《汽車專業(yè) 畢業(yè)論文 翻譯 中英文Lean Remanufacture of an Automobile Clutch》由會員分享，可在線閱讀，更多相關(guān)《汽車專業(yè) 畢業(yè)論文 翻譯 中英文Lean Remanufacture of an Automobile Clutch（37頁珍藏版）》請在裝配圖網(wǎng)上搜索。

1、1LEAN REMANUFACTURE OF AN AUTOMOBILE CLUTCHTony Amezquita*andBert Bras* Saturn CorporationSystems Realization LaboratorySpring Hill, TennesseeWoodruff School of Mechanical EngineeringGeorgia Institute of TechnologyAtlanta, Georgia 30332-0405AbstractIn the history of manufacturing there have been thr

2、ee production systems, namely, craft production, mass production, and lean production. In many automotive remanufacturing operations, craft production and mass production systems are used as the basis for remanufacturing processes. The lean production system has proven to be more effective in the ma

3、nufacture of automotive parts and it has allowed manufacturers who use it to produce in much greater varieties, with higher quality levels, and with lower costs. Hence, if used in remanufacturing, it would greatly enhance it. In this paper, a current remanufacturing process of an automobile clutch i

4、s analyzed, and a lean remanufacturing process is developed and compared to the as is process. Our findings indicate that the lean remanufacturing process provides a more robust process with lower costs when compared with the current clutch remanufacturing process that utilize craft and mass product

5、ion practices.* Assistant Professor, corresponding author.* Remanufacturing Engineer.21Our Frame of Reference Remanufacture in the Automotive IndustryRemanufacturing is the most economically sustainable form of reuse and recycling of manufactured goods, and it can be defined as the industrial proces

6、s where worn out products referred to as cores, are brought back to original specifications and condition. In some cases, especially in the remanufacture of OEM automotive parts, remanufactured products exceed original specifications. The reason is that the latest engineering design and specificatio

7、ns, coupled with failure mode countermeasures derived from failure analysis, are used instead of the original specifications. The benefits of remanufacturing are many, but the most salient are:1) Remanufacturing salvages the material, energy, capital, labor, and emissions that went into the manufact

8、ure and material processing of products. 2) The resulting production costs can often be lower than manufacturing, allowing remanufacturers to sell their units for 25 to 50% less than manufactured units with equivalent or better quality levels.These two benefits are the result of the fact that parts

9、are reused and the embedded utility in the parts are maintained. Hence the resulting production costs, which should be considerably less than in manufacturing, allow remanufacturers to pass the savings on to consumers. Remanufacturing in the automotive industry can be divided into two groups; indepe

10、ndent remanufacturers and Original Equipment Manufacturer (OEM) remanufacturers. Both of these activities in the domain of automotive products constitute the largest remanufacturing consumer market segment in the United States and Europe. In 1978, Kutta and Lund documented a survey capturing some of

11、 the issues important to remanufacturers (Kutta and Lund, 1978). However, we discovered in surveys and interviews with remanufacturers that many changes have occurred in the industry since then (Hammond, et al., 1996, Hammond, 1996). Major changes have been the restructuring of automotive companies

12、into platforms and the trend towards mass customization of products. Especially the latter has resulted in what remanufacturers have termed “Parts Proliferation”, which refers to the practice of making many variations of the same product - differing only in one or two minor areas. However, these dif

13、ferences (such as electrical connectors) are distinct enough to prevent interchanging these similar products. The focus in this paper is on independent automotive remanufacturers, because they remanufacture component parts from most of the automobile manufacturers in the world, and for a very large

14、number of model years. This being the case, independent remanufacturers are faced with a parts proliferation problem which cannot be successfully handled with their current production practices, that consist of a mixture of mass production and craft production practices. As described below craft pro

15、duction practices maintain production costs high regardless of volume, and mass production practices are not compatible with large product varieties. Consequently independent parts remanufacturers are loosing market share to aftermarket parts 3manufacturers, and in some cases, remanufacturers are be

16、ing forced out of the market, as in the case of clutch remanufacturing. For example, in 1989 the price difference between remanufactured and manufactured clutches was 50%. In 1994 the difference dropped to 20%, and now a large number of clutch remanufacturers are getting out of clutch remanufacturin

