Cem ERTÜRK - 030070245 - 2nd week answers

Virtual Prototyping (Protyping)

based on virtual reality technology, involves the use of the CAD geometric model to construct a digital mock-up of the product, enabling the designer and others to obtain the sensation of the real physical product without actually building the physical prototype. Virtual prototyping has been used in automotive industry to evaluate new car style designs. The observer of the virtual prototype is able to assess the appearance of the new design even though no physical model is on display. Other applications of virtual prototyping include checking the feasibility of assembly operations, for example, parts mating, access and clearance of parts during assembly, and assembly sequence.

(Groover, M.P., Automation, Production Systems and Computer - Integrated Manufacturing, pg.704, Pearson Education Inc,2008)

Virtual Prototyping

Prototypes and rapid prototypes have some major problems: the first are

expensive and the latter are not rich enough for a comprehensive validation of the

various relevant aspects of the product. For these reasons, the use of Virtual Prototyping

is a practise that is spreading in the industrial design and engineering fields.

Virtual prototyping aims at effectively supporting the validation of the initial

concept of new products, while leaving the full validation of the complete product

at the end of the design process, through a fully-working prototype (as shown in the

product design process of Fig. 7.2). With this new practice, it is possible to perform

design review before building hardware products. Consequently, the number of

physical prototypes effectively built during the overall product development process

is considerably reduced. And in addition, more variants and iterations are

possible, as well as a direct comparison of the various variants.

(Bordegoni M and Rizzi C. Innovatiın  in Product Design From Cad to Virtual Protyping , page:124)

Proses capability (Manufacturing Planing)

A process is a unique combination of tools, materials, methods, and people engaged in producing a measurable output; for example a manufacturing line for machine parts. All processes have inherent statistical variablity which can be evaluated by statistical methods.

The Process Capability is a measurable property of a process to the specification, expressed as a process capability index(e.g., Cpk or Cpm) or as a process performance index (e.g., Ppk or Ppm). The output of this measurement is usually illustrated by a histogram and calculations that predict how many parts will be produced out of specification.Process capability is also defined as the capability of a process to meet its purpose as managed by an organization's management and process definition structures ISO 15504. Two parts of process capability are:

1) Measure the variability of the output of a process

2) Compare that variability with a proposed specification or product tolerance.

Proses capability

The proses capability study is a powerful tool that, when understood, will provide benefits to almost every department within a manufacturing organization. A wealth of information is available on the technical concepts of the process capability study. Much of what is available has placed a great deal of emphasis on the mathematics and technical nuances that would be of inter-est to quality professionals, engineers, and statisticians. Unfortunately, con-centrating on the math and fine distinctions, such as the difkrence between alpha- and beta-type errors, has created barriers preventing many people from fully appreciating the basic concepts, the simplicity. and the usefulness of the tool. One significant casualty of the narrow acceptance and use of the pro-cess capability study has been an appropriate roturn on investment many companies have failed io realize from their statistical process control (SPO/ Six Sigma effort. In many companies, the Si'(/Six Sigma eftbn has evolved into bulletin boards filled with bar graphs. Pareto charts, and project team reports addressing nonmanufacturing-related concerns. Using well-defined group dynamics and problem-solving activity to address organizational con-cerns can provide significant benefits to a company. However, the essence of the original SPC/Six Sigma approach was directed at understanding and reducing manufacturing proces.s variation.

(Relyea D.B The practical Application of the Process Capability Study,Page,4)

Lapping (Manufacturing)

Lapping is a free abrasive machining process. An abrasive compound in a fluid suspension is applied to the lapping tool, which is called a "lap". The workpiece is placed on top of the lap and moved to cause cutting/material removal at a controlled rate. Lapping is primarily considered to be a three-body abrasive mechanism due to the fact that it uses free abrasive grains that can roll or slide betwwen the workpiece surface and the tool plate, although some grains become embedded in the lap, which would be considered two-body abrasion. A fine abrasion is applied, continuously or at specific intervals, to a work surface to form an abrasive film between the lap and the parts to be lapped or polished.

Each abrasive grain used for lapping has sharp irregular shapes, and when a relative motion is induced and pressure applied, the sharp edges of the grains are forced into the workpiece material. Each loose abrasive particle acts as a microscopic cutting tool that either makes an indentation or causes the material to cut away very small particles.

