Evrim Berk 030060161 1st Week

1-) ROBOTIC ASSEMBLY (previous answer) (group: method) - better one !

Design guidelines for robotic assembly include the following additional considerations.
- Parts should be designed so that they can be gripped and manipulated by the same gripper ( end effector) of the robot.Such a design avoids the need for different grippers.Parts should be made available to the gripper in the proper orientation.
-Assembly that involves threaded fasteners ( bolts , nuts and screws) may be difficult for robots.One exception is the use of self threading screws for sheer metal, plastics, and wooden parts.Also, note that robots easily can handle snap fits, rivers, welds and adhasives.
The development of compliant end effectors and dexterous manipulators has made robotic assembly even more attractive.

(Kalpakjian S., Schmid S.R.,Manufacturing engineering and technology, 5th Edition, p 1185)

ROBOTIC ASSEMBLY (new answer) (group: method)

Assembly and Inspection are growing application areas for industrial robotics. In some respects, they are hybrids of the previous two robot application categories: material handling and processing. Assembly and isnpection applications can involve both the handling of materials and the manipulation of a tool.

The most appealing area fot the application of industrial robotics for assembly is in the production of a mixture of similar products or models in the same workcell or assembly line.

What makes robotics useful in the assembly applications is their capability to execute programmed variations in the work cycle to accommodate different assembly configurations.

(Groover M.P., Automation, Production Systems, And Computer-Integrated Manufacturing, p 351 - 353)

2-) PROCESS CONTROL (previous answer) (group: control)

A field of engineering dealing with ways and means by which conditions of processes are brought to and maintained at desired values, and undesirable conditions are avoided as much as possible.In general , a process is understood to mean any system where material and energy streams are made to interact and to transform each other.

(MCGRAW-HILL encyclopedia of science & technology 6th edition v.14 p.335)

PROCESS CONTROL (new answer) (group: control) - better one !

Process control is one of the strategies in automation. This includes a wide range of control schemes intended to operate the individual processes and associated equipment more efficiency. By this strategy, the individual sprocess times can be reduced and product quality improved.

(Groover M.P., Automation, Production Systems, And Computer-Integrated Manufacturing, p. 41)

3-) LOCAL AREA NETWORK (previous answer) (group: technology)

Ethernet, now known as local area networking, allowed compatible computers to work together. Sharing files, resources and programs would be the next big thing.

William J. Herrmann, KEN OLSON: ULTIMATE ENTREPRENEUR?, s.66

LOCAL AREA NETWORK (new answer) (group: technology) - better one !

When computers, which are connected together normally belong to one organization and all computers are situated within a radius of about 1 km. the networks is called a Local Area Network (LAN). Nowadays all computers are designed so that is easy to connect it to a LAN without buying any extra equipment.

(Rajaraman V., Introduction to Information Technology, Prentice Hall of Indıa , p. 142)

4-) DIRECT NUMERICAL CONTROL (previous answer) (group:method)

Several machines are controlled directly step by step by a central mainframe computer.In this system the operator has access to the central computer through a remote terminal.With DNC,the status of all machines ina manufacturing facility can be monitored and assesed from a central computer.However DNC has a crucial disadvantage:If the computer shuts down all of the machines become inoperative.A more recent definition of DNC is distributed numerical control in which a central computer serves as the control system over a number of individual CNC machines having onoard microcomputers.This system provides large memory and computational facilities and offers flexibility while overcoming the disadvantage of direct numerical control.

(Serope Kalpakjian- Steven R. Schmid p:1155)

DIRECT NUMERICAL CONTROL (new answer) (group:method) - better one !

Direct numerical control can be defined as a manufacturing system in which a number of machines are controlled by a computer through direct connection and in real time. The tape reader is omit

ted in DNC, thus relieving the system of its least reliable component. Instead of using the tape reader, the part program is transmitted to the machine tool directly from the computer memory. In principle, one computer can be used to control more than 100 seperate machines.

The systems consists of four components:

1- Central Computer

2- Bulk Memory, which stores the NC part components.

3- Telecommunication Lines

4- Machine Tools

Two types of DNC:

1- Behind-the-tape Reader System

2- Special Machine Control Unit

(Groover M.P., Automation, Production Systems, And Computer-Integrated Manufacturing, p. 281 - 282 )

5-) DISTRIBUTED NUMERICAL CONTROL (previous one) (group:method)

Sometimes the abbreviation DNC is used to denote distributed numerical control. A computer network for manufacturing may consist of a main frame computer, CAD/CAM work stations, DNC host computer and the CNC systems connected to it. This configuration can be beneficially used for NC data processing. Any complex calculations required for generating NC data can be transferred to the more powerful mainframe computer. Thus the NC DATA processing is done at different hierarchical levels. In a way many of the DNC systems today are in fact distributed processing systems.

