Lecture-5
Assembly Line Balancing
Dr. Dileep S. More Operations Management Group IIM Calcutta
Objectives
• Understand the concept of assembly line balancing • Study a general procedure to balance the line • Study advantages of line balancing
Introduction
• The first movable assembly line was created by Ford to manufacture the Ford Model T • Ford installed a capstan and a thick cable to move the cars between assembly stations
Ford’s assembly line concept
A Line with Multi Operators
A
2 minutes per unit
B
3 minutes per unit
C
5 minutes per unit
D
1 minutes per unit
E
4 minutes per unit
Process Cycle Time = Throughput Rate = Process Capacity = Overall Process Utilization =
A Line with Single
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• Least number of followers heuristics • Individual duration heuristics: Among the eligible tasks, choose the task with the longest/shortest time ti. If there is tie, select the task that the largest total number of following tasks.
Example 1
• You’ve just been assigned the job a setting up an electric fan assembly line with the following tasks:
Task A B C D E F G H Time (Mins) 2 1 3.25 1.2 0.5 1 1 1.4 Description Assemble frame Mount switch Assemble motor housing Mount motor housing in frame Attach blade Assemble and attach safety grill Attach cord Test Predecessors None A None A, C D E B F, G
• The production time available per day is 420 minutes. • Suppose we want to assemble 100 fans per day. • Balance the line using Most Following Tasks Heuristic
2 A
1 B
1 G
1.4 H F 1
C 3.25
D 1.2
E .5
Task A C D B E F G H
Followers 6 4 3 2 2 1 1 0
Time (Mins) 2 3.25 1.2 1 0.5 1 1 1.4
Station 1 A (4.2-2=2.2) B (2.2-1=1.2) G (1.2-1= .2) Idle= .2
Station 2 C (4.2-3.25)=.95
Station 3 D
Ford hired Fredrick Taylor, a motion study expert, to evaluate and refine the efficiency of his factories after years of trying to find ways himself (History.com, 2009). Taylor took what he saw in the factories to make a more efficient workforce while Henry Ford developed tools and equipment to help with a better flow of the workforce. Together, they realized four distinct things from other smaller businesses that they wanted to immolate and bring to the big stage. These four principles were the use of interchangeable parts, division of labor, continuous flow, and reduced wasted effort (Science Odyssey, 1998). With these four principles in mind and the dream to produce a more cost efficient vehicle, Henry Ford and Fredrick Taylor created the first large scale assembly line in 1913 (Goss, 2014). This assembly line was able to transfer the time it took to build a single Model T from twelve hours to a mere two hours and thirty minutes (History.com, 2009). With its eighty-four distinct steps in the flow of the assembly line, a division of labor was created where a worker could be trained to do one specific task making him more efficient at that task and able to do a much better job (History.com, 2009). Secondly, having interchangeable parts that would could be used between any model of Ford allowed Henry to focus on machinery that would produce these
The assembly line needs to produce 6 units per hour and there is room for only four workstations. The tasks and the order in which they must be performed are shown in the following table. Tasks cannot be split, and it would be too expensive to duplicate any task.
1. Great Migration The Great Migration is when African Americans moved from the rural South to the cities up in the North, Midwest and West. The event was important because it began to build a new public life for African Americans which leads to creating a new black urban culture that would influence the United States later on. 2.
One of the biggest needs for improvement was the assembly process. Although several changes were made throughout the years, quality and efficiency still fell below expectations. Hinrichs implemented the newly developed assembly which consists of two separate work stations that allowed operators in the adjacent stations to share the expensive balancer machine. These assembly cells were much more efficient as workers were no longer forced to wait for another person or machine in the process. Each cell was built like the other with quick turn set-up which created flexibility in the process while also reducing tooling inventory by almost a half. Now cells
Doug left me with a couple of people throughout the day having them show me what each machine did as they needed it for a part in a project. In order to have something built people have to go out and get the measurements from the place the finished product will end up and how the client wants it.Once back in the shop they draw out the measurements on the table and make the parts require putin them on top of the table completing the diagram. For about half the time the Doug wasn't to happy because the diagram and the table weren't matching up which would create problems down the line,
Continuing with the development and improvement of the assembly line, in the 1960s, new machines were invented that allowed for five axes of motion. These devices were called the “Versatran”, and were installed a Ford factory in Ohio. But later in the decade, robots became even more complex adding another axis it can work
One of the most influential concepts and innovations to come out of the early twentieth century to change the face of production was the assembly line developed by Henry Ford and the Ford Motor Company and first used in production in 1913 (National Academy of Engineering, 2010) .
