Research libraryUtilisation Decides
Chapter 04 of 14 · Part I · Draft web edition
SMV translates garment work content into earned minutes, but it must sit beside OEE and quality rather than replace them.
The cloth is woven from this chapter's 4 exhibits: each weft is one exhibit's own data, normalised; each warp group is a section. The probe reads the exhibit's own value where it crosses. Procedural visualisation, not a measurement.
Read-out
Derived with illustrative inputs using the SMV and efficiency formulas in S13 and S0402: operation SMVs of 0.8 + 1.2 + 0.6 = 2.6 minutes; 200 good pieces earn 520 standard minutes; 8 operators x 480 minutes = 3,840 attended minutes (13.54 percent efficiency). Intermediate loss buckets are illustrative allocations of the 3,320 unrecovered minutes.
Unit: labour minutes per shift. Status: derived. Sources: S13, S0402.
A garment factory cannot manage sewing capacity with machine counters alone, nor can it diagnose equipment and flow losses using payroll efficiency alone.[S04][S13] Standard minute value (SMV), also called standard allowed minutes (SAM), converts physical garments into human work content by summing the standard time required for every operation in a style.[S13][S0401] Yet when management replaces overall equipment effectiveness (OEE) with SMV-based line efficiency, or collapses the two into a single hybrid percentage, it loses the ability to separate a broken needle from an unbalanced workstation, a material shortage from a slow operator, or a power outage from a style-change delay.[S04][S09][S14] The operating rule for a sewing plant is architectural: use SMV to measure earned labour output across styles of unequal complexity, use the OEE loss tree to isolate availability, speed and defect losses at workstation and line boundaries, and require both measures to count only finished garments that pass quality inspection.[S04][S09][S13]
The stakes are immediate for industrial sponsors building or rehabilitating garment capacity in Cameroon. Sector records indicate that approximately 95 percent of Cameroon's cotton fibre is exported raw while roughly 5 percent is processed locally, against a national policy target of 50 percent local processing by 2030.[R06][R07] Reported capacity utilisation across incumbent textile facilities in July 2023 ranged from 10.83 percent at CICAM 2 to 33.7 percent at Garoua and 48.9 percent at CICAM 1, with underutilisation estimated to have cost around CFAF 2 billion in 2020.[R12] Moving from raw-fibre export to competitive garment assembly requires factories that can quote, schedule and control diverse orders on the same sewing floor without losing visibility into where time goes.[S12][S13] GFT's Cameroon textile programme (prepared 31 January 2024, with sources refreshed in 2026) treats utilisation and effective labour cost per good garment as the primary operational swing variables in factory feasibility, while separating that engineering analysis from investment, legal or tax advice.[R12][R14]
This chapter establishes the calculation contract connecting machine effectiveness to sewing labour across four exhibits. First, Exhibit 17 positions station OEE, SMV-based line efficiency and line-balance efficiency across their diagnostic dimensions.[S04][S13][S15] Second, Exhibit 16 reconciles operation SMVs and earned standard minutes against attended labour minutes on a shift log.[S13][S0402] Third, Exhibit 18 uses published apparel-line baseline data to show how two factories lost effectiveness through different combinations of availability, performance and quality.[S09] Fourth, Exhibit 19 defines the five recurring time standards in sewing-room engineering and specifies which substitutions are prohibited in GFT's data model.[S09][S13][S15][S16]
4.1
Every garment style entering a sewing room is a sequence of discrete physical transformations rather than a homogeneous unit of output.[S13] A basic knit shirt may require fewer than twenty assembly steps, whereas a tailored uniform shirt or trouser can require fifty to eighty operations across lockstitch, overlock, flatlock, buttonhole, bar-tack and pressing stations (illustrative comparison).[S13][S15] Because work content is governed by seam geometry, fabric handling and quality tolerances, industrial engineers decompose each garment into an ordered operation bulletin before production begins.[S12][S13] In the Gender Equality and Returns (GEAR) assessment of Bangladesh garment factories by the International Finance Corporation (IFC) and the International Labour Organization (ILO), industrial engineers divide production of each style into sequential steps, determine the time required for a fully efficient operator to complete each step, and sum those values so that the garment SMV equals the total of the SMVs for all steps required to produce the garment.[S13]
An operation bulletin is the master engineering ledger linking product design to shop-floor capacity.[S12][S13] In the ILO Factory Improvement Toolset (FIT) deployed across Asian garment enterprises, preparing an operation bulletin and monitoring SMV calculations are foundational sewing-floor modules used alongside bundle-system management and line balancing.[S12] To function as an auditable planning standard, each row of the bulletin specifies the operation code, seam and stitch specification, machine type, folders or guides attached, precedent operations, required operator skill grade, quality checkpoint criteria, basic time, allowance percentages by category, and resulting operation SMV.[S12][S13][S17][S0401]
