Assembly Line

Assembly Line         

Assembly line merupakan salah satu cara optimalisasi proses pada operasi sebuah industry. Assembly line dapat menghemat banyak sumber daya dan waktu. Bayangkan butuh berapa banyak SDM dan waktu yang dibutuhkan dalam proses bagaimana manufacturing dalam banyak bidang bisa dilakukan dalam skala massal.

Pada awalnya assembly line diterapkan oleh ford pada proses produksi mobilnya yang awalnya pembuatan sebuah mobil memakan waktu 35 setelah menerapkan konsep assembly line setiap mobil hanya membutuhkan waktu produksi selama 20 menit bayangkan penghematan waktu dan sumber daya yang dilakukan. Awalnya mulanya assembly line ini diterapkan oleh salah satu manajernya, ia mendapat inspirasi pada saat melihat proses pemotongan hewan.

Bayangkan berapa waktu yang dibutuhkan dalam pembutan mobil modern yang memiliki puluhan ribu part tidak seperti mobil ford kuno yang partnya tidak begitu banyak dalam proses produksinya. Assembly line dapat menekan biaya produksi yang dibutuhkan seingga harga jual semakin rendah.

Assembly Line Balancing

Assembly Line Balancing (ALB, Keseimbangan Lini Perakitan) adalah permasalahan penyeimbangan beban pada stasiun-stasiun kerja di bagian lini perakitan. Keseimbangan pada lini perakitan adalah sangat penting karena menentukan seberapa besar kecepatan dan kedayagunaan (efisiensi) produksi.

Secara deterministik, kecepatan produksi lini perakitan ditentukan oleh stasiun kerja yang memiliki kecepatan operasi yang paling lambat (waktu operasi yang terbesar). hal ini dikarenakan stasiun kerja yang lain harus mengalami waktu menganggur (idle) baik menunggu material input maupun menunggu daerah WIP (work in process) di depannya menjadi kosong. Selain itu, jika kecepatan produksi stasiun-stasiun kerja pada lini perakitan berbeda secara signifikan, efisiensi lini perakitan tersebut menjadi rendah. Hal ini diakibatkan waktu operasi tidak digunakan sepenuhnya dalam mentransformasikan barang, akan tetapi ada waktu operasi yang terbuang dikarenakan idle (menganggur).

Pada permasalahan ini, diasumsikan ada serangkaian proses dalam lini perakitan. Setiap proses memiliki waktu operasi yang berbeda-beda. Selain itu, ada batasan keterdahuluan (precedence constraint) yakni sejumlah proses baru dapat dilakukan setelah proses prasyarat -nya (predecessor) selesai. Tujuan dari permasalahan ini adalah menentukan pengelompokan proses-proses pada lini perakitan menjadi stasiun-stasiun kerja yang akan memaksimumkan efisiensi lini perakitan tersebut. Terkadang, pada permasalahan ini juga dapat ditambahkan kendala seperti jumlah maksimum stasiun kerja atau kecepatan minimum lini perakitan (waktu operasi maksimum lini perakitan).

Henry Ford Changes the World, 1908

At the beginning of the 20th century the automobile was a plaything for the rich. Most models were complicated machines that required a chauffer conversant with its individual mechanical nuances to drive it. Henry Ford was determined to build a simple, reliable and affordable car; a car the average American worker could afford. Out of this determination came the Model T and the assembly line - two innovations that revolutionized American society and molded the world we live in today.

Henry Ford did not invent the car; he produced an automobile that was within the economic reach of the average American. While other manufacturers were content to target a market of the well-to-do, Ford developed a design and a method of manufacture that

Henry Ford and his first car the Quadricycle, which he built in 1896

steadily reduced the cost of the Model T. Instead of pocketing the profits; Ford lowered the price of his car. As a result, Ford Motors sold more cars and steadily increased its earnings - transforming the automobile from a luxury toy to a mainstay of American society.

The Model T made its debut in 1908 with a purchase price of $825.00. Over ten thousand were sold in its first year, establishing a new record. Four years later the price dropped to $575.00 and sales soared. By 1914, Ford could claim a 48% share of the automobile market.

Central to Ford's ability to produce an affordable car was the development of the assembly line that increased the efficiency of manufacture and decreased its cost. Ford did not conceive the concept, he perfected it. Prior to the introduction of the assembly line, cars were individually crafted by teams of skilled workmen - a slow and expensive procedure. The assembly line reversed the process of automobile manufacture. Instead of workers going to the car, the car came to the worker who performed the same task of assembly over and over again. With the introduction and perfection of the process, Ford was able to reduce the assembly time of a Model T from twelve and a half hours to less than six hours.

Developing the Model T

The Ford Motor Company manufactured its first car - the Model A - in 1903. By 1906, the Model N was in production but Ford had not yet achieved his goal of producing a simple, affordable car. He would accomplish this with the Model T. Charles Sorensen - who had joined Henry Ford two years earlier - describes how Ford had him set up a secret room where design of the new car would be carried out:

"Early one morning in the winter of 1906-7, Henry Ford dropped in at the pattern department of the Piquette Avenue plant to see me. 'Come with me, Charlie,' he said, 'I want to show you something.'

