VIENIDMY Sign in Start practicing

Home › Lessons › Production Management Operations Grade 3 生産管理オペレーション (BC検定)

Work Management Basics (Production Systems, IE, 5S)

Production Management Operations Grade 3 生産管理オペレーション (BC検定) · ビジネス・キャリア検定 生産管理オペレーション3級 · Written by Tokutei Pass based on the official study texts; not copied verbatim.

1. Production Systems and Objectives of Production Management (QCD, PQCDSME)

In manufacturing, a "production system" is a mechanism that applies transformation processes such as machining and assembly to management resources fed from outside (Inputs) to produce high value-added products or services (Outputs).

Representative input resources are the "3Ms"—Man, Machine, and Material—which are managed together with working Method, Money, and Information.

The fundamental objective of production management is optimizing "QCD": reliably supplying products that meet customer-required "Quality (Q)", at the lowest possible "Cost (C)", by the promised "Delivery date (D)".

Furthermore, modern factory operations require comprehensively improving "PQCDSME" by adding Productivity (P), Safety (S), worker Morale (M), and Environmental protection (E) to the three pillars of QCD.

Key points


  • A production system transforms inputs such as the 3Ms (Man, Machine, Material) and information into value-added products (outputs).

  • The three primary goals of production management are maintaining and improving "Quality (Q), Cost (C), and Delivery (D)" while balancing their trade-offs.

  • Shop-floor supervisors manage the workplace with awareness of PQCDSME, adding Productivity (P), Safety (S), Morale (M), and Environment (E) to QCD.
WordMeaning
production system
3Ms (Man, Machine, Material)
QCD (Quality, Cost, Delivery)
added value

2. Concept of Productivity (Physical vs. Value-Added Labor Productivity) and Work Standardization

The indicator expressing the efficiency of a production process is "productivity," defined by the basic formula: "Productivity = Output ÷ Input." Producing greater output from fewer input resources yields higher productivity.

Productivity that uses labor input (number of workers or total man-hours) as the denominator is called "labor productivity." There are two types: "physical labor productivity," which uses physical quantity (units or weight) as the numerator, and "value-added labor productivity," which uses added value (sales minus externally purchased value) as the numerator.

Work management is the activity of pursuing the "best working method" that enables workers to work safely, reliably, quickly, and comfortably, establishing it as standard work, and training workers to maintain and improve it.

Preparing a documented "Work Standard Sheet (Standard Operation Sheet)" specifying standardized procedures, jigs and tools used, and key quality checkpoints prevents skill dependency and quality variation, building a foundation to move from maintenance (SDCA) to improvement (PDCA).

Key points


  • Productivity = Output ÷ Input; when the denominator is labor input, it is called labor productivity.

  • Physical labor productivity = Production volume ÷ Labor input; Value-added labor productivity = Value added ÷ Labor input.

  • Work management establishes the best working method (standard work) and standard time, providing guidance via work standard sheets and continuous improvement.

  • Example: 5 workers working 8 hours each (40 man-hours total) produce 800 units with sales of 1,000,000 yen and external purchases of 400,000 yen → Physical labor productivity = 800 ÷ 40 = 20 units/man-hour, Value added = 1,000,000 − 400,000 = 600,000 yen, Value-added labor productivity = 600,000 ÷ 5 = 120,000 yen/worker
WordMeaning
physical labor productivity
value-added labor productivity
standard work / standard operation
work standard sheet (SOP)

3. Structure of Standard Time and Calculation by External and Internal Allowance Methods

"Standard Time (ST)" is the time required for an average worker with proper aptitude and skill to perform a task at a standard working pace under specified conditions while maintaining the required quality level.

Standard time is broadly divided into "setup/preparation time," which occurs once per lot, and "principal operation time," which repeats for each unit of product. Each consists of the sum of "net time" and "allowance time" (Standard Time = Net Time + Allowance Time).

Allowance time includes "personal and fatigue allowances" for physiological needs and recovery from fatigue, and "workplace allowances (operation allowances)" that occur irregularly such as oiling, cleaning, waiting for materials, or morning meetings.

There are two methods for calculating the allowance rate. The "external addition method (Sotogake)" defines "Allowance Rate = Allowance Time ÷ Net Time" and calculates "Standard Time = Net Time × (1 + External Allowance Rate)" (e.g., if net time is 20 min and external allowance rate is 15%, 20 × 1.15 = 23 min).

