Osman Pehlivanoğlu 030040089 3rd Week

Variational Design
In variational design, the entire system of constraints for a part or parts is solved simultaneously with a constraint solver (e.g., Newton-Raphson). Variational design systems offer several advantages including the ability to solve problems whose dimensions cannot be calculated with a single algebraic expression as well as subsuming most of the capabilities of parametric desing systems. An entire design sequence in a parametric design system can be thought of as a system of constraints in a variational design system. (A Mathematical Theory of Design, Dan Braha, p 388)

Abrasive Machining
Abrasive machining or grinding is a chip-forming metal cutting operation. Most of us are familiar with the grinding wheels, used to sharpen knives and other tools, and sand paper which is used to smoothen surfaces and sharp corners. For grinding, generally, a rotating grinding wheel is used as a tool. The grinding wheel and sand paper consist of bonded abrasives. The abrasive grains have sharp edges that project out and cut the chips. In grinding, the high circumferential speed of the grinding wheel causes high friction and chips become red hot and fly as sparks.
In grinding and other abrasive machining processes, a very large number of tiny cutting edges simultaneously cut the surface, each taking a very minute cut. (Elements of Manufacturing Processes, Nagendra Parashar, p171)

Ladder Diagram
Ladder Diagram has been developed by the IEC by considering the most commonly used symbols and terminology used in mainstream PLCs.
Ladder Diagram is based on a technique used to design logic using relays. A Ladder Diagram always has a left hand vertical power rail that notionally supplies power through contacts spread out along horizontal rungs. (Programming Industrial Control Systems Using IEC 1131-3, Robert Lewis, 2nd Edition, p153)

Drum-Buffer-Rope System
A drum-buffer-rope production control system has the following basic characteristics.
-The CCR beats the drum to set the pace for entire factory.
-An information rope ties production starts to the CCR.
An inventory buffer at (or heading toward) the constraint protects it from upstream stoppages. (Beyond the Theory of Constraints, William Levinson, p42)

YUNUS EMRE AYDOĞDU (3.WEEK)

030050084

Roll bonding:

A brief discussion of the processes that apply severe plastic deformation to a work piece in order to create small grains and thereby increase the strenght is followed by a detailed description of one of these methods: that of accumulative roll bonding. The process is presented first, followed by a detailed discussion of a set of experiments. In that process ultra low carbon steel strips containing 0,002% C were rolled at 500⁰C. Strips of 32 layers were created. The mechanical attributes after Rolling and cooling were examined and the development of edge cracking was monitored. The metal’s yield and tensile strenghts increased by 200-300% while the ductile dropped from pre-rolled value of 75 to 4%. The Rolling process was stopped when cracking of the edges became pronounced. The shear strength of the bond was about 60% of the yield strength in shear. The accumulation of the retained strain after dynamic recovery caused cracking at the edges. A potential industrial application of the accumulative roll bonding process, that of the creation of tailor rolled blanks, is discussed.

(John G. Lenard,Primer of flat rolling, First Edition, Abstract Section)

Abrasive machining:

Abrasive Machining involves material removal by the action of hard, abrasive particles that are usually in the form of a bonded wheel. Grinding is the most important abrasive process. In terms of number of machine tools in use, grinding is the most common of all metalworking operations. Other traditional abrasive processes are generally used as finishing operations, although some abrasive processes are capable of high material removal rates rivaling those of conventional machining operations.

(Mikell P. Groover,Fundamentals of Modern Manifacturing, 4th Editions, pg604)

Hundred Percent Inspection

A Hundred percent inspection is the inspection of every unit of product(procedure, data, operations,etc.).In same cases of 100 percent inspection, the accepts rejects decision will be made not for the entire lot, but for each unit individually, base upon the results of inspection the unit for the quality characteristics concerned. For critical quality characteristics 100 percent inspection or inspection of relatively large samples is usually required to assure the desired quality protection.