I followed him to the third floor and its north end, which was not fully occupied for assembly work. He looked about and said, 'Charlie, I'd like to have a room finished off right here in this space. Put up a wall with a door in big enough to run a car in and out. Get a good lock for the door, and when you're ready, we'll have Joe Galamb come up in here. We're going to start a completely new job.'

The room he had in mind became the maternity ward for Model T.

It took only a few days to block off the little room on the third floor back of the Piquette Avenue plant and to set up a few simple power tools and Joe Galamb's two blackboards. The blackboards were a good idea. They gave a king-sized drawing which, when all initial refinements had been made, could be photographed for two purposes: as a protection against patent suits attempting to prove prior claim to originality and as a substitute for blueprints. A little more than a year later Model T, the product of that cluttered little room, was announced to the world. But another half year passed before the first Model T was ready for what had already become a clamorous market...

The summer before, Mr. Ford told me to block off the experimental room for Joe Galamb, a momentous event occurred which would affect the entire automotive industry. The first heat of vanadium steel in the country was poured at the United Steel Company's plant in Canton, Ohio.

Early that year we had several visits from J. Kent Smith, a noted English metallurgist from a country which had been in the forefront of steel development...

The 1908 Model T. Two forward gears, a 20 horsepower engine and no driver doors. They sold like hot cakes

Ford, Wills, and I listened to him and examined his data. We had already read about this English vanadium steel. It had a tensile strength nearly three times that of steels we were using, but we'd never seen it. Smith demonstrated its toughness and showed that despite its strength it could be machined more easily than plain steel. Immediately Mr. Ford sensed the great possibilities of this shock-resisting steel. 'Charlie,' he said to me after Smith left, 'this means entirely new design requirements, and we can get a better, lighter, and cheaper car as a result of it.'

It was the great common sense that Mr. Ford could apply to new ideas and his ability to simplify seemingly complicated problems that made him the pioneer he was. This demonstration of vanadium steel was the deciding point for him to begin the experimental work that resulted in Model T...

Actually it took four years and more to develop Model T. Previous models were the guinea pigs, one might say, for experimentation and development of a car which would realize Henry Ford's dream of a car which anyone could afford to buy, which anyone could drive anywhere, and which almost anyone could keep in repair. Many of the world's greatest mechanical discoveries were accidents in the course of other experimentation. Not so Model T, which ushered in the motor transport age and set off a chain reaction of machine production now known as automation. All our experimentation at Ford in the early days was toward a fixed and, then wildly fantastic goal.

By March, 1908, we were ready to announce Model T, but not to produce it, On October 1 of that year the first car was introduced to the public. From Joe Galamb's little room on the third floor had come a revolutionary vehicle. In the next eighteen years, out of Piquette Avenue, Highland Park, River Rouge, and from assembly plants all over the United States came 15,000,000 more."

Birth of the Assembly Line

A few months later- in July 1908 - Sorensen and a plant foreman spent their days off developing the basics of the Assembly Line:

"What was worked out at Ford was the practice of moving the work from one worker to another until it became a complete unit, then arranging the flow of these units at the right time and the right place to a moving final assembly line from which came a finished product. Regardless of earlier uses of some of these principles, the direct line of succession of mass production and its intensification into automation stems directly from what we worked out at Ford Motor Company between 1908 and 1913...

As may be imagined, the job of putting the car together was a simpler one than handling the materials that had to be brought to

The old fashioned way - limousines are assembled at individual stations by a Pittsburg manufacturer, 1912

it. Charlie Lewis, the youngest and most aggressive of our assembly foremen, and I tackled this problem. We gradually worked it out by bringing up only what we termed the fast-moving materials. The main bulky parts, like engines and axles, needed a lot of room. To give them that space, we left the smaller, more compact, light-handling material in a storage building on the northwest comer of the grounds. Then we arranged with the stock department to bring up at regular hours such divisions of material as we had marked out and packaged.

This simplification of handling cleaned things up materially. But at best, I did not like it. It was then that the idea occurred to me that assembly would be easier, simpler, and faster if we moved the chassis along, beginning at one end of the plant with a frame and adding the axles and the wheels; then moving it past the stockroom, instead of moving the stockroom to the chassis. I had Lewis arrange the materials on the floor so that what was needed at the start of assembly would be at that end of the building and the other parts would be along the line as we moved the chassis along. We spent every Sunday during July planning this. Then one Sunday morning, after the stock was laid out in this fashion, Lewis and I and a couple of helpers put together the first car, I'm sure, that was ever built on a moving line.

We did this simply by putting the frame on skids, hitching a towrope to the front end and pulling the frame along until axles and wheels were put on. Then we rolled the chassis along in notches to prove what could be done. While demonstrating this moving line, we worked on some of the subassemblies, such as completing a radiator with all its hose fittings so that we could place it very quickly on the chassis. We also did this with the dash and mounted the steering gear and the spark coil."