17、g altogetherUse Word 6.0c or later to view Macintosh picture. . It is our belief that the trends in mass customization and parts proliferation will not decrease and the small to medium sized independent remanufacturers seem to suffer most from these trends. Our surveys also point out the differences

18、 and sometimes hard “us versus them” attitude between independent remanufacturers and Original Equipment Manufacturers (OEMs), leading us to believe that the sharing of design information between OEM and remanufacturer is not a feasible solution and/or option in many cases. Hence, the only way we ca

19、n help increase the remanufacturability of those products is by improving the remanufacturing processes. In this paper, we present some of our findings which, interestingly enough, indicate that the introduction of lean production techniques (which are one of the main causes of part proliferation an

20、d product diversity) in the remanufacturing industry, and hence creating lean remanufacturing processes, can lead to significant process improvements and savings4Use Word 6.0c or later to view Macintosh picture. compared to the current remanufacturing processes which are heavily batch oriented. In t

21、his paper, a solution to the parts proliferation problem of independent automobile parts remanufacturers is developed by transforming a current remanufacturing process of an automobile clutch into a lean remanufacturing process. This lean clutch remanufacturing process has been developed in great de

22、tail in (Amezquita, 1996). In this paper, we will discuss the as-is process, followed by a discussion on how to convert this process into a lean remanufacturing process. It should be stated up-front that although the proposed lean process offers substantial savings, it has not been implemented by th

23、e company who supported this case study. First, however, we will provide the necessary background on craft, mass, and lean production systems.2Craft, Mass, and Lean ProductionIn the 1800s, automobile manufacturing was the domain of the skilled craftsmen who controlled most of the activities on the m

24、anufacturing floor. These skilled craftsmen designed and built customized vehicles by making and fitting each part by filing it down until it mated with the other vehicle parts. Even if craft producers could make 10,000 identical cars, the price per car would not have dropped by much, because each c

25、ar was essentially a prototype. The biggest benefits of this craft production system in the automotive industry were that: customers were able to obtain products which specifically met their needs, andworkers were satisfied, proud, and fulfilled, and their goal was to hone and perfect their skills a

26、nd one day become independent owners.At the turn of the century, Frederick Taylor removed the control of the manufacturing operations from the hands of the skilled craftsmen by creating divisions of labor. This was the first step towards the development of mass production, which was fully implemente

27、d by Henry Ford. Taking the developments of Taylor, Ford added the standardization of the production of parts, which led to complete parts interchangeability, which in turn led to the simplification of parts assembly. In 1908, an assembler was spending 514 minutes (8.56 hours) assembling a large por

28、tion of the car before moving to the next car (Womack, et al., 1991)5Use Word 6.0c or later to view Macintosh picture. . To reduce the cycle time of assemblers (period of time spent with each vehicle by each employee), Ford had each assembler perform a single task and move from vehicle to vehicle in

29、 the assembly hall. The cycle time per vehicle was reduced from 8.56 hours to 2.3 minutes (Womack, et al., 1991)! Finally, the simplification of assembly tasks allowed Ford to utilize the moving assembly line to bring the cars to the assemblers and eliminate all the walking previously done. In addit

30、ion, the moving assembly line enforced a faster and even work pace. Fords implementation of the moving assembly line, which brought the car past the stationary worker, cut cycle time even further from 2.3 minutes to 1.19 minutes (Womack, et al., 1991).Ford discovered that his new system reduced the

31、amount of human effort needed to assemble a vehicle, and with the same number of people, equipment, etc., the more standardized vehicles he produced, the more the cost per vehicle dropped (economies of scale). By the time Ford reached volumes of two million identical vehicles per year, he had slashe

32、d the real cost to the consumer by an additional two thirds from the time he started production of the Model T in 1908. Consequently, a production system which most closely resembles the mass production system can bring substantial savings to a remanufacturer, and is often advocated. However, this s

33、ystem runs aground when confronted with a large variety of parts, which is the current situation many independent automotive remanufacturers are facing. Most automotive parts remanufacturers (and other remanufacturers) still rely on craft production systems to handle the variability in the number of

