Integration of JIT /MRP in inventory systems. Abstract:

Transcription

1 Integration of JIT /MRP in inventory systems P.Sivasankaran Assistant Professor, Department of Mechanical Engineering, Manakula Vinayagar Institute of Technology, Pondicherry Abstract: Stock performs a important function in production establishments especially small, medium and huge businesses. The point of intake in manufacturing is based on stock system. It is had to have duty of all stocks which can be furnished by way of the companies to the producers. A well balanced stock gadget improves the agencies productiveness by the controlling the level of stocks maintained in every duration with recognizes to the call for requirements. On this paper strive has made to combine each MRP and JIT gadget with regarding optimizing the stock hassle. For the reason that MRP is priority making plans device now not an execution tool so as to conquer the wastage of inventory JIT idea turned into linked in MRP. Accordingly the hybrid concept helps to improve the manufacturing planning and scheduling. Keywords: Inventory, JIT, MRP, Hybrid inventory model 1. INTRODUCTION Fabric necessities making plans (MRP) is a computer-primarily based manufacturing planning and stock manage device. MRP is concerned with each manufacturing/operations scheduling and stock manage. It is a fabric manage machine that tries to hold ok inventory tiers to guarantee that required materials are available whilst needed. MRP is applicable in situations of more than one item with complex bills of substances. MRP is not beneficial for process stores or for continuous methods which can be tightly connected. 550

2 The major objectives of an MRP system are to simultaneously: 1. Ensure the availability of materials, components, and products for planned production and for customer delivery. 2. Maintain the lowest possible level of inventory. 3. Plan manufacturing activities, delivery schedules, and purchasing activities. MRP is especially suited to manufacturing settings where the demand of many of the components and subassemblies depend on the demands of items that face external demands. Demand for end items is independent. In contrast, demand for components used to manufacture end items depend on the demands for the end items. The distinctions between independent and dependent demands are important in classifying inventory items and in developing systems to manage items within each demand classification. MRP systems were developed to cope better with dependent demand items. The three major inputs of an MRP system are the master production schedule, the product structure records, and the inventory status records. Without these basic inputs the MRP system cannot function The demand for end items is scheduled over a number of time periods and recorded on a master production schedule (MPS). The master production schedule expresses how much of each item is wanted and when it is wanted. The product structure records, also known as bill of material records (BOM), contain information on every item or assembly required to produce end items. Information on each item, such as part number, description, quantity per assembly, next higher assembly, lead times, and quantity per end item, must be available. The inventory status records contain the status of all items in inventory, including on hand inventory and scheduled receipts. These records must be kept up to date, with each receipt, disbursement, or withdrawal documented to maintain record integrity. Since there are many methods involved in balancing the inventory system such as ABC analysis is one among the several tools of inventory. But ABC analysis has some demerits such as some material may consume in lower quantity so in this approach the categorization of materials is not much better it is highly advisable to use MRP concepts in inventory management functions. MRP and JIT each have potential benefits but the only difference MRP helps to prioritize the material orders as per master production schedule but JIT system tries to control the wastage of inventory system. 551

3 2. Literature review: John G. Wacker et al [1] proposed theoretical MRP version which incorporates each demand and supply uncertainties from amount and timing variations. The version suggests empirical methodologies to estimate the variances of very last outputs and components for estimates of safety inventory requirements to lessen uncertainty. Kwahng Kim et Al [2] proposed a brand new methodology by means of integrating the desires of client necessities by way of electronic scheduling machine. Abddalah ali et al [3] proposed a machine of production making plans and inventory manage, which is used to manage production techniques. Maximum MRP structures are software program-based totally and are used to make certain that the substances are to be had for manufacturing, that the products are available for transport to customers, that the bottom viable fabric and product degree is maintained in keep, in addition to to devise shipping schedules and shopping sports. Chakraborthy et al [4] proposed MRP method that makes use of bill of materials, inventory facts and a master agenda to calculate necessities for fabric. It additionally takes under consideration the combination of the invoice of cloth structure and meeting lead times. The result of an MRP plan is a fabric plan for every object found inside the bill of material shape which indicates the amount of new material required, the date on which it's miles required. The brand new schedule dates for material this is currently on order. If routings, with defined hard work necessities are to be had, a potential plan could be created concurrently with the MRP cloth plan. The MRP plan may be run for any range entities (which can be bodily separated inventories) and can encompass distributor inventories, if the gadget has get right of entry to to this kind of information. MRP tries to strike the first-class stability feasible among optimizing the provider stage and minimizing prices and capital lockup. The origins of JIT are unsure however it lines its beginnings to the Mitsubishi Heavy Industries shipyard in Hiroshima in the past due 1950's. The Toyota Motor agency is credited for the primary a hit application of a formalized technique to JIT production.considering JIT manages the desired stock in required time. Geraghty and Heavey [5] formulated a hybrid manufacturing system by way of combining each MRP and JIT as included technique. But hybrid device will try and reduce burden inside the stock accordingly it simplifies the inventory preserving cost via minimizing the wastage. Cochran and Kaylani [6] evolved GA (Genetic algorithm) to determine the gold standard inventory level of inventory for the duration of every period. 552

