Industrial Engineering and Operations Management for SSC JE Mechanical: Work Study, EOQ, Forecasting, Quality Control and Plant Layout
Rahul Kumar
SSC Exam Expert & Content Editor
In this note
- 1.Scientific Management
- 2.Work Study
- 3.Inventory Control
- 4.Forecasting
- 5.Plant Layout
- 6.Quality Management
- 7.Break-Even Analysis
- 8.Operations Research
- 9.Solved Examples
- 10.Quick Tips
- 11.Quick Revision Points
- 12.Practice Questions With Answers
- 13.How to Practise This Chapter
- 14.Frequently Asked Questions
PDF Notes: Industrial Engineering and Operations Management for SSC JE Mechanical: Work Study, EOQ, Forecasting, Quality Control and Plant Layout
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Industrial engineering and operations management make up an important topic of SSC JE Mechanical and appear every year with formula-based questions. This guide on industrial engineering and operations management for SSC JE covers work study, inventory control with the EOQ formula, forecasting, plant layout, quality control, the break-even point and operations research, with solved examples, practice questions and FAQs.
Scientific Management
- F. W. Taylor is the father of scientific management; Henri Fayol gave 14 principles of management; the Gilbreths studied motion (therbligs); Henry Gantt developed the Gantt chart.
- Functions of management: planning, organising, directing (staffing and leading) and controlling.
- Types of production: job, batch, mass (flow) and continuous (process) production.
Work Study
| Part | Details |
|---|---|
| Method study (motion study) | Finds the best method of doing a job; tools: flow process chart, flow diagram, man–machine chart, micro-motion study; the steps are select, record, examine, develop, define, install and maintain |
| Work measurement (time study) | Measures the time taken by a qualified worker to do a job at a defined level of performance; techniques are stop watch time study, work sampling, predetermined motion time systems (PMTS) and synthesis |
- Normal time = observed time × (rating factor / 100).
- Standard time = normal time + allowances (personal, fatigue and delay allowances).
- A therblig is a basic element of motion (such as grasp, move, position and release).
- The Rating factor compares the observed speed of the worker with the normal speed; 100% is the normal.
Inventory Control
| Term or Formula | Meaning |
|---|---|
| Economic Order Quantity (EOQ), Wilson’s formula | EOQ = √(2DS / H), where D is the annual demand, S is the ordering cost per order and H is the holding (carrying) cost per unit per year |
| Number of orders per year | D / EOQ |
| Total inventory cost at EOQ | Ordering cost = holding cost |
| Reorder level | Lead time demand + safety stock |
| Safety (buffer) stock | Extra stock to protect against uncertainty |
| ABC analysis | A items: high value, about 10–20% of the items and 70–80% of the value; C items: low value and many in number |
| VED analysis | Vital, Essential and Desirable items |
| FSN analysis | Fast, slow and non-moving items |
| MRP (Material Requirement Planning) | Computerised system for the planning of the dependent demand items |
| JIT (Just in Time) | Materials arrive just when they are needed; Toyota production system; Taiichi Ohno; uses Kanban cards |
Forecasting
- Qualitative methods: Delphi method, market research and expert opinion; quantitative methods: moving average and exponential smoothing.
- Simple moving average = the average of the last n periods.
- Exponential smoothing: Ft+1 = α Dt + (1 − α) Ft, where α is the smoothing constant (between 0 and 1); a larger α gives more weight to the recent data.
- Forecast error = actual demand − forecast; MAD (mean absolute deviation) measures the accuracy.
Plant Layout
| Layout | Features |
|---|---|
| Product (line) layout | Machines are arranged in the order of the operations; for mass production; low material handling cost |
| Process (functional) layout | Similar machines are grouped together; for job and batch production; flexible |
| Fixed position layout | The product stays in one place and the machines and workers move to it; ships, aircraft, bridges |
| Cellular (group technology) layout | Machines are grouped in cells to produce a family of parts |
Quality Management
- Quality control tools: check sheet, histogram, Pareto chart (80/20 rule), cause-and-effect (fishbone or Ishikawa) diagram, scatter diagram, control charts and flow charts.
- Control charts (Shewhart): X-bar and R charts for variables (measurements), and p, np, c and u charts for attributes (defectives and defects). The limits are at ±3σ.
- TQM (Total Quality Management): continuous improvement; Deming (PDCA cycle: plan, do, check, act), Juran (fitness for use) and Crosby (zero defects).
- Six Sigma: a quality target of 3.4 defects per million opportunities; DMAIC (define, measure, analyse, improve, control).
