การจัดการสินค้าคงคลังสำหรับผลิตภัณฑ์หน้ากากอนามัยยี่ห้อ 3M ของบริษัท เชียงใหม่เดลต้าอีเล็คตริค เทรดดิ้ง จำกัด

Abstract

The purpose of this independent study was to study inventory management for 3M face mask products of Chiang Mai Delta Electric Trading Co., Ltd., with a total of 17 target products. The secondary data was obtained from the case study company on the past 5 years (weekly) sales from January 2015 to December 2019 for use in determining the best model for sales forecasting and inventory management. In selecting a suitable sales forecasting model for all 17 items, the researcher used the error measurement technique in the time series forecasting model and criteria for evaluating the validity and accuracy of the model. As for the selection of a suitable inventory management model for all 17 items, the researcher used the Peterson–Silver Rule technique to analyse and classify variance in sales demand resulting from sales forecasting with the best model. For low variance demand, the researcher used the economic order quantity (EOQ model) inventory management technique and for the high variance demand, the researcher used the inventory management technique of pre-ordering at the lowest cost (Silver - Meal Method). The results of the study of the most appropriate sales forecasting model demonstrated that there were 3 products in the sales forecasting model using the Simple Exponential Smoothing Method (SES), 1 product in the forecasting model using the Holt's Exponential Smoothing method Method (HES), 5 products in the forecasting model using Brown's Exponential Smoothing Method (BES), 3 products in the product sales forecasting model using Winter's Additive Exponential Smoothing Method (WAES), and 5 products in the product sales forecasting method by Winter's Multiplication Exponential Smoothing Method (WMES). The results of the optimum inventory management model revealed that all 17 items in this independent study used the economic order quantity (EOQ) inventory management technique due to the low variance in sales demand resulting from sales forecasting with the best model (V < 0.25). All products resulted in total costs (Total Cost) decreased by 85,416.01 baht from the actual cost (decreased by 25.58%) as a result of the cost of storage (Holding Cost) that decreased by 152,638.80 baht from the actual cost (decreased by 54.02%). The cost of ordering increased by 67,222.77 baht from the actual cost (increased by 130.68%) because the cost of purchasing per time was low. By comparing to the holding cost of high-value products, it resulted in the calculation of the economic order quantity (EOQ Model) to increase the ordering frequency from the original ordering of once per 4 weeks to 4 times per 4 weeks which affected the cost of ordering, but it had a good effect on the holding cost. making the overall cost of inventory management to decrease accordingly. Therefore, the benefit of this independent study was to obtain an optimal inventory management model for all 17 products in addition to reducing the total cost of inventory management.