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Profile Cutting Optimization - Specification

Objective

Minimize waste when cutting profile raw materials (steel, etc.) to fulfill customer demands within a defined timespan.

Input Files

Format: CSV

1. Stock Inventory

Column Description
part_number Profile part number
lot_batch Lot/batch identifier (label on physical piece)
length Length of this lot batch
length_limit Upper length limit per piece (if length > limit, split into multiple pieces + remainder)
storage_location Free-text storage location for operator reference
uom Unit of measurement for this file (mm, cm, m, inches)

2. Demand List

Column Description
order_no Order number
line_no Order line number
component_part_number Required profile part number
part_description Part description (informational only)
lot_size Number of assemblies in order
required_qty Pieces required per assembly
length Length per piece (max length considering angle)
demand_date Required date (YYYY-MM-DD)
cut_type straight or miter (Gehrung)
angle_left Left cutting angle in degrees (0 = straight)
angle_right Right cutting angle in degrees (0 = straight)
cutting_code Special cutting code reference (informational)
uom Unit of measurement for this file

Parameters

Parameter Default Description
Cut_Thickness 3.0 mm Material lost per cut (kerf width)
Timespan 30 days Days to optimize (all past demands + today + N days)
Min_Remnant_Length 100 mm Minimum length to save as remnant (below = scrap)
Good_Enough 5% Waste threshold to stop optimization attempts

Business Rules

Demand Processing

  1. Filtering: Include demands where demand_date ≤ today + Timespan
  2. Priority: Cut oldest demands first (sort by demand_date ascending)
  3. Part Matching: Only cut demands from stock with matching part_number (no substitutions)
  4. Partial Fulfillment: If stock can only fulfill some pieces, fulfill what's possible and list remainder as unfulfilled

Stock Processing

  1. Splitting: If length > length_limit, split into floor(length / limit) pieces of limit + remainder
  2. Consumption Order: Suggest oldest lot batch first, but operator may use equivalent piece
  3. Remnant Tracking: After partial cut, remnant gets new lot_batch ID with "-1" suffix
  4. Cutting Direction: Cuts can be made from either end of stock piece
  5. Cut Loss: Each cut consumes Cut_Thickness of material

Cut Ordering

  1. Group by Angle: Cuts are grouped by angle to minimize saw adjustments
  2. Split Across Stock: Pieces from same demand line may come from different stock pieces

Edge Cases

  1. Piece Too Long: If demand length exceeds all available stock → unfulfilled with note "no stock long enough"
  2. No Stock Exists: All demands for missing part number → unfulfilled with note "No stock exists"
  3. Duplicate Lot Batch: Treat as separate pieces (ignore duplicate)
  4. Malformed Demand: length = 0 or required_qty = 0 → unfulfilled with "ERROR - demand UNDEFINED"

Output

Format: Excel (.xlsx) with print-ready formatting, timestamped filename (e.g., cutting_plan_2026-01-26_143022.xlsx)

Sheet 1: Cutting Plan

Hierarchical format per stock piece:

╔══════════════════════════════════════════════════════════════════════════════════╗
║ Stock: PN-001 | Lot: LOT-A001 | Location: Aisle-3-Bin-12 | Length: 6000mm       ║
╠════════╦═══════════╦════════════╦════════╦═══════════╦═══════════╦═══════════╦════════════════╣
║ Cut #  ║ Order     ║ Demand Date║ Length ║ Cut Type  ║ L/R Angle ║ Code      ║ Remaining     ║
╠════════╬═══════════╬════════════╬════════╬═══════════╬═══════════╬═══════════╬════════════════╣
║ 1      ║ ORD-101   ║ 2026-01-15 ║ 1500   ║ miter     ║ 45° / 0°  ║ MC-001    ║ 4497mm        ║
║ 2      ║ ORD-101   ║ 2026-01-15 ║ 1500   ║ miter     ║ 0° / 45°  ║ MC-001    ║ 2994mm        ║
║ 3      ║ ORD-102   ║ 2026-01-18 ║ 2000   ║ straight  ║ 0° / 0°   ║           ║ 991mm         ║
╠════════╩═══════════╩════════════╩════════╩═══════════╩═══════════╩═══════════╩════════════════╣
║ REMNANT: LOT-A001-1 | 991mm (save) or WASTE: 991mm (16.5%) if below threshold                ║
╚═══════════════════════════════════════════════════════════════════════════════════════════════╝

[Next stock piece follows...]

