REFA Time Study
REFA time study is a systematic method for measuring and analyzing work times. It breaks operations into elements and establishes standard times as the basis for planning and improvement.
REFA (Reichsausschuss fuer Arbeitszeitermittlung, now Verband fuer Arbeitsgestaltung) developed a rigorous methodology for time measurement in German-speaking industry. It provides standardized procedures for capturing, analyzing, and setting work times.
A REFA time study breaks a task into individual elements (e.g., reach, grasp, position, fasten), measures each element across multiple cycles, applies statistical analysis to determine the representative time, and adds allowances for personal needs, fatigue, and delays.
The result is a standard time (Vorgabezeit) that serves as the basis for production planning, cost calculation, capacity planning, and performance evaluation. Unlike simple stopwatch measurements, REFA times are statistically validated and reproducible.
Modern REFA practice combines traditional stopwatch studies with video analysis and predetermined motion time systems (MTM). The key advantage remains: Data-based decisions instead of estimates, and a common language for discussing work times across the organization.
Formula
Standard Time = Base Time x (1 + Allowance Factor) where Base Time = Average Observed Time x Performance Rating
Practical Example
A REFA practitioner measures a packing operation across 30 cycles. Average observed time: 34.2 seconds. Performance rating: 105% (slightly above normal pace). Base time: 35.9 seconds. With 12% allowance (personal, fatigue, delays): Standard time = 35.9 x 1.12 = 40.2 seconds per unit.
How Leanshift Helps
Leanshift's stopwatch function captures precise time measurements per process step and automatically calculates averages and variation -- providing the raw data that a REFA analysis requires, directly from the shop floor.
Frequently Asked Questions
Is REFA still relevant today?
Absolutely. While the tools have evolved (digital stopwatches, video analysis, apps like Leanshift), the underlying methodology for fair, reproducible time measurement remains the standard in German-speaking industry.
What is the difference between REFA and MTM?
REFA measures actual times with a stopwatch. MTM (Methods-Time Measurement) uses predetermined times for basic motions. REFA reflects the actual process; MTM designs the theoretical optimal process. Both are complementary.
How many cycles should you measure?
REFA recommends a minimum based on statistical significance -- typically 10-30 cycles depending on variation. Higher variation requires more measurements. The goal is a confidence interval that is narrow enough for reliable planning.
Related Terms
Takt Time
Takt time is the pace at which a product must be completed to meet customer demand. It is determined by the market, not by the machine.
Cycle Time
Cycle time measures how long a single process step actually takes -- from start to finished result. It is the foundation of every process analysis.
Standard Work / Standardized Work
Standard Work documents the current best-known way to perform a task. It defines the sequence, timing, and inventory needed to produce consistent results safely and efficiently.