INVENTORY SYSTEM (Q,R) WITH CRASHING LEAD TIME CONDITION

Abstract

Performansi perusahaan dapat ditingkatkan dengan mengontrol sistem inventorinya secara tepat. Tulisan ini menjelaskan salah satu model inventori probabilistik kontinyu untuk memecahkan masalah inventori yaitu model Q. Kondisi back order dan creasing lead time diperbolehkan di model ini. Back order merupakan suatu kondisi dimana terjadi kekurangan barang karena permintaan yang tidak diekspektasi pada periode lead time. Tujuan model ini adalah meminimasi biaya inventori dengan menemukan jumlah order optimal, reorder point dan level safety stock. Dan permintaan diasumsikan mengikuti distribusi normal dan model ini dihitung menggunakan Delphi. Simulasi model ini menunjukkan bahwa biaya inventori dipengaruhi oleh beberapa variable seperti reorder point, safety stock, level jasa,dan creasing lead time.

Kata Kunci: Model inventory (Q,r), Crashing Lead time, kebijakan back order.

Performance of the companies can be improved by controlling their inventory system properly. This paper explains one of continues probabilistic inventory model to solving inventory problem, that is called Q model. Condition of back order and creasing lead time are allowed in this model. Back order is the condition when lacking of goods happened because of unexpected demand at lead time period. The objective of this model is to minimizing inventory cost by founding the optimal of quantity order, reorder point and level of safety stock. And also, demand is assumed following normal distribution and this model will compute by using Delphi. Simulation of this model shows that inventory cost is affected by several variables, such as, reorder point, safety stock, service level and creasing lead time.

Key Word: (Q,r) inventory model, Crashing Lead time, Back order policy