- Kaizen means continuous improvement (Japanese); 5S: sort, set in order, shine, standardise and sustain.
- ISO 9000 is a series of quality management standards.
- Process capability index Cp = (USL − LSL)/6σ.
Break-Even Analysis
- Break-even point (units) = fixed cost / (selling price per unit − variable cost per unit) = fixed cost / contribution per unit.
- Contribution = selling price − variable cost; margin of safety = actual sales − break-even sales.
- Profit – volume (P/V) ratio = contribution / sales.
Operations Research
| Technique | Notes |
|---|---|
| Linear programming (LP) | Optimises a linear objective under linear constraints; the graphical method for two variables; the simplex method for more |
| Transportation problem | Minimises the cost of moving goods from sources to destinations; the initial solution by North-West Corner, Least Cost or Vogel’s Approximation Method (VAM); the optimal solution by MODI (u–v) method |
| Assignment problem | Assigns jobs to workers at the minimum cost; the Hungarian method |
| Queuing theory | Analysis of waiting lines |
| Game theory | Decision making with competitors |
| PERT and CPM | Project scheduling |
Solved Examples
Example 1. The annual demand is 1,200 units, the ordering cost is 100 rupees per order and the holding cost is 6 rupees per unit per year. Find the EOQ.
EOQ = √(2 × 1200 × 100 / 6) = √40,000 = 200 units; the number of orders = 1200/200 = 6.
Example 2. The fixed cost is 60,000 rupees, the selling price is 50 rupees and the variable cost is 30 rupees per unit. Find the break-even point.
60,000/(50 − 30) = 3,000 units.
Example 3. The observed time for a job is 2 minutes with a rating of 110%, and the allowances are 10% of the normal time. Find the standard time.
Normal time = 2 × 1.10 = 2.2 min; standard time = 2.2 × 1.10 = 2.42 min.
Example 4. If the forecast for a period was 100 units, the actual demand was 120 units and α = 0.2, find the forecast for the next period.
F = 0.2 × 120 + 0.8 × 100 = 104 units.
Quick Tips
- Memorise the EOQ formula and the break-even formula.
- Remember the definitions of normal time and standard time.
- Learn the layouts with their suitable production type.
- Remember the Six Sigma figure of 3.4 defects per million.
Quick Revision Points
- EOQ = √(2DS/H).
- Standard time = normal time + allowances.
- BEP = fixed cost / contribution per unit.
- Product layout is for mass production.
- Six Sigma is 3.4 defects per million.
Practice Questions With Answers
- What is the formula for EOQ?
Answer: √(2DS/H) - Who is the father of scientific management?
Answer: F. W. Taylor - What is the break-even point if the fixed cost is 40,000, the selling price is 40 and the variable cost is 20 per unit?
Answer: 2,000 units - Which layout is suitable for mass production?
Answer: Product (line) layout - What does ABC analysis classify?
Answer: Inventory by value - What does JIT stand for?
Answer: Just in Time - What is the PDCA cycle associated with?
Answer: Deming (TQM) - What does Kaizen mean?
Answer: Continuous improvement - Which method gives the initial solution of a transportation problem by the least cost?
Answer: Vogel’s Approximation Method (VAM) - Which method solves the assignment problem?
Answer: Hungarian method
How to Practise This Chapter
Practise 10 questions every day and write the steps on paper. Then attempt timed sets from our practice papers and the previous year papers page. See all topics on the Mechanical Engineering notes page, read the previous topic Material Science and Heat Treatment.
Frequently Asked Questions
What is work study?
The study of methods and the measurement of work to improve productivity.
What is EOQ?
The order quantity that minimises the total of the ordering and holding costs.
What is the standard time?
The normal time plus the allowances.
What is ABC analysis?
An inventory classification based on the value of items.
What is JIT?
A system in which materials are delivered just when they are needed.
What is a control chart?
A chart used to monitor a process and to detect the variation.
What is TQM?
Total quality management; a company-wide approach to continuous improvement.
What is Six Sigma?
A quality method that aims at 3.4 defects per million opportunities.
What is the break-even point?
The level of sales at which the total revenue equals the total cost.
What is a process layout?
A layout in which similar machines are grouped together.
Is this topic asked in SSC JE?
Yes. Industrial engineering is asked in the mechanical paper.
What is linear programming?
A method for optimising a linear objective subject to linear constraints.
Rahul Kumar
SSC Exam Expert & Content Editor
Rahul is a senior SSC exam strategist with 8+ years of experience helping aspirants crack CGL, CHSL and MTS exams. He writes in-depth notification breakdowns, exam pattern guides and preparation strategies.