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Mechanical and Aerospace Engineering Department

MAE 272 Introduction to Manufacturing Processes

Lab: plug

Introduction

The main goal of this lab was to introducing students to learn how to use machines such as Lath and Band saw to manufacture tools such as plugs and cardholders. In addition, students would be responsible for making their own drawings that has all the directions and dimensions they need to make the plug. Students will be applying what they have on their drawings in the lab workshop to make a plug, with extremely accurate measurements and specific tolerance that fits in a giving block.

Abstract

The objective of this lab is to get familiar working with different kinds of machines and to be able to make simple parts. In this lab experience we used the knowledge we learned in class to make a cylindrical plug that fits nicely in a 0.65- inch hole. At the beginning each student made his own drawing that has all the required dimensions. Using the original drawing of the plug, we were able to find all the uncertainties associated with measurements. The plug has to be manufactured within the tolerance so it can fit inside the hole completely under the pressure of air only. In order to manufacture the plug, we used three different machines. The first machine, the Lathe, was to make the cylindrical part. The second machine, the Band Saw, was to trim the upper part of the plug a little longer than 0.375 inch. Finally, we used a second Lathe machine to trim the upper part exactly within the tolerance. After having our parts done, students were asked to measure their plugs with different tools, such as micrometers and vernier caliper multiple times in order to get accurate measurements.       

Procedure

Before starting the manufacturing we were responsible for choosing the right material for manufacturing the plug, which is aluminum AA6061-T6511. On the first machine, the Lathe, I did the cylindrical part of the plug to make it equal 0.625 inch. At the beginning I had to place the aluminum stick on the Lathe and secure it. Then, I had to set up my x and y-axis by touching the aluminum stick with the cutting machine. In each cut I had to go 0.2 inch in the x-axis and 0.625 inch in the y-axis. I did that three times before I set my X-axis to zero. By switching the gearshift upward and downward, I was able to control the operation to make it either move toward the x or the y-axis. Thereafter, I measured my part using the micrometer caliper to see how much more I need to cut. The diameter of the cylinder was 0.8 inch. Therefore, I had to take off 0.175 inches more in order to get to the correct measurement, which is 6.25 inch. Extremely carefully I tried to cut 0.175 inch. Once again I used the micrometer caliper to measure the diameter and the reading of the micrometer was 0.624 inch. Since we have a tolerance of 0.003 inch my part was within the tolerance so I moved to the next procedure, which is charming the edges of the plug in a 45-degree angle to make it fit nicely in the block. Additionally, I had to trim the extra part of the aluminum stick attached to my plug using the second machine, which is the band saw. After trimming the extra aluminum, I measured the plug using Vernier caliper and found that the height of the polygon was 0.450 inches, 0.150 inch larger than the correct measurements. Because the Band Saw doesn’t give accurate measurement, I had to slightly go over the giving measurement, which was 0.375 inch. On the next step, I moved to the third and final lathe machine to cut the polygon accurately to 0.375 inch. I only had to set up the plug once and immediately started cutting the height after setting my x and y-axis to zero.    

The next and final step was to take the plug’s measurements and test it on the giving block. Using the micrometer caliper I measured the diameter six times and the results were between 0.624 and 0.625 inches. Using the same tool, I measured the width of the polygon and the measurements were between 1.03 and 1.04 inches. Thereafter, by using the vernier caliper I measure the height of the plug and got measurements between 1.00 and 1.01 inches. Moreover, I measured the height of the polygon and the measurements were between 0.374 and 0.376 inches. By subtracting the height of the polygon from the height of the plug I found the height of the cylinder, which was between 0.625 and 0.626 inches. Finally, after having all the measurements recorded I tested the plug. Since all the measurements were within the tolerances, the plug fitted in the block.

Drawing

Inspection Report/

Traveler’s Log

Error Analysis

After taking all the measurements of the plug and testing it on the block, I discovered some slight errors. One of these errors was the rough surface. As a result, my part didn’t fit nicely in the block. The reason behind that was falling the plug on the ground. Unintentionally, I dropped my plug on the ground causing some damages to the edge of the cylindrical part. However, that wouldn't happen to other harder materials such as steel. But because aluminum is a weaker material it had a bigger chance to get damaged. Another mistake I discovered was chamfering the edge more that what was required which damaged the edge of the plug. The reason behind that was the lack of experience, since I had to use my hand to chamfer it.  

Recommendation

First of all, having a clear drawing with accurate dimensions and tolerance is very important to manufacture a part with accurate measurements. Moreover, safety is extremely important when working with machines. For example, the glasses would protect eyes from the fragments that volatilize when cutting solid materials. Furthermore, time is very important to be considered as well. In manufacturing, we learned that time represents money. Therefore, the less time you spend to manufacture the plug, the more money you make.

Conclusion

In conclusion, attending this lab has giving me the chance to work with manufacturing machines such as Lathe and band saw. Additionally I learn how to use very accurate measurement tools such as micrometer and Vernier caliper. Even though we have taken longer time than what we should take to manufacture the plug, we have learned completely how to use the Lathe and Band saw for manufacturing. Most importantly is that, we have always learned math and physics in books and notes, but in this lab we learned how to apply math and physics to the real world.