Zero-Inventory Conditions For a Two-Part-Type Make-to-Stock(17)

We consider the dynamic scheduling of a two-part-type make-tostock production system using the model of Wein [12]. Exogenous demand for each part type is met from finished goods inventory; unmet demand is backordered. The control policy determines which pa

4fails.Thisresultsinproducingsomestockinadvanceforparttypeonewhentherearenobacklogsinthesystem,whilemaintainingazero-inventorypolicyforparttype2.Ontheotherhand,whenh1/h2islargerthan4.1theswitchtoMTSoccurswhenCondition3fails,andresultsinbuildingasafetystockforparttype

two.

Figure5:OptimalityoftheZero-InventoryPolicyforDi erentUtilizationRates

Figure5presentssimilarresultsfordi erentvaluesoftheutilizationrate.Asρincreases,theregionwhereazero-inventorypolicyisoptimalgetssmaller.Themaximumvalueofh1/h2forwhichaswitchinproductionmoderesultsinholdingpartsoftypeone(thatis,whenCondition4fails)alsodecreases.Inotherwords,formake-to-ordersystemswithmoderatetohighutilizationincreasingb/hprecipitatesholdingsafetystockforthelessimportantparttypeintermsofbackordercost.

Inpractice,backordercostsareverydi culttomeasureanddemandmay

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