4 Beamon and Bermudo [7] suggested hybrid push/pull algorithm to reduce the costs of stock. They have got chosen multi level meeting line station to control the wastages of costs in buffer storage in addition to uncooked cloth storage. From the above literature it turned into observed that various scholars have contributed their valuable thoughts in optimizing the operational making plans selections in inventory systems. As a result on this literature survey strive has been made to mix both MRP/JIT as unified approach. However the fulfillment of Integrating JIT with MRP especially relies upon on employee co ordination as well as know-how the guidelines of JIT. 3. Evaluation of stock levels using theoretical MRP system: In this section sample case study was discussed as shown below: A firm producing Hand Trolley has the following master production schedule (MPS). MASTER PRODUCTION SCHEDULE: Week Demand Each hand trolley has a bin, two wheel assemblies, two handle bars and a mounting base. Each wheel assembly has a wheel and two bearings. Order quantities, lead times and inventories on hand at the beginning of period 1 are shown below: Bill of materials: Part Order quantity Lead time ( months) Inventory on hand Hand trolley Bin Wheel assemblies

5 Handle bars Mounting base Wheel Bearing Complete the MRP for hand trolley and show what quantities of orders must be released and when they must be released in order to satisfy the MPS. SOLUTION: Product structure for hand trolley is shown below: Fig1. Product structure of Hand trolley From product structure diagram it is indicated that the components/ sub assemblies are arranged as per precedence relationship. Based on the above inputs such as BOM, Product structure and MPS the evaluation of stock on hand can be estimated. In this case study the evaluation of stock on hand is estimated for only main product assembly as given below: 554

6 Let us consider order quantity for final assembly of product = 350 units Stock on hand = 220 units Lead time = 1 month Based on the data given in master production schedule the stock positions are evaluated for every period individually MRP Table for Hand Trolley Empirical equation for stock on hand calculation SOH t = R + SOH t-1- Projected requirements Months Projected requirement Receipt SOH(220) POR Table 1. MRP Table for Hand trolley Where SOH t --- Stock on hand for period (t) R --- Receipt SOH t-1 = Stock on hand for previous period. 555

7 From the above table it is indicated that stock on hand was maintained for every period also shortage of materials was overcome by placing a planned order release well in advance by one month. So that the shortage problem was solved successfully without any barriers. INTEGRATION OF MRP AND JIT: DEMAND INVENTORY STATUS FILE NO YES MASTER PRODUCTION SCHEDULE INTEGRATED MRP/JIT SYSTEM BILL OF MATERIAL PREPARATION PLAN FOR PRODUCTION FIG2. INTEGRATED OF MRP/JIT A FRAMEWORK 556

8 In the preceding section a case have a look at turned into illustrated with the help of MRP tool by means of theoretical method however so one can modernize the inventory machine we require automatic inventory gadget to improve the customer service. Subsequently strive has been to expand a logical framework for MRP at the side of JIT as proven in fig. 2. The concept of logical diagram became defined beneath: Once after accumulating the demand primarily based on the consumer perception feed all the ones demand information s into integrated MRP/JIT machine. This proposed machine will evaluate the call for primarily based on inventory stage if the stock is extra it won t take delivery of if so we need to rework the stock level further master manufacturing agenda information additionally feed into the included device as described within the above go with the flow diagram. If each MPS and stock inventory records are pretty good enough then we've prepare the BOM (bill of materials). After making ready that very last production ought to start in the shop floor. This sophisticated device can be controlled by using JIT concept by means of revising the stock level primarily based on call for each time. 557

9 Conclusion: On this paper importance of MRP turned into discussed inside the introduction phase in conjunction with the targets and simple parameters. Also case have a look at was discussed which tells approximately the inventory available issues additionally cloth scarcity with the help of the illustrative examples. The significance and the need for material requirements making plans within the small and medium establishments and to larger organizations as nicely, is superb. While there are still a considerable amount of companies relying on beyond information and their experience to determine amount of substances to buy, increasingly companies are switching to a few form of cloth requirement making plans solutions. In this paper idea on JIT additionally addressed together with MRP in an effort to recall it as hybrid device. For this reason both JIT and MRP attained advantages to optimize the inventory. References: 1. Alain, G. (1999), A Primal-Dual Approach for Capacity-constrained Production Planning with Variable and Fixed Costs, Computer & Industrial Engineering, Vol. 37, Albritton, M., Shapiro, A., and Spearman M. (2000), Solve the Problem with Two variants of Monte Carlo. Stochastic Programming E-Print Series. 3. Andersson, L. E. and Grubbström, R. W. (1994), Asymptotic Behaviour of a Stochastic Multi- Period Inventory Process with Planned Production, Working Paper WP-210, Department of Production Economics, Linköping Institute of Technology. 4. Aseltine, J. A. (1958), Transform Method in Linear System Analysis, McGraw-Hill, New York 558