(Boljanovic V., Metal Shaping Processes: Casting and Molding, Particulate Processing, Deformation Processing, Metal Removal, 2010, pg.411)

Lapping

Lapping is an abrasive process used to produce surface finishes of extreme accuracy and smoothness. It is used in the production of optical lenses, metallic bearing surfaces, gages, and other parts requiring very good finishes. Metal parts that are subject to fatigue loading or surfaces that must be used to establish a seal with a mating part are often lapped. Instead of a bonded abrasive tool, lapping uses a fluid suspension of very small abrasive particles between the workpiece and the lapping tool. The process is illustrated in Figure 25.17 as applied in lens-making. The fluid with abrasives is referred to as the lapping compound and has the general appearance of a chalky paste. The fluids used to wake the compound include oils and kerosene. common abrasives are aluminum oxide and silicon carbide with typical grit sizes between 300 and 600. The lapping tool is called a lap, and it has the reverse of the desired shape of the workpart. To accomplish the process, the lap is pressed against the work and moved back and forth over the surface in a figure•eight or other motion pattern, subjecting all portions of the surface to the same action. Lapping is sometimes performed by hand, but lapping machines accomplish the

(Groover M.P. Fundamentals of Modern Manufacturing. Page:613)

My definiton is greater than older one and also give example what kind of techniques.

Abrasive Saw(Manufacturing)

Saw machines are also made with circular abresive or metal-cutting wheels. The abrasive saw may be used for high-speed cutting where a narrow saw kerf is desirable or when very hard materials must be cut. One advantage of the abrasive saw is its ability to cut a variety of materials-from soft aluminum to case-hardened steels. (cutting a variety of metals on the bando r the power hacksaw requires blade and speed changes.) A disadvantage of the abrasive saw is the expense of abrasive discs. Many companies use this saw only when versatility is needed. The abrasive saw is usually found in the grinding room where abrasive particles can be contained, but may also be used in the shop for general-purpose cutting. Metal cutting saws with teeth, also known as cold saws, are used for precision cutoff operations, cutting saw kerfs, slitting metal, and other manufacturing uses.

(David A. Madsen, Print Reading For Engineering And Manufacturing Technology, P.120)

Abrasive Saw

Abrasive machining involves material removal by the action of hard, abrasive particles that arc usually in the form of a bonded wheel. Grinding is the MOSE important of the abrasive processes. In terms of number of machine tools in use, grinding is the most common of all metalworking operations FIJI. Other abrasive processes include honing, lapping, sum-finishing, polishing. and buffing. The abrasive machining processes are gen-erally used as finishing operations, although some abrasive processes arc capable of high material removal rates rivaling those of conventional machining operations. The use of abrasives to shape parts is probably the oldest material removal process (Historical Note 25.1). Abrasive processes are important commercially and technologi-cally for the following reasons:

·         They can be used on all types of materials ranging from soft metals to hardened Mat and hard nonmetallic materials such as ceramics and silicon.

·          Some of these processes can produce extremely fine surface finishes, to 0.025 gm (1 g-in). For certain abrasive processes, dimensions can be held to extremely close tolerances.

Abrasive water jet cutting and ultrasonic machining arc sometimes classified as abrasive processes, because they accomplish cutting by means of abrasives. However, these processes arc commonly known as nontraditional material removal processes and are coveted in the following chapter.

(Groover M.P. Fundamentals of Modern Manufacturing. Page:594)

My defintions is greatest the older one because, this definition was explained, how can be used and what are the advantages. Also older one is mentioned different term.

Holonic Manufacturing (Manufacturing Organization)

Holonic manufacturing is a new concept describing a unique organization of manufacturing units. The word holonic is from the Greek holos (meaning whole) and the suffix on (meaning a part of). Thus, each component in a holonic manufacturing system (at the same time) is an independent entity (or whole) and a subservient part of a hierarchial organization. We describe this system here because of its potential beneficial impact on computer-integrated manufacturing operations.

Holonic organization systems have been studied since 1960s, and there are a number of examples in biological systems. Three fundamental observations of these systems can be stated as:

1. Complex systems will evolve from sipmle systems much more rapidly if there are stable intermediate forms than if there are none. Also, stable and complex systems require a hierarchial system for evolution.

2. Holons simultaneously are self-contained wholes to their subordinated parts and the dependent parts of other systems. Holons are autonomous and selfreliant units, which have a degree of independence and can handle contingencies without asking higer levels in the hierarchial system for instructions. At the same time, holons are subject to control from multiple sources of higher system levels.

3. A holarchy consists of (a) autonomous wholes in charge of their parts and (b) dependent parts controlled by higher levels of a hierarchy and (c) are coordinated according to their local environment.

