If you have problems with planning. Part two

Any planning at the level of ERP limited to the formation of bulk-month (decadic) plan. Adjust such plans can not be promptly and that's why their implementation requires a rigorous discipline in performing all those involved in the production chain units of the enterprise. That is, You can talk about the organization of production controlled by ERP, as the production of a certain stock of "sustainability" in relation to the emerging deviations from the plan drawn up by volume. The entire burden falls on it at the contestants: "as you like, but the planned target for the calculated time, to!" And, most importantly, ERP, issuing job to all units, when in need of updating the plans, unable to cope with it, that k. any recount would the same picture of the general tasks - tasks in the volume, but not in the detailed terms of products and operations that need to control the level shops. Planning for APS In terms of precise planning of work at enterprises of interest are the classes of APS (Advanced Planning & Scheduling Systems) and MES (Manufacturing Execution Systems). APS-systems, which appeared on the market in the mid-90s, are already planning tool for the direct operations of the enterprise. Despite the unambiguous designation, many writers and even the developers interpret this name differently: "Optimized production planning", "advanced planning", "better planning", "advanced planning", "optimized and synchronized planning," "detailed planning" "operational planning" and even "careful planning"! Agree, so many interpretations, the question arises - what is actually wrong? Compared to what an expanded, improved, how accurate than with synchronous, that is optimized and how quickly? Expanded and improved. In the early 90s after the first experimental implementation of ERP, understanding the advantages and disadvantages of planning according to the standard MRPII company faced a major problem - the reliability of planning. The reliability and accuracy over time. Market dynamics, trends JIT concept demanded by enterprises more accurate delivery time, full participation in supply chain management. The imperfection of planning with MRPII required a revision of "values" - which is important in planning? Speed, contrary to its accuracy, and what need these metrics? It was found that without solving the problem of supply management, without the possibility of predicting the exact dates of production enterprise is a thing in itself. Therefore, the main goal for the next generation of planning systems - APS is a solution to automate the supply chain management (SCM - Supply Chain Management), and this functional APS, is implemented by allowing the planning of all work in time with respect to capacity utilization, has a dual purpose - it is implemented as for the company, acting subject to the entire chain in a dynamic market for goods and objects of the enterprise itself - shops, sections and units. Thus, the ability to plan in APS expanded and improved on the standard MRPII. Synchronicity. The concept of synchronicity to be understood in the APS, on the one hand, the possibility of planning materials, resources and time schedule of construction taking into account the actual loading of equipment over time. On the other hand, the timing is expressed in the fact that the schedules are constructed for all business units, taking into account the timing of delivery partners and the timetable for the production of all these structures are always interrelated, since they are derived from the general schedule for the entire enterprise. Promptness. Efficiency for APS - this is an opportunity for the shortest possible time to determine on an optional time of its manufacture. Efficiency in terms of supervisory control and rapid conversion schedules to APS, as a rule, has nothing to do, because if you do not change the external constraint (violation of the terms of supply of partners, and other unexpected delays), and the portfolio of orders every five minutes is not introduced a new product , the conversion schedules will not work. Accounting for the same internal disturbances from numerous departments (equipment failures, marriage to operations, etc.) may result in a significant weighting in the existing loop scheduling problem dimension. Accuracy and optimization. The accuracy and optimal schedules are generated - the prerogative of any planning system algorithms. Compared with the algorithms of MRPII, APS algorithms for scheduling at the same time take into account the needs of both materials and capacity of the enterprise, taking into account their current and planned load. The algorithms take into account APS setup and some other parameters of the technological environment, which for some reason, the pessimists are called "constraints". In the address algorithms APS occurs much deserved epithets, but in some cases, in a burst of enthusiasm for these systems are attributed to the features that baffled even the experts. In particular, it is stated that the basis of algorithms APS-systems are based on simulation models, neural network models, planning, knowledge-based, fashionable nowadays heuristic techniques such as genetic algorithms, simulation annealing, linear programming, and even (!). Figure 2. APS: The calculation of the integrated timetable for the production units. In fact, an algorithm for constructing schedules for APS is quite simple [4]. There are a number of operations for the whole set of manufactured products, a lot of machines and every product has its limitations - in terms of release, by the presence of material, etc. Constraints are divided into major and not so. Initially, the first pass of the algorithm is the timetable, taking into account the feasibility of important limitations, such as no violation of the terms of supply. If the schedule is received, it shall be deemed valid and accepted as a base for further "optimize" - on subsequent passes of the algorithm is attempting to take into account the remaining less important limitations. In fact, it is not optimized. This is nothing but an iterative process of obtaining a feasible schedule with the new restrictions introduced in the next iteration, ie Very simple heuristics. In some cases, simplify the planning process even more - at first planned one piece, then another, until, until all the many details will not be planned. Assessment of the schedules about the true optimum in this case may be quite low, but it should be noted that if we make a schedule for a few thousand pieces of equipment from hundreds of thousands of transactions a month or six months, then this fact can be tolerated. Especially when you consider that at a later stage for the actual implementation of production schedules will meet the MES-system. Thus, the simplified algorithm for the construction schedule, the developers made it possible to APS within the existing computing power to get a feasible schedule and more or less accurately predict the timing of deliveries. At the same APS-systems do not pose a more complex tasks such as finding a schedule minimizing the time in