When any contextual field is omitted, the numerical SMV loses operational validity.[S26][S0401] Standardized work provides a documented process for all shifts, reduces variability, eases operator training, lowers strain and creates the baseline for improvement activities.[S26] If an operation SMV of 0.65 minutes (illustrative) was established on a lockstitch machine with an edge-guide folder and automatic thread trimmer, moving that operation to a plain machine where the operator aligns plies by hand and trims thread with scissors invalidates the 0.65-minute standard.[S26][S0401] Without a documented method boundary, the slowdown is misdiagnosed as poor operator pace rather than an unrecorded change in equipment configuration.[S07][S26]
Operator skill assumptions are likewise embedded inside every operation standard.[S17] Research on garment assembly-line balancing with labour skill levels notes that worker performance on each task varies across a defined rating scale, such as from 0 for no skill to 1.5 for a fully skilled operator in published skill tables.[S17] Recording the bulletin SMV alongside achieved cycle time separates structural work content from temporary learning variance, a mechanism examined in Chapter 6.[S13][S17]
In garment work measurement, an operation SMV is never raw stopwatch time.[S0401] Whether derived from predetermined motion-time systems (where motions are measured in Time Measuring Units with 1 TMU equal to 0.0006 minutes) or from direct stopwatch time study, the calculation passes through two explicit stages: establishing basic time, and adding policy and technical allowances.[S0401]
In direct time study, an engineer observes a qualified operator over consecutive cycles, discards abnormal readings from external interruptions, and calculates mean observed cycle time from initial part pickup to the next part pickup.[S0401] The engineer applies a performance rating factor so that basic time equals observed cycle time multiplied by the operator's performance rating.[S0401] In the published garment time-study method, an observed cycle time of 0.60 minutes at an 80 percent rating yields a basic time of 0.48 minutes, whereas a motion analysis totaling 400 TMU yields a basic time of 0.24 minutes.[S0401]
whereas a motion analysis totaling 400 TMU yields a basic time of 0.24 minutes
S0401
Basic time represents uninterrupted execution and cannot be sustained over a full shift without recovery, material handling and minor machine tending.[S0401] To convert basic time into Standard Allowed Minutes (SAM or SMV), the engineer adds allowances for bundle handling, machine contingencies and personal relaxation needs.[S0401] In the published SAM calculation example, adding a 10 percent bundle allowance (0.048 minutes) and a 20 percent machine and personal allowance (0.096 minutes) to a 0.48-minute basic time produces an operation SAM of 0.624 minutes.[S0401]
adding a 10 percent bundle allowance (0.048 minutes) and a 20 percent machine and…
S0401
Construction of operation SMV and garment SMV from time-study inputs
T_basic): Normalised time at reference pace, T_basic = T_obs x (R / 100), where R is performance rating in percent (or T_basic = TMU x 0.0006).[S0401]SMV_i): SMV_i = T_basic,i x (1 + a_bundle + a_machine + a_personal), with each allowance fraction stored separately in the operation bulletin.[S0401]SMV_garment): Total work content for the style, SMV_garment = sum(SMV_i) across all operations in the bulletin.[S13]Preserving the separation between basic time and allowances is essential when connecting SMV to OEE.[S04][S0401] Because an operation SMV already embeds a standard allowance for routine bobbin changes, bundle handling and personal recovery, logging those routine pauses a second time as availability downtime double-counts the loss and inflates operating performance.[S04][S07][S0401] Conversely, equipment breakdowns, material starvation, power outages and style changeovers fall outside the allowance envelope and belong in the availability loss tree described in Chapters 2 and 3.[S02][S04][S06]
4.4
Related · chapter 139 paragraphs step it
Read-out
Sourced from the shared register: Cameroon SMIG raised to XAF 43,969 per month from 23 February 2024 (about US$76, R14); Cambodia garment minimum wage US$204 per month for 2024 (R17); Cameroon cross-sector average salary about US$359 per month (R15). Currency conversions are approximate estimates (R32). Monthly wages do not adjust for earned standard minutes, skill or quality.
Unit: US$ per month (approximate). Status: sourced. Sources: R14, R15, R17, R32.
Read this exhibit in its chapter ↗Once the operation bulletin establishes the garment SMV, the factory possesses a common unit of output across styles: the earned standard minute, also called produced minutes or output minutes.[S13][S0402] In a commercial garment plant serving workwear, school uniform and retail orders, lines switch between styles whose work content differs by a factor of two to four (illustrative range).[S12][S13] Evaluating a sewing line by daily piece count alone penalises lines assigned to complex garments and rewards lines running simple styles.[S13][S0402]
SMV-based line efficiency resolves product-mix distortion by converting physical output into standard minutes accomplished and dividing by labour minutes invested.[S13][S0402] In the IFC and ILO Better Work assessment of Bangladesh garment factories, daily output minutes equal style SMV multiplied by pieces completed on that day, and line efficiency equals output minutes divided by available labour minutes (workers involved in sewing multiplied by minutes the line operated).[S13] Across 159 production lines in 20 factories analysed in that study, daily line efficiency typically ranged between 45 and 70 percent, with a sample mean of 57.2 percent, showing that even established export lines operate well below 100 percent nominal efficiency because of bottlenecks, breakdowns, input shortages and supervisory variation.[S13]