Implementation

The basics of the Assembly Line had been established but it would take another five years for the concept to be implemented. Implementation would await construction of the new Highland Park plant which was purpose-built to incorporate the assembly line. The process began at the top floor of the four-story building where the engine was assembled and progressed level by level to the ground floor where the body was attached to the chassis.

End of the Line. The Model T's body is joined to its chassis at the Highland Park plant

"By August, 1913, all links in the chain of moving assembly lines were complete except the last and most spectacular one - the one we had first experimented with one Sunday morning just five years before. Again a towrope was hitched to a chassis, this time pulled by a capstan. Each part was attached to the moving chassis in order, from axles at the beginning to bodies at the end of the line. Some parts took longer to attach than others; so, to keep an even pull on the towrope, there must be differently spaced intervals between delivery of the parts along the line. This called for patient timing and rearrangement until the flow of parts and the speed and intervals along the assembly line meshed into a perfectly synchronized operation throughout all stages of production. Before the end of the year a power-driven assembly line was in operation, and New Year's saw three more installed. Ford mass production and a new era in industrial history had begun"

References:
   Charles Sorensen's account can be found in: Sorensen, Charles, E., My Forty Years with Ford (1956); Banum, Russ, The Ford Century (2002); Brinkley, Douglas, Wheels for the world: Henry Ford, his company, and a century of progress, 1903-2003 (2003).

How To Cite This Article:
"Henry Ford Changes the World, 1908," EyeWitness to History www.eyewitnesstohistory.com (2005).

Sumber : http://www.eyewitnesstohistory.com/ford.htm

What Is Assembly Line Balancing?

Balancing an assembly line can speed production or save money.

Some companies hire outside consultants for assembly line balancing.

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Assembly line balancing can be loosely defined as the process of optimizing an assembly line with regard to certain factors. Configuring an assembly line is a complicated process, and optimizing that system is an important part of many manufacturing business models. Maintaining and operating one is often quite costly, as well. The main focus of balancing is usually to optimize existing or planned assembly lines to minimize costs and maximize gains.

For instance, a car company might want to alter its assembly line layout in order to speed production. The company might consider the number of work stations a manufactured item must pass before it is complete and the time required at each point. Of course, each stage of this process requires a certain length of time, and the allotted time to finish a process, the number of workers, or the resource demand may also be considered, based on the specific manufacturing requirements.

The possible results of an assembly line balancing process might be maximized efficiency, minimized time to finish a process, or minimized number of work stations necessary within a certain time frame. Each manufacturing process might be quite different from another, so a company balancing unique workloads must work within the constraints and restrictions affecting its specific assembly line.

To optimize very specific operations, balancing an assembly line might require different methods, some of which include equations and algorithms concerning specific aspects of the manufacturing process. Complex manufacturing processes, such as making automobiles in large quantities, can be broken down into smaller parts, such as individual task times or the resource demands for each machine. This might be especially helpful in manufacturing processes that require the consideration of many variables, such as customized vehicles. Assembly line balancing can also guide decision-making based on the multitude of variables that can affect the manufacturing process.

Many times, this process might be used as support in decision making by offering many different models and types of data. For instance, the manager of a car manufacturer might analyze his or her operation based on the concepts of assembly line balancing using many different variables, and then make a decision based on that analysis. While this might provide the best response to an optimization effort based on one set of variables, the final decision may rest on multiple mathematical perspectives of the same problem.

Sumber: http://www.wisegeek.com/what-is-assembly-line-balancing.htm

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assembly line, industrial arrangement of machines, equipment, and workers for continuous flow of workpieces in mass-production operations.

The design for an assembly line is determined by analyzing the steps necessary to manufacture each product component as well as the final product. All movement of material is simplified, with no cross flow, backtracking, or repetitious procedure. Work assignments, numbers of machines, and production rates are programmed so that all operations along the line are compatible.

An automotive assembly line starts with a bare chassis. Components are attached successively as the growing assemblage moves along a conveyor. Parts are matched into subassemblies on feeder lines that intersect the main line to deliver exterior and interior parts, engines, and other assemblies. As the units move by, each worker along the line performs a specific task, and every part and tool is delivered to its point of use in synchronization with the line. A number of different assemblies are on the line simultaneously, but an intricate system of scheduling and control ensures that the appropriate body type and colour, trim, engine, and optional equipment arrive together to make the desired combinations.

Automated assembly lines consist entirely of machines run by machines, with little or no human supervision. In such continuous-process industries as petroleum refining and chemical manufacture and in many modern automobile-engine plants, assembly lines are completely mechanized and consist almost entirely of automatic, self-regulating equipment.

Many products, however, are still assembled by hand because many component parts are not easily handled by machines. Expensive and somewhat inflexible, automatic assembly machines are economical only if they produce a high level of output. However, the development of versatile machinery and the increased use of industrial robots have improved the efficiency of fully automated assembly operations.

Sumber : http://www.britannica.com/EBchecked/topic/39246/assembly-line