Production Lead-time Research Articles

Case Study: Maintenance Proposal of Press Parts Production for Minimize Waste by Lean Manufacturing – Value Stream Mapping (VSM)

Abstract—Higher competition in businesslike field demanded each company acted as a value creator with progressive fixing performance. One of effort in increasing productivity was reducing waste. Enterprise T have seven type of extravagance were over production, transportation, inventory, over processing, motion waiting and defect. Minimize waste have bond with production time which could increase efficiency on using electricity and decreased lead time. Production process in this company showed non-value added time such as excessively material transportation in picking area and so the workers too much waited for the next schedule activity. This condition caused higher product lead time. Lean manufacturing idea necessary was implemented with using tool Value Stream Mapping – VSM. This strategy would resumed for the company maintenance and the result showed that lacking as much 26,45% of lead time could be a problem solution. Reducing lead time could be higher if the company have applied and played continue improvement.Keywords—lead time, lean manufacturing, value stream mapping.

Machining Process Evaluation Indices for Developing a Computer Aided Process Planning System

In the manufacturing industry, there is an urgent need to shorten the manufacturing lead time of products. Therefore, optimizing process planning is essential to realize high efficiency machining. In this study, in order to develop a computer aided process planning (CAPP) system using previously proposed machining features, a prediction method for some process evaluation indices is proposed. Many candidates for the machining process exist, depending on the recognized machining features in a previous study. Therefore, by using these indices, operators can select a suitable process from among these candidates according to their ideas. Case studies of process planning are conducted to confirm that the operator’s strategy affects the selection of the machining process candidates. From the case study results, it is found that the proposed process evaluation indices have potential use in determining the machining process utilized, and are suitable for a flexible CAPP system of multi-tasking machine tools.

Case Study: Maintenance Proposal of Press Parts Production for Minimize Waste by Lean Manufacturing – Value Stream Mapping (VSM)

Abstract—Higher competition in businesslike field demanded each company acted as a value creator with progressive fixing performance. One of effort in increasing productivity was reducing waste. Enterprise T have seven type of extravagance were over production, transportation, inventory, over processing, motion waiting and defect. Minimize waste have bond with production time which could increase efficiency on using electricity and decreased lead time. Production process in this company showed non-value added time such as excessively material transportation in picking area and so the workers too much waited for the next schedule activity. This condition caused higher product lead time. Lean manufacturing idea necessary was implemented with using tool Value Stream Mapping – VSM. This strategy would resumed for the company maintenance and the result showed that lacking as much 26,45% of lead time could be a problem solution. Reducing lead time could be higher if the company have applied and played continue improvement.Keywords—lead time, lean manufacturing, value stream mapping.

Peningkatan Produksi Minyak Sereh Wangi Pada Penyulingan Minyak Sereh Wangi Di Desa Cimungkal-Sumedang

Inability to fulfill the demand of consumers is becoming the major issues on citronella oil refinery in the village of Cimungkal Sumedang. This study was conducted to formulate alternative measures in order to increase the production of citronella oil distillates in the Cimungkal village. Mapping of the production process is done with Value Stream Mapping (VSM) as a first step to determine the processing time (lead time of production) and identify the waste that occurs, analyze the causes of the problems at the manufacturing level, and formulate remedial measures to increase the production of oil of citronella. The results show some activity in the production process of citronella oil which is a waste and should be minimized. By mapping, it can be seen that the lead time citronella oil refining initial amounted to 647 minutes or 10.78 hours. After repairs (Future State) improvements Total lead time to 274 minutes. Value-added activity increased by 38.93%, non-value added decreased by 3.63%, and necessary but non-value added fell by 35.3%. The study also resulted in the formulation of strategies that can be done to increase the production of oil of citronella.

Inventory Optimization using ERP to reduce final product lead time, Inventory value an inbound logistics cost for MTO, FMCG Company

