ANALISIS PERSEDIAAN MATERIAL DENGAN METODE MATERIAL REQUIREMENT PLANNING (MRP) PADA PT. WASKITA BETON PRECAST PLANT SIDOARJO - NURMELASARI, INDAH (Rekayasa Teknik Sipil, 2018)
Material merupakan salah satu komponen penting dalam sistem produksi. Semakin banyaknya suatu permintaan produksi, kebutuhan material juga semakin meningkat. Oleh karena itu, ketersediaan material harus diperhitungkan agar tidak terjadi permasalahan seperti kehabisan material (stockout) maupun kelebihan material (overstock). Tujuan penelitian ini adalah untuk mengetahui prediksi kebutuhan material, teknik lotsizing dengan biaya persediaan paling efektif dan ekonomis serta total biaya persediaan. Jenis penelitian ini ialah deskriptif kuantitatif dengan teknik pengumpulan data berupa wawancara, observasi dan dokumentasi. Teknik analisis data menggunakan metode Material Requirement Planning (MRP) dengan empat teknik lotsizing yaitu Lot For Lot, Economic Order Quantity, Period Order Quantity dan Part Period Balancing sedangkan peramalan menggunakan metode Single Moving Average dan Single Exponential Smoothing. Hasil penelitian menunjukkan bahwa prediksi kebutuhan material di waktu mendatang ialah Semen 49.345.038 Kg, Pasir 60.172 m3, Kerikil 70.360 m3, Besi D13 5.876.541 Kg, Besi D16 235.169 Kg, Besi D19 100.570 Kg dan PC Bar 3.628.641 Kg. Berdasarkan analisis, teknik lotsizing yang menghasilkan biaya paling efektif dan ekonomis ialah teknik Part Period Balancing dengan total biaya persediaan material sebesar Rp 21.464.706,56 dan persentase biaya persediaan material sebesar 0,01% dari biaya pembelian material. Kata Kunci: Beton Precast, Material Requirement Planning, Biaya Persediaan Abstract Material is one important component in the production system. The more a production demand, the material demand is also increasing. Therefore, the availability of materials must be taken into account, so as not to occur problems stockout or overstock. The purpose of research is to know the prediction of material needs, lotsizing technique with the cost of inventory is most effective and ecomonical, and total inventory cost. The type of research is descriptive quantitative with the data collection techniques such as interviews, observation and documentation. The data analysis technique using method Material Requirement Planning (MRP) with four lotsizing technique are Lot For Lot, Economic Order Quantity, Period Order Quantity and Part Period Balancing and forecasting uses the method Single Moving Average and Single Exponential Smoothing. The result show that prediction of material needs in the future is Cement 49.345.038 Kg, Sand 60.172 m3, Gravel 70.360 m3, Steel Bar D13 5.876.541 Kg, Steel Bar D16 235.169 Kg, Steel Bar D19 100.570 Kg and PC Bar 3.628.641 Kg. Based on analysis, lotsizing technique that produces the most cost effective and economical is Part Period Balancing Technique with total material inventory cost  is Rp Rp 21.464.706,56 and the percentage of material inventory cost is 0,01% from material purchase cost. Keywords: Concrete Precast, Material Requirement Planning, Inventory Cost