Elif Temiz, 030070195, 6th Week Definitions

1-Laser Beam Cutting:(Previous) 


A laser weld and laser cut both bring the maetrial to a molten state. In the welding process the matreial is allowed to flow together and cool to form the weld metal. In the cutting process a jet of gas is directed into the molten material to expel it through the bottom of the cut. Although the alser is used primarily to cut very thin materials, it can be used to cut up to 1 inch of carbon steel. The cutting gas assist can be either a nonreactive gas or an exothermic. Nonreactive gases do not add any heat to the cutting process; they simply remove the molten material by blowing it out of the kerf. Exothermic gases react with the material being cut, like an oxyfuel cutting torch. The additional heat produced as the exothermic cutting gas reacts with the metal being cut helps blow the molten material outmof the kerf. Some of the advantages of laser cutting include: *narrow heat-affected zone- little or no heating of the surrounding material is observed. ıt's possible to make very close parallel cuts without damaging the strip that's cut out. *no electrical conductivity required- the part being cut does not have to be electrically conductive, so materials like glass, quartz, and plastic can be cut. There is also no chance that a stray electrical charge might damage delicate computer chips while they are being cut using a laser. *noncontact- nothing comes in contact withb the part being cut except the laser beam. Small parts that may have finished surfaces or small surface details can be cut without the danger of disrupting or damaging the surface. It's also not necessary to hold the parts securely as it is when a cutting tool is used. *narrow kerf- the width of the kerf is very small, which allows the nesting of the parts in close proximity to each other, which will reduce waste of expensive materials. *automation and robotics- the laser bema can easily be directed through an articulated guide to the working end of an automated machine or robot. *top edge- the top edge will be smooth and square without being rounded.


(L. F. Jeffus, Welding: principles and applications, p.190)




Laser Beam Cutting(New) (Better) (Cutting Method)

The cutting procedure by means of a laser beam can be broken down into different processes: Laser beam cutting, upon which the most significance has been placed to date, laser beam piercing and laser beam ablation, which to date has not been particularly well established.

Laser beam cutting can also be broken down into different types of process application. To do this, a differentiation is made between the process gas and the material behaviour during the application of energy. If oxygen is used, laser beam thermal cutting is a term that is used. With this process high cutting speeds can be achieved. On the negative side, however, oxidation can form on the cut. This means that the material must be treated where necessary.

 Laser melt shearing is referred to if an inert gas is made available as the process gas. With this process, oxidation is avoided. The dross in this instance is also pushed downwards out of the kerf (gap made by laser cut) by means of a gas beam.

 Another cutting process is called sublimate laser cutting. With this process, the material is changed directly from the fixed to the gaseous phase. Inert gas is also used as the process gas here normally as the materials to be processed are normally organic, flammable materials or plastics.

 The laser cutting procedure is the most commonly used laser application process around the world and has since become well established in many areas of industry. Applications can be found in all sheet metal processing companies and are partly in direct competition with other thermal or mechanical cutting processes. The most outstanding features of laser cuts are the very small kerfs with cut flanks running parallel to them of high surface quality.

(Axel von Starck, Alfred Mühlbauer, Carl Kramer, Handbook of thermoprocessing technologies: fundamentals, processes, components, safety, pp.243.244)

2-In-transit inventory: (Previous) (Better)

During transportation goods are also in stock, even if they are not available for use. The calculation of in-transit inventory is fairly obvious. Goods are held in inventory fort he duration of the in-transit period. All this time they are subject to inventory costs, which, no less than when they are in the storage, comprise interest costs, insurance costs and depreciation. There is this difference, that in-transit inventory generates no warehousing costs. There might, on the other hand, be a slightly higher insurance cost, for there is a greater risk factor during transportation than in the warehouse.

 In-transit inventory mus not be underestimated. In volume it can surpass cycle stock. For example, if a firm replenishes its stock on a regular monthly basis, an average tonne of goods will remain in cycle stock for only a fortnight. It is quite possible that the total transportation time, say from an overseas origin, exceeds a fortnight. Thus the goods actually spend a longer time in transit thant they do in the cycle stock.

 In-transit inventory costs have a very different effect from cycle stock costs on transport decisions. Cycle stock costs encourage transportation in small consignments, whereas in-transit inventory costs encourage a faster mode of transport. This difference is frequently overlooked, because the fastest means of transport also tend to carry the smallest consignments. Since the two elements overlap, the difference easily goes unnoticed. In essence, however, they are quite different.