(John Langford,Logistics: Principle and Applications, second edition,page 93)

Hierarchical Coding

An alternative form of progressive coding known as hierarchical coding uses a set of successively smaller images that are created by “downsampling” (low-pass filtering and subsampling) the preceding larger image in set is coded with increasing resolution. After the first stage, each lower-resolution image is scaled up to the next resolution (upsampled) and used as a prediction fort he following stage. When the set of images is stacked, it sometimes resembles a pyramid. Consequently this form of codingis also called pyramidal coding.

(William B. Pennebaker, Joan L. Mitchell,JPEG Still image data compression Standard,First edition,pg 79)

Barış ERDEM (030060085) 3rd Week

Plasma arc cutting

                The plasma arc cutting process severs metal bymeans highly concentrated arc jet that has sufficient energy and force not only to melt the metal, but also to eject the molten metal. Because melting rather than oxidation is the predominant cutting mode plasma arc cutting can be used to cut any metal. 

                It is important to bear in mind that plasma arc cutting is a fundamentally different process from oxyfuel cutting, retying primarily on the heat generated by an electric arc to melt and sever the parent material. Consequently, additional safety hazards exits from operator should understand these hazards and take appropriate precautions. Appropriate safety information is referenced in AWS C5.2-83 “Recommended Practices For Plasma Arc Cutting.”
(Transportation Research Board, National Research Council, NCHRP Report 384, Plasma Arc Cutting of Bridge Steels, p.80)

Cold Welding

                According to American Welding Society (AWS), “Cold welding(CW) is a solid-stade process in which pressure is used at room temperature to produce coalescence of metals with substantial plastic deformation at the weld.” Cold welding processes are characterized by a notable absence of heat, whether appied from an external source or generated internal to the process itself.

                Cold welding is ideally suited to the joining of dissimilar metals since no intermixing of base metals is required or obtained. This allows inherent chemical incompatibilities that would prevent or make fusion welding difficult to be overcome. The best example is the cold welding of relatively pure aliminum to relatively pure copper to produce electrical connections.

(Messler R. W., Principles of Welding, 2004, p.98)

Forge Welding

                According to AWS, “Forge welding (FOW) is a solid-state welding process that produces a weld by heating workpieces to welding (hot working) temperatures and applying blows sufficient to cause deformation at the faying surfaces.” Without question, forge welding was the earliest form of welding, and still used today by blacksmiths, among others. The well-known and highly regarded Damascus steel swords made by ancient Syrians are an excelent example of ancient forge welding, while hand-forged chains and wrought-iron products are good examples of modern forge welding by blacksmiths.

(Messler R.W., Principles of Welding, 2004, p.101)

Explosive Welding

                Explosive welding is a process based on the controlled application of enormous power generated by detonating explosives. The surfaces of the parts to be joined must be clean without contamination of oxides etc. These clean surfaces are pressed at pressure of the order of million kg/sqcm generated by the explosive. Combination of dissimilar metals-aliminium to steel or titanium to steel – can be readily obtained by this process.

(Radhakrishnan V. M., Welding Technology and Design, Second Edition, 2005, p.38)

Taha Selman Cakir
030070023
3rd week

Vertical machining centers (VMC):

Also called vertical-spindle machining centers, these are capable of performing various machining operations on parts with deep cavities, such as in mold and die making. Because of the thrust forces in vertical machining are directed downward, such machines have high stiffness and produce parts with good dimensional accuracy. These machines generally are less expensive than horizontal-spindle machines.

(Kalpakjian S., Schmid S.R., Manufacturing engineering and technology, Ed. 5th, p. 765)

Horizontal machining centers (HMC):

Also called horizontal-spindle machining center, these are suitable for large as well as tall workpieces that require machining on a number of their surfaces. The pallet can be swiveled on different axes to various angular positions. Another category of horizontal-spindle machines is turning centers, which are computer-controlled lathes with several features.