(Radhakrishnan P., Subrahmanyan S., Raju V., CAD/CAM/CIM, 3rd Edition, p. 384 )

DISTRIBUTED NUMERICAL CONTROL (new one) (group:method) - better one !

The evolution of hierarchical control configuration, in which the machine tool MCUs are connected to a central plant computer and the controllers are themselves CNC units, has an architecture very similar to direct numerical control. To distinguish this configuration from DNC, the term distributed numerical control is used. The difference is simply in the presence of the CNC controllers in the hierarchy to replace har-wired MCU. Today, distributed numerical control represents the generally accepted approach for central computer control of NC machine tools. In present usage, the initials DNC refer to this modern control configuration.

(Groover M.P., Automation, Production Systems, And Computer-Integrated Manufacturing, p. 295 )

Hakan YORULMUŞ 030070111 1.ST WEEK

1) Optimized Production Technology; (Manufacturing method) 
Optimized Production Technology (previous)
Optimized production technology (OPT) is an approach to scheduling, which places the primary focus upon the "bottleneck" process or processes. Bottlenecks are an everyday concept. Motorway roasworks and super market chechouts are bottlenecks at busy times of the day. They restrict the flow of work through the operation. Processes may be bottlenecks because either their capacity is less than the level of demand or because their capacity is used in an inefficient manner. Once bottleneck processes are identifiedi supplying processes are backward scheduled from the bottleneck. At all of the bottleneck processes, therefore, operations are activated on the basis of delivering products just in time for their linked downstream processes. OPT is a computer-based scheduling system. The more bottlenecks a system contains, the more complex the scheduling task becomes and a computer is essential.
OPT is based on the view that the goal of the operation is to make money. It was developed for manufacturing, however some of the principles of OPT are applicable to all organizations.
(Azhashemi M., Galloway L., Rowbotham F.,Operations Management in Context, 2nd Ed., pg.259, Kayra Ermutlu)


Optimized Production Technology (new)

OPT’s objective is to schedule production so that the production output is maximised.

The key distinctive feature is its ability to identify and isolate bottleneck operations,

then to focus on these bottlenecks to determine production plans and schedules for the

entire shop. This simple idea could lead to the better utilisation of manufacturing

resources, resulting in greater productivity and lower costs.

Evans [1993] perceives that OPT can be viewed form several perspectives. These

being: as a philosophy for scheduling, as a language for modelling manufacturing

operations, as a software system for manufacturing resource planning, or as a tool for

co-ordinating the efforts of marketing, engineering and manufacturing to realise the

common goals of the organisation. Moreover, Hill [1991] describes OPT as a sound

aid to achieve the only goal in any manufacturing organisation, and that goal is to

make money.

 The ten rules of OPT.

To achieve this goal, Hill [1991] goes on to suggest that there are three important

factors that have to be carefully considered. They are throughput (rate at which the

manufacturing system generates money through sales), inventory and the operational

expense (amount in which is spent to turn the inventory into sales). These in turn feed

into the ten rules of its philosophy [Hill, 1991]:

1) Balance flow, not just capacity: Capacity and a smooth flow of materials should

be considered and maintained simultaneously, which is similar to the JIT

approach.

2) The level of utilisation of a non-bottleneck is determined not by its own potential
but by some other constraint in the system: The throughput (rate of which the
manufacturing system generates money through sales) of a system is limited bythe bottleneck (a resource whose capacity is equal to or less that the demand placed upon it). Therefore, it is necessary to control the inputs into the system
since it should be the bottleneck that dictates the throughput of the system. If nonbottlenecks resources produce more than bottlenecks can absorb, or more than the
demand dictates, then inventory builds up and operating expenses are increased.
3) Utilisation and activation of a resource are not synonymous: This rule defines utilisation as the degree to which a resource should be used in order to achieve the strategic goal of profitability, and activation as the degree to which the resource can be used.

4) An hour lost at a bottleneck is an hour lost for the entire system: Bottleneck resources should be utilised 100% at all times: breaks should not occur and set-up times must be reduced.

5) An hour saved at a non-bottleneck is just a mirage: Bottleneck resources limit the

capacity of the system, hence, saving non-bottleneck time does not effect the efficiency of the system.

