Optimal and simple algorithms to solve integrated procurement-production-inventory problem without/with shortage

2018 ◽  
Vol 52 (3) ◽  
pp. 755-778 ◽  
Author(s):  
Amir Hossein Nobil ◽  
Leopoldo Eduardo Cárdenas–Barrón ◽  
Erfan Nobil
Keyword(s):  
Raw Materials ◽  
Research Work ◽  
Exact Algorithms ◽  
Optimal Number ◽  
Raw Material ◽  
Convex Programming Problem ◽  
Inventory Problem ◽  
Lot Size ◽  
Total Cost ◽  
Production Inventory

This research work deals with an imperfect production system considering the purchasing of raw materials in order to study the economic production quantity (EPQ). This manufacturing system produces perfect and defective finished products; defectives are considered as scrap. A single product is manufactured from multiple raw materials which are purchased from outside suppliers. In the integrated procurement-production-inventory (IPPI) model, one of the principal decisions, in addition to determining the optimal lot size to produce, is to define the number of optimal orders of each raw material with respect to rate of consumption in the manufacturing of finished product. Two cases are considered: without shortage (first model) and with shortage (backordering, second model). In the first model, the purpose is to determine jointly the optimal lot size to manufacture and the optimal number orders of each raw material in order to minimize the total cost. The second model obtains the optimal number of orders of each raw material, the optimal lot size to manufacture and the optimal shortage level with aim to minimize the total cost. This research also shows that both of the proposed inventory models are a convex programming problem, so exact algorithms to solve these inventory problems are proposed.

scholarly journals PERENCANAAN DAN PENGENDALIAN PERSEDIAAN BAHAN BAKU PAIL CAT MENGGUNAKAN METODE MATERIAL REQUIRMENT PLANNING (MRP) PADA PT. XYZ

JUMINTEN ◽  
2020 ◽  
Vol 1 (4) ◽  
pp. 163-172
Author(s):  
Vify Elviana ◽  
Akmal Suryadi
Keyword(s):  
Inventory Management ◽  
Consumer Demand ◽  
Raw Materials ◽  
Raw Material ◽  
Economic Order Quantity ◽  
Economic Order ◽  
Order Quantity ◽  
Material Requirements Planning ◽  
Total Cost ◽  
Material Requirements

Persediaan merupakan aset perusahaan yang memiliki peran penting dalam operasi bisnis, sehingga perusahaan penting untuk melakukan manajemen persediaan yang baik, artinya perusahaan harus mampu mengantisipasi kendala maupun tantangan yang ada dalam pengelolahan persediaan untuk meminimalisasi total biaya yang harus dikeluarkan oleh perusahaan. Permasalahan yang timbul pada persediaan bahan baku di PT XYZ adalah perusahaan melakukan perencanaan dan pengendalian bahan baku hanya berdasarkan pada pengalaman-pengalaman sebelumnya dan tidak berdasarkan pada metode yang sudah baku. Oleh karena itu pembelian bahan baku tidak sesuai dengan permintaan konsumen. Hal tersebut sering menyebabkan terjadinya kelebihan maupun kekurangan stok bahan baku. Kesalahan dalam penentuan besarnya investasi dalam persediaan akan mengurangi keuntungan perusahaan. Adanya persediaan bahan baku yang terlalu besar, akan menambah beban biaya pemeliharaan dan penyimpanan dalam gudang, serta kemungkinan terjadinya penurunan kualitas bahan baku yang dapat menyebabkan berkurangnya keuntungan perusahaan. Namun jika persediaan bahan baku terlalu sedikit maka akan berakibat pada terhambatnya proses produksi, sehingga tidak terpenuhinya permintaan konsumen. Hasil penelitian ini dapat menyimpulkan bahwa perencanaan kebutuhan bahan baku dengan metode perusahaan didapatkan total cost sebesar Rp 1.796.762.429,-, sedangkan metode Material Requirements Planning (MRP) didapatkan total cost sebesar Rp 1.576.011.801,-. Maka dapat disimpulkan telah terjadi penurunan total cost seluruh bahan baku sebesar 12,28%. Hal ini membuktikan bahwa metode Material Requirements Planning (MRP) lebih efisien daripada metode PT. XYZ. Oleh karena itu untuk mendapatkan total cost yang minimum, metode Material Requirements Planning (MRP) diterapkan pada periode Februari-Juni 2020 sehingga didapatkan total cost sebesar Rp 1.576.011.801,-. Kata Kunci:         Material Requirements Planning (MRP), PT XYZ, Pail Cat, Economic Order Quantity (EOQ), Period Order Quantity (POQ), Lot For Lot (LFL). ABSTRACT                     Inventory is a company asset that has an important role in business operations, so the company is important to conduct good inventory management, meaning that the company must be able to anticipate obstacles and challenges that exist in managing inventory to minimize the total cost to be incurred by the company.The problem that arises in the supply of raw materials in PT XYZ is that the company plans and controls raw materials based only on previous experiences and not based on established methods. Therefore, the purchase of raw materials is not in accordance with consumer demand. This often leads to excess or shortage of raw material stock. Mistakes in determining the amount of investment in inventories will reduce company profits. The availability of raw materials that are too large, will add to the burden of maintenance and storage costs in the warehouse, as well as the possibility of a decline in the quality of raw materials that can lead to reduced company profits. However, if the supply of raw materials is too little, it will result in obstruction of the production process, so that consumer demand is not fulfilled. The results of this study can conclude that the planning of raw material needs by the company method obtained a total cost of Rp 1,796,762,429, - while the Material Requirements Planning (MRP) method obtained a total cost of Rp 1,576,011,801, -. Then it can be concluded that there has been a decrease in the total cost of all raw materials by 12.28%. This proves that the Material Requirements Planning (MRP) method is more efficient than the PT. XYZ. Therefore, to get the minimum total cost, the Material Requirements Planning (MRP) method was applied in the February-June 2020 period so that a total cost of Rp 1,576,011,801 was obtained.   KeyWords: Material Requirements Planning (MRP), PT XYZ, Pail Cat, Economic Order Quantity (EOQ), Period Order Quantity (POQ), Lot for Lot (LFL).

