What Is an Operation Breakdown / Operation Bulletin?

The planning document that tells a factory exactly how many machines and workers a style actually needs.

An operation bulletin document listing operations, machines, and manpower

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Two Documents, One Purpose: Set Up the Line Correctly

Before a style can go into bulk sewing, someone has to answer very specific questions: exactly which operations are needed, in what order, on which machines, and how many operators and machines each one requires to hit the daily target. That's the job of the Operation Breakdown and the Operation Bulletin (OB) — the core planning tools of industrial engineering (IE).

Operation Breakdown vs. Operation Bulletin

Operation Breakdown: A sequential list of every single operation needed to assemble the garment (attach collar, join shoulder, hem sleeve, etc.), in the order they happen. This matters most in assembly-line production, where each operator does only one step — it's far less relevant in a make-through system where one person sews the whole garment.
Operation Bulletin (OB): Builds on the breakdown by adding the SMV, machine type, and calculated manpower/machine requirement for every operation, plus a total summary — effectively the full resourcing plan for the line.

How Machine Requirement Gets Calculated

For each operation, the number of machines needed is roughly:

Machine Requirement = (Operation SMV × Hourly Production Target) ÷ 60

The result is rounded to a practical whole number, and operations needing less than half a machine's worth of time are often combined onto a shared machine where possible. This calculation is what tells a factory, before a single machine is switched on, exactly how many of each machine type an order will require.

Why This Step Matters

Benefits of a Proper OB

Gives an accurate machine and manpower count before the line is set up
Sets a realistic, achievable daily production target from the start
Helps identify likely bottlenecks before they cause real delays

Risks of Skipping or Rushing It

Wrong machine counts, leaving some operations under-resourced
Targets set on guesswork rather than actual timed operations
An outdated OB left unrevised after a construction method changes

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