| dc.description.abstract | PT XYZ is one of the companies concerned in paint and coating industry in
Indonesia based in Surabaya. The higher demand for paint products, PT. XYZ also
has to perform raw material inventory planning effectively and efficiently.
Effectively means the company must able to meet the needs of raw materials
without running out of raw materials, and efficiently means the company meets the
needs of raw materials with minimal cost. The problem is that companies
sometimes run out of stock for resin and solvent raw materials and have problems
on the determination of the volume of orders, considering about shipping costs and
storage costs of raw materials in warehouse. Deterministic and probabilistic EOQ
methods are used to determine the optimal quantity of raw materials ordered to
obtain minimal cost.
Based on the result of time series and causal forecasting analysis, the
selected forecasting method was additive decomposition with the smallest Mean
Square Error (MSE) value that is 210,046 (resin) and 68,607 (solvent). These results
became the basis of raw material needs to calculate the EOQ. The deterministic
EOQ calculation results showed that the company must do 27 times order resin and
34 times solvent per year with total cost of inventory is Rp. 528,522,601.35 (resin)
and Rp. 568,007,155.37 (solvent) per year. The safety stock to be provided is
1,202.75 Kg (resin) and 1,594.46 Kg (solvent) with a reorder point of 170.2 Kg
(resin) and 268.96 Kg (solvent). The probabilistic EOQ calculation showed that the
optimum order quantity is the same as the deterministic method, the expectation of
raw material usage at lead time is 211.68 Kg (resin) and 334.51 Kg (solvent). The
probability of stock depletion is 2.869% (resin) and 1.984% (solvent). The safety
stock is 1,384.95 Kg (resin) and 1,987.95 Kg (solvent). Total probabilistic EOQ
cost is slightly higher than deterministic method due to the addition of safety stock
and inventory depleting costs. Total cost with probabilistic method is Rp.
530,290,065.11 + Rp. 33,528.13 K (resin) and Rp. 570,234,459.42 + Rp. 29,007.98
K (solvent) per year. | en_US |