(Kalpakjian S., Schmid S.R., Manufacturing engineering and technology, Ed. 5th, p. 765,766)

Product Data Exchange Specification (PDES):

A solid-model-based standard called the Product Data Exchange Specification (PDES), which is based on the Standard for the Exchange of Product Model Data (STEP) developed by the International Standards Organization. PDES allows information on shape, design, manufacturing, quality assurance, testing, maintenance, etc., to be transferred between CAD systems.

(Kalpakjian S., Schmid S.R., Manufacturing engineering and technology, Ed. 5th, p. 1196)

Surface grinding:

Surface grinding is one of the most common operations, generally involving the grinding of flat surfaces. Typically, the work-piece is secured on a magnetic chuck attached to the work table of the grinder; nonmagnetic materials are held by vises, vacuum chucks, or some other fixture. A straight wheel is mounted on the horizontal spindle of the surface grinder. Traverse grinding occurs as the table reciprocates longitudinally and is fed laterally (in the direction of the spindle axis) after each stroke. In plunge grinding, the wheel is moved radially into the workpiece, as it is when grinding a groove.

(Kalpakjian S., Schmid S.R., Manufacturing engineering and technology, Ed. 5th, p. 809)

Elif Naz Aladağ, 030060027, 3rd Week

Constructive Solid Geometry (CSG):

The methods of constructive solid geometry (CSG) gives us a way to describe complicated solid shapes as combinations of simpler solid shapes. This makes it an important tool for computer graphics and geometric modelling. CSG uses Boolean operators to construct a procedural model of a complex solid. This model, or rather the data describing the model, is stored in the mathematical form of a binary tree, where the leaf nodes are simple shapes, or primitives, sized and positioned in space, and each branch node is a Boolean operatör: union, difference, or intersection.

(Mortenson, M., E., Mathematics for Computer Graphics Applications, 2nd ed.)

Geometrical Tolerances:

Geometric tolerances apply variably constraints to a particular feature having a geometrical form.

A GT can be applied to any feature that can be defined by a theoretically exact shape, e. g. A plane, cylinder, cone, square, circle, sphere or a hexagon.

GTs are needed because in the real world, it is impossible to produce an exact theoretical form.

GTs define the geometric deviation permitted such that the part can meet the requirements of correct functioning and fit.

Note it is always assumed that if GT sor indeed tolerances in general are not given on a drawing, it is with the assumption that, regardless of the actual situation, a part will normally fit and functional satisfactorily.

(Griffiths, B., Engineering Drawing for Manufacture, 2003)

Sweep Representation:

A set of points moving in space may sweep a one-, two-, or three- dimensional object, which can be

represented by the moving set plus the trajectory. Sweep representations for modeling solids are easy to

understand and execute yet offer a fertile field for development. Basically there are two kinds of sweep

representation: translational sweeping and rotational sweeping.

(Xue, Q., World Scientific Series in Robotic and Automated Systems - Vol. 3, Intelligent Robotic Planning Systems, p. 13)

Ertan Toparlak 3rd Week

1-Vertical Machining Centres

2-Horizontal Machining Centres

3-Geometrical Tolerances

4-Parametric Design

5-Variational Design

6-Positive Features

7-PDES

8-Direct Data Translators

9-Sweep Representation

10-Negative Features

Armin Bijanzad 3.WEEK

1.Abrasive machining
2.Tool-post grinders
3.Surface grinding
4.Adequate clamping forces
5.Plasma arc cutting
6.Forge welding
7.Cold welding
8.Explosion welding
9.Phosphate coating
10.Roll bonding

Armin Bijanzad 2.WEEK Definitions

1.High-speed steel

First introduced in 1900 by Taylor and White , high speed steel is superior to tool steel in that it retains it's cutting ability at temperatures up to 1100F.exhibiting good 'red hardness'.Compared with tool steel, it can operate at about double the cutting speed with equal life, resulting High-speed steels, often abbreviated HSS.
High-speed steels contain significant amounts of W,Mo,Co,V,and Cr besides Fe and C.W,Mo,Cr, and Co in the ferrite as a solid solution provide strengthening of the matrix beyond the tempering temperature,thus increasing the hot hardness.Vanadium(V),along with W,Mo,and Cr, improves hardness and wear resistance.Extensive solid solutioning of the matrix also ensures good harden ability of these steels. (MATERIALS AND PROCESSES IN MANUFACTURING 7th edition E.PAUL DEGARMO P.551)