* Record the list of tools required in each zone across all seven lines, roofs and mid-decks.
The third core competency is Boeing’s dynamic assembly line. This was a valuable change to Boeing because it reduced assembly time by 50%, or from 22 days down to 11 days. The planes move 80 feet every shift and lights determine the status of the assembly line. Dynamic assembly lines are costly to imitate and rare due to the size of the plant and the components used in order to pull such a large craft throughout the building. The only substitute of a dynamic assembly line is a static assembly line, and the dynamic one performs much more efficiently.
Since the current assembly line layout should achieving 100% line efficiency when running at maximum capacity of 215 units. Thus, to operate at target 300 units/day, the current assembly line needs to redesign.
Boeing made use of lean techniques in their production system and increased its production by 50% and also reduced its floor space by 40%. Assembling a Boeing 737 is a typical job. Workers should take 367,000 parts, an same number of bolts, rivets, other equipment and 36 miles (58 kilometres) of electrical wire and then keep them all combined to make an airplane [2]. Engineers to machinists were involved in lean (reducing waste) in the factory. By creating an assembly line, aircraft will pass through the workers were they going to concentrate on assembling. Allocating all employees in the factory building and organising special teams helped a lot to solve the errors in the assembly line [2]. In the assembly line, there are eight beacon lights which reflect the production status. If everything is good it shows green colour. If an error occurs, the worker will press a button and the green light will changes to yellow and the panel board will shows the category of the problem(which category it is related to). The worker will pass on to a computer and writes about the problem in a brief manner and the problem should be assigned to special team to solve it within 30 minutes if not, the light turns to purple and the assembly line will shuts down. This moving assembly is the icon of factory’s lean strategies.
Nowadays, in an era that has advanced technology and a place in the world. Everything can be linked only at your fingertips in the times of rapidly developing with the sophisticated technology of today. Therefore, an inventory system is also not lagging behind in introducing a method of keeping an inventory data systematically and safely. The system plays a very important role in improving the competitiveness of a business. Usually, organizations today face too many challenges to achieve the cost, speed and reliability. Efficient inventory system really help in order to make sure the store’s performance and data record is always in good condition and secured from abusers. The system basically to ease the admin to manage the
We analyzed a Toshiba assembly line plan for a new subnotebook computer. The engineering section manager, Toshihiro Nakamura, wants to make changes to the line process as designed by the engineers. The basic assembly line equipment and space already exist within the Toshiba plant, so the subnotebook assembly process must conform to those preexisting constraints. Specifically, the assembly line is a straight 14.4-meter conveyor system that can accommodate 8 to 12 workers plus one supporter to aid in the assembly process. The employees work at assembling for 7.5 hours a day. The computers are assembled from
In most cases, computer controlled machinery affixes components onto the casing using advanced adhesives. However, because of incompatibility issues between materials, the batteries and electric motors have to be bolted on to the casing by hand, using power tools. Operatives work on the line, each making an average of 12 bolts onto the casing, ie, 1 person bolts the battery and then someone further down the line bolts the electric motor. The inspection section for the back casing of the body is the most active, the rejection rate for loose components at this point is approximately 1.2 %. A further 0.5% are rejected at final inspection, causing expensive rework situations. There is a staff turnover of 25% per annum amongst such operatives in the back casing sub assembly section.
| This fits our production system adequately. Since our assumed working cycle time is 6sec(=10 cycles/min) and it meets the requirement of 1300cars/day. On the other side, this is capital intensive but not as expensive as the first one.