(Gust Blauwens,Peter De Baere,Eddy Van de Voorde, Transport Economics, pg:205)

In-transit Inventory(New) (Inventory Method)

The vulnerability of in-transit inventory to waste, fraud, and abuse is another area of concern. Similar to last year results, auditors were not able to confirm the in-transit inventory, which is included in the reported overall inventory balance on hand. For example.,auditors could not determine the reasonableness of almost $600 million of the Army's reported inventory in-transit from procurement. In addition, preliminary audit results indicate that the Navy's reported in-transit inventory differed from subsidiary records by about $2 billion and that the Navy had not determined the cause for the difference between the detail records and the reported amount.  We also recently testified on the Navy's problems with controlling in-transit items. Specifically, we reported that Navy activities were not adhering to control procedures to ensure that in-transit items are accounted for and that responsible commands had not been performing adequate oversight. As a result, the Navy wrote off as lost over $3 billion of in-transit inventory over the last 3 years, including some classified and sensitive items such as aircraft guided-missile launchers, military night vision devices, and communications equipment. This lack of control leaves enormous amounts of inventory at risk of undetected theft or misplacement.

(GAO, Department of Defense status of financial management weaknesses and actions needed to correct continuing challenges,pp.8-9)

3(EMS) Electronic Manufacturing Service (Previous)

Companies who offer manufacturing related services to OEMs. A similar acronym, CEM (contract electronics manufacturer) was used widely to describe companies who concentrate more on production, while EMS companies are those which concentrate more on providing comprehensive services.

(E. Zhai et al., Int. J. Production Economics 107 (2007), page 2)

Electronic Manufacturing Service (EMS) (New) (Better)(The Strategy oof Outsourcing)

In competitive environments (like that of consumer electronics) where time is the most precious commodity, most consumer electronics firms are virtual with respect to manufacturing (and often additional activities). Their absence from manufacturing has been filled by electronics manufacturing service (EMS) firms that extended their activity scope and proportion of value adding services to fill the vacuum created by the virtualization decisions of consumer electronics firms. Soon many traditional OEMs(original equipment manufacturers)  had shifted from a vertical- to a virtual-manufacturing model by divesting their manufacturing assets (equipment inventory, facilities, and people) -- by selling these assets to their EMS partners and outsourcing increasing percentages of production from them. 

Although personal computer makers were among the first consumer electronics firms to shed manufacturing plants, the large, vertically integrated telecommunications OEMs also quickly adopted the virtual-manufacturing model — with an interesting twist that consolidated the market. For example, Motorola, Ericsson, and Nokia were fierce rivals in the cellular telephone device market, but all three outsourced handset manufacturing from the same contract manufacturer: Flextronics. (Motorola formed a five-year outsourcing agreement in 2000 with Flextronics for $30 billion: in mid-2001, Flextronics was suitor for two troubled Lucent Technologies factories.)

 Incremental divestitures to alliance partners such as these have heightened the urgency and magnitude of outsourcing arrangements by electronics competitors -- as witnessed by outsourcing announcements made in 2000 by firms such as Alcatel, Ericsson, Lucent Technologies, Marconi, NEC, Nokia and Sony. In April 2000, Nortel Networks made the largest OEM-asset divestiture in the history of the EMS industry (to date) by selling Solectron its four plants for $900 million. Nortel also awarded Solectron a four-year, S 10 billion outsourcing contract.

Virtual manufacturing had become a legitimate strategy alternative in consumer electronics by 2000; partnering was a prelude, intermediate step. and way of aligning partners' interests as their needs for close coordination increased. As EMS firms increased their share of a product's total value added by taking on new tasks for their partners, their scope extended to: (a) product design. (b) manufacturing protocols. (c) supply chain management -- buying the parts and ensuring that components and machinery were in place when the customer needed a quick ramp up. (d) making of the actual circuit boards, (e) fabricating the plastic or metal boxes to hold the electronic device, and (f) shipping directly to customers. Some EMS contract manufacturers have even assumed responsibility for repairs and technical support. The services provided to the virtual consumer electronics firms assumed became increasingly central to marketplace success.

(Eli M. Noam,Dan Steinbock, Competition for the mobile Internet, pp.94-95)