2. Tool steels

Carbon steels and low/medium alloy steels, called tool steels,were once the most common cutting tool materials. Plain carbon steels of 0.90% to 1.30% carbon when hardened and tempered have good hardness and strength and adequate toughness and can be given a keen cutting edge. However, tool steels lose hardness at temperatures above 400F because of tempering and have largely been replaced by other materials for metal cutting. (MATERIALS AND PROCESSES IN MANUFACTURING 7th edition E.PAUL DEGARMO P.551)

3. Dynamic properties

In many engineering applications, materials are subjected to dynamic loadings. These may include (1) sudden loads (impacts) or loads that vary rapidly in magnitude; (2) repeated loading and unloading ; or (3) frequent changes in the mode of loading , such as from tension to compression. For such operating conditions , the engineer must be concerned with properties other than those determined by the static tests. (MATERIALS AND PROCESSES IN MANUFACTURING 7th edition E.PAUL DEGARMO P.51)

4.Casting terminology

The casting starts with the construction of a pattern, an approximate duplicate of the final casting. The modeling material is then packed around the pattern, and the pattern is removed to produce a mold cavity. The flask is the box that contains the molding aggregate. In a two-part mold, the cope is the top half of the pattern, flask , mold or core. The drag is the bottom half of any of these features. A core is a sand shape that is inserted into the mold to produce internal features on a casting , such as holes or passages for water cooling. A core print is the region added to the pattern, core or mold that is used to locate and support the core within the mold. The mold material and the core then combine to form the mold cavity, the void into which the molten metal will be poured and solidified to produce the desired casting .A riser is an extra void created in the mold that will be filled with molten metal. It provides a reservoir of molten metal that can flow into the mold cavity to compensate for any material shrinkage that occurs during solidification. Any shrinkage voids should then be in the riser and not in the final casting.
(MATERIALS AND PROCESSES IN MANUFACTURING 7th edition E.PAUL DEGARMO P.309)

Sezgin Koçak - 030070026 - Third Week

First-Pass Yield:

This is the number of units taht make it through your final test station without incident-usually expressed as a percent. In other words, of 100 units submitted for final test, 99 units pass and one unit fails. This is a first-pass yield of 99 percent. Any unit that gets to the end of the line and requires rework of any kind is a failure. Each failure should be recorded and the failure mode defined for further analysis, such as a Pareto analysis of all failures. This will facilitate identification of the most critical areas that are causing the failures and the ones needing attention first. Obviously, first-pass yields should be measured after final product burn in, if there is one, so that failures after burn in will be included in the analysis and resolution process.
(Buckley R.L., Winning in high competitive manufacturing environment, p.179)

Affinity Diagram:

The purpose of affinity diagram is to organize large groups of information to meaningful categories. The affinity diagram helps break old patterns of thought, reveal new patterns, and generates more creative ways of thinking. The affinity diagram helps organize team's thoughts most effectively when:the issues seem to large and complex;you need to break out of old,traditional ways of thinking; everything seems caotic; or there are many customer requirements. The affinity diagram helps tonaturally group ideas or your customer's valid requirements and showthe relationship between items and groups. The affinity diagram helps you gather and group large amounts of language (e.g., needs, wants, wishes, ideas, amd opinions) into natural relationships.