scholarly journals MATERIAL REQUIREMENT PLANNING UNTUK MEMENUHI PRODUKSI PADA CV. BANGUN CIPTA ARTHA DI BADUNG

2020 ◽  
Vol 9 (2) ◽  
pp. 426
Author(s):  
I Made Sugita Yasa ◽  
Kastawan Mandala
Keyword(s):  
Inventory Management ◽  
Lot Sizing ◽  
Raw Materials ◽  
Raw Material ◽  
Exact Order ◽  
Lot Size ◽  
Inventory Costs ◽  
Material Requirement Planning ◽  
Material Requirement ◽  
Total Inventory

Inventory management without Material Requirement systems in CV. Bangun Cipta Artha resulted in the lot size for each order of raw materials not optimal. One concept that can be used to plan and control raw materials is the Material Requirement Planning. This study is to determine the number of sizes of raw material orders, the exact order time, the method that produces the lowest cost for each raw material, and the effect of using MRP on inventory costs. This research conducted on 160x200cm spring bed products. Data was analyzed by making production master schedules, determining net requirements, determining lot size, and making MRP tables. Based on the results, the determination the best lot sizing is the order quantiy period which results in a total inventory cost of Rp. 26,475,220 where the total cost is lower, compared to lot for lot method which Rp. 43,464,000. part period balancing Rp. 33,106,576, and conventional method Rp.49,472,912. Keywords: Material Requirement Planning (MRP), Sizing Lot, Lot For Lot, Balancing Part Period, Period Order Quantiy

scholarly journals Optimal Pricing and Ordering Policy for Two Echelon Varying Production Inventory System

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Brojeswar Pal ◽  
Shib Sankar Sana ◽  
Kripasindhu Chaudhuri
Keyword(s):  
Supply Chain ◽  
Raw Materials ◽  
Chain Model ◽  
Selling Price ◽  
Lot Size ◽  
Ordering Policy ◽  
Supply Chain Model ◽  
Production Inventory ◽  
Test Feasibility ◽  
Optimal Ordering

The paper proposes a two-stage supply chain model for price sensitive demand in imperfect production system while manufacturer and supplier are the members of the chain. The supplier screens the raw materials first and supplies good materials to the manufacturer at a constant rate. The production rate varies randomly within a finite interval. The inventory cycle of the manufacturer starts with shortages and production and it finishes with shortages again, in which shortages are partially backlogged. We consider a mixture of LIFO (last in, first out) and FIFO (first in, first out) dispatching policies to fill the backlogged demand. Thus, the objective of the proposed paper is to determine the optimal ordering lot-size and selling price of the manufacturer such that the per unit average integrated expected profit of the supply chain model is maximized. A numerical example is provided to analyze and illustrate the behavior and application of the model. Finally, sensitivity analysis of the key parameters are presented to test feasibility of the model.