34、 parts to be remanufactured and the variability inherent in refurbishing operations due to wear differences. However, as noted already by Henry Ford, craft production system has two main drawbacks:1) Production costs remain high regardless of volume (economies of scale are not possible, e.g. Ferrari

35、 Automobiles).2) Quality, consistency, and reliability are poor due to the lack of standardization.Thus, a different approach to remanufacturing which uses elements of the mass and craft production systems may prove to be more suitable for automotive parts remanufacturing.6Lean production takes the

36、best elements of the craft and mass production systems. This system was developed by the Toyota Motors Corporation, and later is was implemented by all Japanese automotive manufacturers. Lean production can be defined as an entire production system with the following fundamental characteristics:1) E

37、conomies of scale (from mass production),2) Production of large varieties of products (from craft production),3) Elimination of non-value added resources and activities, and4) Integration of all production system elements and functions to obtain long term functional relationships.Compared to the lea

38、n production system, the traditional mass production system can be fundamentally defined as having the following characteristics:1) Economies of scale,2) Very limited range of product varieties,3) Non-value added resources and activities are perceived as necessary, and 4) Division of all production

39、system elements and functions to obtain specialization resulting in short term strained relationships. Given the fact that the lean production system is most suitable for the production of large varieties of products, and it allows the attainment of economies of scale, it would seem that using this

40、production system as a basis for remanufacturing processes would provide better results than the ones currently obtained, which are forcing independent parts remanufacturers away from remanufacturing. In the remainder of this paper the remanufacturing process of an automobile clutch at one of the la

41、rgest independent automotive parts remanufacturers is used as a case study. 3Automobile Clutch Remanufacturing at RaylocThe Rayloc Company is a division of the Genuine Parts Company which provides aftermarket replacement parts at 6,500 NAPA Auto Parts stores nationwide. Rayloc is one of the largest

42、automotive parts remanufacturers in the world, and they remanufacture parts such as alternators, starters, drive shafts, brake master cylinders, calipers, wiper motors, window lift motors, rack and pinion units, steering boxes, power steering pumps, brake shoes, disc brakes and clutches. The focus o

43、f this paper is placed on the remanufacturing process of clutches.The clutch remanufacturing process at Rayloc was analyzed for six months at one of the remanufacturing plants. The process material flow is represented schematically in Figure 1.7Use Word 6.0c or later to view Macintosh picture. Figur

44、e 1 - Current Clutch Remanufacturing Process Material Flow With BatchingIn this process cores are supplied by customers, and are accumulated randomly in drums without identification at the NAPA jobbers or retailers. Cores (c1, c2, etc., see Figure 1) are then identified and sorted by part number and

45、 manufacturer, and are again accumulated in a core warehouse at the Rayloc plant. Based on a forecast, cores are removed from a core warehouse and processed in a batch. Batches of the same part number are randomly mixed and the reusable components are assembled together with replacement component pa

46、rts. Non-reusable components are recycled after work has been done on them. The remanufactured cores (rc1, rc2, etc., see Figure 1) are placed in a finished goods warehouse to start the cycle over again after a customer buys the remanufactured clutch. The assumption behind this remanufacturing proce

47、ss is that identical cores can be easily collected into economic batches and together they can be disassembled, cleaned, inspected, refurbished, and reassembled. The process is distinguished by having large enough volumes to obtain some form of economies of scale. The practice of batching in remanuf

48、acturing was adopted from mass production, but batching is also done in remanufacturing for the purpose of cannibalizing reusable parts and reduce the need to purchase new manufactured replacement parts. Purchasing manufactured replacement components is for the most part more expensive than cannibal

49、izing cores. In fact, a fundamental principle of economic remanufacturing is the maximization the reused content in finished remanufactured products. After the completion of the study, the clutch remanufacturing process was characterized using the criteria as shown in Table 1. The characteristics of

50、 this process reflect the problems and issues independent auto parts remanufacturers face, and are not indicators that Rayloc is poorly run. In fact, Rayloc is one of the most efficient remanufacturers in the U.S.A. with a proven track record exemplified by the fact that Raylocs remanufactured clutc

