Production Planning, Productivity and Quality Management
Operations Management is the newest paper on a CMA's syllabus and the one most different in flavour from costing — it asks how a factory floor is actually run, not how its costs are recorded, and a CMA is expected to speak this language because cost control ultimately happens on the shop floor, not in the ledger.
1. Production Planning and Control — the four-stage cycle
Production Planning and Control (PPC) is the function that converts a sales forecast into a day-by-day shop-floor schedule, and it is best learned as four sequential stages rather than as a single activity.
| Stage | What it does | Typical tool |
|---|---|---|
| Routing | Decides the sequence of operations and machines a job passes through | Route sheet, operation process chart |
| Scheduling | Decides when each operation happens, fitting jobs to available capacity | Gantt chart, master production schedule |
| Dispatching | Releases work orders to the shop floor and authorises the start of work | Job cards, dispatch list |
| Follow-up (expediting) | Tracks actual progress against the schedule and corrects delays | Progress reports, bottleneck escalation |
Aggregate planning sits above this four-stage cycle and decides the medium-term production rate, workforce level and inventory policy needed to meet forecast demand over roughly 3 to 18 months, before routing and scheduling turn that aggregate plan into specific shop-floor instructions.
A firm facing seasonal demand can meet a peak either by level production (build inventory in advance, at the cost of carrying it) or by chase production (vary the workforce or overtime with demand, at the cost of hiring/firing or overtime premiums) — the choice is a cost trade-off, not a technical one, which is exactly why it sits inside a CMA's syllabus rather than a pure engineering course.
Material Requirements Planning (MRP) takes a master production schedule, a bill of materials and current inventory records, and works backward to tell purchasing and production exactly what to order or make, in what quantity, and by when — so that materials arrive just in time for the operation that needs them rather than sitting as idle stock or, worse, being missing when a machine is ready for them.
MRP II (Manufacturing Resource Planning) extends this same backward-scheduling logic to capacity, labour and finance, turning a materials plan into a full resource plan for the business.
2. Productivity — measuring output against input
Productivity is the ratio of output produced to the input consumed to produce it, and the single most important thing to get right is that productivity is not the same as production. Production can rise while productivity falls, if output grows more slowly than the inputs consumed to achieve it.
Partial productivity measures output against a single input (labour productivity = output ÷ labour hours; capital productivity = output ÷ capital employed), while Total Factor Productivity (TFP) measures output against a weighted combination of all inputs — labour, capital, material and energy together — and is the harder but more complete measure, since a firm that improves labour productivity purely by substituting more machinery has not necessarily become more efficient overall.
3. Work study — method study and work measurement
Work study has two complementary halves, and confusing them is the most common definitional error in this topic: method study asks "what is the best way to do this job," while work measurement asks "how long should the best way take."
Method study proceeds through select, record, examine, develop, install and maintain (the SREDIM sequence) — recording the current method (using tools such as a process flow chart or a two-handed process chart for repetitive manual work), critically examining each step for necessity, and developing an improved method that removes unnecessary movement, waiting or backtracking.
Work measurement, most commonly through time study, builds up a standard time in a fixed sequence: an observer times a worker performing the job over several cycles to get an observed time; this is adjusted by a rating factor (the observer's judgment of how the worker's pace compares to a defined "normal" pace) to get the normal time.
Finally, relaxation, personal and contingency allowances are added to the normal time to arrive at the standard time — the time a qualified worker, working at a normal pace with allowances for rest, should take to complete one unit of the job.
Standard time is not a target to be beaten — it is a fair benchmark built from an actual observed pace, and this is the figure a cost accountant later uses to set a standard labour cost per unit, which is exactly why work study and standard costing are taught as connected ideas rather than separate ones.
4. Quality management — from inspection to prevention
Quality control, quality assurance and total quality management are frequently used as if interchangeable, but they describe three progressively earlier points of intervention. Quality control inspects output after production and rejects or reworks defects; quality assurance builds process controls in during production to prevent defects from occurring in the first place.
Total quality management (TQM) goes further still, making quality the responsibility of every employee and every function, not just a dedicated inspection department, and pursuing continuous improvement as an organisation-wide culture rather than a departmental task.
The Deming or PDCA cycle — Plan, Do, Check, Act — is TQM's basic improvement engine: plan a change, implement it on a small scale, check whether it actually improved the outcome, and act by standardising the change if it worked or abandoning it if it did not, then repeating the cycle continuously.