6) Bottlenecks govern both the throughput and the inventory in the system: Inventories can be controlled where the bottlenecks are located, and which determines the throughput.

7) The transfer batch may not, and many times should not, be equal to the process batch: The transfer batch is the amount of product transferred from one operation to another, and the process batch being the amount processed at any operation between transfers. The numbers should be flexible, since it is essential for the flow of product from raw material to the finished goods.

8) The process batch should be variable, not fixed: When there is a different number

of parts to an object that are to be manufactured on different equipments, the

process batch needs to be varied in order to maintain a smooth and rapid flow, and

hence reducing inventory.

9) Schedules should be determined by looking at all constraints simultaneously.

Lead-times are the result of a schedule and cannot be predetermined: Lead-times

depends upon the sequencing (the sequence in which different parts, with different

processing times are being loaded), and so cannot be determined in a capacity

bound situation unless the capacity is considered.

10) The sum of the local optima is not equal to the optimum of the whole: OPT seeks

to measure the performance of the plant as a whole based on its raw material input

and the final product output.

(A Study of Production Management (Manufacture) , Lee Angela ,University of SalfordResearch Unit, (January 1999), page 9-10)

New answer is better it is more simple and it has more information.

2)Production Activity Control (Manufacturing method)

Production Activity Control (previous)

There is a widely perceived gap within the domain of scheduling for manufacturing systems, namely, many of the methods employed by production supervisors are quite different from those developed by researchers. In a sense, this inconsistency highlights the important fact that much scheduling research has failed to win approval where it matters most, namely, within the manufacturing system.

In this article, we argue for a practical approach to scheduling for manufacturing systems, one that we believe can narrow, and possibly bridge, the gap between theory and practice. This approach is based upon a well-defined and modular architecture for scheduling, termedproduction activity control. This architecture is the foundation of our proposed solution to scheduling, since it provides a coherent blueprint for the synthesis of information technology and scheduling strategies. The result of this synthesis is a design tool for production activity control, which allows for detailed and disciplined experimentation with a range of scheduling strategies in a controlled and simulated environment. Due to the unique modular property of the design tool, these strategies may then be implemented live in a flexible manufacturing facility, hence narrowing the gap between scheduling theory and manufacturing practice. Our overall approach is tested through an appropriate implementation in a modern electronics assembly plant.

(Internal Journal of Flexible Manufacturing Systems, Volume 4, Number 1, p. 79-103)

Production Activity Control (New)

Operational production management system issues take the tactical schedule outputs and

manage the manufacturing system to meet those requirements. Production Activity Control

(PAC) describes the principles and techniques used by management to plan in the short term

and to control and evaluate the production activities of the manufacturing organisation [2].

PAC architecture is a self contained series of tasks which control a specific cell within a

factory. The aim of PAC is to reduce complexity and uncertainty in task execution and

improve the co-ordination of decision making. With an SME their size should help them to

deal with PAC more easily, but in a study by Stahl [7] it was found that the SME was

constrained by a lack of access to knowledge and skills. It found that they lack the capacity

to define real training needs and they were unable effectively to plan, organise and implement

training. Further, the external training market did not meet the specific needs of an SME and

the tight financial margins and small number of employees made it very difficult to attend off

site training programmes. Larger companies with greater access to technical resources, such

as dedicated vendor planners, buyers and supervisors are better able to manage the PAC

process. Not surprisingly the cynical view is that the larger company, normally the customer

has the planning skills but is dependant on the smaller company, the supplier who has to

deliver against short term plans with limited knowledge and operational planning skills. The

planning process in both large and small companies may be the same, but the SME’s

effectiveness is constrained by shortcomings in understanding and executing basic planning

discipline and control.

(PRODUCTION ACTIVITY CONTROL FOR SMALL AND MEDIUM SIZED ENTERPRISES, SMEs WITH LESS THAN 500 EMPLOYEES; Neil Towers; Manchester Metropolitan University)
New definition is better than previous one


3)Production Planning (Manufacturing method) 


Production planning (previous) and control are the manufacturing support functions concerned with logistics problems in manufacturing.Production planning is concerned with planning what products are to be produced, in what quantities, and when.It also considers the resources requried to accomplish the plan.