The numerator of line efficiency is earned standard minutes: Earned Minutes = Q_good x SMV_garment, where Q_good is completed garments passing end-of-line quality verification.[S13][S14][S0402] In practitioner terminology, if a line completes 400 garments of a 25-minute SAM style, total minutes produced equal 400 x 25 = 10,000 standard minutes.[S0402] If the line shifts the next week to a 40-minute SAM garment and completes 250 good pieces in the same shift duration, piece output falls by 37.5 percent (from 400 to 250 pieces), but earned output remains 250 x 40 = 10,000 standard minutes.[S13][S0402]
Just as the numerator depends on an honest SMV and strict good-unit counting, the denominator depends on an explicit boundary for attended labour minutes.[S13][S0402][S0403] In the Better Work GEAR lexicon, available labour minutes equal actual manpower total (machine operators and line helpers present on that day) multiplied by operating hours multiplied by 60 minutes.[S13] Practitioner guides similarly define minutes attended as total manpower (operators plus helpers) multiplied by working hours multiplied by 60, and note that when whole shift hours are used in the denominator regardless of off-standard or idle time, the ratio yields overall line efficiency.[S0402][S0403]
Two denominator manipulations distort reporting when rules are unwritten.[S03][S0403] First, excluding sewing helpers, bundle handlers and inline trimmers from headcount while still crediting the SMVs of the manual tasks they perform shrinks attended minutes and overstates line efficiency.[S13][S0402] Every worker whose tasks are included in the operation bulletin SMV must have their attended minutes included in the line's denominator.[S13][S0402]
Second, undeclared overtime distorts both efficiency and unit cost.[R16][S14][S0403] In Cameroon, the statutory working week for non-agricultural establishments is 40 hours, with a 48-hour maximum and overtime compensated at 1.2 times the ordinary rate under the applicable labour rules in the shared register, while the statutory minimum wage (SMIG) was raised to XAF 43,969 per month from 23 February 2024 (up 5 percent from XAF 41,875 in 2023).[R14][R16] If a line runs two hours of overtime to meet a shipment target but leaves the denominator fixed at a standard 480-minute shift per operator instead of 600 attended minutes, reported efficiency is inflated by 25 percent while unit labour cost rises under the 1.2x overtime premium.[R16][S14][S0403]
Exhibit 16 illustrates how earned standard minutes reconcile against attended labour minutes on an eight-operator cell. Using the SMV and efficiency structure in the Better Work assessment, a three-operation subassembly has individual operation SMVs of 0.8, 1.2 and 0.6 minutes, summing to 2.6 standard minutes per piece.[S13] Completing 200 good pieces generates 200 x 2.6 = 520 earned standard minutes against 8 x 480 = 3,840 attended minutes, yielding an SMV-based line efficiency of 520 / 3,840 = 13.54 percent.[S13][S0402]
As Exhibit 16 makes visible, the 13.54 percent efficiency figure shows that 3,320 of the 3,840 attended labour minutes did not convert into good standard minutes (an 86.46 percent capacity loss in this illustrative scenario).[S13][S0402] Yet the 13.54 percent ratio alone cannot prove how much of that 3,320-minute gap came from unplanned downtime (480 minutes), line imbalance and waiting (1,440 minutes), pace and skill ramp (1,248 minutes) or rework and scrap (152 minutes).[S04][S13][S15] Partitioning those intermediate bars requires pairing SMV accounting with OEE capture.[S04][S09]
4.7
Station OEE
Station OEE: Labour and work-content sensitivity 2.4, Equipment and flow loss specificity 8.6. Quadrant: Workstation loss tree · illustrative
Because OEE and SMV-based line efficiency are both expressed as percentages between 0 and 100, factory reports often treat them as interchangeable.
Balance efficiency
Balance efficiency: Labour and work-content sensitivity 6.6, Equipment and flow loss specificity 5.8. Quadrant: Integrated line control · illustrative
SMV line efficiency
SMV line efficiency: Labour and work-content sensitivity 8.8, Equipment and flow loss specificity 2.8. Quadrant: Payroll work accounting · illustrative
GFT line scorecard
GFT line scorecard: Labour and work-content sensitivity 8.6, Equipment and flow loss specificity 8.7. Quadrant: Integrated line control · illustrative
Illustrative diagnostic mapping derived from the definitions in S04 (OEE loss tree), S13 (SMV-based line efficiency) and S15 (assembly-line balance efficiency). Coordinates on the 0 to 10 scale represent analytical coverage of labour content versus equipment loss specificity, not empirical factory measurements.
Unit: illustrative index (0 to 10). Status: illustrative. Sources: S04, S13, S15. Illustrative figures are teaching examples, not measured factory results.
4.7 · the bodyExhibit 17 above; its figures are illustrative where marked.
Because OEE and SMV-based line efficiency are both expressed as percentages between 0 and 100, factory reports often treat them as interchangeable.[S03][S14] Overall equipment effectiveness is a multiplicative loss tree (OEE = Availability x Performance x Quality) decomposing planned production time into downtime, speed and defect losses.[S01][S04] SMV-based line efficiency is a ratio of standard work content earned to human labour time attended.[S13][S0402] Line-balance efficiency compares total garment work content across stations against the product of workstations and the governing cycle or pitch time.[S15][S16]