OPTIMALISASI PENGADAAN BAHAN BAKU DALAM RANGKA MEMINIMALKAN TOTAL BIAYA PERSEDIAAN TEMBAKAU PADA PT BENTOEL INTERNATIONAL INVESTAMA DI MALANG

2019 ◽  
Vol 2 (1) ◽  
pp. 23
Author(s):  
Dwi Dayanti Oktavia ◽  
Peni Indarwati ◽  
Marhaerni Fikky Febriananta
Keyword(s):  
Production Process ◽  
Raw Materials ◽  
Cost Savings ◽  
Optimal Level ◽  
Raw Material ◽  
Economic Order Quantity ◽  
Economic Order ◽  
Order Quantity ◽  
Total Cost ◽  
The Cost

A company should maintain an adequate or optimal level of inventory so that production operations can run smoothly and efficiently. What needs to be considered in this case is that the required raw materials are always available, so as to guarantee the smooth production process. However, the amount of inventory should not be too much because this will harm the company. Too much inventory will increase maintenance costs and storage costs in the warehouse. In addition, the amount of inventory that is too much can also increase the likelihood of losses due to damage and loss of quality that can reduce company profits. And vice versa, the amount of inventory that is too small will hamper the production process so that the company will suffer a lot of losses including: the machine does not work as it should, many workers are unemployed, and can even result in the cessation of the production process. This study aims to determine how the calculation of raw materials, what is the total cost of raw material inventory if the company establishes an EOQ (Economic Order Quantity) policy, what is the limit or point of ordering raw materials needed by the company during the grace period at PT.Bentoel International Investama in Malang.The population used is the supply of tobacco raw materials at PT. Bentoel International Investama, where this research was conducted by interview and documentation. The variable in this study is the supply of raw materials. The analysis used is the EOQ (Economic Order Quantity) method.The results of the study, if using the EOQ method in 2017 the cost savings of Rp 40,290,256,931, while in 2018 the cost savings of Rp. 44,388,428,549. Thus there is a difference between inventory policies carried out according to the company with EOQ calculations. It can be concluded that the supply of raw materials every year has increased raw materials, the frequency of purchasing raw materials when using raw materials when using the EOQ method is 2 times in one period, the limit for ordering raw materials needed by companies when using the 2017 EOQ method is 218,176.7 kg, while in 2018 it will be 210,853 kg. The total cost of raw material inventory calculated according to EOQ is less than that spent by the company, so there is a cost savings of raw material inventory

scholarly journals A Mathematical Model of the Production Inventory Problem for Mixing Liquid Considering Preservation Facility

Mathematics ◽  
2021 ◽  
Vol 9 (24) ◽  
pp. 3166
Author(s):  
Md Sadikur Rahman ◽  
Subhajit Das ◽  
Amalesh Kumar Manna ◽  
Ali Akbar Shaikh ◽  
Asoke Kumar Bhunia ◽  
...  
Keyword(s):  
Raw Material ◽  
Production Model ◽  
Sensitivity Analyses ◽  
Maximization Problem ◽  
Mixing Process ◽  
Inventory Problem ◽  
Highly Nonlinear ◽  
Production Inventory ◽  
The Impact ◽  
Mixing Problem

The mixing process of liquid products is a crucial activity in the industry of essential commodities like, medicine, pesticide, detergent, and so on. So, the mathematical study of the mixing problem is very much important to formulate a production inventory model of such type of items. In this work, the concept of the mixing problem is studied in the branch of production inventory. Here, a production model of mixed liquids with price-dependent demand and a stock-dependent production rate is formulated under preservation technology. In the formulation, first of all, the mixing process is presented mathematically with the help of simultaneous differential equations. Then, the mixed liquid produced in the mixing process is taken as a raw material of a manufacturing system. Then, all the cost components and average profit of the system are calculated. Now, the objective is to maximize the corresponding profit maximization problem along with the highly nonlinear objective function. Because of this, the mentioned maximization problem is solved numerically using MATHEMATICA software. In order to justify the validity of the model, two numerical examples are worked out. Finally, to show the impact of inventory parameters on the optimal policy, sensitivity analyses are performed and the obtained results are presented graphically.

scholarly journals Joint lot sizing and scheduling of a multi-product multi-period supply chain