(Mikell p.Groover,Fundamentals of modern manufacturing second edition ,page 928)


Production planning (new)
Manufacturing planning and control address decisions on the acquisition, utilization and
allocation of production resources to satisfy customer requirements in the most efficient
and effective way.  Typical decisions include work force level, production lot sizes,
assignment of overtime and sequencing of production runs. Manufacturing planning and control entails the acquisition and allocation of limited resources to production activities so as to satisfy customer demand over a specified time horizon. As such, planning and control problems are inherently optimization problems,
where the objective is to develop a plan that meets demand at minimum cost or that fills
the demand that maximizes profit.  The underlying optimization problem will vary due to
differences in the manufacturing and market context.

(Manufacturing Planning and Control; Stephen C. Grave; Massachusetts Institute of Technology
November 1999)
New answer is better it is more simple and it has more information.

4)Turbucharger (product)
Turbocharger: (previous)
The purpose of supercharging is to increase the mass of air trapped in the cylinder of the engine, by raising air density. This allows more fuel to be burnt, inreasing the power output of the engine, for a given swept volume of the cylinders. Thus the power to weight and volume ratios of the engine increase. Since more fuel is burnt to achieve the power increase, the efficiency of the engine cycle remains unchanged. A compressor is used to achieve the increase in the air density. Two methods of supercharging can be distingused by the method to drive the compressor. If the compressor is driven form the crankshaft of the engine, the system is called "mechanically driven supercharging" or often just" supercharging". If the compressor i driven by a turbine, which itself driven by exhaust gas from the cylinders, the system is called "turbocharging". The shaft of the turbocharger links the compressor and turbine, but is not connected to the crankshaft of the engine. Thus the power developed by the turbine dictates the compressor operating point, since it must equal that absorbed by the compessor.

(Diesel engine reference book, Second edition, p. 29-Edited by Bernard Challen and Rodice Baranescu)


Turbocharger: (new)
Turbochargers are precision pieces of machinery which operate at high speed, using heat of expanding
exhaust gasses to “boost” intake manifold pressure. Turbochargers increase performance and decrease
exhaust smoke through improving an engine’s volumetric efficiency.

(Technician Turbocharger Guide for the Powerstroke Engine; International Truck and Engine Corporation; September 2003 Rev. 3)




New definition and old definition is good. 


5) Euro Emission Standart (Standart) 
Euro Emission Standart (previous)
I can not find the previous answer

Euro Emission Standart(new):
Before a new vehicle can be approved for sale in the EU it must meet certain standards for
exhaust emissions as specified by EU directives.  These standards are vehicle type specific and for
petrol fuelled vehicles are sub-divided into passenger cars and light-duty vehicles.  The
passenger cars are further sub-divided according to their laden weight (below or above 2.5
tonnes) and the number of seats they have, whilst the light-duty vehicles are sub-divided into
three different categories by vehicle mass.
For all petrol vehicles the regulatory test cycle involves starting the engine when cold followed
by driving a cycle simulating urban and sub-urban driving (ECE 15 + EUDC).  The emissions
are monitored for the whole cycle and, after dividing by the cycle’s length (11.007 km), the
emission standards are expressed in grams of pollutant per kilometre.

(Appendix 1EU Emission standards for petrol vehicles; AEAT/ENV/R/0679 Issue 3)

Şakir ÇELİK,503111313,1st week words

1- Manual Assembly

2- High-speed Automated Assembly

3- Integral Transfer Devices

4- Total Quality Management (TQM)

5- Return On Quality (RQO)

6- Acceptance Quality Level (AQL)

7- Lot Size

8- Automated Inspection

9- On-line Inspection

10- In-process Inspection

060070103-Rifat Yılmaz- 1st week definitions

Rapid Prototyping (Previous)-GROUP: Manufacturing Method

Rapid prototyping is a technology which relies on CAD/CAM and on various manufacturing techniques (Using metallic or nonmetallic materials as work pieces) to produce prototypes rapidly and at low cost, in the form of a solid physical model of a part

(manufacturing engineering and technology-Serope kalpakjian, page 14)

Rapid Prototyping (New)

Rapid prototyping is a means of producing component parts or accurate replicas of them in a short lead time. These parts are made with special automatic non-traditional fabrication methods from sophisticated computerized designs, without the use of special dies, molds, jigs or other tooling. All common rapid prototyping methods build the parts with a layer-by-layer approach, under computer control. Parts thus made can be tested and evaluated much sooner than would be possible if traditional production methods were employed.