The temptation to collapse OEE into SMV-based line efficiency appears in garment practitioner literature.[S14] A cited garment OEE tutorial defines line availability as Hours Worked / Planned Hours, line performance as (Line Output x Garment SMV) / (Hours Worked x 60), and line quality as (Line Output - Defective Units) / Line Output.[S14] For a 30-machine line working an 8-hour shift (240 planned machine-hours) with 20 hours of downtime (220 hours worked), producing 400 pieces of a 30-minute SAM style (200 standard hours produced) with 15 defective pieces (385 good pieces), the tutorial computes availability = 0.9166, performance = 0.9090, and quality = 0.9625, multiplying to 80.19 percent.[S14]
The tutorial then cancels the intermediate terms algebraically to avoid double data entry: Simplified Ratio = ((Line Output - Defective Units) x Style SMV) / (Planned Hours x 60).[S14] When Hours Worked and Line Output are cancelled, the remaining expression is simply good earned standard minutes divided by planned operator minutes: it is overall SMV-based line efficiency on good output, not an OEE loss tree.[S04][S13][S14][S0403] A factory that adopts this shortcut stops recording downtime hours and total starts.[S07][S14] When the score drops from 80.19 percent to 55.00 percent on the next shift (illustrative), management has no evidence to tell whether machines broke down, operators waited for cut panels, a seam slowed sewing pace, or a bad thread cone caused defects.[S02][S04][S14]
Exhibit 17 maps Station OEE, Balance Efficiency, SMV Line Efficiency and an Integrated Line Scorecard across two axes: sensitivity to garment work content and labour attendance on the horizontal axis, and specificity to workstation availability, speed and quality losses on the vertical axis.[S04][S13][S15]
| Measure | Numerator | Denominator | Unit | Decision owner and question answered |
|---|---|---|---|---|
| OEE | Good units x ideal cycle (A x P x Q)[S04][S09] | Planned time at station or constraint[S01][S04] | %[S01][S04] | Maintenance, quality, supervision: which downtime, speed or defect loss restricts capacity?[S02][S04] |
| SMV line efficiency | Good garments x style SMV (sum(SMV_i))[S13][S0402] | Attended labour minutes (operators + helpers)[S13][S0402] | %[S13][S0402] | Production and costing: how effectively did attended labour convert into standard work content?[S13][S0403] |
| Balance efficiency | Sum of operation times (sum(t_i))[S15] | Workstations x bottleneck time (K x C_max)[S15][S16] | %[S15] | Industrial engineering: how evenly is work content distributed relative to the bottleneck?[S15][S16] |
Understanding why these three indicators diverge prevents misdirected engineering effort.[S06][S15] In a published trouser assembly-line study using ranked positional weight, the initial line had 61 workstations and a balance efficiency of 35.66 percent; unconstrained balancing reduced theoretical stations to 27 at 80.56 percent efficiency, while imposing real machine and resource constraints yielded 39 workstations at 55.77 percent efficiency.[S15] If those 39 operators experience a two-hour power outage, structural balance efficiency remains 55.77 percent, but actual SMV-based labour efficiency and line OEE plunge because attended minutes accumulate while output stands still.[S06][S13][S15]
Conversely, high local performance at non-constraint stations often coexists with low balance efficiency and downstream starvation.[S06][S15] Manufacturing systems research notes that workstation OEE is affected by equipment-independent conditions such as lack of input items (starvation) or downstream blockage.[S06] When upstream stations have shorter SMVs than the collar-attach bottleneck, upstream operators build work in progress ahead of the bottleneck while downstream stations sit starved of panels, recording low availability and low OEE despite sound machines.[S06][S15][S16]
Empirical evidence from the apparel industry confirms that different factories lose OEE through different combinations of availability, performance and quality.[S09] In the 2025 study by Koc and Eryuruk examining OEE in the apparel industry, baseline measurements were captured across sewing lines in two firms, Company X and Company Y.[S09] Exhibit 18 plots the baseline percentages reported for both companies.[S09]
The component separation in Exhibit 18 shows why a single composite percentage is insufficient.[S04][S09] Company X recorded baseline availability of 73.04 percent, performance of 64.64 percent and quality of 89.46 percent (composite OEE of 42.91 percent), suffering a 10.54 percent defect penalty (where lockstitch repair and stain accounted for 54.77 percent of defects and the top five defect categories accounted for 87.56 percent) alongside 4,923 minutes of technical malfunction, 3,694 minutes of machine adjustment, 2,432 minutes of faulty needle stops and 1,427 minutes of thread breakage.[S09] Company Y recorded availability of 83.39 percent, performance of 71.66 percent and quality of 98.42 percent (composite OEE of 58.81 percent), meaning its primary loss sat in performance (a 28.34 percent speed and minor-stoppage gap).[S09] Lean and digital interventions subsequently lifted Company X's OEE from 42.91 percent to 52.27 percent.[S09] However, Exhibit 18 cannot serve as a universal benchmark target for Cameroon factories, because product mix, machine age and grid stability differ across contexts.[S03][S09]
Interlude · the cloth half-woven
Woven: sections 4.0 to 4.7Still to weave: 4.10 to 4.16
Read-out
Sourced from World Bank research and Enterprise Survey indicators: unconditional average revenue-based total factor productivity (TFP) gap for outage-exposed manufacturers across 84 developing countries, 2006 to 2019 (S36); share of surveyed Cameroon firms experiencing electrical outages in 2024 (S0301); and average value lost due to electrical outages as a share of sales for affected Cameroon firms in 2024 (S0302). Cross-country and sector-aggregate figures are context, not a single-factory garment forecast.
Unit: percent. Status: sourced. Sources: S36, S0301, S0302.