changeovers, traffic operations, reduce the amount of equipment involved, etc., as these requirements will inevitably lead to weighting algorithms and the inability to obtain the shortest possible time schedule for large of dimensions. In this regard, APS-systems are in service with its very limited part of planning criteria. It should be noted that this possibility exists of obtaining at least feasible schedules (within an hour) is not for nothing appeared in the mid 90s. Increased productivity of computers while reducing their cost, once again, was a catalyst for progress in the field of management. Other features. Although it is said that APS may reschedule, but the first loop scheduling is not all APS-systems, and secondly, the frequency of rescheduling in the APS due to the frequency of appearance of new orders (feedback in real time for the APS is considered to be excessive), in Unlike the MES, which makes the operation much more likely (for a much smaller dimension of the problem, correcting the plans only individual shops), as react to any change in the course of the process. The permanent correction of production plans - this is typical for small-scale industries and unit types, they are often called in literature "pozakaznymi." Note that, for a more precise feedback loop with the "pozakaznym" manufacturing suppliers APS-systems in some cases, use the integration with MES-systems. The planning horizon is rarely stated in the APS-one - shift, week, month, up to six months. But no matter how wondered about the "average value" of the planning horizon for APS-systems it is determined by extremely simple - from the basic tasks of the functional system, which is the supply chain management. Length of planning horizon in the APS-systems - it is always the difference in time between the date of issue of the most distant orders of the total portfolio of orders the company and the current date, as when a new order and the relevant terms of the schedule, we must determine not only the timing of its production, but also an opportunity non-violation of the terms that had already been running orders. So, these new features, caused by the need for supply chain management, have resulted in the fact that the growth rate of APS-systems have become significantly outpace the growth of solutions in the segment of ERP. Along with foreign systems (Berclain, Chesapeake Decision Sciences, CSC, Fygir, i2 Technologies, Manugistics, Numetrix, Optimax, Ortems, Preactor, Pritsker, Paragon Management Systems, ProMIRA, Red Pepper Software, Thru-Put Technologies, etc.) in the past years, began to appear and domestic products (infor: APS, Adexa eGPS, etc.). Fears that the APS will grow to new ERP were, perhaps, only the journalists, because originally it was clear that the APS-system is responsible for finance, procurement, document management, and other transactional functions of ERP, but the leading vendors of ERP-systems (People Soft , SAP, Oracle, SSA Global, JD Edwards, Marcam and others) have responded quickly and were noted in the desire to share their solutions with the products of APS. Gradually, this cooperation has developed into a natural need for integration at the kernel level planning ERP, which can be replaced APS-system. At the same time, APS is available as a separate product. The integrated circuit interaction ERP and APS is shown in Figure 3. Figure 3. The integrated circuit interaction ERP and APS. An example of the production program with start dates-release products. Organizing element in this scheme is the ERP-system, performing the role as accounting and information systems, and systems management. Its tasks include a portfolio of orders of products demanded by the market. A necessary step in the formation of the portfolio of orders is to assess the possibility of any given order, which has properties such as cost, production time, volume, quality parameters, compliance with the required specifications, etc. The evaluation is carried out both by means of simple logistic tools to determine the feasibility of of the order in terms of existing enterprise-level technology (or - technological system), the possibility of purchasing materials and components, as well as by the APS-systems, whose main task - to determine the ability to execute orders in time with respect to employment capacity. In this case the timetable of work needed to produce the analyzed products for various departments of the enterprise. Schedule for re-entering the order portfolio of products made in view of the fact that for the previously planned for production orders are not revised since the launch and release, ie used in the planning or existing reserves of time, or planning to manufacture supposed time of release required by OZ from earlier running in production orders. If the resulting time scale manufacturing planning satisfied customer, this product comes in a portfolio, and then incorporated into the production program. Otherwise, the products concerned can not be admitted into the portfolio. As a result, the relevant manufacturing units are on the APS-systems as a blueprint for a certain amount of product that must be manufactured within a specified time. APS-system planners, as a rule, at the moment the new order. The plan adopted for the production of products down to production in those shops, which should be made certain parts and assembly units (DSE) of the product. As a result of tandem ERP + APS allows you to create not only the production program (plan output), but also to build an aggregate schedule of works for the enterprise. Due to more accurate planning of operational, ie, calculation of the production schedule, APS, based on information on the status of supplies, inventory and availability of production capacity, said the planned launch date-release products. Emerging mismatch of the timing requirements of the current production program leads to the need for correction of target dates at the level of ERP. To be continued ... Published with the permission Frolov EB References: 1. Production management. Ed. SD Ilyenkov .- M.: UNITY-DANA, 2000. - 583s. 2. Timkovskii VG Discrete Mathematics in the world of machine tools and parts. - Science, Moscow, 1002. - 144s. 3. DA Gavrilov Control of production based on the standard MRP II. - St. Petersburg. Peter, - 2003. - 352. 4. J. Bermudez, optimized production planning systems: a new fad or a breakthrough in the field of production management and supply chain? Manufacturing survey. AMR Research. 5. Frolov, EB, RR Zagidullin MES-systems as they are, or Evolution of manufacturing planning. / / The Director-General, № 4, 2008, sec. 84-91. 6. Zagidullin, RR Operative and scheduling in flexible manufacturing systems / under. Ed. V.TS. Zoriktueva. - Moscow: Publishing House of Moscow Aviation Institute, 2004. - 208s. About the Authors: Evgeniy Frolov © 2010, Professor, Moscow State Technological University "Stankin" Department "Information technologies and computer systems." Zagidullin Ravil Rustem-Bekovich © 2010, Professor, Ufa State Aviation Technical University (USATU), Department of "Automation of technological processes."