2019 ◽  
Vol 10 (5) ◽  
pp. 1516
Author(s):  
Ahmed Othman El-meehy ◽  
Amin K. El-Kharbotly ◽  
Mohammed M. El-Beheiry
Keyword(s):  
Supply Chain ◽  
Lot Sizing ◽  
Raw Materials ◽  
Supply Chain Design ◽  
Raw Material ◽  
Design Parameters ◽  
Distribution Centers ◽  
Lot Size ◽  
Holding Cost ◽  
Lot Sizing And Scheduling

The joint lot sizing and scheduling problem can be considered as an evolvement of the joint economic lot size problem which has drawn researchers’ interests for decades. The objective of this paper is to find the effect of a capacitated multi-period supply chain design parameters on joint lot sizing and scheduling decisions for different holding and penalty costs. The supply chain deals with two raw materials suppliers. The production facility produces two products which are shipped to customers through distribution centers. A mathematical model is developed to determine optimum quantities of purchased raw materials, production schedule (MPS), delivered quantities and raw material and products inventory for predetermined number of periods. The model is solved to maximize total supply chain profits. Results showed that at high capacity and low holding cost, the supply chain tends to produce only one product each period, for limited capacity and high value of holding cost, the supply chain may produce the two products together each period.

scholarly journals ANALISA PENGENDALIAN PERSEDIAAN DAUN KAYU PUTIH YANG OPTIMAL DENGAN METODE CONTINOUS REVIEW SYSTEM DI PT. XYZ

2021 ◽  
Vol 16 (1) ◽  
pp. 106-117
Author(s):  
Enny Aryanny ◽  
Ragil Kusuma Jati
Keyword(s):  
Raw Materials ◽  
Raw Material ◽  
Lost Sales ◽  
Continuous Control ◽  
Review System ◽  
Total Cost ◽  
Continuous Review ◽  
Eucalyptus Oil ◽  
Inventory Costs ◽  
Eucalyptus Leaves

Persediaan adalah sumber daya yang perlu diadakan dan dipelihara untuk menunjang kelancaran produksi. PT. XYZ merupakan perusahaan yang bergerak di proses pembuatan minyak kayu putih. Perusahaan memproduksi minyak kayu putih dimana bahan baku utamanya adalah daun kayu putih. Perusahaan ini memiliki permasalahan dalam melakukan pengendalian persediaan bahan baku daun kayu putih yang disebabkan oleh permintaan minyak kayu putih oleh konsumen yang tidak menentu. Perusahaan mengalami keadaan persediaan yang berlebih yang mengakibatkan tingginya biaya persediaan dan kurangnya persediaan yang mengakibatkan produksi yang tidak memenuhi pesanan. Berdasarkan permasalahan di atas, maka dilakukan pengendalian persediaan dengan metode continuous review system backorder dan lost sales. Tujuan dari penelitian ini adalah melakukan pengendalian persediaan daun kayu putih sehingga dapat meminimumkan biaya persediaan. Metode continuous review system backorder dan lost sales akan dibandingkan dengan metode perusahaan dan dipilih metode terbaik dengan total biaya paling minimum. Hasil dari perhitungan diperoleh total biaya persediaan minimum dengan metode continuous review system backorder sebesar Rp 2.459.692.004, sedangkan metode perusahaan sebesar Rp 2.595.684.800, sehingga mendapatkan penghematan biaya sebesar Rp 135.992.796 dengan efisiensi sebesar 5,2%. Jumlah pemesanan bahan baku per pesan bulan November 2019 – Oktober 2020 sebesar 1.812 ton, dengan total biaya persedian bahan baku sebesar Rp 2.544.762.825.   Kata Kunci: Continuous, Pengendalian, Persediaan.   ABSTRACT Inventories are resources that need to be procured and maintained to support the continuity production. PT. XYZ is a company engaged in the process of making eucalyptus oil. The company produces eucalyptus oil where the main raw material is eucalyptus leaves. This company has problems in controlling the supply of raw materials of eucalyptus leaves caused by the erratic demand of eucalyptus oil by consumers. The company experiences a state of excess inventory which results in high inventory costs and lack of inventory resulting in production that does not fulfill orders. Based on the above problems, inventory control is carried out using the continuous review system backorder and lost sales method. The purpose of this study is to control the inventory of eucalyptus leaves so as to minimize inventory costs. The continuous review system backorder and lost sales method will be compared with the company method and the best method is chosen with the minimum total cost. The results of the calculation obtained the minimum total inventory cost with the continuous review system backorder method of Rp.2,459,692,004, while the company's method of Rp2,595,684,800, so as to get a cost savings of Rp.135,992,796 with an efficiency of 5.2%. The number of raw material orders per message in November 2019 - October 2020 amounted to 1,812 tons, with a total cost of supplying raw materials amounting to Rp 2,544,762,825.   Keywords: Continuous, Control, Inventory.