Read this exhibit in its chapter ↗4.10
Of the three OEE components, performance is the most vulnerable to definitional drift in a sewing plant.[S03][S05][S09] Availability compares operating time against planned production time, and quality compares good units against total units checked.[S04][S09] Performance compares actual output achieved during operating time against theoretical output at an ideal cycle time: Performance = (Actual Output x Ideal Cycle Time) / Operating Time.[S04][S09] In a manual sewing operation where an operator guides pliable fabric panels under a needle foot, selecting the right reference cycle is critical.[S07][S09][S14]
Three operation-level time concepts compete for the role of reference cycle in a sewing room: pure machine cycle, observed operator cycle (T_obs), and operation SMV (SMV_i or basic time T_basic,i).[S09][S13][S15][S0401] 1. Machine cycle vs basic cycle (T_basic): A lockstitch machine running at 4,500 stitches per minute (illustrative) completes a 120-stitch seam in 0.0267 minutes (1.6 seconds) of needle movement, yet ply pickup, alignment, pivoting and stacking occupy 60 to 80 percent of the workstation cycle (illustrative range).[S0401] Bare needle time is physically unattainable for the full operation; the validated basic time (T_basic) of a skilled operator following the standard work method without minor stoppages provides the rigorous ideal cycle for station OEE.[S09][S26][S0401] 2. Observed operator cycle (T_obs): In line-balancing research, cycle time is the elapsed time a job remains in a workstation during observation.[S15] Because manual and semi-automatic timing of speeds and short stoppages introduces measurement uncertainty, setting the "ideal cycle" equal to a trailing average of observed cycles artificially pins performance near 100 percent even on poorly methodised stations.[S03][S07] 3. Operation SMV (SMV_i): Because SMV_i adds 15 to 30 percent in bundle, machine and personal allowances on top of basic time, using SMV_i in the OEE performance numerator while subtracting downtime in availability can push reported performance above 100 percent (for example, 115 to 130 percent under the 30 percent combined allowances in S0401), masking micro-stoppages.[S04][S14][S0401] Whichever convention a plant adopts, ISO 22400-2 and NIST guidance require the formula elements, time behaviour and units to be declared explicitly and held constant.[S01][S03]
While ideal cycle, observed cycle and SMV describe a single operation, takt time and pitch time govern the whole assembly line.[S15][S16][S26] Takt time is available planned production time divided by required good customer demand (Takt = T_planned / D_good), translating market demand into a required rhythm (for example, 480 planned minutes divided by 480 required good garments equals 1.00 minute per garment, illustrative).[S15][S26] Pitch time is the governing workstation time ceiling in mathematical line balancing; as formulated by Zhang et al. (Equation 8), the operating time of each process assigned to a workstation must not exceed the assembly-line pitch time (C_max <= Pitch Time <= Takt Time).[S15][S16]
Read-out
| Ideal cycle time | Reference shortest sustainable cycle for the standard method in OEE performance (S09; S0401) | Single operation or constraint station | Never replace with trailing average observed cycle to hide slow pace |
|---|---|---|---|
| Observed cycle time | Measured elapsed time a job remains at a workstation from pickup to next pickup (S15; S0401) | Operator and station during study window | Never use raw unrated stopwatch average as a costing or pay standard |
| Operation or style SMV | Basic time (observed cycle x rating) plus bundle, machine and personal allowances (S13; S0401) | Operation bulletin or whole garment style | Never alter SMV allowances to mask line imbalance or machine downtime |
| Takt time | Planned available production time divided by required good customer output (S15) | External demand on the whole line | Never treat takt as achieved line capacity without a feasible balance |
| Pitch time | Governing workstation time ceiling in line balancing that no station may exceed (S16) | Workstation allocation model | Never assume theoretical pitch equals actual bottleneck cycle on floor |
Illustrative engineering reference table synthesising definitions from S09 (apparel OEE ideal cycle), S13 and S0401 (basic time and SMV), S15 (workstation cycle time) and S16 (assembly-line pitch time). Prohibited substitutions reflect GFT's data-governance rules.
Unit: minutes per piece or workstation cycle. Status: illustrative. Sources: S09, S13, S15, S16, S0401. Illustrative figures are teaching examples, not measured factory results.
As Exhibit 19 shows, each time standard belongs to a specific physical boundary.[S01][S15][S16] Substituting demand takt time for ideal cycle time in an OEE calculation, or using unrated observed cycle time in place of rated SMV on an operation bulletin, renders downstream efficiency percentages uninterpretable.[S03][S09][S0401] Exhibit 19 defines the vocabulary for a single line and style; Chapter 5 extends these definitions into precedence networks and bottleneck identification.[S15][S16]
4.13
In both OEE and SMV-based line efficiency, the most common operational failure on the sewing floor is counting pieces sewn rather than pieces that are right first time or verified good.[S04][S09] In OEE literature, the quality component captures defect losses and reduced yield so that defective and reworked units reduce effective capacity multiplicatively.[S04][S09] In total productive maintenance (TPM), quality-related losses and startup losses are integral parts of the six-loss structure aimed at zero breakdowns and zero defects.[S02]
Why do sewing lines credit standard minutes to defective garments? Because in manual bundle-ticket systems, operators clip coupons or clerks tick hourly boards when a bundle leaves the last sewing machine, before end-of-line inspection or after an unrecorded return to the operator for repair.[S12][S14] Consider an illustrative line of 30 operators sewing a 20.0-minute SMV garment during a 480-minute shift (14,400 attended minutes) that passes 300 garments across the final table, of which 45 garments fail inspection (15 permanently rejected and 30 returned to operators for in-shift unpicking and re-stitching).[S04][S09][S14]
If the clerk credits all 300 sewn pieces, the line claims 300 x 20.0 = 6,000 earned minutes (41.67% efficiency, illustrative).[S13][S14] In reality, only 255 garments passed first time (5,100 first-pass standard minutes, or 35.42% first-pass efficiency) and 285 good garments reached packing after repair (5,700 net earned minutes, or 39.58% net efficiency, illustrative), while the 30 repaired garments consumed sewing labour twice.[S04][S13][S14] All rework labour must remain inside the attended-minutes denominator.[S12][S13]
In the ILO Factory Improvement Toolset implementation in Pakistan (Factory AM), introducing stricter inline quality assurance in the stitching room eliminated the need for third-party contractual workers previously hired for re-working defective garments.[S12] Across the Asian FIT programme, sewing-room line achievement improved by 9.49 percent while work in progress and defects per hundred units (DHU) both declined by 22 percent, proving that tightening quality at the source raises net line achievement.[S12]
sewing-room line achievement improved by 9.49 percent while work in progress and defects per…
S12
While OEE requires a dimensionless quality proportion between 0 and 1 (such as first-pass yield), sewing supervisors also track defects per hundred units (DHU) because a single rejected or reworked garment may carry multiple stitch, measurement or stain defects.[S09][S12][S14] If 100 inspected shirts include 88 defect-free shirts and 12 defective shirts containing 18 distinct defects, first-pass yield is 88 / 100 = 88.0 percent while the defect rate is 18.0 DHU (illustrative).[S09][S12][S14] First-pass yield feeds the multiplicative OEE equation (OEE = A x P x Q), whereas DHU by defect code feeds the Pareto root-cause huddles treated in Chapter 11.[S04][S09][S12]
Furthermore, any manual quality metric is bounded by inspection accuracy.[S07][R29] Industry inspection evidence in the shared register notes that manual fabric and defect inspection is typically 60 to 70 percent accurate, missing 20 to 30 percent of defects, whereas automated computer-vision systems can exceed 90 percent accuracy across more than 40 defect types at speeds up to 60 metres a minute on fabric rolls.[R29] Standardizing inline and end-of-line inspection lighting, templates and defect codes ensures that rising first-pass yield reflects fewer defects rather than lax inspection; inspection hardware is addressed in a companion paper on quality systems.[S12][S26][R29]
4.16
Read-out
Derived with illustrative inputs using the OEE loss structure in S04 and SMV accounting in S13: 500 scheduled shift garment equivalents less 50 availability loss and 70 speed loss leaves 380 gross pieces completed; 57 defective pieces (15 per cent first-pass defect share) reduce first-pass good output to 323 pieces, while inline re-sewing of 48 repairable pieces at 0.5 garment-equivalent cycle each displaces 24 additional new-garment equivalents of station capacity, leaving 299 net first-pass equivalents.
