Section 7 Outbound Work Space Calculation

1. Calculation Approaches for Case Shipping vs. Piece Shipping

Because outbound work methodologies differ fundamentally between case and piece operations, floor areas are calculated using separate logic.

• Case Shipping: Goods are retrieved in bulk per item and sorted directly onto roll-box carts assigned per destination.
• Piece Shipping: Goods are picked from storage shelving (flow racks or medium-duty shelving) and transported to dedicated inspection and packing stations.

2. Racking Design for Piece Shipping (Flow Racks & Medium-Duty Shelving)

Racking specifications depend on the balance between item counts and inventory holding days.

• Adjusting for Unlisted Inventory Items: Inventory items not listed in shipping data (zero-shipment stock) are added to "Piece Shipping Rank D" to guarantee sufficient rack openings for all active SKUs.
• Target Inventory Days Benchmarks:
  • Flow Racks: 3 to 5 days of inventory.
  • Medium-Duty Shelving: 7 to 14 days of inventory.
  • While reducing inventory days decreases footprint area, it increases replenishment frequency and operational strain; thus, optimal balance is required.
• Cubic Volume Calculation Details: Effective rack dimensions minus material thickness, bottom-shelf clearance loss, and fill rates yield true usable storage volume capacity.

3. Case Sorting and Roll-Box Cart Calculations

Calculates required roll-box cart quantities based on volume per destination rank tier.

• Roll-Box Cart Specifications: Selects from 3 standard dimensions (1100×1100, 1100×800, 850×650 mm), factoring in footprint area and aisle clearances.
• Cart Quantity Logic: Establishes conditional criteria based on destination density (e.g., 1 cart per destination if volume ≥ 0.5; 1 cart shared across 5 destinations if volume ≤ 0.2).

4. Inspection / Packing Space and Achieving "Inspection-less" Operations

Floor area for piece shipping inspection stations is calculated based on throughput processing capacity (number of lines).

• Area Formula: "Number of Lines × Area per Line (6 m²) × Expansion Multiplier (110%)".
• Inspection-less Process Flow:
  1. Link shipping data to location barcodes; assign optimal carton sizes.
  2. Execute highly accurate picking using handheld terminals or digital pick-to-light systems.
  3. Perform random sample inspections only.
• Observations: Achieving inspection-less operations requires advanced WMS information systems and rigorous operational management.

Sequence of Outbound Work Space Calculation

In practical engineering, facility scale is finalized backward in the following sequence:

Shipping Space (Exit) → Outbound Work Space → Storage Space (Entrance)

Subsection 1 Calculating Outbound Work Space Floor Area

Because case shipping and piece shipping employ distinct work methods, their required work spaces and calculation logic differ. Calculating case shipping and piece shipping separately establishes clear outbound work spaces and increases engineering accuracy. Case shipping retrieves bulk items from storage and sorts them per destination. Piece shipping retrieves items from storage to replenish flow racks or medium-duty shelving, where goods are picked per destination.
Outbound Work Space includes areas dedicated to outbound inspection and packing.
In Tera Calculation 2, outbound inspection for case shipping is performed during sorting, while piece shipping performs inspection and packing in dedicated stations. If picking-stage inspection is adopted instead, dedicated inspection areas become unnecessary, leaving packing areas to handle cardboard packing for small-account or home delivery orders that cannot use tote containers.

Subsection 2 Processing Items Not Appearing in Shipping Data

In the inventory estimation screen, inventory items not present in shipping data (zero-shipment items) were configured; these unlisted items are added to Piece Shipping Item Rank D for calculation.
In Tera Settings, 120% of active shipping item counts is calculated as total inventory item count, setting unlisted items = 918. Thus, Piece Racking Item Rank D = 2164 + 918 = 3082 items for racking calculations.
This calculation directly determines required shelf opening counts. The primary prerequisite for racking calculations is providing storage openings matching total item counts.

The procedure calculates shelf opening counts and opening volume capacities (determined by openings per shelf level) to evaluate shelf inventory holding days. To increase inventory holding days, openings per level are reduced (increasing opening volume); to decrease inventory days, openings per level are increased (reducing opening volume). More openings per level reduce total rack counts, whereas fewer openings increase rack counts.
Target inventory days: Flow Racks = 3 to 5 days; Medium-Duty Shelving = 7 to 14 days. While smaller inventory days reduce rack counts (smaller floor footprint), replenishment frequency increases, creating operational hardship.

Subsection 3 Case Shipping Sorted to Roll-Box Carts (Destinations)

1. Determine calculated parameter values for 3 roll-box cart sizes.

2. Based on step 1 calculations, calculate required carts per destination across rank tiers.
Volume per Rank / Destination Count yields per-destination volume. Conditions: Volume ≥ 0.5 → 1 cart per destination; 0.4–0.5 → 1 cart per 2 destinations; 0.3–0.4 → 1 cart per 3 destinations; 0.2–0.3 → 1 cart per 4 destinations; ≤ 0.2 → 1 cart per 5 destinations. Calculates total carts set up for sorting.

3. Dividing step 2 cart totals into 3 batch shifts yields sorting area footprint per batch.

4. Apply Area Expansion Multiplier to step 3 calculated area.

Subsection 4 Flow Racks

1-3. Calculating Usable Opening Volume per Flow Rack Unit:
Effective Shelf Width A = Width - 60
Effective Opening Width = (Effective Width - (Openings per level * 20) + 20) / Openings per level (20 mm gap × (openings + 1))
Effective Opening Depth = Rack Depth
Effective Opening Height = (Rack Height - (80 * Levels + 20)) / Levels (80 mm shelf thickness; 20 mm bottom clearance)
Effective Opening Volume = (Effective Width * Effective Depth * Effective Height) / 1000^3
Calculated Opening Volume = Effective Volume * (Fill Rate / 100)
Calculated Rack Volume = Calculated Opening Volume * Levels * Openings per level.
1-4. Default Tera Settings assign Flow Racks to Ranks A1 and A2.

Subsection 5 Medium-Duty Shelving

Int(*** + 0.5) represents rounding decimals to the nearest integer.
Piece Racking Summary Tables display calculation procedures and results based on the above formulas.

Subsection 6 Inspection and Packing for Piece Shipping

All picked piece goods are placed into tote containers and transported to inspection / packing stations.
(Case shipping goods are inspected during case sorting). Floor area for inspection / packing stations:
1. Hourly Piece Throughput 8,252 units = Total Piece Volume 26,449 / Peak Volume Ratio 31%
2. Total Processing Time 24,756 seconds = Hourly Pieces 8,252 / Inspection Time per Piece 3 seconds

3. Inspection Lines = Total Processing Time 24,756 / 3600 seconds = 7 lines
6. Required Floor Area 45.4 m² = 7 Lines * 6 m² per Line * Expansion Multiplier 110%
Area per line (6 m²) adjusts based on tote container dimensions.

Outbound Work Space Area Multipliers
Multipliers are configured individually per task type because multiple distinct tasks coexist in outbound operations.

Displaying Outbound Work Space Calculation Results
When configuring racking while monitoring shelf inventory days, "Inventory" figures in this table (Flow Racks = 3.5 days; Medium-Duty Shelving = 12.8 days) represent target shelf inventory days.
Work space inventory volume equals:
Bulk Storage Inventory = Total Inventory － Work Space Inventory,
which directly dictates required bulk storage capacity.

Subsection 7 Inspection, Packing, & Piece Picking Flowchart

Tera Calculation 2 Distribution Center Scale Calculation assumes inspection-less operations.
Operational workflows achieving inspection-less processing are detailed below: