We study the influence of limited capacity and multiple products on the optimal sourcing decisions for a manufacturer subject to supply and demand uncertainty. The manufacturer produces two products. The component of one product is sourced from two suppliers, one perfectly reliable and the other cheaper but unreliable, failing to deliver the order with some probability. We develop a mathematical model for a single-period setting and study the associated optimality conditions. Our results show that the supplier diversification strategy is significantly different when the buyer has limited capacity. Specifically, we find that single sourcing from an expensive and reliable supplier may be an optimal procurement strategy even when a cheaper option exists. In addition, when producing multiple products, the optimal sourcing strategy may hold inventory of one component to reduce the amount of capacity idling when the supply of a different component is disrupted. We use stochastic programming to validate our single-period findings in a multi-period setting. Although carrying inventory of finished products provides another tactic to mitigate supply uncertainty in a multi-period environment, we observe the key findings from single period, like single-sourcing from an expensive but reliable supplier, remain valid.

我们研究了有限的产能和多种产品对受供需不确定性影响的制造商的最佳采购决策的影响。制造商生产两种产品。一种产品的组件来自两个供应商，一个非常可靠，另一个更便宜但不可靠，有一定的概率无法交付订单。我们为单周期设置开发了一个数学模型，并研究了相关的最优条件。我们的研究结果表明，当买方产能有限时，供应商多元化战略存在显着差异。具体来说，我们发现即使存在更便宜的选择，从昂贵且可靠的供应商处单一采购也可能是最佳采购策略。此外，在生产多种产品时，最佳采购策略可能会保留一个组件的库存，以在不同组件的供应中断时减少产能闲置的数量。我们使用随机规划来验证我们在多期设置中的单期发现。尽管持有成品库存提供了另一种在多时期环境中减轻供应不确定性的策略，但我们观察到单一时期的主要发现，例如从昂贵但可靠的供应商处单一采购，仍然有效。