Unit: good-garment equivalents per shift. Status: derived. Sources: S04, S13.
Read this exhibit in its chapter ↗4.16 · Introduction
Every growing garment factory transitions from clipboards and spreadsheets to digital production monitoring, whether through end-of-line tablets, motor power sensors or manufacturing execution systems (MES) with process monitoring devices (PMDs).
Exhibit 51, chapter 11: Scheduled shift base
4.17 · Formula drift between manual shift sheets and vendor software invalidates historical baselines
The ASME Standards Subcommittee meeting at the National Institute of Standards and Technology (NIST) concluded that industry guidance still requires a generally accepted definition of OEE because multiple definitions and calculations coexist across practitioners and vendors.
Exhibit 51, chapter 11: Scheduled shift base
4.18 · A governed calculation contract with unit tests protects the transition from logbook to edge platform
To prevent formula drift, GFT treats the calculation contract as version-controlled engineering code from Day 1.
Exhibit 51, chapter 11: Availability downtime
4.16 · the bodyThe film above follows these sub-steps.
Every growing garment factory transitions from clipboards and spreadsheets to digital production monitoring, whether through end-of-line tablets, motor power sensors or manufacturing execution systems (MES) with process monitoring devices (PMDs).[S09][S14] Assuming that buying software solves measurement inconsistency is a costly mistake: if mathematical definitions of planned time, basic time, SMV allowances, ideal cycle time and good output are not frozen beforehand, software merely automates ambiguity.[S01][S03][S05]
The ASME Standards Subcommittee meeting at the National Institute of Standards and Technology (NIST) concluded that industry guidance still requires a generally accepted definition of OEE because multiple definitions and calculations coexist across practitioners and vendors.[S03] Similarly, formal analysis of ISO 22400-2 found that the standard presents two versions of the OEE indicator that appear substantially different without demonstrating their equivalence in the text.[S05]
When a garment factory moves from an engineer's workbook to a vendor platform without a governed specification, three silent discrepancies appear:[S01][S03][S05] 1. Denominator drift: The manual sheet divided earned minutes by total attended clock minutes of all operators and helpers, whereas the vendor software divides by active terminal login minutes of machine operators only, excluding helpers and subtracting off-standard time so reported "efficiency" jumps from 54 percent to 72 percent (illustrative) with zero change in physical output.[S13][S0402][S0403] 2. Ideal-cycle drift: The pilot line calculated OEE performance using rated basic time (T_basic), whereas the vendor software imports allowance-inclusive SMV_i or recalculates a rolling 30-day average of observed cycles.[S03][S09][S0401] 3. Quality-boundary drift: The manual log tracked first-pass yield, whereas the packing scan calculates net yield after inline repair, erasing rework losses from OEE quality.[S04][S09][S14]
To prevent formula drift, GFT treats the calculation contract as version-controlled engineering code from Day 1.[S01][S03][S26] Under ISO 22400-2, every key performance indicator must be documented by its formula, constituent elements, time behaviour, unit and boundary conditions.[S01] Embedding deterministic numerical unit tests guarantees that any spreadsheet, database query, web simulator or vendor MES reproduces the exact same numbers before acceptance.[S01][S03][S05] All inputs in the verification table below are illustrative test vectors.[S01][S03]
| Vector | Inputs (illustrative) | Intermediate values | Output |
|---|---|---|---|
| TV-01: SMV | T_obs = [0.50, 1.00, 0.50]; R = [100%, 96%, 100%]; a = [0.60, 0.25, 0.20][S13][S0401] | T_basic = [0.50, 0.96, 0.50]; SMV_i = [0.80, 1.20, 0.60][S13][S0401] | SMV = 2.60 min[S13] |
| TV-02: Line eff. | SMV = 2.60; started = 210; rejected = 10; Q_good = 200; 8 x 480 min[S13][S0402][S0403] | Earned = 520.00 min; attended = 3,840.00 min[S13][S0402] | 13.54%[S13][S0402] |
| TV-03: Balance | K = 3 stations; SMV_i = [0.80, 1.20, 0.60]; C_max = 1.20 min[S15][S16] | Content = 2.60 min; capacity = 3.60 min[S15][S16] | 72.22%[S15] |
| TV-04: OEE | Planned = 450; down = 45; ideal = 0.96; total = 360; good = 342[S01][S04][S09] | Op = 405; A = 90.0%; P = 85.33%; Q = 95.0%[S04][S09] | 72.96%[S04][S09] |
Notice how TV-02, TV-03 and TV-04 evaluate the same three-operation garment (SMV_garment = 2.60 minutes, with Operation 2 as the 1.20-minute bottleneck whose basic cycle is 0.96 minutes) and produce three distinct outputs: 13.54 percent line labour efficiency, 72.22 percent structural balance efficiency, and 72.96 percent constraint workstation OEE (illustrative verification suite).[S04][S13][S15] Any spreadsheet or software dashboard that conflates those three ratios fails the unit test suite immediately.[S01][S03]
With the measurement foundation of Part I complete (spanning Chapter 1's economic case, Chapter 2's OEE loss tree, Chapter 3's time base, and this chapter's standard-minute labour connection), Part II turns to balancing work content around the constraint so that earned minutes and good garments rise together.[S13][S15]
Check the record
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24 sources · 407 citation marks on this pageMost cited: S13, 67 times
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R06 · Grade C · inherited record
Inherited evidence R06
About 95 percent of cotton fibre exported raw against 5 percent processed locally; industrialisation target of 50 percent local processing.