(Kalpakjian S., Schmid S.R., Manufacturing Engineering And Technology, p. 1224)

Holonic Manufacturing

A holonic manufacturing system is based on the concept of “holonic systems”,

developed by Arthur Koestler [6]. Holons in a holonic manufacturing systems assist

the operator in controlling the system: holons autonomously select appropriate

parameter settings, find their own strategies and build their own structure.

Work in the HMS program has translated these concepts to the manufacturing

world, viewing the manufacturing system as one consisting of autonomous modules

(holons) with distributed control. The goal is to attain the benefits that holonic organization

provides to living organisms and societies, in manufacturing, i.e., stability

in the face of disturbances, adaptability and flexibility in the face of change, and

efficient use of available resources. The HMS concept combines the best features of

hierarchical and heterarchical organization [8]. It preserves the stability of hierarchy

while providing the dynamic flexibility of heterarchy.

(Botti V. And Giret A. ANEMONA A Mulit-agent Methodology for Holonic Manufacturing SystemsPage:9)

Shortest Processing Time (SPT) (Manufacturing Planing)

In single-machine scheduling problem, sequencing the jobs in increasing order of processing time is known as shortest processing time (SPT) sequencing. In single-machine scheduling, sometimes we may be interested in minimizing the time spent by jobs in the system. This in turn will minimize in process inventory. Also, we may be interested in rapid turnaround/throughput times of the jobs. The time spent by job in the system is nothing but its flow time and the “rapid turnaround time” is the mean flow time of the jobs in the system. Shortest processing time (SPT) rule minimizes the mean flow time.

(R. Panneerselvam, Operations Research, Second Edition, p. 496)

Shortest Processing Time (SPT)

Shortest processing (SPT) time implies that the next job to be processed is the one that has the least time necessary to complete. The philosophy here is to get the smallest jobs over quickly. which gives a physiological impression that one is being more productive. The problem with this approach is that large jobs, which might be inure urgent, are done later

(Production Planning and Control: Text and Cases Prentice Hall India Pvt., Limited page:182)

Cellular Manufacturing (Manufacturing Planing)

 - The machines in a multi-station system with variable routing may be manually operated, semi-automatic, or fully automated. When manually aoperated or semi-automatic, the machine groups arte often called machine cells, and the use of these cells in a factory is called cellular manufacturing.

Cellular manufacturing is an application of group technology in which dissimilar machines or processes have been aggregated into cells, each of which is dedicated to the production of a part, product family, or limited group of families. The typical objectives in cellular manufacturing are similar to those group technology:

To shorten manufacturing lead times by reducing setup, workpart handling, waiting times, and batch sizes.

To reduce work-in-process inventory. Smaller batch sizes and shorter lead rines reduce work-in- process.

To improve quality. this is accomplished by allowing each cell to specialize in producing a smaller number of different parts. This reduces proces variability.

To simplify production scheduling. the similarity among parts in teh family reduces the complexity of production scheduling. Instead of scheduling parts through a sequence of machines in a process-type shop layout, the system simply schedules the parts though the cell.

To reduces setup times. This is accomplished by using group tooling (cutting tools, jigs, and fixtures) that have been designed to process the part famiy, rather than ğart tooling, which is designed for an individual part. this reduces the number of individual tools required as well as the time to change tooling between parts.

(Groover, M.P., Automation, Production Systems and Computer - Integrated Manufacturing, pg.376,518-519, Pearson Education Inc,2008)

Cellular Manufacturing

Group technology(GT) is a manufacturing concept that seks to identify and groupsimilar parts to take advantage of their similarites in manufacturing and design

Cellular Manufacturing (CM) is an application of the GT concepts to factory reconfiguration and shop floor layout design. Cellular Manufacturing Systems (CMS), as illustrated in Figure 1. have been proposed as an alternative to job shops since they provide the operational benefits of flow line production. Cellular Manufacturing involves processing a collection of similar parts on a dedicated group of machines or manufacturing processes. A manufacturing cell can be defined (Ham et al.. 1985) as "an independent group of functionally dissimilar machines. located together on the floor, dedicated to the manufacture of a family of similar pzu-ts.- Furthermore, a part family can be defined (Ham et al.. 1985) as "a collection of parts which are similar either because of geometric shape and size or because similar processing steps are required to manufacture them.- Usually it is preferable that a cell be dedicated to a single part family. that each part family be preferably produced completely within its cell, and that cells in a CMS have minimum interaction with each other. In summary. a CMS is essentially a set of manufacturing and/or assembly cells, each dedicated to the manufacture or assembly of a pan family or group of products, respectively.

(Iranic S.A Handbook of cellular manufacturing systems page:1,2)

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