§ 16
How many kanban cards should be in circulation for this item?
Answer: With a kanban system you order new when a bin is empty, and the card goes back to the supplier or warehouse. The number of cards determines how much is in circulation at most. With too few, the line runs dry whilst restocking. With too many, the warehouse piles up. Toyota's formula takes the daily consumption, restocking time, a safety factor and number of pieces per bin. You enter your own figures from your operation.
Antal kort N = forbrug pr. dag (D) × genopfyldningstid i dage (L) × (1 + sikkerhedsfaktor α) ÷ stk pr. kasse (C), rundet op
Stk i omløb = N × C
Toyota recommends keeping the safety factor low and instead shortening the replenishment time
| Symbol | Meaning | Unit |
|---|---|---|
| efterspoergsel | Consumption per day | stk/dag |
| genopfyldning_dage | Replenishment period (from card sent until full box back) | dage |
| sikkerhed_pct | Safety factor | % |
| kasse_stk | Pcs per box (per card) | stk |
| = | Kanban cards in circulation | kort |
| = | Pcs in circulation in total | stk |
| = | Consumption in replenishment time (without safety) | stk |
| = | Pcs over consumption in replenishment time | stk |
Does not apply when
The calculator's own default values inserted. The figures are calculated with exactly the formula the tool uses.
Substituted
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Når et lager eller en linje skal styres med kanban, skal antallet af kort besluttes. Det er antallet af kasser i omløb. Toyotas formel bruges, når systemet startes op, og når forbruget eller leverandøren ændrer sig.
Monteringslinjen bruger 200 skruer om dagen. Genopfyldningen tager 2 dage, sikkerheden er 10 %, og der er 50 skruer i en kasse.
It means: Der skal være 9 short i omløb, i alt 450 pcs. Det dækker forbruget i genopfyldningstiden på 400 pcs med 50 pcs ekstra.
Rengøringsafdelingen bruger 4 æsker handsker om dagen, leverandøren er 5 dage om at levere, og der er 10 æsker i en karton.
It means: Der skal være 3 short i omløb, altså 30 pcs på hylden og undervejs.
En komponent bruges med 1.500 stk om dagen, leveres to gange dagligt (halv dag), med 5 % sikkerhed og 200 stk pr. kasse.
It means: Systemet skal have 4 short. Den korte genopfyldningstid holder lageret nede.
Kort ≈ forbrug i genopfyldningstiden ÷ kassestørrelse + lidt.
Stk i omløb skal være mindst forbruget i genopfyldningstiden.