Clock Project

For this project, I was tasked with creating a clock assembly (pictured on right), from raw aluminum bar stock (base), brass stock (left, pen holder), and steel stock (right, pencil holder), and acrylic (face). This was all done with a manual lathe and vertical mill.

To go above and beyond, I chose to have a mirror finish on my base (seen to the left).

Lessons Learned

This was my first work piece in my Introduction to Manufacturing Processes class, so there were many learning curves that I was in store for throughout this project.

The first lesson I learned was that this class would require far more in person hours. For most classes, you go to lecture, take notes, then do homework on your own time. This class was much different, since you needed to use the equipment in our lab all time spent on these projects was done in person. This made me think more about my daily schedule and how to plan my days accordingly to accommodate for lab time.
The next lesson I learned was how time consuming and also important finishing processes are. As I said, I chose a mirror finish on my base. This particular finish is easily the most time consuming, requiring hours of sanding, followed by polishing, and cleaning. This taught me how it is very important to specify with a machinist the finish that is necessary for assembly, not always appearance.
The last lesson I will mention is, what you put in you get back out. Throughout the beginning of this first project I found myself restarting on pieces often. Over time, I learned that going slow and being meticulous while working pieces often resulted in a better quality. The effort you put into a project you will get back out in a product that you are proud of. I believe that this is the most important lesson that I learned.

Cost Estimate

This estimate will take into account the price of the raw stock and the labor cost. (To view links of individual stock click on the size of each to be redirected)

Raw Stock Cost:

Aluminum:

$9.77

(0.375" x 2" Aluminum Rectangle Bar 6061-T6511-Extruded)

Steel:

$9.58

(5/8" 1018 Cold Rolled Steel)

Brass:

$23.48

(0.625" Brass Round Bar 360-H02 Extruded)

Acrylic:

$9.66

(12 in. x 12 in. x 1/8 in. Thick Acrylic Clear Sheet)

Total Material Cost:

$52.49

Labor Cost:

Colorado hourly wage of Machinist:

$18.53

Days spent (Rough estimate):

Rough average of hours per day:

Total Hours:

Total Labor Cost:

$630.02

Total Project Cost:

$682.51

Note: I was generous on the amount of hours I said I spent on this. I think it would have been closed to 50.

Improvements to be Made

When being asked how would I reduce the time and cost of this project, there is balance between the two. Automation along with CNC would reduce the time to produce this project, however the price of the necessary machinery may not be worth the decreased time. This has lead me to a process that I believe would both decrease time and money.

New Process

To begin, for the purpose of saving money, we will cut down the raw aluminum, brass, and steel stock using a horizontal band saw. This will be done by a machinist.
Instead of a manual lathe we will use a CNC lathe to quickly and precisely turn down, face, and thread both the pen and pencil holder. A sanding tool could also be used to quickly finish these pieces all in one process.
Instead of a manual vertical mill, we'll use a CNC mill to cut the raw stock of aluminum down to size. With the advent of a CNC mill, we'll also be able to mill both the top and bottom of the stock to ensure parallelism, and also cut the chamfers into the top edge of the piece. This may require the operator to change the orientation of the piece and re-fixture, however a custom fixturing devise that would autonomously change the orientation would again increase the price of the operation significantly. After the aluminum is cut to tolerance and made parallel, the CNC would then cut the counter bore and counter sinks.
Next the machinist would remove the work piece and secure it in a vice. Then to finish the surfaces, they would use a disk sander, decreasing finish time, up to the specified grit.
To cut the engravement and slot for the face, since this was already done on the CNC, step 3 and step 5 will become one process. The operator would have to change the orientation of the aluminum, and to further decrease time this step may make the most sense to be done directly after the stock has been faced and made parallel.
Next, to create the bolt which secures the pen holder, we will use an operator who will use a turret lathe set up to make the bolt. This process does not change.
Instead of hand cutting and drilling the PMMA face, we'll CNC it to ensure decreased time and accuracy. However, in order two secure this piece to be cut, we'll first have the center hole drilled by the CNC, then have the operator use the center hole alone with a custom vice fixture to secure the PMMA. This would allow for clearance to cut the corners.
Lastly, we have finishing and assembly. The CNC will produce very clean edges so the machinist will only have to spray the finishing coats onto the pen and pencil holder, and assemble the project.

Final Note:

I believe this process balances both time and money spent on this project effectively.

Mass Production Estimate

I've been tasked to answer the question of how would the price compare if I made 10,000 of these clocks vs the price of 10,000 clocks manufactured through automation. To establish a baseline we'll first find the price of a machinist hand producing 10,000 clocks.

Cost of 1 Machinist Produced Clock:

$682.51

Time Spent on 1 Machinist Produced Clock:

34 hours

Cost of 10,000 Machinist Produced Clocks:

$6,825,100

Time to Produce 10,000 Machinist Produced Clocks:

340,000 hours = 14167 days

Cost of 1 Automation Produced Clock:

$52.49, this is the price for only the stocks, no labor cost.

Time Spent on 1 Automation Produced Clock:

15- 30 minutes, this was estimated using manufacturing time of similar size and complexity items, such as a water steel water bottle.

Cost of 10,000 Automation Produced Clocks:

$524,900

Time to Produce 10,000 Automation Produced Clocks:

2,500 hours = 104 days

Finals Notes:

It should be noted that if a factory were choosing to switch from manual labor to primarily automated processes, the need to an operator to over year and serviced the machines would still be on the pay role. 3 machinists however vs 1 operator is still a significant saving. Also, when you take into account the insurance cost to cover multiple employees in a factory environment there is significant savings there as well. So, despite the installation cost money will eventually be made back.