(Soleimannejed F., Six Sigma, Basic Steps & Implementation , p. 94)

Kano Diagram:

Kano diagram depicts the idea that one might consider customer satisfaction on one scale from disgusted to delighted. Similarly, one might consider product functions on a scale from being absent to being fully implemented. If the product function is agood surrogate for the customer need being considered, one could plot a 45 degree line, which wolud indicate the nominal supplied satisfaction for any specification level of the function. This line is known as "one-to-one quality" or "linear quality", the minimum expectations of any new product development undertaking. On the other hand, one could also plot a lower curve that would indicate the minimum, basic level of satisfaction that a customer persumes must exist for the function implementation level. This plot, known as "basic performance" represents assumed functionality that must be in the product. It is expected and latent;if it does not exist in the product, satisfaction of customer will be greatly deteriorated. Similarly, one could plot an upper curve that would indicate the delighted state that a customer would hope to have for the function implementation level. The delighted is what a design team should strive for, to provide performance beyond what the customer expects, which delights them. These three states of satisfaction and the spectrum between them forms the background thinking behind customer needs.

(K.N. Otto,K.L. Wood, Product Design, p. 114-115)

Direct Shell Production Casting:

This three dimensional printing was invented and developed at The Massachusetts Institude of Technology and has been licensed to Soligen based in Northridge California for metal casting. Where this method differs from the rest is that there are no actual patterns made for removing the shell. This process manufactures ceramic shells that have integral cores direct from the CAD data; these shells are similar to those created by the dipping method. The system works by a type of printhead moving over a layer of fine Alumina powder, depositing tiny drops of colloidal silica onto the powder in a pattern the same as that of the section of the part. The next layer of powder is applied and the process is repeated until the shell is complete. When the shell is completed the loose powder is removed and teh shell is fired and poured with metal. This process is particularly good for complex geometries that need a fast turnaround. Soligen do not actually market this system ( at the time of writing) but run a one-stop shop for metal components, offering a complete foundary service also. This can be thought of as an advantage owing to the other systems manufacturers needing to train foundries to work with their processes.

(G. Tromans, Developments in rapid casting, p. 4-5)

Bahadır Coşkun 030070008 (3rd Week)

Innovation

Innovation is about having and applying a new idea, or sometimes applying other peoples ideas in new and novel ways. As aptly noted by Michael Vance:

“innovation is the creation of the new or the re-arranging of the old in a new way.”

In a mundane sense at many points in our lives, we are all innovators. The challenge arises when innovation is about an idea that is implemented successfully resulting in a positive outcome. For a firm this connected to the launching new products or improving on an existing product. Sometimes it involves organizational innovation that enhances firm efficiency. At a macro level, innovation is intimately connected to economic growth and welfare

(Sarkar S., Innovation, Market Archetypes and Outcome, 2007, p. 1)

Stable Schedule

Lean Production requires a stable schedule over a lenthy time horizon. This is accomplished by level scheduling, freeze windows, and under-utilization of capacity. A level schedule is one that requires material to be pulled into final assembly in a pattern uniform enough to allow the various elements of the production to respond to pull signals. Id does not necessarily mean that the usage of every part on an assembly line is identified hour by hour for days on end; it does not mean that a given production system equipped with flexible setups and a fixed amount of material in the pipelines can respond.

(Sinha P. K., Manufacturing and Operations Management, 2008, section 9-12)

JIT firms require a stable schedule over a lengthy time horizon. This is accomplished by level scheduling, freeze windows and underutilization of capacity. A level schedule is one that requires material to be pulled into final assembly in a pattern uniform enough to allow the various elements of production to respond to pull signals. In does not necessarily mean that the usage of every part on an assembly line is identified hour by hour for days on end; it does not mean that a given production system q-equipped with flexible set-ups and a fixed amount of material in the pipelines can respond.

(Sinha P.K., Sinha S., Current Trends in Management, 2007, section 5.28)

Forge Welding

According to American Welding Society, “Forge Welding (FOW) is a solid-state welding process that produces a weld by heating workpieces to welding [hot working] temperatures and applying blows sufficient to cause deformation at the faying surfaces.” Without question, forge welding was the earliest form of welding and is still used today by blacksmiths among others.