Rapid prototypes have the following uses: 1) as visual concept models - to visualize and verify appearance, fit and design features. 2) as casting patterns. Wax or plastic prototypes can be used as

patterns for the manufacture of investment, plaster or sand-mold cast metal prototypes. 3) for use as patterns for producing non-consumable short-run tooling of epoxy, rubber or other materials for plastic molding of prototypes or short-run production parts. 4) as functional prototypes. Sometimes, rapid prototypes can be made sufficiently strong that they can be used in operational testing of the product that uses the part.

(James G. Bralla, Handbook of Manufacturing Process, page  585)

New definition is better than previous one. New definition give good information.

Friction Stir Welding (FSW) (Previous)-GROUP: Manufacturing Method

Friction stir welding (FSW) is a solid-state welding process that is gaining wide acceptance in industry, especially the shipbuilding, aerospace, mass transportation and automotive industries. FSW is particularly suited to those industries that use aluminium and its alloys. This authoritative book provides a comprehensive review of the subject of friction stir welding and covers topics such as process basics, equipment, modelling, inspection and quality control and applications.

(Friction stir welding from basics to applications D. Lohwasser, Z. Chen 2009 p.1)

Friction Stir Welding (FSW) (New)

Friction stir welding is a solid-state joining process developed at the Welding Institute. As shown in Figure 15.23a, a rotating cylindrical tool with a probe is plunged into a rigidly clamped work piece and traversed along the joint to be welded. Welding is achieved by plastic flow of frictionally heated material from ahead of the probe to behind it. For welding aluminum alloys, the tool is usually made of tool steel. As shown in Figure 15.23b, the resultant weld consists of three zones: thermally affected zone, thermo mechanically affected zone, and dynamically recrystallized zone for aluminum welding.

(Sindo Kou, Welding Metalurgy, Second Edition, page 370-371.)

New definition is better than previous one. Because new one give us visual demonstration of welding method.

Total Quality Management (Previous)-GROUP: Quality control

TQM is a system that emphsizes the concept that quality must be desinged and built into a product. It is a systems approach in that both managements and employees make a concerted effort to consistently manufacture high-quality products. Defect preventation (rather than defect detection) is the major goal here.

Leadhership and teamwork in the organization are essential. They ensure that the goal of continuous improvement in manufacturing operations is imperative,be-cause they reduce product variability and they improve customer satisfaction. The TQM concept also requires us to control processes and not the parts produced, so that process variability is reduced and no defective parts are allowed to continue through the production line.

(Kalpakjian S., Schmid S.R.,Manufacturing engineering and technology, 5th Edition, p. 1113)

Total Quality Management (New)

Total Quality Management involves the understanding and implementation of quality management principles and concepts in every aspect of business activities. Total Quality Management demands that the principles of quality management must be applied at every level, every stage and in every department of the organization. The idea of Total Quality Management philosophy must also be enriched by the application of sophisticated quality management techniques. The process of quality management would also be beyond the inner organization in order to develop close collaboration with suppliers.

In general we will follow the definition of TQM by Kanji (1990). According to him ‘TQM is the way of life of an organization committed to customer satisfaction through continuous improvement. This way of life varies from organization to organization and from one country to another but has certain essential principles which can be implemented to secure greater market share, increase profits and reduce cost.

(Jens J. Dahlgaard, Kai Kristensen, Gopal K. Kanji, Fundamentals of Total quality Management, page 8,14)

New definition is more specific and widely used for TQM. So it is better.

Wire Cut (Previous)-GROUP: Manufacturing Methods

Wire cut or wire EDM : In wire electric discharge machining a wire (about 0.05-0.30 mm in diameter) is used as an electrode and deionized water as dielectric. A nozzle is employed to inject the dielectric in the machining area in wire EDM.

(Advanced machining processes Vijay k.jain 12 th edition 2010 p.165 )

Wire Cut (New)

Wire-cut EDM - uses a constantly-moving wire instead of a shaped electrode. The wire, of 0.00 1 to 0.013 in (0.025 to 0.33 mm) diameters, passes through the work, with a vertical axis, (though it may be set at an angle when required when cutting apertures for stamping tools.) Tungsten, copper, and brass are common wire materials. The wire or the work, is fed horizontally as the cut progresses, to cut a slit or shaped through-hole in the workpiece. Different wire material is constantly exposed to the spark, so wear of the wire is widely distributed and is not a problem. The process, shown in Fig. 3Ilb, is often used to cut die openings in hardened stock to produce dies and die components. A high level of accuracy and fine detail can be achieved.

(James G. Bralla, Handbook of Manufacturing Processes, page 120)

New definition is more obvious than previous one. It is better one.

