Efficiency Calculation

oee efficiency kpi

Kartorium calculates efficiency at two levels: OEE (Overall Equipment Effectiveness) for machine/station performance, and OPS Efficiency for labor productivity.

OEE (Overall Equipment Effectiveness)

OEE is the standard manufacturing metric that combines three factors:

$\text{OEE}=\text{Availability}\times \text{Performance}\times \text{Quality}$

Each factor is a percentage (0-100%). OEE is calculated per machine, per station, or across a site, over any time range.

Availability

Availability measures what proportion of time the machine was actually running vs. stopped.

$\text{Availability}=\frac{\text{Run Time}}{\text{Run Time}+\text{Downtime}}$

Which types of downtime count in the denominator depends on the calculation mode:

Mode	Denominator	Description
standard	Run Time + Unplanned Downtime	Excludes idle and planned downtime. Only unplanned stops reduce availability.
strict	Run Time + Unplanned + Planned Downtime	Excludes only idle time. Both planned maintenance and unplanned stops reduce availability.
teep	Total Calendar Time	Most stringent. All time counts — run time, planned downtime, unplanned downtime, and idle time.

Downtime type is inherited from the downtime reason’s parent group:

• Unplanned — breakdowns, equipment failures. Always reduces availability.
• Planned — scheduled maintenance, changeovers. Reduces availability in strict and teep modes.
• Idle — no production scheduled, waiting for work. Reduces availability only in teep mode.

See Reason Taxonomy for how downtime reasons are organized into typed groups.

Performance

Performance measures how fast equipment produces relative to its target rate (SEMI E79: Performance Efficiency).

$\text{Performance}=\frac{\text{Actual Output}}{\text{Expected Output at Target Rate}}\times 100\%$

For concurrent batch equipment (equipment with multiple parallel positions, like a sterilization chamber with 8 pallet slots), Performance is the product of two sub-metrics:

$\text{Performance}=\text{Rate Efficiency}\times \text{Operational Efficiency}$

Sub-metric	What it measures	Formula
Rate Efficiency	Are batches completing on time?	Standard Hours ÷ Actual Hours
Operational Efficiency	Are all positions being used?	Actual position-hours ÷ Available position-hours

Example: A sterilizer with 8 positions runs an average of 3.5 concurrent batches. Each batch completes in ~110 hours vs. a 108-hour standard.

• Rate Efficiency = 108 ÷ 110 = 98.2% (batches are fast)
• Operational Efficiency = 3.5 ÷ 8 = 43.8% (half the positions are empty)
• Performance = 98.2% × 43.8% = 43.0%

This decomposition is visible in the Performance KPI card tooltip on the equipment dashboard.

For regular equipment (one batch at a time), Rate Efficiency equals Performance and Operational Efficiency is 100%.

Target rate is configured per equipment and derived from product standards:

• theoretical_cycle_time_seconds — target time per part (legacy, per-equipment)
• Product-equipment config standard_hours — planned batch duration (preferred, per-product-per-equipment)
• target_concurrent_batches — number of parallel positions (default 1)

Performance can exceed 100% if equipment produces faster than target (capped at 100% in display).

Quality

Quality measures the proportion of good parts vs. total parts produced.

$\text{Quality}=\frac{\text{Good Parts}}{\text{Good Parts}+\text{Scrap Parts}}$

Part counts are recorded when batches/jobs are completed. Aborted batches are excluded from quality calculations but included in availability and performance.

Target OEE

Each machine has configurable target percentages:

• target_oee_percent (default 85%)
• target_availability_percent (default 90%)
• target_performance_percent (default 95%)
• target_quality_percent (default 99.5%)

Target OEE is also configurable per Product Family per Station via Station Product Standards, enabling different targets for different products at different stations.

OPS Efficiency (Labor Productivity)

OPS Efficiency measures how productively labor time was used compared to the expected time for the work completed:

$\text{Efficiency}=\frac{\text{Standard Hours}}{\text{Actual Hours}}\times 100\%$

This is distinct from OEE. OEE tracks machine effectiveness; OPS Efficiency tracks labor productivity.

Standard Hours

Standard hours represent the expected labor time to complete a job. They come from the product hierarchy with fallback:

1. Product-level — the product’s standard_hours (most specific)
2. Family-level — the product family’s standard_hours (fallback)
3. Zero if neither is defined (efficiency returns NULL)

Actual Hours

Actual hours come from labor time entries — time clocked by workers against jobs. Only closed entries (where the worker has clocked out) are counted. See Job Time Tracking for the full time accumulation model.

Efficiency Granularities

Five views are available:

View	Aggregation
Per Job	Efficiency for each completed/scrapped job in a time range
Per Station	Total standard hours / total labor hours across all jobs at each Station
Per Person	Each worker’s clocked hours vs. earned hours from completed jobs
Per Team	Aggregate across all workers at a site
Per Product Family	How efficiently each Product Family is produced

Station View Summary

A single-station summary provides:

• Job counts (queued, in progress, completed, scrapped)
• Part totals and scrap rate
• Efficiency percentage
• Average cycle time in minutes

Key Behaviors

• Efficiency can be NULL when there are no labor hours or no standard hours. The system does not default to 0% or 100%.
• Per-station snapshots are stored in station history for per-station analysis.
• All functions validate site-organization ownership before returning data.

Standards Reference

Kartorium’s OEE calculations align with:

• SEMI E79 — Specification for Definition and Measurement of Equipment Productivity (Performance Efficiency = Operational Efficiency × Rate Efficiency)
• ISO 22400 — Key Performance Indicators for Manufacturing Operations Management (OEE = Availability × Effectiveness × Quality)
• NIST — Kang et al., “A Hierarchical Structure of Key Performance Indicators” (formal KPI hierarchy and formulas)

See Also

• Analytics — user-created OEE charts with calculation mode selection
• Machines — how machines provide data for OEE
• Station Dashboard KPIs
• Product
• Product Family
• Station Analytics
• Job Time Tracking