(Wessler R.W., Principles of welding: processes, physics, chemistry, and metallurgy, 1999, p. 101)

Explosion Welding

Explosion welding (EXW) is a pressure-welding process that represents a special case. In explosion welding, the workpieces usually start out cold but heat significantly and extremely rapidly very locally at their faying surfaces during the production of the actual weld. The controlled detonation of a properly placed and shaped explosive charge causes the properly aligned workpieces to come together extremely rapidly at a low contact angle. When this occurs, air between the workpieces is squeezed out at supersonic velocities. The resulting jet cleans the surfaces of oxides and causes very localized but rapid heating to high temperatures.

(Wessler R.W., Principles of welding: processes, physics, chemistry, and metallurgy, 1999, p. 103)

Ahmet Alp Gündüz - 030060034 - 3rd Week

Bulk Deformation

The bulk deformation process refine the starting shapes, sometimes improving mechanical properties, and always adding commercial value. Deformation process work by stressing the metal sufficently to cause it to plastically flow into the desired shape. Bulk deformation processes are performed as cold, warm, and hot working operations. Cold and warm working is appropriate when the shape change is less severe, and there is need a to improve mechanical properties and achieve good finish on the part. Hot working is generally required when massive deformation of large workparts is involved.

(Fundamentals of Modern Manufacturing, 3rd Edition; Mikell P. Groover ; Page: 390,391)

Statistical Quality Control

Statistical Quality Control is a set of techniques intended to aid in the improvement of system quality. Statistical Quality Control(SQC) refers to the application of statistical methods to monitor and evaluate systems and to determine whether changing key input variable (KIV) settings is appropriate. Specifically, SQC is associated with Shewhart’s statistical process charting (SPC) methods. These SPC methods include several charting procedures for visually evaluating the consistency of key process outputs (KOVs) and identifying unusual circumstances that might merit attention. In common usage, however, SQC refers to many problem-solving methods. Some of these methods do not relate to monitoring or controlling processes and do not involve complicated statistical theory. In many places, SQC has become associated with all of the statistics and optimization methods that professionals use in quality improvement projects and in their other job functions. This includes methods for design of experiments (DOE) and optimization.

(Introduction to Engineering Statistics and Six Sigma, Theodore T. Allen; Page: 29)

Brinell Hardness

Brinell hardness test has a hard spherical indenter which is pressed under a fixed normal load on to the smooth surface of the metal under examination. The load and indenter are removed after balance has been reached like 15 or 30 seconds and diameter of permanent impression measured. Brinell hardness number (BHN) is then expressed as the ratio of load W to curved area of indentation.

(The Hardness of Metals, D. Tabor; Page:6)

Overall Equipment Efficiency(OEE)

OEE stands for Overall Equipment Efficiency and is the primary measure of production effectiveness. It can be used for value stream or individual work station performance evaluation. Good value stream OEE is one of the key precursors to the implementation of Lean and is the product of three important operational parameters. These are: Equipment availability, quality yield, cycle-time performance. To calculate OEE, you will need five parameters. First is the planned production time for the line. Second is the unplanned line downtime. Third is the line cycle time, or cycle time, of the bottleneck. Fourth is the total production including scrap, and fifth is the total amount of salable product.

(How to Implement Lean Manufacturing, Lonnie Wilson; Page:61)

Gökçe Dil 3. week

1.Annealing
2.Brinell Hardness
3.Final Product
4.Raw material
5.Semifinished part
6.Innovation
7.Custom part
8.standard parts
9.Bulk deformation
10.Sintering

Buğra Cengiz 030060178

Sintering
Sintering brings about the removal of pores between the starting particles (accompanied by shrinkage of the component), combined with strong bonding between the adjacent particles. The primary mechanisms for transport are atomic diffusion and viscous flow. In some cases, hot die pressing is employed, whereby pressure and temperature are applied simultaneously to accelerate the kinetics of densification. Only a limited number of shapes can be produced by this technique.
John Martin, Materials for Engineering, P.157

Life Cycle Engineering
Aims to provide a set of referance models, architecture, methhodogies tools and techniques to integrate these important cycles in manufacturing enterprises

Arturo Molina,José Manuel Sánchez, Handbook of Life Cycle Engineering: Conceps, Models and Technologies. P.11