High-Speed Steels (Previous)-GROUP: Material

High-speed steels are usually used for drilling, milling, broaching, sawing, and turning tools. Their hot hardness (up to approximately 600 ◦C) is far superior to that of tool steels Their hardness results from their basic martensitic structure and from interspersed carbides: tungsten carbides,
tungsten-molybdenum carbides, chromium carbides, and vanadium carbides.

(Grote Antonsson, Springer Handbook of Mechanical Engineering, pg.628)

High-Speed Steels (New)

The high-speed tool steels are very highly alloyed, with tungsten and molybdenum as the major alloying elements in the T and M grades, respectively. The tungsten, molybdenum, chromium, and vanadium in these steels produce very high densities of stable carbides. As a result, the high speed tool steels are capable of retaining hardness at temperatures as high as 600 ᵒC (1112 F) and are widely used for high-speed cutting and machining applications.

(George Krauss, Steels: Processing, Structure, and Performance, page 538)

New definition is better than previous.

Onur Özçelik, 503111324, 1st week

1- Component Reuse

2- Flexible Manufacturing Lines

3- Robot safety

4- Synchronous Systems

5- Nonsynchronous Systems

6- Continuous System

7- Flexible Assembly System (FAS)

8- Robotic Assembly

9- Database (About CAD Systems)

10- Visual Sensing 

Yilmaz Dogan (503072026) 1st Week Words

1.rapid prototyping

2.process control

3.six axis manufacturer

4.ball milling

5.unisurf

6.product lifecycle management

7.IGES

8.ANSI

9.wire cut

10. Friction Stir Welding (FSW) 

Esin Coskuner- 503091330 (1st week)

1. Integrated Manufacturing
2. Order Management Process
3. Logistic Process
4. Production Process
5. Resource Planning Process
6. Demand Management(*was taken)
7. Production Planning(*was taken)
8. Production Activity Control(*was taken)
9. Optimized Production Technology(*was taken)
10. Global Manufacturing Planning and Control

Eren GÜVEN 514111006 (1st Week)

1-  CFD - Computational Fluid Dynamics

2-  High Cycle Fatigue

3-  Low Cycle Fatigue

4-  Creep

5-  SI Engine

6-  CI Engine

7-  Feasibility

8-  Turbocharger

9-  Euro Emission Standarts

10-Wankel Engine

Mehmet Özer, 030070050, 1st Week

1.Martensitic transformation (Group: material)

Previous answer:

A martensitic transformation is a structural phase transformation of the diffusionless and cooprative type, where the rearrangement of atoms occurs with relatively small displacements compared to inatomic distancesç There is a rigorous crystallographic connection between the lattices of the initial and final phases. The trasnsformation is of the first order. The martensitic transformation is called thermoelastic, when it is thermally reversible.

During martensitic transformation, the high-temperature phase,called austenit, transforms to the low- temperature phase, called martensite. As it is a firts-order structural phase transformation, the high-temperature asutenite and the low- temperature martensitic phases coexist in a specific temperature range. This is due to the elastic strains that accompany the nucleation and growth of the martensitic or austenitic phase. The austenite-martensite phase boundaries are fully or partially coherent. The elastic strains due to teh martensitic transformation increase with increasing martensite fraction. To compensate the transformation strains, different crystallographic domains are formed within the martensite. Macroscopically, they are often visible as paralel bands on the sample surface.

(J. Ping Liu, Nanoscale Magnetic Materials And Applications, p. 401)

New answer:

Martensitic transformation consists in the alteration of the distance between neighbouring atoms and it manifests itself as a change of crystallographic structure from face-centred-cubic γ parent phase to body-centred-cubic α′ product phase. The applied stress or the plastic strain influence the free energy change, which acts as the driving force and can cause the phase transformation even above the martensite start temperature Ms. The deformation-induced martensitic transformation can be related to the TRIP (transformation-induced plasticity) effect, resulting in the uniform, unrecoverable, macroscopic strain, which occurs in some high-strength metastable austenitic steels. Kinematically controlled plastic strain-induced martensitic transformation may be used as a method of creating functionally graded materials with “tailored” mechanical properties. The functionally graded materials belong to the family of modern engineering materials, that are characterised by gradually evolving micro-structure, composition, phase distribution, porosity, etc. They are designed to obtain optimal spatial variation of properties, adapted to the specific application. FGMs join advantages of composite and layered materials and eliminate such problems like material discontinuity as well as associated high stresses and initiation of cracks and damage at the boundaries between two constituents or two layers.