Many multinational companies have adopted ERP systems to make sure material is available on time and inventory levels are low. However most of the companies are unable to choose between the most suitable master data configuration such that common objectives are achieved. Objective of this project was to develop a master data configuration to optimize inventory in such a way that material availability for production is high and inbound logistics costs were low with very low inventory levels. To apply this methodology as a case study we selected MTO, FMCG Company which has been using SAP as its ERP system. Initially at two stages the master data configurations were changed and performance was monitored subsequently. ABC analysis was done to identify the top materials which will be in “A” category in terms of consumption value. After that different master data configurations were adopted at three stages for each of the selected materials and the performance was monitored accordingly. The basic criteria’s for measuring performance were average inventory value, material availability, inbound logistics costs and consumption percentage vs purchases. Finally the best master data configuration was identified based on said performance measures. It was found that majority of the time EOQ theory is correct and it can be used for any FMCG, MTO business models. On the other hand, ROL theory is not practical to use in a FMCG, MTO business model if the demand variation is high. It was also found that MTO, FMCG company material master data should be planned based on SAP MRP planning and for regular items Safety stocks should be maintained based on past consumption and for irregular items safety stocks should not be kept to minimize inventory. This method can be adopted by any company to improve their material availability rate, inventory and reduce inbound logistics cost. The project resulted in 1.2 million USD reduction in inventory within a years’ time, an inbound logistics were reduced by closer to 100000 USD and material availability rate was increased by closer to 20% for an X company which was operating under FMCG, MTO environment. The project was successful because of the efficient material master data planning in SAP. Main limitation of the application is that if a regular item becomes obsolete the entire safety stock allocated for that particular item will be obsolete leading to inventory issues. KEYWORDS: ERP Systems, Inventory, Inbound logistics cost, MTO, FMCG, SAP

Reduction of Process Lead Time Using Lean Tool - Value Stream Mapping (VSM)

The research is designed to reduce production lead time using Value Stream Mapping (VSM). The purpose of this lean tool is to uncover the wastes in supply and production process by separating value-adding and non-value-adding steps first and then reduce non-value added steps. A map shows the current state of the operation is drawn first using the time and flow data. By this non-value added actions are recognized and the waste of time and resources between the steps are also identified. To reduce lead time and streamline the process the map is analyzed. The lead time can be reduced by taking some actions or applying some lean tools. Value adding time in the whole process increases and the process production lead time decreases after reducing the wastes. A future state map is made with new and improved processes. Future state map makes the reformed process more effective and more efficient. It comprises the developments through some value stream symbols used only for this mapping. Bata, a leading shoe company was selected for this research work. To draw the current state map, data was collected from the floor. The wastes identified then which were waiting, motion, inventory & transport. The lean tools that were suggested to apply for reducing these wastes were Kanban, Kaizen, Safety Stock and some manpower adjustment. Kanban is a method to achieve JIT, a system to control the logistical chain from a production point of view and also an inventory control system. Safety stock represents an inventory hedge against problems such as downtime, to protect the system against sudden fluctuations in customer orders or system failures. And Kaizen is the small and continuous improvement methods. The result of the research was quite remarkable as this decreases the lead time by around 8% and increases the capacity by 8.8%. It is feasible to use value stream map in the current situation.

Supply Chain Coordination with Multiple Shipments: The Optimal Inventory Subsidizing Contracts

We study a supply chain involving a supplier–retailer relationship. When production lead-time is long and the selling season is short, the retailer has to place an order ahead of the season, which resembles the classical Newsvendor model. However, we consider the situation when the supplier agrees to deliver the order in multiple shipments in the season, and then the retailer needs to determine the quantity and/or timing of each shipment. Under a centralized setting, we derive the optimal quantity and/or timing decisions of the retailer. Under a decentralized setting, incentive misalignment arises from ineffective allocation of inventory costs between the parties, in addition to the well- known double marginalization effect. Hence, we devise an incentive contract, which involves a risk-sharing mechanism at the end of the season and an inventory subsidizing scheme for the entire season; in practice, the inventory subsidizing scheme can be implemented in different ways, such as a direct subsidizing scheme or a delayed-payment scheme. The proposed contract can achieve channel coordination and Pareto optimality. Furthermore, we can show that the inventory subsidizing scheme plays a key role in channel coordination because without the inventory subsidizing scheme, the loss of supply chain efficiency is almost always significant.

Production lead-time hedging and coordination in prefabricated construction supply chain management

This paper studies a coordination scheme to solve a production lead-time hedging (PLTH) issue in the prefabricated construction supply chain management. To mitigate tardiness delivery owing to prefab production uncertainty, the project contractor (PC) prefers to inform the prefab factory (PF) an earlier due date which is termed as PLTH strategy. However, this strategy forces the PF to compress its production process. A balance must be optimised through the proposed PLTH coordination scheme. It includes a PLTH-related cost term, i.e. crashing money (charged by the PF to the PC) and a constant transfer term. Three models with different power structures are considered. Firstly, two Stackelberg games with alternative decision-making sequences and an equal power model are discussed to obtain the optimal PLTH amount and crashing money. Later on, a cost-sharing term is used to fairly allocate the system surplus. It is observed that this coordination scheme reduces the PLTH amount and ensures win–win coordination for both parties. Some interesting managerial implications are also obtained from comparison analysis and numerical studies.

