Work in Process

The phenomena of machine failures, defects, multiple rework loops, etc., results in much difficulty in modeling rework systems, and therefore the performance analysis of such systems has been investigated limitedly in the past. We propose an analytical method for the performance evaluation of rework systems with unreliable machines and finite buffers. To characterize the rework flow in the system, a new 3M1B (three-machine and one-buffer) Markov model is first presented. Unlike previous models, it is capable of representing multiple rework loops, and the rework fraction of each loop is calculated based on the quality of material flow in the system. A decomposition method is then developed for multistage rework systems using the proposed 3M1B model as one of the building blocks. The experimental results demonstrate that the decomposition method provides accurate estimates of performance measures such as throughput and Work-In-Process (WIP). We have applied this method to several problems, such as the determination of the optimal inspection location and the identification of bottleneck machines in rework systems.► We propose an analytical model for manufacturing systems with multiple rework loops. ► We solve problems such as inspection allocation and bottleneck identification. ► Bottlenecks of rework systems migrate differently compared to systems without rework. ► We propose a continuous improvement strategy in the paper.

In today's tight, competitive, and volatile market in semiconductor manufacturing, a successful semiconductor manufacturer has to look into multiple performance indices such as cycle time and on-time delivery. Effective dispatching mechanism is a widely used strategy to achieve these performance indices simultaneously. In the past, dispatching studies in semiconductor manufacturing have primarily focused on the level of tool dispatching. This

En un sistema de producción que cuenta con varias líneas de productos, y en el que los recursos son compartidos por los diferentes procesos de fabricación, es importante mantener en cada centro de trabajo niveles de inventario de producto en proceso bajos y cercanos a los deseados, con el fin de mantener una línea de producción ordenada. Este artículo propone una heurística de balanceo de Inventario en Proceso (WIP) basada en la ley de Little, que se encarga de mantener un nivel de WIP ideal mediante una lógica de envío y recepción de señales a lo largo de toda la línea de producción. Palabras clave: WIP, balanceo de líneas de producción, Planificación diaria

Manufacturers always face cost-reduction and efficiency challenges in their operations. Industries require improvement  in  Production  Lead  Times,  costs  and  customer  service  levels  to  survive.  Because  of  this, companies  have  become  more  customers  focused.  The  result  is  that  companies  have  been  putting  in significant effort to improve their efficiency.

In  this  paper  Value  Stream  Mapping  (VSM)  tool  is  used  in  bearing  manufacturing  industry  by  focusing both on processes and their cycle times for a product UC- 208 INNER which is used in plumber block. Inorder to use the value stream mapping, relevant data has been collected and analyzed. After collecting the data  customer  need  was  identified.  Current  state  map  was  draw  by  defining  the  resources  and  activitiesneeded  to  manufacture,  deliver  the  product.  The  study  of  current  state  map  shows  the  areas  for improvement  and  identifying  the  different  types  of wastes.  From  the  current  state  map,  it  was  noticeable that Annealing and CNC Machining processing have higher cycle time and work in process.

The  lean  principles  and  techniques  implemented  or  s
uggested  and  future  state  map  was  created  and  the
total  lead  time  was  reduced  from  7.3  days  to  3.8  da
ys.  The  WIP  at  each  work  station  has  also  been
reduced. The production lead time was reduced from
409 seconds to 344 seconds.

The “lean” approach has been applied more frequently in discrete manufacturing than in the continuous/process sector, mainly because of several perceived barriers in the latter environment that have caused managers to be reluctant to make the required commitment. We describe a case where lean principles were adapted for the process sector for application at a large integrated steel mill. Value stream mapping was the main tool used to identify the opportunities for various lean techniques. We also describe a simulation model that was developed to contrast the “before” and “after” scenarios in detail, in order to illustrate to managers potential benefits such as reduced production lead-time and lower work-in-process inventory.

This paper provides a simulation model to study the effect of the work-in-process control on due date performance in job shop environment. The due date performance is measured by both the number of tardy jobs and the total tardiness. The simulation runs include different shop configurations (flow shop and general job shop), workloads and sequencing rules. As expected, the results reveal that due date performance is highly dependent on the work-in-process, particularly after the system reaches saturation. Nevertheless, the model is very useful to show job shop managers the effect of the work-in-process control in the due date meeting performance.

The aim of the paper is to analyze the cost effect of component,commonality. Despite its project management expertise, the case company has been developing mass-customized standard conveyors that it could sell through a dealer network. The empirical data deals with the development of a standardized roll conveyor, and the unit of analysis is a new subassembly, i.e. a motor

Manufacturers always face cost-reduction and efficiency challenges in their operations. Industries require improvement  in  Production  Lead  Times,  costs  and  customer  service  levels  to  survive.  Because  of  this,
companies  have  become  more  customers  focused.  The  result  is  that  companies  have  been  putting  in significant effort to improve their efficiency.

In  this  paper  Value  Stream  Mapping  (VSM)  tool  is  used  in  bearing  manufacturing  industry  by  focusing both on processes and their cycle times for a product UC- 208 INNER which is used in plumber block. In order to use the value stream mapping, relevant data has been collected and analyzed. After ollecting the data  customer  need  was  identified.  Current  state  map  was  draw  by  defining  the  resources  and  activities needed  to  manufacture,  deliver  the  product.  The  study  of  current  state  map  shows  the  areas  for improvement  and  identifying  the  different  types  of wastes.  From  the  current  state  map,  it  was  noticeable that Annealing and CNC Machining processing have higher cycle time and work in process.

The  lean  principles  and  techniques  implemented  or  suggested  and  future  state  map  was  created  and  the
total  lead  time  was  reduced  from  7.3  days  to  3.8  days.  The  WIP  at  each  work  station  has  also  been reduced. The production lead time was reduced from 409 seconds to 344 seconds.

The supply chain is a system coordinated by organizations, humans, activities, information and resources involved in the movement of a product in a physical and virtual manner from the supplier to the client. The activities from the supply chain transform raw materials and components in a product that is delivered to the consumer or to the user. The inventory, together with the transport, the location of the production spaces and of the storage represent an important factor that influences the performance of the supply chain. Inventory contains the raw materials, the work in process and all the finished products of a supply chain. The changes of the inventory policies can lead to a dramatic alteration of the supply chain’s efficiency and responsiveness. The managers of the firms that build up a supply chain have to identify the main categories of inventory and the way that they can be dimensioned. In every company we can identify cycle inventory, safety inventory and seasonal invent...

The operational cost of 300mm wafer production is significantly greater than that of 200mm fabs. Real-time monitoring of product can save time and money through reduced scrap and decreased cycle time. Current process monitoring generally incorporates stand-alone metrology, which is time consuming and requires excessive wafer handling by production operators. The benefits of integrated metrology are measured by considering the

Various inventory studies have been published in the last decades. Some studies emphasize the importance of low inventories, other examine the evolution of inventories over time and especially focus on the impact of the just-in-time (JIT) revolution. The aim of this paper is to investigate the level of inventories held by Belgian companies at one moment in time, namely May

The supply chain is a system coordinated by organizations, humans, activities, information and resources involved in the movement of a product in a physical and virtual manner from the supplier to the client. The activities from the supply chain transform raw materials and components in a product that is delivered to the consumer or to the user. The inventory, together