Organisational structure
Organisational Structure technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Type of layout (process / cellular)

  • Management style

  • Company culture

  • Flexibility


Barber hollier 1986
Barber & Hollier (1986) technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Worked aimed establish suitability of computer aided production management techniques for different types of company

  • Based upon production control complexity

  • Developed work of Colin New (1976)

  • Used numerical taxonomy to identify clusters of common companies

  • Work identified 6 groups of company


Chris voss 1987
Chris Voss (1987) technical function. The emphasis should be on supporting the market” Terry Hill (1996)


Modelling simulation

Modelling & Simulation technical function. The emphasis should be on supporting the market” Terry Hill (1996)


References5
References technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Kreutzer W. (1986), “System Simulation: Programming Languages and Styles”, Addison-Wesley

    ISBN 0-201-12914-0

  • Mitrani I (1982),”Simulation Techniques for Discrete Event Systems”, Cambridge University Press

    ISBN 0-521-23885-4


Modelling
Modelling technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Systems identification

  • System representation

  • Model design

  • Model coding

  • Validation

    (last two points relate to simulation modelling)


Types of model
Types of Model technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Iconic models: e.g. a globe is an iconic model of the earth

  • Analytical models: general solutions to families of problems based upon some strong theory (close form solutions)

  • Analytical models: represent systems through some abstract notion of similarity

  • Symbolic models: use of symbols to describe objects, relationships, actions and processes

    Churchman 1959


  • Induction: technical function. The emphasis should be on supporting the market” Terry Hill (1996)“deducing a general principle from particular instances”

  • Deduction: “deducing a particular instance from a general law”


Descriptive model
Descriptive Model technical function. The emphasis should be on supporting the market” Terry Hill (1996)

“Descriptive models offer some symbolic representation of some problem space without any guidance on how to search it. The use of descriptive models is an inductive, experimental technique for exploring possible worlds”

Kreutzer 1986


Simulation
Simulation technical function. The emphasis should be on supporting the market” Terry Hill (1996)

“The term simulation is used to describe the exploration of a descriptive model under a chosen experimental frame”

Kreutzer 1986

“Simulation is partly art, partly science. The art is that of programming: a simulation should do what is intended. One should also know how to answer questions about the system being simulated”

Mitrani 1982


Limitations of simulation
Limitations of Simulation technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • Expensive in terms of manpower and computing

  • Often difficult to validate

  • Often yields sub-optimum results

  • Iterative problem solving technique

  • Collection, analysis and interpretation of results requires a good knowledge of probability and statistics

  • Difficult to convince others

  • Often a method of last resort


When to use simulation
When to use Simulation technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • The real system does not exist, or it is expensive, time consuming, hazardous or impossible to experiment with prototypes

  • Need to investigate past, present and future performance in compressed, or expanded time.

  • When mathematical modelling is impossible or they have no solutions

  • Satisfactory validation is possible

  • Expected accuracy meets requirements


Simulation methodology
Simulation Methodology technical function. The emphasis should be on supporting the market” Terry Hill (1996)

  • System identification

  • System Representation

  • Model design

  • Data collection and parameter estimation

  • Program design

  • Program implementation

  • Program verification

  • Model validation

  • Experimentation

  • Output analysis


System Identification technical function. The emphasis should be on supporting the market” Terry Hill (1996)

“A system is defined as a collection of objects, their relationships and behaviour relevant to a set of purposes, characterising some relevant part of reality”

Kreutzer (1986)


System Representation technical function. The emphasis should be on supporting the market” Terry Hill (1996)

“Symbolic images of objects, relationships and behaviour patterns are bound into structures as part of some larger framework of beliefs, background assumptions and theories of the problem solver”

Kreutzer 1986


Model Design technical function. The emphasis should be on supporting the market” Terry Hill (1996)

“A model is an appropriate representation of some mini-world. Models can very quickly grow to form very complicated structures. Control and the constraint of complexity lie at the heart of any modelling activity. Care must be exercised to preserve only those chracteristics that are essential. This depends upon the purpose of the model”

Kreutzer 1986


“It is necessary to abstract from the real system all those components (and their interactions that are considered to be important”

Mitrani 1982


Model Coding those components (and their interactions that are considered to be important”

“This stage exists when computers are being used as the modelling medium. This stage seeks a formal representation of symbolic structures and their transformations into data structures and computational procedures in some programming language”

Kreutzer 1986


Types of simulation model
Types of Simulation Model those components (and their interactions that are considered to be important”

  • Monte Carlo

  • Quasi-continuous

  • Discrete event

  • Combined simulation


Monte carlo simulation
Monte Carlo Simulation those components (and their interactions that are considered to be important”

  • Derives name from roulette

  • Static simulation

  • Distribution sampling

  • No assumptions about model

  • Only statistical correlation between input and output explored

  • Results often summarised in frequency tables

  • Used for complex phenomena that are not well understood, or too complicated and expensive to produce other models


Quasi continuous simulation
Quasi- Continuous Simulation those components (and their interactions that are considered to be important”

“Dynamic simulation. The clock is sequenced by a clock in uniform fixed length intervals. The size of the increment determines the resolution of the model”

Kreutzer 1986


Discrete event simulation
Discrete Event Simulation those components (and their interactions that are considered to be important”

  • Asynchronous clock

  • Assumes nothing interesting happens between events

  • Queuing networks in which the effects of capacity limitations and routing strategies often studied using DES

  • This type of simulation most frequently used for simulating manufacturing systems


Types of discrete event simulation
Types of Discrete Event Simulation those components (and their interactions that are considered to be important”

  • Event scheduling

  • Process interaction

  • Object orientated

  • Activity scanning


Event scheduling approach
Event Scheduling Approach those components (and their interactions that are considered to be important”

  • Event scheduling binds actions associated with individual events into event routines.

  • The monitor selects event for execution, processing a time ordered agenda event notices.

  • Event notices contain a time and a reference to an event routine.

  • Each event can schedule another event, which is placed in the correct position of the agenda.

  • The clock is always set to the time of the next immanent event”


Process interaction approach
Process Interaction Approach those components (and their interactions that are considered to be important”

  • Focuses on the flow of entities through the model

  • Views system as concurrent, interacting processes

  • Life cycle for each class of entities

  • Monitor uses agenda to keep track of pending tasks

  • Monitor records activation times, process identities and state that the process was last suspended


Object orientated programming
Object Orientated Programming those components (and their interactions that are considered to be important”

  • Process records the values of all local variables

  • Object contains, attributes (data), activities (processes) and lifecycle

  • Communication between objects only through well defined interfaces provided by messages which an object is programmed to respond to

  • Classes / sub classes

  • Instances

  • Inheritance


Activity scanning approach
Activity Scanning Approach those components (and their interactions that are considered to be important”

  • Each event is specified in terms of the conditions that need to apply for the event to start and finish

  • Each event has a set of actions that take place when it finishes

  • Model execution is cyclic, scanning all activities in the model testing which can start / finish.

  • Clock only moves when whole cycle leaves status unchanged

  • 3 phase structure computationally expensive

  • “Conditional Sequencing” since programmer only states start and end conditions


Types of simulation
Types of Simulation those components (and their interactions that are considered to be important”

  • Deterministic - no random component

  • Stochastic - represents uncertainties


Stochastic simulation
Stochastic Simulation those components (and their interactions that are considered to be important”

  • Sampling experiments

  • Standard statistical approaches such as design of experiments used

  • Random processes based upon pseudo random number generators


Pseudo random number generators
Pseudo-Random Number Generators those components (and their interactions that are considered to be important”

  • Seed based: algorithm produces “random” number from seed. Repeated execution gives same streams of random numbers

  • Non-seed based, random number generated using time, or status of computer


Validation
Validation those components (and their interactions that are considered to be important”

Model qualification

CONCEPTUAL

Analysis

REALITY

MODEL

Programming

Computer

Simulation

Model

Model

verification

validation

Computer

Model


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