Wrapping Up!

Analysis of Scaled - Up Production:

Having produced 100 parts, we have done an analysis of the production run, calculating how much it costs to make each yoyo. We also extrapolated and calculated the costs associated with producing 100,000 parts.

Material Costs

	100 Parts	100,000 Parts
Circuit Components	$100	$54,010
Ring	$4.17	$632
Body	$19.14	$2930
Window	$4.40	$666
Circuit Holder	$4.40	$666
Rounded Total	~$135	~$60,000

Labor and Overhead Costs

D – Design, T – Tooling Production, P – Production

	100 Parts	$60/hr	100,000 Parts	$60/hr
Circuit Components	P - 4 hrs	$240	P – 4000
Ring	D, T - 15 P - 2 hrs	$1020	D, T – 15 P – 2000
Body	D, T – 10 P – 4 hrs	$840	D, T – 10 P – 4000
Window	D, T – 12 P – 3 hrs	$900	D, T – 12 P – 3000
Circuit Holder	D, T – 20 P – 2 hrs	$1320	D, T – 20 P – 2000
Total	72 hrs	$4230	~15060 hrs	$903600

The analysis assumes equipment is either outsourced and factored into labor costs or.

	100 Parts	Cost per yoyo	100000 Parts	Cost per yoyo
	$4375	43.75	$963600	$9.636

Cost Analysis Summary:

	100 Parts	100,000 Parts
Material Costs	$132	$58,904
Labor & Overhead Costs ($60/hr)	$4,320	$903,600
Total Cost	$4,452	$962,504
Cost/Yo-yo	$44.52	$9.63

Design Modification due to Machine Limitation:

In order to conform to the limitations of the 2.008 equipment, we had to design the circuit sub-assembly piece to be thermoformed. This was due to limited access to injection molding machine as well as the limited automation of the injection molding machine. Ideally, the sub-assembly would be designed so that the electronics could be injection molded along with the sub-assembly piece. Instead, we opted to have the circuits assembled by hand because attempting to do it with the injection molding machine would have actually required more time.

While the circuit sub-assembly was the only major part that was driven by the limitation of our equipment, many of our design decisions were made with the limitations in mind. Everything from the thickness of our ring to the diameter of our yo-yo were all made to account for the capabilities of the injection molding machine. We had to be careful of placement of features, maximum material thickness, and feature symmetry in order to ensure the production of quality parts that would be within specifications. One example was that we had to keep the predicted shrinkage percentage of parts in mind as we designed pieces to fit together.

2.008 Feedback:

The following comments are compiled from the feedback and recommendations of all team members. They address both the yo-yo project and 2.008 as a whole. We hope that this will help make the class an even smoother experience for students in future semesters.

• An electronic scheduling system for signing up for shop slots would have allowed teams to see open machining time slots and sign up for them much more conveniently.
• The bottleneck of the entire project was definitely the availability of the injection molding machine.
• Both plant field trips were scheduled during the Thursday afternoon lab section, which meant we had an incomplete team and no access to machine shops in lab for two weeks in a row. It would be helpful to spread the two tours out among different sections.
• At around the same time of these trips, there were two weeks where the molds had been machined and our process was optimized, but there was lack of direction on whether/how to proceed. The deliverables served as good checkpoints, but having the lab instructors reiterating where we should be in the process and what we should be doing next would serve as guidance.
• More information about how circuits/electronics can be integrated into pieces/parts during manufacturing and assembly, and the challenges of doing so would have been appreciated and I think very applicable to the sort of projects we will work on in the future.
• More feedback needs to be given to students regarding performance in the class. At the very least, receiving grades back for the reading quizzes would have given students a basic idea of their standing in the class.
• The lecture material, especially towards the end, gave us a basic understanding of many different manufacturing processes. We believe that this exposure was valuable, especially when presented by the various different guest lecturers.
• We really liked how the lectures were often case studies or incorporated case studies. It really gave insight on applications and kept us grounded in how what we we learn is applicable in the real world.
• Some of the topics at the beginning of the semester were kind of rushed despite their importance and depth of coverage. Topics such as metal cutting and molding/casting.
• The depth of coverage of metal cutting was really helpful and interesting. It gave us intuition for a very important and widely use manufacturing process. We do think that it felt a bit rushed despite the importance and depth of the material.
• The reading quizzes was a topic of much discussion and after much contention, we came to several consensus. We did not like the reading quizzes, though we do understand that there is really no alternative to ensure the reading is done. However, the quizzes made it hard for even students who did the reading to do well. The lack of feedback on performance was also a point that we thought could be improved.

Conclusion:

It has been a long road with many seemingly endless nights, but sadly our journey comes to an end. At the beginning of the semester, our team sat down and decided that we wanted a yo-yo that all team members could become really excited about and take pride in. We were looking for a design that was both feasible and challenging. We wanted something that not only functioned well as a yo-yo, but also looked good. We decided on the arc reactor idea with the knowledge that it had been done before; we wanted to make it better. After countless of hours iterating through designs, optimizing processes, and manufacturing parts, the result of this project was awesome. We all walked away having learned more than we could have imagined and had a blast doing it.

Team Arc XV, Fall 2013

We would like to give a BIG thank you to the lab instructors, Dave Dow and Dave Lemelin, for their mentorship and guidance, without which this project would not have been successful.

Please check out our video, posted above!