Conversely, the "internal addition method (Uchigake)" defines "Allowance Rate = Allowance Time ÷ Standard Time" and calculates "Standard Time = Net Time ÷ (1 - Internal Allowance Rate)" (e.g., if net time is 16 min and internal allowance rate is 20%, 16 ÷ (1 - 0.20) = 20 min).

Key points


  • Standard Time = Net Time + Allowance Time, divided into lot-based "setup time" and unit-based "principal operation time."

  • External method (Sotogake): Allowance Rate = Allowance Time ÷ Net Time ⇒ Standard Time = Net Time × (1 + External Allowance Rate).

  • Internal method (Uchigake): Allowance Rate = Allowance Time ÷ Standard Time ⇒ Standard Time = Net Time ÷ (1 - Internal Allowance Rate).

  • Example: Net time per unit for main work 2 min, external allowance factor 10%, standard setup time per lot (100 units) 15 min → Standard time per unit = 2 × (1 + 0.10) = 2.2 min, Total standard time per lot = 15 + 2.2 × 100 = 235 min

  • Example: Net time per unit 45 sec, internal allowance ratio 10% (allowance time 5 sec) → Standard time = 45 ÷ (1 − 0.10) = 50 sec (internal allowance ratio = 5 ÷ 50 × 100 = 10%)
WordMeaning
Standard Time (ST)
net time and allowance time
external allowance method (Sotogake)
internal allowance method (Uchigake)
setup and preparation time

4. System of Industrial Engineering (IE) and Process Analysis (JIS Symbols)

Industrial Engineering (IE) originates from the pioneering work of Frederick Taylor (founder of Scientific Management and Time Study) and Frank Gilbreth (founder of Motion Study and Therblig analysis), consisting of two pillars: "Method Engineering" to improve work methods and "Work Measurement" to measure time.

The first step of method engineering, "process analysis," represents the process from raw materials to finished goods using four basic chart symbols defined in JIS Z 8206 to visualize overall flow and waste in delays and transport.

The four basic elements and symbols are: 1. "Operation" = large circle (○: changing shape/properties or assembling), 2. "Transportation" = small circle or arrow (〇 / →: moving location), 3. "Inspection" = square (□: quantity inspection) and diamond (◇: quality inspection), 4. "Delay/Storage" = inverted triangle (▽: planned storage) and D-shape (D: temporary delay between processes).

Depending on the subject analyzed, it is classified into "product process analysis" tracking material flow (simple, straight-line, converging, and diverging types), "operator process analysis" tracking human movement, and "combined process analysis" tracking interactions between workers and machines.

Key points


  • History of IE: Taylor founded "Time Study (stopwatch method)," while Gilbreth founded "Motion Study (Therblig analysis)."

  • Process chart symbols (JIS Z 8206): Operation = large circle (○), Transportation = small circle (〇) or arrow (→), Quantity inspection = square (□), Quality inspection = diamond (◇).

  • Delay symbols: Planned keeping "Storage" = inverted triangle (▽); temporary waiting between processes "Delay" = D-shape (D).
WordMeaning
Industrial Engineering (IE)
method engineering and work measurement
process analysis
storage (▽) and delay (D)

5. Motion Study (18 Fundamental Therblig Motions) and Time Study (Rating)

"Therblig analysis," devised by Gilbreth, breaks down a worker's hand and eye movements into 18 fundamental motions (therbligs) grouped into Classes 1 to 3 to eliminate wasteful movement.

"Class 1" consists of 9 effective motions necessary to advance work (transport empty/reach, grasp, transport loaded, position, assemble, use, disassemble, release load, inspect), which are streamlined by shortening distances or using jigs.

"Class 2" consists of 5 motions that retard Class 1 due to mental or visual searching (search, find, select, plan, pre-position), which are eliminated through 5S (Set in Order and fixed-location storage).

"Class 3" consists of 4 non-productive motions that do not advance the work at all (hold, rest, unavoidable delay, avoidable delay); in particular, "Hold" (continuing to hold a part with one hand) should be eliminated first using holding fixtures.

Meanwhile, in "Time Study (stopwatch method)," observed times are measured for each work element and adjusted by "Rating (work pace evaluation)" against standard speed (= 100). Net time is calculated as: "Net Time = Observed Time × (Rating Factor ÷ 100)" (e.g., 50 sec observed at rating 110 gives 55 sec).

Key points


  • Therblig Class 1 = fundamental motions that advance work (grasp, transport, assemble, use, etc.).

