Supply — Manufacturing Yield Cascade

// A production yield cascade for one week of assembly. The shift split
// has to sum back to the units started, every scrap reason has to account
// for its drop, and the released total is derived from the two streams
// that feed it rather than typed in by hand.

supply_chain assembly {
  title: "Pump assembly — week 19 yield"
  product: "Circulator pump, 40 mm inline"
  currency: "USD"
}

sc_node machining {
  name: "Machining cell"
  role: "factory"
  location: "Plant 2, Monterrey"
  capacity: 9000
}

sc_node line {
  name: "Assembly line"
  role: "factory"
  location: "Plant 2, Monterrey"
  capacity: 8600
}

sc_node test_rig {
  name: "End-of-line test"
  role: "factory"
  location: "Plant 2, Monterrey"
  capacity: 8600
}

sc_node fg_store {
  name: "Finished-goods store"
  role: "warehouse"
  location: "Laredo, TX"
  capacity: 20000
}

sc_link machined_to_line {
  from: machining
  to: line
  lead_time_days: 1
  cost_per_unit: 0.90
  mode: "truck"
}

sc_link line_to_test {
  from: line
  to: test_rig
  lead_time_days: 1
  cost_per_unit: 0.15
}

sc_link test_to_store {
  from: test_rig
  to: fg_store
  lead_time_days: 3
  cost_per_unit: 2.40
  mode: "rail"
}

cohort units_started {
  n: 8400 source "MES batch report, week 19"
}

// The two shifts are drawn from the same start, so they must sum to it.
arm day_shift {
  n: 4880
  from: units_started
  label: "Day shift"
}

arm night_shift {
  n: 3520
  from: units_started
  label: "Night shift"
}

cohort units_assembled {
  n: 8106
  from: units_started
  excluded: {
    missing_component: 171
    operator_scrap: 123
  }
}

// Nothing is lost between assembly and test, and saying so explicitly is
// what makes the next subtraction checkable.
cohort units_tested {
  n: 8106
  from: units_assembled
}

cohort first_pass {
  n: 7692
  from: units_tested
  excluded: {
    leak_test_fail: 268
    electrical_fail: 146
  }
}

cohort sent_to_rework {
  n: 414 source "MES rework queue, week 19"
}

cohort rework_recovered {
  n: 361
  from: sent_to_rework
  excluded: {
    unrecoverable_casting: 38
    scrapped_after_second_fail: 15
  }
}

// Two streams merge, so this total is derived rather than typed: 7692
// first-pass units plus 361 recovered from rework.
cohort released {
  n: = first_pass.n + rework_recovered.n
}

cohort shipped {
  n: 7994
  from: released
  excluded: {
    held_for_qa_audit: 44
    packaging_damage: 15
  }
}

kpi first_pass_yield {
  title: "First-pass yield"
  baseline: = pct(first_pass.n, units_started.n)
  target: 95
  unit: "%"
}

kpi rework_recovery {
  title: "Units recovered from the rework loop"
  baseline: = pct(rework_recovered.n, sent_to_rework.n)
  target: 90
  unit: "%"
}

view yield: consort(units_started)
view chain: supply_map