scholarly journals DEVELOPMENT OF FUNCTIONAL BEVERAGES FROM PLANTRAW MATERIALS — REPLACEMENTS FOR DAIRY PRODUCTS

Food systems ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 44-47
Author(s):  
N. E. Posokina ◽  
N. M. Alabina ◽  
A. Yu. Davydova
Keyword(s):  
Dairy Products ◽  
Nutritional Value ◽  
Raw Materials ◽  
Research Work ◽  
World Market ◽  
Raw Material ◽  
Sesame Seeds ◽  
Functional Beverages ◽  
Poppy Seeds ◽  
Functional Drink

Nowadays, there is a growing consumer interest in food products, made from vegeta-ble raw materials. The article is devoted to an actual topic related to the choice of plant mate-rials, based on its nutritional and biological value, in order to create functional beverages. The analysis of the world market of vegetable analogues of milk was implemented. Based on the literature, the following raw materials were analyzed: cashew nuts, cannabis fruits, sesame and poppy seeds, almond kernels, buckwheat seeds and oats, soybeans. The data on nutritional value, vitamin-mineral and amino acid composition, as well as the composition of fatty acids of the specified raw materials was presented. The conclusion is made about the perspective of its use for the manufacture of drinks, alternative cow’s milk. The article reflects the results of research work on the creation of a functional drink based on sesame seeds, provides information about the nutritional value and biochemical composition of the drink, made on the basis of this raw material. Sesame milk when used regularly can help prevent diseases of the car-diovascular system, the gastrointestinal tract, the musculoskeletal system.

scholarly journals A model of a production-repair inventory system with time-varying demand and quality-dependent recovery channels

2021 ◽  
Vol 36 ◽  
pp. 04002
Author(s):  
Ivan Yeo
Keyword(s):  
Raw Materials ◽  
Planning Horizon ◽  
Inventory System ◽  
Raw Material ◽  
Time Varying ◽  
Total Cost ◽  
External Sources ◽  
Varying Demand ◽  
Infinite Planning Horizon ◽  
Better Than

In this paper, we study an inventory system over an infinite planning horizon where a time-varying demand is satisfied by process cycles that consist of a production batch followed by a recovery batch. Our model considers three types of inventory—returned items, serviceable items, and raw material. Furthermore, our model considers two recovery channels—recovery into serviceable items and recovery into raw material. Serviceable items are thus sourced from two inputs—direct recovery and production from raw material. These raw materials can be salvaged from returned items, as well as bought from external sources whenever required. We propose an expression for the unit time total cost as well as a numerical method to find the optimal policy. The properties of the model are studied through numerical experiments, in particular, the feasible situations where hybrid policies are better than pure policies.

scholarly journals Cost Analysis of Various Factors for Geopolymer 3D Printing of Construction Products in Factories and on Construction Sites

Recycling ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 60
Author(s):  
Qaisar Munir ◽  
Timo Kärki
Keyword(s):  
3D Printing ◽  
Carbon Dioxide Emissions ◽  
High Performance ◽  
Raw Materials ◽  
Research Work ◽  
Transportation Cost ◽  
Raw Material ◽  
Low Carbon ◽  
Construction Sites ◽  
Construction Products

The utilization of geopolymer 3D printing for construction products in recent years has been exceptionally substantial, owing to their low carbon dioxide emissions, high-performance properties such as durability, and good thermal and mechanical properties. This automated manufacturing process reduces the need for additional formworks, capital investments, and human resources. Geopolymer 3D printing development is emerging because of its advanced use in construction applications. However, high costs of the initial stages of geopolymer production and 3D printing has inhibited the development of this technology in many countries. This research presents a comprehensive economic evaluation of the investment for each principal stage that facilitates a better deployment of the resources. The study investigated all phases of geopolymer production, from the extraction of raw materials to printing. The cost for the four fundamental stages, namely raw material availability and transportation, pretreatments for raw materials, parameter selection and strength requirements, and printing in factories and on construction sites, were analyzed. The results show that 3D printing of a geopolymer on a construction site is economically more advantageous compared to printing in the factory. The study also verified that raw material transportation cost has the least effect on the finished product cost, whereas pretreatments of raw material and mixing parameters significantly influenced the ultimate cost of the product. Finally, research work suggested the need for future tasks to make geopolymer 3D printing a viable construction approach.

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