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Selecting and sizing an order picking system

Performance comes from the coordinated system of goods, orders, people, information and material flow—not from one isolated technology.

In brief

An order picking system assembles partial quantities from an available assortment according to orders. Its performance results from provision, movement, picking, checking, transfer, information and labour—not from an isolated equipment choice.

What belongs to an order picking system?

The established VDI 3590 framework treats order picking as an integrated system of material, information and organisational functions. Current planning adds today's requirements for ergonomics, software, sensors and automation to that foundation.

VDI 3657:2025-09 covers physical and mental workload as well as digital assistance. VDI 4481:2019-04 complements it with labour-requirement calculation.

Order and item profiles before technology

Data areaExamplesPlanning impact
ItemsDimensions, weight, turnover, hazardous goods, batchesStorage zone, picking method and aids
OrdersLines per order, units per line, time windowsBatching, zones, sorting and peak performance
InventoryCoverage, seasonality, reserve, replenishmentProvision quantity and replenishment strategy
LabourShifts, skills, performance variabilityWorkstations, staffing and ergonomics
QualityError tolerance, identification, traceabilityChecks, assistance and system guidance

Six design elements

  1. Provision: static or dynamic, goods-to-person or person-to-goods.
  2. Movement: walking, driving, conveying or automatic feeding.
  3. Picking: manual, assisted or automated, including gripping and handling conditions.
  4. Checking: identification, quantity, weight, scanning and traceability.
  5. Transfer and consolidation: order carriers, buffers, sorting and shipping handover.
  6. Information: WMS order, dialogue guidance, status, exceptions and feedback.

Compare typical system families

System familyStrengthsCheck carefully
Person-to-goodsFlexible, low technology thresholdTravel share, ergonomics and peak staffing
Goods-to-personShort reaches, high space utilisationReplenishment, sequencing and availability
Zone pickingSpecialised areas and parallel workHandover, balancing and consolidation
Automated pickingRepeatability and low walking effortItem suitability, exceptions and economics

Size for peaks, not averages

Design should use order lines and picks per time unit, not merely order counts. Peak profiles, breaks, replenishment, order mix, travel, failures and shift handovers are considered separately. Required workplaces and staff follow from effective rather than theoretical performance.

Ergonomics and digital assistance

Reach height and depth, load weight, repetition, posture and travel influence both performance and health. Digital assistance can reduce search and checking effort but creates visual, acoustic and cognitive demands of its own. Planning therefore tests not only technical function, but whether people can operate the system safely and reliably throughout a shift.

Technical basis

  • VDI 3590 Parts 1 and 2, fundamentals and system selection for order picking.
  • VDI 4481:2019-04, determination of labour requirements in order picking.
  • VDI 3657:2025-09, ergonomic design of manual order picking systems.

For application, see warehouse planning, warehouse technology and warehouse management systems.

FAQ

Frequently asked questions

Which measure is decisive for sizing?

Order lines or picks per time unit are usually more informative than orders per time unit. Peak profiles and effective performance must also be considered.

When is goods-to-person suitable?

For an appropriate item range, high picking demand and sufficiently stable processes. Replenishment, exceptions and technical availability must be sized with it.

How is labour demand calculated?

From work content, volume profile, effective performance, shift time and allowances for supporting and recovery time, checked against observed process data.

Is maximum automation always economical?

The maximum level of automation is not automatically economical. Item structure, volume, variability, exceptions, life-cycle cost and adaptability determine the appropriate level of automation.

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