Manufacturing system

Ali Vatankhah

Definition of manufacturing system

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2.

A manufacturing system can be defined as the arrangement and operation of machines, tools, material, people and information to produce a value-added physical, informational or service product whose success and cost is characterized by measurable parameters.

A manufacturing system is an approach to making products that is based upon several factors.

These include how much of the product is needed, how quickly the product must be produced and how unique the product must be to ensure sufficient sales. Manufacturing systems include custom, assembly, flexible, intermittent, reconfigurable, just-in-time and lean manufacturing systems.

Decision hierarchy of industrial information system

Level 5: Distribution Level 4: Plant Level 3: Factory Floor Level 2: Work cell/ Production line Level 1: Machine Transportation planning Supply chain inventory control Demand forecasting Order processing Purchasing Aggregate production planning Accounting Materials management Maintenance management Shop floor scheduling Quality management ERP MES Inspection/ SPC Materials handling Part sequencing CNC machine tools Robots Programmable controllers CONTROLS

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The machine control

level is responsible for ensuring that the sequence of machine operations corresponds to the planned sequence necessary to fabricate the part. Typically, the sequence of operations is carried out as prescribed by the program resident in the machine controller, and there are few, if any, decisions to be made.

the production line

or work cell level, the objective is to supervise the interactions between a group of related machines or processes. This level of decision making is not concerned with the operation of the machine or process. The emphasis here is on the release and delivery of materials to a machine in the work cell at the correct time.

the factory floor level,

decisions are made that affect groups of production lines or work cells. For example, several production lines or work cells may be serviced by the same materials management system that requests the movement of raw materials from storage to production so that they can be manufactured into a finished product.

4.

the plant level

, decisions are less concerned with the daily operation of the factory and are more closely related to the business planning objectives of the fi rm. A typical plant-level production control decision is aggregate production planning, which refers to the process of planning the use of the plant’s production capacity to meet customer demands over a period of months or a year. The output of this plan is a master schedule of what products will be produced during each period of time going forward over the planning horizon of the plan.

5. the

distribution system level

the emphasis is on coordinating the supply of finished product to the end customer. Maintaining appropriate and cost effective inventory levels, as well as managing the transportation of product between warehouse locations in the supply chain, is a problem addressed at this level.

Coordinating the layers of the system

ERP Forecasting Production planning Inventory control Costing Purchasing Recipe management Transportation Supply chain management What was produced What to produce MES Operation scheduling Lot traceability CCs Production dispatching Quality control Work in process status Maintenance management HiCs HeCs Data acquisition Real time actual results Control Layer Process set point control Process monitoring Machine tool control Cell control IoT Sensor Controller How to manufacture

• • ERP:

Enterprise resource planning

(

ERP

) is business management software—usually a suite of integrated applications—that a company can use to collect, store, manage and interpret data from many business activities, ERP provides an integrated view of core business processes, often in real-time, using common databases maintained by a database management system. ERP systems track business resources—cash, raw materials, production capacity—and the status of business commitments: orders, purchase orders, and payroll.

MES:

Manufacturing Execution Systems

(MES) are computerized systems used in manufacturing. MES can provide the right information at the right time and show the manufacturing decision maker "how the current conditions on the plant floor can be optimized to improve production output." MES work in real time to enable the control of multiple elements of the production process (e.g. inputs, personnel, machines and support services).

NETWORK ARCHITECTURE

• • The network architecture is a description of how the various layers of the decision hierarchy will communicate with one another. The network architecture is typically implemented with the use of local area networks. A local area network (LAN) is a communication network that is implemented over a limited area and is usually owned by one organization. It is a common medium that allows several computers or several machine controllers to be connected, and, as long as each computer uses the protocol convention of the LAN, communication can take place at high data rates.

Figure 1.4 shows a typical example for a modern industrial company. This architecture shows three distinct layers. At the bottom, the physical processes of manufacturing on the shop floor are arranged in stations along a production line or in manufacturing cells. Controllers that are dedicated to those physical processes control the operations at each station. These controllers may be computers, but they are more likely special-purpose computers, called programmable logic controllers (PLC), which have been specifi cally designed to control and collect formation from machinery.