Publication date unrecorded. Inherited source-text record. The original publication has not been independently reopened for this web edition.
R07 · Grade C · inherited record
Inherited evidence R07
SND30 restates the 50 percent local-processing target by 2030.
Publication date unrecorded. Inherited source-text record. The original publication has not been independently reopened for this web edition.
R12 · Grade C · inherited record
Inherited evidence R12
CICAM capacity utilisation, July 2023 report: Garoua 33.7 percent, CICAM 1 48.9 percent, CICAM 2 10.83 percent; underutilisation cost about CFAF 2 billion in 2020.
Publication date unrecorded. Inherited source-text record. The original publication has not been independently reopened for this web edition.
R14 · Grade C · inherited record
Inherited evidence R14
Cameroon minimum wage (SMIG) XAF 41,875 a month in 2023, raised to XAF 43,969 a month from 23 February 2024, about US$76, a rise of 5 percent.
Publication date unrecorded. Inherited source-text record. The original publication has not been independently reopened for this web edition.
R16 · Grade C · inherited record
Inherited evidence R16
Informal share of employment about 90 percent; standard 40-hour week, 48-hour maximum, overtime at 1.2 times.
Publication date unrecorded. Inherited source-text record. The original publication has not been independently reopened for this web edition.
R29 · Grade C · inherited record
Inherited evidence R29
Manual defect inspection 60 to 70 percent accurate, missing 20 to 30 percent of defects; computer vision above 90 percent across more than 40 defect types; line-scan inspection up to 60 metres a minute.
Publication date unrecorded. Inherited source-text record. The original publication has not been independently reopened for this web edition.
c04-S01 · Grade A
ISO 22400-2:2014: Automation systems and integration: Key performance indicators for manufacturing operations management, Part 2
The KPIs are presented by means of their formula and corresponding elements, their time behaviour, their unit/dimension and other characteristics.
2014. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c04-S02 · Grade A
The Costs and Benefits of Advanced Maintenance in Manufacturing
Total productive maintenance (TPM) is a program that aims for zero breakdowns and zero defects and focuses on eliminating six losses: equipment breakdown, setup and adjustment slowdowns, idling and short-term stoppages, reduced capacity, quality-related losses, and startup/restart losses.
2018. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c04-S03 · Grade A
Summary Report: Meeting of the ASME Standards Subcommittee on Advanced Monitoring, Diagnostics, and Prognostics for Manufacturing Operations Hosted at NIST
Guidance should include a generally-accepted definition of Overall Equipment Effectiveness (OEE); there are currently multiple definitions, interpretations, and calculations for OEE.
2020. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c04-S04 · Grade B
Overall Equipment Effectiveness: Systematic Literature Review and Overview of Different Approaches
Availability measures downtime losses due to breakdowns or setup/adjustments; performance measures speed losses due to minor stoppages and reduced speed; and quality measures defect losses due to process defects or reduced yield [9].
2020-09-17. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c04-S05 · Grade B
Overall Equipment Effectiveness: consistency of ISO standard with literature
The standard presents two versions of the Overall Equipment Effectiveness (OEE) indicator: apparently the two versions are radically different and no effort of highlighting their equivalence is evident in the text.
2020. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c04-S06 · Grade B
Equipment Effectiveness: OEE Revisited
OEE does include equipment-independent conditions, such as lack of input items.
2005-02-28. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c04-S07 · Grade B
Overall equipment effectiveness when production speeds and stoppage durations are uncertain
In practice, components of OEE may consist of uncertainty due to manual or semi-automatic measurement systems.
2017-10-12. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c04-S09 · Grade B
Achieving Sustainable Overall Equipment Effectiveness (OEE) in Apparel Industry With Lean and Digital Integration
Company X improved its OEE from 42.91% to 52.27% using PMDs and digital line balancing.
2025-07-26. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c04-S12 · Grade B
Implementation of the Factory Improvement Toolset in the Asian garment sector: Final report
Sewing-room line achievements improved by 9.49 per cent and the work in progress and defect per hundred units of garments both reduced by 22 per cent.
2023. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c04-S13 · Grade B
Creating Better Jobs for Women and Boosting Productivity in Bangladesh's Garment Factories: An assessment of the Gender Equality and Returns Program
The SMV for the garment is the sum of the SMVs for each of the steps required to produce the garment.
2025. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c04-S14 · Grade C
How to Calculate OEE in the Garment Manufacturing Industry?