Production process improvement of buildings’ prefabricated steel frames using value stream mapping

The ultimate goal of lean philosophy is to eliminate or decrease wastes and deliver value to the customer. After successful implementation of lean principles to the manufacturing sector, researchers have been trying to apply lean principles to the construction sector. However, construction is completely different from manufacturing. Prefabricated and industrialized buildings bear a striking resemblance to manufacturing due to completing most processes in the factory environment. This paper uses value stream mapping (VSM) as a lean technique in the production phase of Pprefabricated steel frames (PSFs) in a case study. The case includes construction of three 16-story residential buildings made of PSFs with bolt and nut connections in Iran. The production processes are investigated, and the current state of the production line is examined. The VSM uses elaboration of maps to identify the current state of production, diagnose wastes and their root causes, and finally, propose improvements in the future state. To investigate the productivity of the production line and implement lean principles, discrete event simulation (DES) was carried out. After identifying and reducing some of the wastes in the current state, the future state was modeled. The results showed 34 % reduction in the lead time of production and 16 % reduction of costs. These results support the hypothesis that lean principles can be successfully applied to industrialized and prefabricated construction.

Getting confidence for flying additive manufactured hardware

In the next coming years, the European space industry must assume the challenge of implementing in an efficient way additive manufacturing (AM) technology due to the continuous need for reducing costs and improving performances. Together with the advantage of producing very complex and optimized geometries, AM can reduce drastically part weight and lead time of unique products (Tomlin and Meyer in Topology optimization of an additive layer manufactured (ALM) Aerospace part. In: The 7th Altair CAE Technology Conference, pp 1–9, 2011; Emmelmann et al. in Phys Procedia 12A:364–368, 2011). Similar to what happened during the implementation of composite materials within the aeronautics and space sectors at the early 80s, efforts must be directed to the development of fabrication and design rules, together with appropriate means of verification (Lasagni et al. in On the investigation of processing parameters and NDT inspection on additive manufacturing materials for future launchers, workshop on additive manufacturing for space applications. ESA-ESTEC, Noordwijk, The Netherlands, 2014). This work reports on the development, optimization, and AM fabrication of flight hardware for launchers, under the European Space Agency Future Launcher Preparation Programme. Articles for the clamp band separation system from Ariane 5 has been analysed together with other secondary structural items. The paper presents the full complete story, starting with the optimization of processing parameters for selective laser melting in different alloys, up to the qualification test of the whole system. A feasibility analysis for non-destructive evaluation is presented as well.

Novel Research on a Fibration Knowledge-Based Solution for Engineered Surface Tolerances within the Modern GPS Context

Geometrical product specification and verification (GPS) is the only worldwide tolerancing specification language available for unambiguously communicating functional requirements and precisely expressing geometrical tolerances of workpieces on technical drawings. Although the understanding and application of GPS are of vital importance for modern manufacturing industry, the latest GPS standards contain huge amounts of data, information and knowledge that are obscurely linked together, so they are very difficult for designers, engineers and metrologists to understand, remember and comprehensively use them. This is especially true for surface texture that is one of the most complicated geometrical characteristics in GPS domain. To overcome the implementation barrier of GPS surface texture, a novel knowledge-based solution supported formally by a unified knowledge modeling of the complete GPS surface texture standard chain has been researched. This knowledge model can serve as a formal basis for developing more intelligent and reliable tolerance design and measurement systems. This paper starts with an introduction on how to build up a formal knowledge model based on category theory, called categorical fibration model, to unified acquisition and representation of all surface texture knowledge. It then moves on to define a recursive knowledge refinement process for the devised model to enable the recursive multi-level GPS knowledge transformations and refinements. This knowledge model is validated naturally by checking rules identified from category theoretic notions. Finally, this paper presents a general framework for applying the modeled GPS knowledge in practice, from the aspects of the integrated and complete modeling of all surface texture knowledge, detailed knowledge acquisition and modeling examples for four sub-knowledge bases of the proposed software solution, core functional features of this software, and a comprehensive case study for testing its validity and usability. This knowledge-based solution facilitates life cycle collaboration and integration of the complete GPS surface texture chain to reduce product development cost and lead time, and to ensure functional requirements of geometrical workpieces.

Approach to Reducing Production Lead Time to 1/20 in Small-scale Corrugated Cardboard Factory

In response to population decline in Japan, the production demand has shifted from mass production to quick production of multiple products in small lot since 2005. In this paper, we delineate the method that conducts production in one-twentieth (1/20) of usual lead time (hereinafter referred to as L/T), which is revolutionary short, is able to respond to the needs of the users concerning delivery, among QCD (quality, cost and delivery). This proposed method is energy efficient, and it is designed for the companies that strive to be the top company in the region. It aims for development of corrugated cardboard makers and optimum efficiency of management.