  • Therblig Class 2 = motions that delay work (search, select, plan → eliminate via Set in Order); Class 3 = non-productive motions (hold, delay, rest → eliminate via fixtures).

  • Net Time in time study = Observed Time × (Rating value ÷ 100).

  • Example: Stopwatch observed time 40 sec, rating factor 120 (normal pace standard = 100) → Normal (net) time = 40 × (120 ÷ 100) = 48 sec
WordMeaning
Therblig motion analysis
Hold (Class 3 Therblig)
Time Study
Rating (work speed evaluation)

6. Operation Analysis (Work Sampling) and Combined Work Analysis (Man-Machine Chart)

"Operation analysis" investigates what percentage of time workers and machines spend in each state (operating, waiting, setup, breakdown, etc.), comprising the "continuous observation method" and the "instantaneous observation method (Work Sampling method)" conducted at random times.

Based on statistical probability theory, Work Sampling has the major advantages that a single observer can survey many workers or machines simultaneously with little effort while causing minimal psychological pressure on those observed.

When total observations are N and occurrences of the target event are n, the occurrence ratio is "p = n ÷ N." At a 95% confidence level (factor 2), the required number of observations for an allowable absolute error E is "N = 4 × p × (1 - p) ÷ E²" (or "N = 4 × (1 - p) ÷ (S² × p)" for relative error S; e.g., if p = 0.2 and E = 0.04, N = 400).

Additionally, "combined work analysis (Man-Machine Chart)" plots time-series bar charts of a worker collaborating with one or more machines. Dividing human activity into "independent work, combined work, waiting" and machine state into "automatic run, combined work, idle" helps reduce waiting time and achieve multi-machine handling.

Key points


  • Work Sampling performs instantaneous observations at random times, allowing one person to efficiently determine operating and allowance ratios for many targets.

  • Required observations N at 95% confidence: for absolute error E, N = 4 × p × (1 - p) ÷ E²; for relative error S, N = 4 × (1 - p) ÷ (S² × p).

  • A Man-Machine Chart visualizes human "waiting" and machine "idle" times to shorten cycle time and study multi-machine operation.

  • Example: Work sampling pilot study shows 25 non-working observations out of 100 (occurrence ratio p = 0.25), 95% confidence with allowable absolute error E = 0.05 → Required observations N = 4 × 0.25 × (1 − 0.25) ÷ 0.05² = 300 (for relative error S = 0.10, N = 4 × (1 − 0.25) ÷ (0.10² × 0.25) = 1,200)

  • Example: On a man-machine chart, loading/unloading (combined work) is 15 sec + automatic machining is 65 sec (during which operator independent work is 45 sec) → Cycle time = 15 + 65 = 80 sec, Operator idle time = 65 − 45 = 20 sec (idle ratio = 20 ÷ 80 × 100 = 25%)
WordMeaning
Work Sampling method
occurrence ratio (p)
Man-Machine Chart
worker waiting and machine idle time
multi-machine handling

7. Basic Principles of Work Improvement (ECRS Principles, 4 Principles of Motion Economy, Poka-yoke)

The "ECRS principles" indicate the priority order for improvement: 1. Eliminate (Can we remove it?) → 2. Combine (Can we do them together?) → 3. Rearrange (Can we change the sequence or person?) → 4. Simplify (Can we make it simpler?).

The greatest impact comes from the first step, "E (Eliminate)"; never automate or simplify (S) unnecessary tasks without first trying to eliminate them.

Meanwhile, the "Four Principles of Motion Economy" are: 1. Use both hands simultaneously (move symmetrically), 2. Minimize the number of motions (reduce unnecessary movements), 3. Shorten motion distances (place part bins in a fan-shaped normal working area), and 4. Make motions easier (use gravity chutes and fixtures to eliminate holding).

Furthermore, mechanisms that physically or mechanically prevent human error are called "Poka-yoke (foolproofing)," classified into the "stop method" (stopping the machine on abnormality), "control method" (using asymmetric pins to make reverse assembly impossible), and "warning method" (alerting with sound or light).

7. Basic Principles of Work Improvement (ECRS Principles, 4 Principles of Motion Economy, Poka-yoke)

Key points


  • Apply ECRS in strict priority order: "E (Eliminate) → C (Combine) → R (Rearrange) → S (Simplify)," always considering E first.

  • Four Principles of Motion Economy: 1. Use both hands together, 2. Reduce number of motions, 3. Shorten motion distance, 4. Make motions easier (use gravity and jigs).