51、hes are still selling well, in a time when other remanufacturers clutches are being phased out from the market.8Table 1 - Summary of Current Characteristics of Clutch Remanufacturing ProcessCriteriaCurrent ConditionsCriteriaCurrent ConditionsAverage Direct Labor Requirements43Maintenance Personnel R

52、equirementsLowDaily Average Output per Employee9.6 Units (413/43)Machine Investment vs. ManufacturingLowParts Transportation Distances1759 feetProcess Engineering MinimalProcessing Lead Times 21 daysDirect Labor SkillsHighCore Replacement Parts Needed (“New” and Cannibalized)Diaphragms, Straps, Rive

53、ts, Pressure Plates, Facings, ShimsIn-Process Core DamageHighProcess Cycle Time255 minutesHazardous Residue Streams 3Batch Sizes10 Bs 200 (avg. Bs=120)Product Design Changes AdaptabilityLowAverage Setup Times42 minutesCustomer Service LevelsLowQuality & Reliability LevelsLower than clutch manufactur

54、ingFinished Goods Warehouse CostsVery HighThe relatively long processing lead time requires the use of a warehouse to buffer the factory from the market. When product varieties are small, this approach does not require the need to store a large quantity of parts, as was once the case in the 1960s at

55、 Rayloc, when remanufactured products where shipped directly from the remanufacturing process (LeCour, 1996)Use Word 6.0c or later to view Macintosh picture. . But when varieties are large, inventory levels in the warehouse increase considerably, and customer service levels drop. 4Designing a Lean P

56、rocess for Automobile Clutch Remanufacturing A lean remanufacturing process must have the following elements as stated earlier:91) Economies of scale (from mass production),2) Production of large varieties of products (from craft production),3) Elimination of non-value added resources and activities

57、, and4) Integration of all production system elements and functions to obtain long term functional relationships.In the following sections, we present how these elements can be achieved for the Rayloc clutch remanufacturing process.4.1Obtaining Economies of Scale and the Ability to Handle Large Vari

58、eties of ProductsIn order to obtain economies of scale, one must do what Henry Ford did: standardize. However, in traditional remanufacturing processes it is very difficult to standardize because of the “stochastic nature of both the amount of work and the routings required to rebuild a unit” (Guide

59、, 1996)Use Word 6.0c or later to view Macintosh picture. . This argument is applicable in the remanufacturing shop which utilizes a job shop layout and the work is performed in a manner consistent with the craft production system. Thus, the first step in obtaining a lean remanufacturing operation is

60、 to move away from craft production or “artisan work” and create a standardized process. This however, cannot be done in the same fashion Ford did. At the beginning of the century, Ford relied on hard automation to standardize the production work, and thus eliminating adjustments, in contrast to cra

61、ft production where multi-purpose machines require various adjustments which require skilled craftsmen. Ford had standardized all the tooling and tasks so well that he practically eliminated all adjustments. The penalty with this system was that he had no flexibility to switch between models with th

62、e same machinery. When Ford redesigned the Model A, he discarded the machinery along with the old model (Womack, et al., 1991). To obtain standardization and eliminate adjustments, but still maintain the flexibility to handle a large variety of parts or models, flexible or programmable automation is

63、 needed in a modern process.10Programmable automation has traditionally had the following features (Chang, et al., 1991)Use Word 6.0c or later to view Macintosh picture. :1) High initial investment 2) High complexity 3) High programming costs In this paper, the concept of Lean Machines is developed

64、for the purpose of counteracting the above mentioned drawbacks of programmable automation. The concept of Lean Machines is derived from the Nagara system, which is a recent development of lean production to further reduce lead times and eliminate waste. The biggest accomplishment of this development

65、 is the obliteration of boundaries between departments. In other words, this development allows for a comprehensive and coherent one-piece-flow, without the need to transport parts to the paint department, stamping department, the cleaning department, etc. A production example illustrates the concep

66、t of the Nagara System.“After machines perform the drilling and tapping on the line, parts are placed in one-meter cubical box that is, in fact, a device for spray-painting parts. Closing the lid of the box trips a switch and sets the operation in motion. Small fittings and wires are attached to the parts in a one-piece flow after they are removed from the box. More than one hundred of these boxes have been integrated into processing and assembly lines. This has eliminated approximately 80 perce