Additive manufacturing of biomedical implants: A feasibility assessment via supply-chain cost analysis

The adoption of additive manufacturing (AM) for fabricating biomedical implants at hospitals provides many potential benefits. Relative to biomedical implants fabricated via traditional manufacturing (TM), typically available by suppliers out of the immediate region, biomedical implants fabricated through AM provides an opportunity to receive more patient-specific, customized parts with faster response, a lower inventory level, and reduced delivery costs. Despite the promising features of AM technologies, the make-or-buy decisions are not straightforward and require careful investigation due to the relatively high AM machine and production costs. Most of the existing studies focus on the analysis of process-level costs, which are usually evaluated/calculated based on individual AM processes. No research efforts, to the best of our knowledge, have been dedicated to the quantitative analysis of the costs of supply chains integrated with AM facilities, e.g., inventory cost, transportation cost, product lead time, etc. In this study, we propose a stochastic cost model to quantify the supply-chain level costs associated with the production of biomedical implants using AM techniques, and investigate the economic feasibility of using such technologies to fabricate biomedical implants at the sites of hospitals. The problem is formulated in the form of a stochastic programming model, which determines the number of AM facilities to be established and volume of product flow between manufacturing facilities and hospitals. A customized Sample Average Algorithm (SAA) is developed to obtain the solutions. We apply the cost model to a real-world case study that focuses on the use of biomedical implants for hospitals in the state of Mississippi (MS), and identify the conditions and cost parameters that have significant impact on the economic feasibility of AM. We find that the ratio between the unit production costs of AM and TM (ATR), as well as product lead time and demands, are key cost parameters that determine the economic feasibility of AM.

Production Lead Time in Serial Lines: Evaluation, Analysis, and Control

Production Lead Time $\mbi (LT)$ is the average time a part spends in the system, being processed or waiting for processing. In systems with unlimited buffers, $\mbi LT$ may be orders of magnitude larger than the total processing time, leading to serious economic and quality problems. At present, no systematic analytical methods for evaluation, analysis, and control of $\mbi LT$ in systems with machines having up- and downtime characterized by continuous random variables are available. This paper is intended to develop such methods. Specifically, we address synchronous serial lines with exponential machines and derive formulas for $\mbi LT$ as a function of machine parameters and raw material release rate. Using these formulas, we develop methods for open- and closed-loop raw material release, which result in the desired $\mbi LT$ . For asynchronous exponential lines, we provide an upper bound on $LT$ . For non-exponential lines (e.g., Weibull, gamma, and log-normal), we offer an empirical formula for $\mbi LT$ as an affine function of the coefficient of variation. The results reported in this paper enable a new paradigm for production systems management, namely: manage a production system so that the desired $\mbi LT$ is ensured, while the throughput is maximized.

A dynamic programming approach to integrated assembly planning and supplier assignment with lead time constraints

As manufacturers face fierce competition in the global market, responsiveness has become an important competitiveness factor in addition to quality and cost. One essential responsiveness strategy is to reduce product development and lead times by integrating assembly planning with supplier assignment. This paper addresses the problem of integrated assembly and supply chain design under lead-time constraints by formulating and solving an optimisation problem with minimal total supply chain costs. This new time-constrained joint optimisation problem belongs to an NP-hard resource-constrained scheduling problem. To model this problem effectively, we develop a novel Hyper AND/OR graph and apply it for integrating assembly and supply chain decisions. We also develop a dynamic programming model and associated algorithm in order to solve the integrated optimisation problem with pseudo-polynomial time complexity in practice. Numerical case studies validate that the methods developed can solve the integrated decision-making problem optimally and efficiently. This paper overcomes the limitations of previous studies on concurrent assembly decomposition and supplier selection, which optimises cost without time constraints. The models and results of this research can be applied to a variety of areas including assembly design, maintenance module planning and supply chain restructuring.

Retailer driven supply chain with limited transportation capacities and supply demand market index

This paper addresses the problem of allocating the optimal shipping rates within a supply chain (SC) of minimum collaboration between its partners in a stochastic demand environment. Particularly, we consider a SC that consists of a set of manufacturers, distribution centres and retailers. The logistic service provider (LSP) limited transportation capacities restrict the retailers' aspiration to meet the entire demands. The objective function is to determine the optimal shipping rates that maximise the retailers' returns subject to the available LSP capacities and stochastic demand. An algorithm is presented to solve the optimisation model by finding the optimal rates. The algorithm works in a decentralised mode at the retailers' side. Intensive simulation experiments are conducted to test the model and the operational algorithm. The algorithm can be implemented at the retailer side without having to access the network global parameters except the knowledge of the product lead-times.