  • Poka-yoke (mistake-proofing) includes "stop, control, and warning methods" to achieve zero defects without relying solely on human attention.
WordMeaning
ECRS principles
Four Principles of Motion Economy
normal working area
Poka-yoke (mistake-proofing / foolproofing)

8. 5S Activities (Sort, Set in Order, Shine, Standardize, Sustain), Red Tag Strategy, and Shadow Boards

"5S," the foundation of workplace management and improvement, stands for "Seiri (Sort), Seiton (Set in Order), Seisou (Shine), Seiketsu (Standardize), and Shitsuke (Sustain)." Rather than mere beautification, it is the basis for safety, quality improvement, and waste elimination.

"Seiri (Sort)" means clearly separating items in the workplace into "necessary and unnecessary" and discarding (disposing of or removing) unnecessary ones. The "Red Tag Strategy"—attaching red tags to items of unclear necessity to decide disposal within a deadline—is highly effective.

"Seiton (Set in Order)" means "deciding fixed locations, storage methods, and labels (max/min quantities) for necessary items kept after sorting so anyone can retrieve and return them immediately." Practices include the "Signboard Strategy" showing location, item name, and quantity, and "trace/shadow management (shadow boards)" drawing tool outlines so missing tools are spotted at a glance.

"Seisou (Shine)" means removing trash, dirt, and chips while checking equipment for looseness or oil leaks (cleaning as inspection). "Seiketsu (Standardize)" refers to the state where the first 3Ss (Sort, Set in Order, Shine) are thoroughly maintained, and "Shitsuke (Sustain)" means building the habit of properly following established rules and procedures.

8. 5S Activities (Sort, Set in Order, Shine, Standardize, Sustain), Red Tag Strategy, and Shadow Boards

Key points


  • Seiri (Sort) = separating necessary from unnecessary items and discarding the unnecessary (Red Tag Strategy).

  • Seiton (Set in Order) = deciding fixed location, fixed item, and fixed quantity with clear labels for instant retrieval (Signboard Strategy, shadow boards).

  • Seisou (Shine) = inspecting equipment through cleaning; Seiketsu (Standardize) = state of maintaining the 3Ss; Shitsuke (Sustain) = habitual rule compliance.
WordMeaning
Seiri (Sort) and Seiton (Set in Order)
Seiketsu (Standardize) and Shitsuke (Sustain)
Red Tag Strategy (for Seiri)
shadow board / trace management (for Seiton)

Frequently Tested Points & Memory Aids

Exams very frequently swap the definitions of "Seiri - Sort (discarding unnecessary items)" and "Seiton - Set in Order (designating and labeling locations for immediate retrieval)," as well as swapping "Seisou - Shine" and "Seiketsu - Standardize (the state where 3S is maintained)."

When calculating Standard Time (ST), always verify whether the problem specifies the "External method: ST = Net Time × (1 + Allowance Rate)" or the "Internal method: ST = Net Time ÷ (1 - Allowance Rate)." Also note that setup time is added only once per entire lot.

Memorize the process analysis inspection symbols "Quantity inspection = square (□), Quality inspection = diamond (◇)," delay symbols "Storage = inverted triangle (▽), Delay = D," and Therblig Class 2 (search, select, plan) vs. Class 3 (hold, delay, rest).

Key points


  • Standard Time formulas: External = Net × (1 + Allowance Rate) / Internal = Net ÷ (1 - Allowance Rate) / Net Time = Observed Time × (Rating ÷ 100).

  • Work Sampling required observations (95% confidence): N = 4 × p × (1 - p) ÷ E² (E = allowable absolute error, p = occurrence ratio).

  • Process chart symbols: Operation = ○, Transport = 〇 or →, Quantity inspection = □, Quality inspection = ◇, Storage = ▽, Delay = D.

  • Therblig classes: Class 1 = effective motions (grasp, assemble, etc.), Class 2 = delaying motions (search, select, plan), Class 3 = non-productive motions (hold, delay, rest).

  • ECRS priority: E (Eliminate) → C (Combine) → R (Rearrange) → S (Simplify) / 5S: Seiri (discard = Red Tag) vs. Seiton (display location = Signboard & Shadow Board).
WordMeaning
external vs. internal allowance rate
quantity inspection (□) and quality inspection (◇)
Therblig Classes 1 to 3
ECRS (Eliminate, Combine, Rearrange, Simplify)

Work Management (IE, Standard Time, 5S)

Practice this chapter in the app

Official references

Zalo