Sheet 2: Unfulfilled Demands

Order Line Part Number Qty Needed Length Reason
ORD-105 2 PN-003 5 2500 No stock exists
ORD-106 1 PN-001 2 8000 no stock long enough
ORD-107 3 PN-002 1 0 ERROR - demand UNDEFINED

Sheet 3: Summary

Part Number Total Used (mm) Total Waste (mm) Waste % Orders Fulfilled
PN-001 45000 3200 7.1% 12
PN-002 28000 1800 6.4% 8
TOTAL 73000 5000 6.8% 20

User Interface

Type: Simple GUI (tkinter or similar)

Features

  • File selectors for Stock Inventory CSV and Demand List CSV
  • Output directory selector
  • Parameter fields with defaults:
    • Cut Thickness: 3.0
    • Timespan (days): 30
    • Min Remnant Length: 100
    • Good Enough (%): 5
    • Sort By: Dropdown with options:
      • "Date (Oldest First)" - sorts results by demand date ascending
      • "Part Number" - sorts results alphabetically by part number
  • "Run Optimization" button
  • Progress/status display
  • "Open Output Folder" button after completion

Result Sorting

The optimization results can be sorted by the user-selected parameter:

  • Date (Oldest First): Groups cutting plans by the earliest demand date of cuts in each stock piece, oldest demands processed first
  • Part Number: Groups cutting plans alphabetically by stock part number (A-Z)

The selected sort order is applied to:

  1. Pattern Visualization in the GUI (rows ordered by sort parameter)
  2. Excel Output - Sheet 1 "Cutting Plan" (stock pieces ordered by sort parameter)

Pattern Visualization

After optimization completes, display a graphical cutting pattern diagram within the GUI:

Visual Layout

  • Title: "PATTERN" header above the diagram
  • Row Label (Left side): Part number and part description for each stock piece
  • Rows: Each row represents one stock piece being cut
  • Segments: Horizontal colored blocks showing individual cuts
  • Segment Labels: Order number displayed centered within each segment (if space permits)
  • Colors: Different colors distinguish different part numbers (e.g., yellow, pink, gray)
  • Waste/Remnant: Gray segment at the end of each row for remaining material

Example Reference

Pattern Visualization

Specifications

Element Description
Row label Part number + description shown to the LEFT of each pattern row
Segment text Order number centered in segment (only if segment width > text width)
Block width Proportional to cut length relative to stock length
Block height Fixed height per row (e.g., 25-30 pixels)
Row spacing Small gap between rows for visual clarity
Color palette Predefined set of 6-8 distinct colors, cycling per part number
Segment border Thin black border around each segment
Font Small, readable font (centered)

Smart Text Visibility

  • If segment is wide enough: Display order number centered inside
  • If segment is too narrow: Hide text, show via hover tooltip instead

Hover Tooltips

Always available on hover, showing:

  • Order number
  • Length
  • Cut type and angles (if miter)

Scrolling

  • Vertical scroll if many stock pieces exceed visible area

Technical Requirements

  • Language: Python 3.10+
  • Dependencies: openpyxl (for Excel output)
  • Algorithm: Best Fit Decreasing (BFD) with local swap optimization
  • Optimization Scope: Per stock piece

Notes

  • Cutting plan language: English
  • Date format: YYYY-MM-DD
  • Excel formatted for direct printing (no manual page setup needed)
  • System is re-executed regularly with fresh ERP data (no reservation tracking)