顧客満足とサービス品質を考慮したサービス生産に関する実験的検討

This paper analyzes customer satisfaction and service quality through subjective experiments using a proposed service production game. In the game, players are provided information of demand forecasting with different accuracy and make paper triangular pyramids considering production efficiency and service quality. Making a paper triangular pyramid is simulated to produce and deliver dishes in a labor intensive production system in restaurant services. The players are required to make a production plan and manage delivery lead time and quality of products to satisfy both customer satisfaction and production efficiency. Produced products are evaluated quality by evaluation index such as laminating quality, cutoff line, crease line and edge etc. The experiments conduct a questionnaire of subjective assessment about service quality and employee satisfaction. In the questionnaire, the players answer their degree of service quality and productivity of subjective view. The employee satisfaction is analyzed considering the employee’s conscious of advance planning and setup with adaptation of variation of demand by using correlation analysis.

クラウドマニュファクチャリングの生産効率性に関する研究

Industrial Internet and Industry 4.0, which refer to the integration of physical industrial machinery with software, internet, along with network sensors, actuators, and other industrial components, are discussed intensively. These technologies provide decantation of manufacturing with cloud-based manufacturing system (CBMS). Since the CBMS enables cross sourcing between connected companies, higher utilization of manufacturing facilities and reduction of manufacturing lead time of products seem to be brought in these companies. As a result, these companies can reduce production cost. We have developed new concept of CBMS which implements dynamical generation of common manufacturing-bill of materials (M-BOM) from engineering-bill of materials (E-BOM). Simulation study on the effectiveness of the CBMS is summarized.

A Review on Valuable Trends of Product Data Management (PDM) Occupied in New Product Development (NPD)

Presently the prime task of manufacturing engineers is to make products within a short span by maintaining the best quality at minimum cost. Recent market trends confirm the continuation of New Product Development (NPD) as a change agent for many more years to come with a focus on high product variety and shorter product life cycles. The effective introduction of new products is critical to the performance of manufacturing industries in more industrial sectors. It is a measure of an industry's strength in innovation and competitiveness in NPD. Manufacturing industries are forced to accept that the focus on NPD is on increasing product variety and shorter product life cycle. For many manufacturing industries, mass customization with "voice of customer", agility and leanness are some of the vital prerequisites to survive in the current global competitive environment. NPD is no longer an isolated process; it requires close integration between all active members within the supply chain such as customers, suppliers, manufacturers, etc. and must be viewed as an integrated business process. The proper use of advanced IT has enhanced NPD in manufacturing enterprises. It facilitates shorter product lead-times and increases responsiveness to changes in the market along with improved product quality, as well as maintaining low product cost.

Simulated Annealing Applied to Optimize the Efficiency of Flexible Manufacturing Cells

This work proposes a new methodology to optimize flexible manufacturing cells applying Simulated Annealing and Contribution Margin concepts. This methodology helps to determine the number of extra products that could be sold and manufactured while taking advantage of this idleness. The price formation to sell the extra products was based on contribution margin concepts. The main concept is to use cell idleness to increase profits while the costs are already paid. Equipment and workers have their fixed costs paid regardless of whether they are active or not. When they are not active, all of their costs are considered to be losses. What motivated the present work was the fact that, in general, the idleness detected in manufacturing processes does not receive adequate attention in the sense of taking advantage of it. To achieve this purpose, a program was developed to implement the methodology. This program generates user interfaces that allow the prediction of daily scheduling parts production. The first interface identifies only bottlenecks and idleness. The second interface, based on the Simulated Annealing (SA) metaheuristic technique, was designed to perform the management of idleness. A database was organized to present current and future daily scheduling parts production. Based on the volume of sales and the lead time of sold products, sellers are always able to update this database. Thus, the program can provide through its user interface, at any time, all of the information about production data for a specific schedule day that comes from the database. The user mentioned here is expected to be an industry salesman. Thus, it will always be possible to have previous knowledge about the bottlenecks and idleness that exist for any scheduled day in the future. This knowledge allows for planning the process of selling extra products made from the existing idleness. Two aspects were considered with respect to selling extra products that are produced via taking advantage of the idleness: the delivery time and the contribution margin of each product. To validate the program, a simulation was performed to determine which products should be produced during a scheduled day to ensure the delivery times or to ensure the maximum contribution margin, while considering the delivery time that is available. As a final consideration, the software can be considered to be functional and responsive to the possibility of profit maximization from the use of cell idleness.