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Unit 3 of 4 · MBA Sem 4

Unit 3: Routing, scheduling and dispatching

Production Planning and Control notes · PTU syllabus (MBA 955-26)

3 min read6 topics10 exam questions
On this page
  1. Unit summary
  2. Routing and route sheets
  3. Bill of materials
  4. Scheduling policies and techniques
  5. Dispatching procedures
  6. Progress reporting and expediting
  7. Correcting schedule deviations
  8. Key terms
  9. Quick revision
  10. Important questions

Unit summary

Routing, scheduling and dispatching put the plan into action on the shop floor. This unit covers the routing procedure and route sheets, bills of material, scheduling policies and techniques for job shops and flow shops, dispatching procedures, progress reporting and expediting, and correcting schedule deviations.

After this unit you can

  • Explain routing and prepare route sheets and BOMs
  • Apply job shop and flow shop scheduling techniques
  • Explain dispatching procedures
  • Explain progress reporting, expediting and correcting deviations

PTU syllabus topics

  • Routing procedure and route sheets
  • bill of material
  • scheduling policies and techniques (job shop, flow shop)
  • dispatching procedures
  • progress reporting and expediting
  • correcting schedule deviations
ProcessRouting, scheduling and dispatching
  1. 1Routing

    Decide the path and sequence

  2. 2Scheduling

    Decide when each job runs

  3. 3Loading

    Assign work to machines

  4. 4Dispatching

    Release work orders

  5. 5Expediting

    Follow up and fix delays

1

Topic 1

Routing and route sheets

  • Routing: determining the path and sequence of operations a product follows.
ProcessRouting procedure
  1. 1

    Analyse the product into parts

  2. 2

    Make or buy decision for each part

  3. 3

    Determine operations and sequence

  4. 4

    Select machines and work centres

  5. 5

    Estimate times

  6. 6

    Prepare route sheets

  • Route sheet: shows for each part the operation sequence, work centres, set-up and run times — travels with the job.
2

Topic 2

Bill of materials

  • BOM: structured list of all components and quantities needed to make one unit of a product.
ClassificationBOM levels for a chair
Chair (level 0)

  • Seat assembly (level 1)

    Seat board, cushion, fabric

  • Back assembly (level 1)

    Back frame, cushion

  • Legs (level 1)

    4 legs

  • Fasteners (level 1)

    Screws, brackets

  • Uses: MRP explosion, costing, purchasing, assembly instructions.
3

Topic 3

Scheduling policies and techniques

ComparisonPriority rules for job shops
Rule
Effect

FCFS

First come, first served

Fair but ignores due dates

SPT

Shortest processing time first

Minimises average flow time and WIP

EDD

Earliest due date first

Minimises maximum lateness

CR

Critical ratio = time to due date ÷ work remaining

Prioritises jobs most behind schedule

  • Forward vs backward scheduling: from the start date onward, or from the due date backwards.
  • Flow shop scheduling — Johnson's rule (n jobs, 2 machines): pick the smallest time; if it is on machine 1 schedule that job first, if on machine 2 schedule it last; repeat.

Example

Jobs A (3, 6), B (5, 2), C (1, 4), D (6, 6) on machines 1 and 2: C first (1 on M1), B last (2 on M2), then A next (3 on M1), D remaining — sequence C–A–D–B.

  • Gantt charts show load and progress by machine.
4

Topic 4

Dispatching procedures

  • Dispatching: releasing orders and authorising work to start as scheduled.
  • Activities: issue job cards, route sheets and drawings; release materials and tools from stores; assign work to machines; record start and finish times.
  • Centralised vs decentralised dispatching.
5

Topic 5

Progress reporting and expediting

  • Progress reporting: comparing actual progress with schedule using job cards, production reports, shop-floor data collection, MES dashboards.
  • Expediting (follow-up): chasing delayed materials and jobs, removing bottlenecks, coordinating departments.
6

Topic 6

Correcting schedule deviations

  • Causes: machine breakdowns, material shortages, absenteeism, rework, rush orders, poor estimates.
  • Corrective actions: overtime, alternate routing, splitting lots, subcontracting, rescheduling priorities, preventive maintenance, revising the MPS.

Key terms

Routing
Path and sequence of operations
Bill of materials
Structured list of components for a product
SPT rule
Scheduling shortest jobs first
Johnson's rule
Sequencing rule for two-machine flow shops
Expediting
Following up to keep work on schedule

Quick revision

  • Routing procedure; route sheets.
  • BOM levels and uses.
  • FCFS, SPT, EDD, CR; forward and backward scheduling; Johnson's rule; Gantt charts.
  • Dispatching activities.
  • Progress reporting, expediting, corrective actions.

Important exam questions

Practice questions written to the PTU exam pattern for this unit's syllabus: short answers (Section A style) and long answers (Sections B and C style).

Short-answer questions

  1. Q1.What is routing?
  2. Q2.What is a bill of materials?
  3. Q3.Which rule minimises average flow time?
  4. Q4.State Johnson's rule.
  5. Q5.What is dispatching?
  6. Q6.Give three causes of schedule deviations.

Long-answer questions

  1. Q1.Explain the routing procedure and the use of route sheets and BOMs.
  2. Q2.Explain scheduling policies and techniques for job shops and flow shops.
  3. Q3.Sequence jobs using Johnson's rule (numerical).
  4. Q4.Explain dispatching, progress reporting and correcting schedule deviations.

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