Engineering 181

Winter Quarter 2001

Camera Lab #5

Assembly Operations

 

 

Introduction:  Manufacturing operations are often divided into two categories: processing operations and assembly operations.  This lab demonstration is focused on assembly operations.  Assembly can be accomplished in a variety of ways.  This lab demonstration will examine two common approaches: 1) the fixed material location, and 2) the sequential assembly line. 

 

If large, bulky products (aircraft, building air conditioning units) are being assembled; the assembler(s), materials, and assembly fixtures are transported to one location where the entire product is built without moving.  This approach is called a fixed material location assembly operation.  Using this approach, the assembler(s) are often very knowledgeable, to the degree that they could assemble the entire product alone.

 

For smaller, more portable products, another method is the assembly line where the product moves sequentially from one assembler to the next, and the assemblers remain stationary.  In the assembly line approach, the concept of division of labor is used – every assembler becomes an expert at their particular sub-assembly operation.  Since not all assembly operations require exactly the same amount of time, sequential assembly lines will have bottleneck operations - activities that take longer than any of the other operations.  Identifying and eliminating bottleneck operations in assembly lines is a common problem assigned to Industrial and Systems Engineers.

 

Activity:  In this demonstration, we will set up and concurrently operate a fixed material location assembly operation and a sequential assembly line operation.  Twelve students will be assigned as assemblers for each assembly operation (24 total).  The remaining students will be the timers/data recorders.

 

In the fixed material location assembly operation, each of the 12 students will be given a workspace and box containing all of the parts required to assemble an entire camera.  When the signal is given, each student will assemble the camera and record the time required to complete their individual assembly operation.  Testing of the completed camera is included in the time for assembly.  The timers/data recording students assigned to this operation will assist in collecting the time, recording the data on the white board at the front of the classroom, and calculating the average, range, and standard deviation of the production rate using the fixed material location approach.  While the data are being summarized, the students that did the camera assembly will be asked to fully disassemble the cameras and place the parts back in the boxes.

 

For the sequential assembly line operation, each of the 12 students will provided a work space and a box containing a supply of the parts needed to complete their sub-assembly operation.  When the signal is given, the first student will perform the first sub-assembly operation and immediately pass the camera to the second student - and so on – until the camera is completely assembled and tested.  Each student will be asked to work as quickly and accurately as possible and pass the camera on to the next person immediately. This approach is the traditional “push” system sequential assembly line.  The assembly line will be halted when approximately 5 cameras have been completely assembled.  The timers/data recorder students assigned to this operation will assist in collecting the average time required for each of the 12 operations, recording the data on the white board at the front of the classroom.  Also, the average, range, and standard deviation of the overall production rate using the sequential assembly line approach should be recorded.  Students should also count the number of partially completed cameras there are at each assembly station when the production line is halted (work in process).  While the data are being summarized, the students that did the camera assembly will be asked to fully disassemble the cameras and place the parts in back their respective boxes.

 

Time permitting; the sequential assembly line demonstration will be conducted again, but this time using a “pull” system approach using a “kanban” quantity of one. The timers/data recorder students assigned to this operation should record the same information as with the “push” system.

 

Analysis:  Calculate and compare the mean and standard deviation production rate for the assembly systems demonstrated. 

 

What to submit for grading:  Discuss some advantages and disadvantages when comparing the fixed material location, “push”, and “pull” sequential assembly line systems.  Think in terms of production rate, system variability, work in process (WIP), floor space requirements, bottlenecks, and identification of quality issues.