Six Sigma's DMAIC methodology — Define, Measure, Analyse, Improve, Control — is a more statistically rigorous variant aimed at reducing process variation to a target of no more than 3.4 defects per million opportunities (a "six sigma" level of process capability), and it is commonly examined as a five-letter sequence a candidate should be able to name and briefly explain in order.
The four-bucket Cost of Quality framework
The Cost of Quality classifies every quality-related cost into exactly four buckets, and the framework's real teaching point is that money spent in the first two buckets reduces the much larger costs that show up in the last two.
| Bucket | What it covers | Example |
|---|---|---|
| Prevention cost | Spent to stop defects before they occur | Quality training, process design review |
| Appraisal cost | Spent to detect defects that have already occurred | Inspection, testing, calibration of gauges |
| Internal failure cost | Cost of defects caught before the product reaches the customer | Scrap, rework, re-inspection |
| External failure cost | Cost of defects the customer discovers | Warranty claims, product recalls, lost goodwill |
External failure cost is almost always the largest and most damaging of the four, because it includes reputational and lost-business effects that are hard to quantify but very real — which is the underlying argument for spending more on prevention (the cheapest bucket to act in) rather than accepting a higher rate of appraisal, rework and warranty cost downstream.
Worked Examples
Example 1. A worker is observed completing a task in 12 minutes per unit. The observer rates the worker's pace at 110% of normal. Relaxation and other allowances are 20% of normal time. Find the standard time.
Normal Time = 12 × 1.10 = 13.2 minutes. Allowances = 20% × 13.2 = 2.64 minutes. Standard Time = 13.2 + 2.64 = 15.84 minutes.
Example 2. A factory produced 5,000 units last month using 2,000 labour hours and 4,500 units this month using 1,800 labour hours. Compare labour productivity across the two months.
Last month: 5,000 ÷ 2,000 = 2.5 units per hour. This month: 4,500 ÷ 1,800 = 2.5 units per hour. Productivity is unchanged even though total production fell — this illustrates why production and productivity must not be treated as the same measure.
Example 3. Classify each cost into one of the four Cost of Quality buckets: (a) cost of a quality-training workshop for new operators, (b) cost of reworking a batch of defective units before dispatch, (c) cost of a customer's warranty claim after a product failure, (d) cost of inspecting incoming raw material.
(a) Prevention cost. (b) Internal failure cost. (c) External failure cost. (d) Appraisal cost.
Example 4. A firm follows a chase production strategy rather than a level production strategy to meet seasonal demand. What cost trade-off is it accepting, and what cost is it avoiding?
It accepts variable costs from hiring, overtime or layoffs as demand fluctuates, in exchange for avoiding the inventory carrying cost that a level-production strategy (building stock ahead of the peak) would incur.
Example 5. Arrange the following PPC activities in their correct sequence: dispatching, scheduling, follow-up, routing.
Routing, scheduling, dispatching, follow-up.
Example 6. A process operating at Six Sigma quality is producing how many defects per million opportunities, approximately?
Approximately 3.4 defects per million opportunities.
Example 7. A process improvement team plans a change to a workstation layout, tests it on one shift, compares defect rates before and after, and then rolls it out factory-wide once confirmed. Which quality-improvement cycle does this describe, and name its four stages?
The Deming (PDCA) cycle — Plan, Do, Check, Act.
Summary
Production Planning and Control runs through four sequential stages — routing, scheduling, dispatching and follow-up — sitting below a medium-term aggregate plan that chooses between level and chase production as a cost trade-off, and below MRP/MRP II, which back-schedules material and resource requirements from the master production schedule.
Productivity (output ÷ input) is distinct from production (total output), and is measured either partially (against one input, such as labour) or as Total Factor Productivity (against all inputs combined). Work study splits into method study (finding the best method, via SREDIM) and work measurement (timing that method to build a standard time from observed time, rating factor and allowances).
Quality management progresses from inspection-based quality control, to prevention-based quality assurance, to organisation-wide TQM, using improvement engines such as the PDCA cycle and Six Sigma's DMAIC methodology. The four-bucket Cost of Quality framework — prevention, appraisal, internal failure, external failure — is this topic's most frequently tested idea, and its core argument is that prevention spending reduces the much larger, harder-to-quantify cost of external failure.