Parametric Design
The need for parametric design emerged once it became apparent that the impact of conventional CAD systems on industrial productivity is limiyed. This limitation is due to the fact that early CAD systems where developed following the drafting paradigmi where the draft-person is responsible for all the details embedded in a paper drawing. The drafting paradigm does not protect the design from inevitable human errors. Consequently, engineering changes introduced during the life-cycle of a product often require the laborious redesign of the product or component, even in aread ehich should not be directly affected by the design change.
Parametric design attempts to overcome these limitations  and thus, obtain a significant-additional improvemet in industrial productivity. Parametric design may be viewed as an extension of featıre-based design, such that not only the different features are parametrized but also the geometric inter-relationships between features are expressed parametricly. In principle, if all geometries are expressed through parametric relationships than any design change can invoke an automatic reconstruction of the design, based ın the parametric structure and design rules.

Dorf, R.C., Kusiak, A., Handbook of Design, Manufacturing and Automation, 1994, John Wiley & Sons, Inc.,pg.125

TO BE CONTINUED...

 

Didem Tarkun(503101304) - 3rd week

1. Discounted cash flow
2. Remote terminal unit
3. Early equipment management
4. Supervisory control and data acquisition
5. Distributed control systems
6. Human-machine interface
7. Benefits measurement
8. Weighted failure rate
9. Overall eqipment efficiency
10. First pass yield (FPY)

Selçuk TEVRÜZ, 030070128, 3rd week

Polycodes

In the direct contrast to monocodes, in a polycode each digit has a distinct meaning across all parts. Thus a 2 in the sixth field always indicates the same part attribute. Coding schemes that generate polycodes are easier to develop and apply than monocode schemes. Obviously, polycodes can be quite long. The differences between the information storage capacity of the monocodes and polycodes can be illustrated using the following example. Assume that the code is to consist of two symbols and that in each of the code fields the digits 0 through 9 are to be used. With a monocode 110 (10^1 + 10^2) unique characteristics can be potentially stored, whereas with a polycode only 20 (10^1 +10^1) can be stored.

(Dorf, R.C., Kusiak, A., Handbook of Design, Manufacturing and Automation, 1994, John Wiley & Sons, Inc.,pg. 439)

Safety Stock

The safety stock is a randomly varying reserve stock kept to ensure the stock availability during the replenishment time against random variations of demand and/or replenishment times.

(Gudehuss, T., Kotzab, H., Comprehensive Logistics, 2000, pg.295)

Finite Loading

Finite loading is a technique for not allowing work to be loaded beyond the stated capacity

of a work center. It assumes that there is a defined limit to available capacity at any

workstation. If enough capacity is not available at a workstation because of other shop

orders, the orders has to be rescheduled in a different time period. The prioritizing of

work is based on predetermined rules such as work center completion date and operation

availability.

CRP uses infinite loading in conjunction with backward scheduling, to generate the capacity

requirements plan, or work center load reports. Operation sequencing, which is a part

of production activity control, uses finite loading and various forms of scheduling.

Before finite loading can begin, however, priorities must be established for individual orders.

The highest priority orders get first claim on the available capacity in each work.

(Mukhopadhyay, S.K., Production Planning and Control: Text and Cases, 2004, Prentice

Hall India Pvt., Limited, pg.147)

PAC (Production Activity Control)

Production activity control describes the principles and techniques used by

management to plan in the short termi control and evaluate the production activities

of the manufacturing organisation (Browne 1988).

As stated before, PAC realizes the lowest level of the PMS hierarchy, and the

COSIMA project recognized the need for a generic and flexible architecture which

identified and seperated the different functions of PAC (COSIMA 1987). This separation,

or modularization of PAC, is important, because a system of interacting well defined

components can easily be changed by replacing or modifying these components on an

individual basis, without effecting the other modules of the system.

(Bauer, A., Shop Floor Control Systems: from Design to Implementation, 1994, Chapman &

Hall, pg.37)