The FGMs can be easily obtained within the structural members made of metastable austenitic stainless steels by loading them above the yield point and inducing the γ − α′ phase transformation. It is possible to obtain various distributions of mechanical properties, generated by two-phase micro-structure of the material, depending on the distribution of plastic strain fields as a function of the shape of structure.

(M. Sitko, B. Skoczen, Effect of γ − α′ phase transformation on plastic adaptation to cyclic loads at cryogenic temperatures, International Journal of Solids and Structures (2012), p.613)

2.Life Cycle Costs (Group: Accounting)

Previous answer:

One of the externalities of DFM. Throughout their life cycles, certain products may incur some company or social costs which are not (or are rarely) accounted for the manufacturing cost. For example, products may contain toxic materials requiring special handling in disposal. Products may incur service and warranty costs. Although these costs may not appear in the manufacturing cost analysis, they should be considered before adopting a DFM decision.

(Kalpakjian S.,Manufacturing Engineering and Technology, 5th Edition, p.229)

New answer:

Life cycle cost is the total cost of ownership of machinery and equipment, including its cost of acquisition, operation, maintenance, conversion, and/or decommission (SAE 1999). LCC are summations of cost estimates from inception to disposal for both equipment and projects as determined by an analytical study and estimate of total costs experienced in annual time increments during the project life with consideration for the time value of money. The objective of LCC analysis is to choose the most cost effective approach from a series of alternatives (note alternatives is a plural word) to achieve the lowest long-term cost of ownership. LCC is an economic model over the project life span. Usually the cost of operation, maintenance, and disposal costs exceed all other first costs many times over (supporting costs are often 2-20 times greater than the initial procurement costs). The best balance among cost elements is achieved when the total LCC is minimized (Landers 1996). As with most engineering tools, LCC provides best results when both engineering art and science are merged with good judgment to build a sound business case for action.

(Barringer H. P., A Life Cycle Cost Summary, p.2)

3.CFD - Computational Fluid Dynamics (Group: analyze method)

Previous answer:

The physical aspects of any fluid flow are governed by the following three fundamental principles: 1)mass is conserved; 2)F=ma; and 3)energy is conserved. These fundamental principles can be expressed in terms of mathematical equations, which in their most general form are usually partial differential equations. CFD is, in part, the art of replacing the governing partial differential equations of fluid flow with numbers, and advancing these numbers in space and/or time to obtain a final numerical description of the complete flow field of interest. This is not an all-inclusive definition of CFD; there are some problems which allow the immediate solution of the flow field without advancing in time or space, and there are some applications which involve integral equations rather than partial differential equations. In any event, all such problems involve the manipulation of, and the solution for, numbers. The end product of CFD is indeed a collection of numbers, in contrast to a closed-form analytical solution.

 (Computational Fluid Dynamics, John F. Wendt, 3rd Edition, p6)

New answer:

The basic idea is to model the derivatives by finite differences. When this approach is used the entire flowfield must be discretized, with the field around the vehicle defined in terms of a mesh of grid points. We need to find the flowfield values at every mesh (or grid) point by writing down the discretized form of the governing equation at each mesh point. Discretizing the equations leads to a system of simultaneous algebraic equations. A large number of mesh points is usually required to accurately obtain the details of the flowfield, and this leads to a very large system of equations. Especially in three dimensions, this generates demanding requirements for computational resources. To obtain the solution over a complete three dimensional aerodynamic configuration millions of grid points are required!

Originally, CFD was only associated with the 2nd and 3rd items listed above. Then the problem with establishing a suitable mesh for arbitrary geometry became apparent, and the specialization of grid generation emerged. Finally, the availability of large computers and remote processing led to the need for work in the last two items cited. Not generally included in CFD per se, a current limiting factor in the further improvement in CFD capability is development of accurate turbulence models.