The sewing floor is labor intensive and overall production performance depends on the employees' performance instead of machine and equipment performance.
2024-11-14. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c04-S15 · Grade B
Improvement of garment assembly line efficiency using line balancing technique
The cycle time is an amount of time for which a job remains in a workstation.
2020-04-03. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c04-S16 · Grade B
Carbon Emission Evaluation Based on Multi-Objective Balance of Sewing Assembly Line in Apparel Industry
Equation (8) guarantees that the operating time of each process in any workstation should not exceed the assembly line pitch time.
2019-07-19. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c04-S17 · Grade B
Applying Meta-Heuristics Algorithm to Solve Assembly Line Balancing Problem with Labor Skill Level in Garment Industry
The workers' performances for each task are rated from 0 (no skill at all) to 1.5 (fully skilled) according to the workers' skill table provided by Chan et al. [2].
2021-04-26. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c04-S26 · Grade B
Standardized Work
The benefits of standardized work include documentation of the current process for all shifts, reductions in variability, easier training of new operators, reductions in injuries and strain, and a baseline for improvement activities.
2020-07-02. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c04-S0401 · Grade C
How to Calculate Garment SAM (Standard Allowed Minute)?
To convert this cycle time into the basic time, you need to multiply the cycle time by the operator's performance rating.
2025-07-26. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c04-S0402 · Grade C
Difference between Minutes Produced and Minutes Attended
The total minute produced is calculated from the production quantity and garment SAM.
2020-04-18. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c04-S0403 · Grade C
How to Calculate Overall Line Efficiency?
When the whole shift hours are used in the calculation, irrespective of how much time (hours) operators do an off-standard job and remain idle, it gives overall efficiency.
2018-11-29. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗S04 MDPI, Applied Sciences. 2020-09-17.
S13 International Finance Corporation and International Labour Organization, Better Work. 2025.
S0401 Online Clothing Study. 2025-07-26.
S09 Wiley, Engineering Reports. 2025-07-26.
S14 Online Clothing Study. 2024-11-14.
R06 Cameroon Trade Hub. Publication date unrecorded; inherited source-text check.
R07 Ecofin Agency. Publication date unrecorded; inherited source-text check.
R12 Business in Cameroon. Publication date unrecorded; inherited source-text check.
S12 International Labour Organization. 2023.
R14 WageIndicator. Publication date unrecorded; inherited source-text check.
S15 Wiley, Engineering Reports. 2020-04-03.
S0402 Online Clothing Study. 2020-04-18.
S16 MDPI, Energies. 2019-07-19.
S17 Atlantis Press, International Journal of Computational Intelligence Systems. 2021-04-26.
S26 Lean Enterprise Institute. 2020-07-02.
S07 Springer, International Journal of Advanced Manufacturing Technology. 2017-10-12.
S02 National Institute of Standards and Technology. 2018.
S06 IEEE, IEEE Transactions on Semiconductor Manufacturing. 2005-02-28.
S0403 Online Clothing Study. 2018-11-29.
S03 National Institute of Standards and Technology. 2020.
R16 WageIndicator. Publication date unrecorded; inherited source-text check.
S01 International Organization for Standardization. 2014.
S05 Elsevier, Computers and Industrial Engineering. 2020.
R29 MDPI; industry inspection literature. Publication date unrecorded; inherited source-text check.
Keep the thread · chapter 04 of 14
Move the shuttle along the rack to preview any chapter: its sections, exhibits and reading time. Draft web edition. This research is not investment, legal or tax advice; illustrative models are not measured factory results.
The paper's rack · 14 boltsBolt length: reading time
01Part I: Measure the factory that actually exists
A garment factory creates value when the whole line converts available time and skill into accepted output. Installed machines and busy stations are evidence of resources, not proof of delivery.
02Part I: Measure the factory that actually exists
A single OEE score can start a conversation, but only its components and loss codes can tell a supervisor what to fix.
03Part I: Measure the factory that actually exists
A factory cannot interpret downtime until it has separated legal hours, planned production, external interruptions and losses inside the line.
04Part I: Measure the factory that actually exists
SMV translates garment work content into earned minutes, but it must sit beside OEE and quality rather than replace them.
05Part II: Balance work to the constraint
Balancing begins with operation precedence and required output, then tests how work can be shared without violating machine, skill or quality constraints.
06Part II: Balance work to the constraint
A workstation assignment is feasible only when the operator can perform the method safely and repeatedly at the assumed cycle and quality.
07Part II: Balance work to the constraint
A balance that ignores machine availability, skill or precedence can look efficient on screen and fail on the floor.
08Part II: Balance work to the constraint
A balance calculated for one style and crew decays as absence, learning, defects and order mix change the work.
09Part III: Design flow instead of local busyness
Balanced work needs controlled release. A line shortens delivery time when it admits work that downstream operations can use, makes queues visible and protects good output at its constraint.
10Part III: Design flow instead of local busyness
Small batches become practical when style changes are short, methods are standard and the layout lets qualified operators share work around the constraint.
11Part III: Design flow instead of local busyness
Defects consume capacity twice, first through lost good output and then through rework, queues and repeated interruption.
12Part IV: Turn measurement into sustained performance
A technically balanced line still fails when learned operators are absent, hours are unsustainable or electricity interrupts production.
13Part IV: Turn measurement into sustained performance
The financial benefit is not a higher dashboard score; it is more good garments at acceptable labour, energy, capital and working-capital cost.
14Part IV: Turn measurement into sustained performance
Release the next commitment only when a measured trial shows that good throughput, safe work and controlled flow survive ordinary operating conditions.