• • Historically, manufacturers of machine controllers have implemented communication requirements using local area networks designed specifically for their own controllers. In Figure, we are assuming that the controllers have the capability of communicating with each other over a common local area network, sometimes called a shop floor data highway. Such communication capability allows individual machines to “talk” to one another as peers. This is known as “peer to peer” communication capability. So, for example, if a machine at one station has a failure, the controller at that station can transmit that information to other stations or to the supervisory controller, which may respond by stopping the processes and signaling for assistance.

Another distinct layer of the architecture is the business layer, at which functional departments are connected to one another via computers and a local area network.

The factory host computer is the repository of data for factory operation. The individual functions shown are the high-level business and planning functions of the factory. In Figure, these functions are interconnected Figure Typical network architecture. 8 Introduction with each other and the factory database over their own local area network. The distinction between the shop floor LAN and the business level LAN is one that has developed in practice over time because of differences in the communication performance requirements at each level as well as available LAN options on the factory floor.

Computer integrated Manufacturing

•

Computer-integrated manufacturing

(

CIM

) is the manufacturing approach of using computers to control the entire production process.This integration allows individual processes to exchange information with each other and initiate actions.

Through the integration of computers, manufacturing can be faster and less error prone, although the main advantage is the ability to create automated manufacturing processes. Typically CIM relies on closed-loop control processes, based on real-time input from sensors. It is also known as

flexible design and manufacturing

CIM

http://www.technologystudent.com/rmprp / 07 lmth.

1 namtni

Manufacturing Execution System

• • • • • • MRP/MRP II/ERP are generally thought of as “planning” systems. They are responsible for supporting the planning of production, but they are not very well integrated into the execution of production. This void in available software solutions on the shop floor has led to the development of the manufacturing execution system (MES). The MES is an attempt to manage resources, including materials, machines, and personnel, on a daily or even hourly basis. Typical MES functions include the following: Dispatching and monitoring production Detailed scheduling associated with specific production units in order to meet specific performance criteria.

Data collection from factory floor operation to provide a history of factory events.

Quality data analysis Product history recording

Manufacturing Control

- Managing and controlling the physical activities in the factory aiming to execute the manufacturing plans. Normally, a manufacturing control comprises the short-term process plan and the shop floor activities.

Three indicators for testing a manufacturing execution system

• • •

Agility

- Capability to react in a short period of time to the occurrence of unexpected disturbances (i.e. production environment changes).

Flexibility

- Capability to adapt to new, different or changing environments.

In manufacturing world, several flexibility classifications are presented in literature, like mix, changeover, volume, product and sequencing.

Re-configurability

- Ability to support different manufacturing system configurations, i.e. different production systems scenarios, with a small customization task.

Traditional Manufacturing execution Approaches

Centralized Control Structures

 is characterized by a single decision node, where all the planning and processing information functions are concentrated.

•

Advantage

:

optimization a better management and control

•

Disadvantage: complexity, low, tolerance speed to specially for large systems

.

of faults response, and control expandability,

Hierarchical Control Structures

Hierarchical Control Structures

 In the hierarchical architecture, a complex problem is decomposed in several simpler and smaller problems, and distributed among multiple control layers. This architecture is characterized by the existence of some control levels, distributed in a tree structure, allowing the distribution of decision-making among these hierarchical levels. The relations between hierarchical levels are based on the master-slave concept.

• • Advantage: The main advantages of this architecture are the

robustness

, the

predictability

and the

efficiency

that are better than in centralized architectures.

Disadvantage: the appearance of disturbances in the system reduces significantly its performance.

Heterarchical Control Structures

• •  The heterarchical architecture, also designated by autonomous agent approach in the agent domain, is characterized by the high level of autonomy and co operation, being the client-server structure with fixed relations no more applied.

Advantage: allow a high performance against disturbances, The expandability of the system is an easier task, because it is enough to modify only the functioning of some modules or add new modules to the control system.

Disadvantage: is a novel technology, needs more research works, at the time the implementation of this control structure is not common