usefulweb.site Twinworks Line Balancing

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Twinworks Line Balancing

Assign assembly tasks to stations for a takt time: efficiency, balance delay and smoothness index.

Tasks (required)
Tasks
#Task idDescriptionTime (s)Predecessors (comma-separated ids)
1
2
3
4
5
6
7
8
s

Leave empty to compute it from available time ÷ demand.

min

Per period, e.g. 450 min per shift.

units

Try an example: Wheelbarrow-style example: 8 tasks, 450 min shift, demand 270 · Six tasks with a fixed takt time of 10 s

How it works

Solves the simple assembly line balancing problem (type 1) with the Ranked Positional Weight (Helgeson–Birnie) and Largest Candidate rules: tasks with times and precedence relations are assigned to as few stations as possible without exceeding the takt time. Returns the station assignment, line efficiency, balance delay, smoothness index and a ready-to-simulate Twinworks model of the balanced line.

  • Takt time = available production time ÷ demand (or as given). Theoretical minimum stations = ⌈Σ task times ÷ takt⌉.
  • RPW: positional weight = own time + times of all direct and indirect successors; LCR: task time. Stations are filled one by one with the highest-priority task whose predecessors are all assigned and that still fits into the remaining takt time.
  • Efficiency = Σ task times ÷ (stations × takt); balance delay = 1 − efficiency; smoothness index = √Σ(max station time − station time)².
  • The result includes a Twinworks model (one constant-time machine per station, single-place buffers) so the balance can be simulated or opened in the app.

Heuristics give good but not always optimal balances. Zoning constraints, operator skills and task variability are not considered.

Sources

  • Helgeson, W. B. & Birnie, D. P.: Assembly line balancing using the ranked positional weight technique (Journal of Industrial Engineering 12, 1961)
  • Groover, M. P.: Automation, Production Systems and Computer-Integrated Manufacturing, ch. “Manual assembly lines” (Pearson) (Pearson)
  • Scholl, A.: Balancing and Sequencing of Assembly Lines (Physica, 1999) (Physica-Verlag)

For scripts and AI agents

  • JSON API: POST https://twinworkslinebalance.usefulweb.site/api/v1/calculate (same calculation as this page)
  • Interface description: OpenAPI 3.1 · AI guide: llms.txt
  • MCP server (Streamable HTTP): https://twinworkslinebalance.usefulweb.site/mcp · tool name twinworks_line_balance
Example request
curl -s -X POST https://twinworkslinebalance.usefulweb.site/api/v1/calculate \
  -H 'content-type: application/json' \
  -d '{"tasks":[{"id":"A","name":"Fit frame","time":60,"predecessors":""},{"id":"B","name":"Mount axle","time":40,"predecessors":"A"},{"id":"C","name":"Fit wheel","time":55,"predecessors":"B"},{"id":"D","name":"Attach tray","time":50,"predecessors":"A"},{"id":"E","name":"Fit legs","time":30,"predecessors":"D"},{"id":"F","name":"Attach handles","time":45,"predecessors":"D"},{"id":"G","name":"Grips","time":20,"predecessors":"F"},{"id":"H","name":"Final check","time":35,"predecessors":"C,E,G"}],"availableMinutes":450,"demand":270,"method":"best"}'

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