(W.H. Mason, Applied Computational Fluid Mechanics Volume 2, 8,1-2)

4.The Impact Test (Group:Testing method)

Previous answer:
When a material is subjected to a sudde, intense blow, in which the strain rate is extremely rapid, it may behave in a much more brittle manner than is observed in the tensile test. An iimpact test is often used to evaluate the brittleness of a material under these conditions. Many test procedures have been devised, including the Charpy test and the Izod test. Izod test is often used for nonmetalic materials. The test specimen may be either notched or unnotched; V-notched specimens better measure the resistance of the material to crack propagation. In the test, a heavy pendelum, starting as an elevation h0, swinging through its arc, strikes and breaks the specimen, and reaches a lower final elevation hf. If we know the initial and final elevations of the pendelum, we can calculate the difference in potencial energy. This difference is the impact energy absorbed by the specimen during failure. The ability of a material to withstand an impact blow is often referred to as the roughness of the material. The material properties obtained from a serşes of impact tests are transition temperature, notch sensitivity an relationship to the stress-strain diagram.
(Askeland D.R., The Science and Engineering of Materials, 3rd Ed., Pg. 149-150, Kayra Ermutlu)

New answer:

A material is regarded as being tough if it absorbs a large amount of energy in breaking. In a tension test, the energy per volume to cause failure is the area under the stress– strain curve and is the toughness in a tension test. However, the toughness under other forms of loading may be very different because toughness depends also on the degree to which deformation localizes. The total energy to cause failure depends on the deforming volume as well as on energy per volume. Charpy test: Impact tests are often used to assess the toughness of materials. The most common of these is the Charpy test. A notched bar is broken by a swinging pendulum. The energy absorbed in the fracture is measured by recording by how high the pendulum swings after the bar breaks. Figure 13.21 gives the details of the test geometry. The standard specimen has a cross section 10 mm by 10 mm. There is a 2-mm-deep V-notch with a radius of 0.25 mm. The pendulum’s mass and height are standardized. Sometimes bars with U or keyhole notches are employed instead. Occasionally subsized bars are tested.

One of the principal advantages of the Charpy test is that the toughness can easily be measured over a range of temperatures. A specimen can be heated or cooled to the specified temperature and then transferred to the Charpy machine and broken quicklye nough so that its temperature change is negligible. For many materials there is a narrow temperature range over which there is a large change of energy absorption and fracture appearance. It is common to define a transition temperature in this range. At temperatures belowthe transition temperature the fracture is brittle and absorbs little energy in a Charpy test. Above the transition temperature the fracture is ductile and absorbs a large amount of energy. Figure 13.22 shows typical results for steel.

(Hosford W.F., Mechanical Behaviour of Materials, pp.220,221)

5.Tooling Costs (Group: Accounting)

Previous answer:
These are the costs involved in making the tools, dies, molds, patterns, and special jigs and fixtures required for manufacturing a product. High tooling costs may be justified in high-volume production of a single item. The expected life of tools and dies and their obsolescences ( because of product changes ) also are important considerations.
(Kalpakjian S., Schmid S.R.,Manufacturing Engineering and Technology, 5th Edition, pg.1262)

New answer:

The manufacture of a component consumes resources (Figure 13.35), each of which has an associated cost. The final cost is the sum of expenses of all of the resources it consumes (detailed in Table 13.5). Thus the cost of producing a component of mass m entails the cost Cm ($/kg) of the materials and feedstocks from which it is made. It involves the cost of dedicated tooling Ct ($) and that of the capital equipment Cc ($) in which the tooling will be used. It requires time, chargeable at an overhead rate C_ oh (thus with units of $/hr), in which we include the cost of labor, administration, and general plant costs. It requires energy, which is sometimes charged against a process step if it is very energy intense but more commonly is treated as part of the overhead and lumped into C˙ oh, as we shall do here. Finally there is the cost of information, meaning research and development, royalty or license fees; this, too, we view as a cost per unit time and lump it into the overhead. Think now of the manufacture of a component (the “unit of output”) weighing m kg, made of a material costing Cm $/kg. The first contribution to the unit cost is that of the material mCm magnified by the factor 1/(1−f) where f is the scrap fraction—the fraction of the starting material that ends up as sprues, risers, turnings, rejects, or waste:

The cost Ct of a set of tooling—dies, molds, fixtures, and jigs—is what is called a dedicated cost: one that must be wholly assigned to the production run of this single component. It is written off against the numerical size n of the productionrun. Tooling wears out. If the run is a long one, replacement will be necessary. Thus tooling cost per unit takes the form

where nt is the number of units that a set of tooling can make before it has to be replaced, and Int is the integer function. The term in curly brackets simply increments the tooling cost by that of one tool set every time n exceeds nt.

(Ashby M., Material Selecting in Design and Manufacturing 4^th edition, pp.409-410)

Burcu HASDEMİR (503101302) 1st week words

1.        Composite

2.        Polymer Matrix Composite (PMC)

3.        Matrix material

4.        Epoxy

5.        Resin

6.        Reinforced plastic

7.        Elastomers

8.        Conceptual design

9.        Layout design

10.     Drafting