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§ 16

Stock coverage and reordering of casings

How long will the stock last, and should we order now?

Answer: Casing is bought and sold in hanks and has long lead time when imported. Calculator shows how many production days stock lasts and if stock is below reorder point: the consumption that occurs during lead time plus a safety buffer.

Formula

Lagerdækning (dage) = lager ÷ forbrug pr. dag

Genbestillingspunkt = forbrug pr. dag × (leveringstid + sikkerhedsbuffer)

Order when stock reaches reorder point

Dage til bestilling = (lager − genbestillingspunkt) ÷ forbrug pr. dag

Symbols and units in the formula
SymbolMeaningUnit
lager_hankStock nowhank
forbrug_dagConsumption per production dayhank
levering_dageDelivery timedage
sikkerhed_dageSafety bufferdage
=Stock lastsdage
=Reorder pointhank
=Lager over genbestillingspunktet (minus = bestil nu)hank
=Days until reorderdage

Validity and source

Source
Competence objective (casing technician): 'knowledge of budgeting, calculation computation and production reporting and inventory management'

Does not apply when

  • Calculate in production days not calendar days if consumption is only on weekdays. Use the same unit all the way (box or metre). Large orders and season (Christmas grilling season) change consumption.

Worked example

The calculator's own default values inserted. The figures are calculated with exactly the formula the tool uses.

Substituted

  • Stock now1,200 hank
  • Consumption per production day45 hank
  • Delivery time21 dage
  • Safety buffer7 dage

Giver

  • Stock lasts26.7 dage
  • Reorder point1,260 hank
  • Lager over genbestillingspunktet (minus = bestil nu)-60 hank
  • Days until reorder0.0 dage

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Sådan bruger du den

Tarm fra udlandet har lang leveringstid. Du bruger beregneren til at se, hvor mange produktionsdage lageret rækker, og om der skal bestilles nu, så produktionen ikke løber tør.

Step by step

  1. Tæl lageret op i hank (eller meter).
  2. Find forbruget pr. produktionsdag.
  3. Genbestillingspunkt = forbrug × (leveringstid + sikkerhedsbuffer).
  4. Er lageret under genbestillingspunktet, skal der bestilles nu.
  5. Ellers viser beregneren, hvor mange dage der er, til I skal bestille.

Typical errors

  • At regne leveringstiden i kalenderdage og forbruget i produktionsdage.
  • At glemme store ordrer, der allerede er lovet væk fra lageret.
  • At sætte bufferen til 0. Leverancer bliver forsinket.

Examples from everyday life

Lageret er lige under grænsen

Der er 1.200 hank på lager. Forbruget er 45 hank om dagen, leveringstiden er 21 dage, og I vil have 7 dages buffer.

Stock now
1,200 hank
Consumption per production day
45 hank
Delivery time
21 days
Safety buffer
7 days

It means: Lageret rækker 26.7 days, men genbestillingspunktet er 1,260 hank. Lageret er -60 hank i forhold til punktet, så der skal bestilles i dag.

Lang leveringstid fra udlandet

Der er 3.000 hank på lager. Forbruget er 60 hank om dagen, leveringen tager 35 dage, og bufferen er 10 dage.

Stock now
3,000 hank
Consumption per production day
60 hank
Delivery time
35 days
Safety buffer
10 days

It means: Lageret rækker 50 days. Genbestillingspunktet er 2,700 hank, og der er 5 days, til I skal bestille.

Rule of thumb

Bestil, når lageret kun rækker leveringstiden plus en uge.

How to check the answer

Gang dagene til bestilling med forbruget, og læg genbestillingspunktet til. Det skal give lageret, når lageret er over punktet.