PERANCANGAN KEBIJAKAN INVENTORI SERVICE PARTS DENGAN MENYESUAIKAN MODEL P DAN Q UNTUK MEMAKSIMALKAN NILAI AFR DENGAN TETAP MEMINIMASI ONGKOS INVENTORI (STUDI KASUS: PT TOYOTA ASTRA MOTOR)

• Main Author: Abdul, Nebiba
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/63949
• Institution: Institut Teknologi Bandung

One of the biggest industry in Indonesia which have tendency to grow annually is automotive industry, especially car. Despite Covid-19 pandemic, car sales could recover and grow again with the discount of PPnBM from government. Service parts industry is equally large as automotive industry. Toyota Astra Motor as one of the biggest player in this industry via Service Parts Logistic Division (SPLD) manage the distribution of service parts for Toyota cars in Indonesia. SPLD had problem namely Allocation Fill Rate (AFR) that was not maximum. AFR is an indicator for customer demand fulfilment rate in the form of lines. Based on January 2020 data, AFR value in SPLD was 96,41%, whereas the target is 100%. There was 3,59 GAP AFR which become the problem to be solved. After conducted problem decomposition, concluded that service parts within category PCC A – local supplier and PCC C – import supplier deal significant impact in form of huge loss lines. Through root cause analysis, identified causes are SPLD is not considering inventory cost, only have one forecasting method (MAD/DAD), inconsistent safety stock calculation method, also safety stock and reorder period is calculated based on expert judgement. Looking for these condition, research plan is made to develop new forecasting scheme and inventory policy which aimed to maximize AFR value while minimizing total inventory cost. New forecasting scheme include Augmented Dickey-Fuller test, train-test split scheme, also additional forecasting methods: ARMA, Holt’s, and Winters’ besides MAD and DAD method. Proposed inventory policy are customized P model customized Q model. There are three adjustment for those model. First, combined buying cost and order fee to be procurement cost. Second, combined backorder and lost sales condition with the introduction of ? constant. Third, using modified Hadley-Within method to search for local optimal solution. The modification made is prioritize the iteration looking for solution which have smallest shortage inventory (N) value first so that the AFR will be maximum. The result of this research are as follows: new forecasting scheme will replace existing forecasting and customize model P will be used to calculate inventory policy for both service parts in category PCC A – Local and PCC C – Import. This solution generate AFR and total inventory cost for service parts in PCC A – Local category respectively 98,3% and Rp 13.099.691.234,00. For service parts in PCC C – Import category, this solution generate AFR and total inventory cost value respectively 95,44% and Rp 78.898.679.851,00. Inventory cost can be lowered by changing lower limit of T value during the searching process of local optimal solution. Based on this research, it is also known that the solution is insensitive against change of lead time, saving cost/unit/period, backorder cost, and lost sales cost.