Deliverable 2-b: Time Table

Component Time Table

Component	Time per Part	Number of Runs	Total Time for parts	Component Total Time
Bow Tie
Bow Tie Cavity Mold	42 min 10 sec	1	42 min 10 sec
Bow Tie Core Mold	35 min 56 sec	1	35 min 56 sec
Bow Tie Injection Mold	0 min 15 sec	105	26 min 15 sec
				104 min 21 sec
Retaining Ring
Ring Cavity Mold	45 sec	1	0 min 45 sec
Ring Core Mold	41 sec	1	0 min 41 sec
Ring Injection Molding	8 sec	210	28 min   0 sec
				29 min 26 sec
Window
Window Thermo-Mold	1 min   2 sec	1	1 min  2 sec
Window Thermo-Forming	0 min 35 sec	210	122 min 30 sec
				123 min 32 sec
Yo-Yo Body
Body Cavity Mold	3 min 43 sec	1	3 min 43 sec
Body Core Mold	6 min 14 sec	1	6 min 14 sec
Body Injection Molding	0 min 20 sec	210	70 min 0 sec
				79 min 57 sec
Extra Set-Up
Preparing Machine per Component	10 min	4	40 min
				40 min
Yo-Yo Assembly
Assembling a Yo-Yo	3 min	100	300 minutes
				300 minutes
Complete Fabrication of Project				11 hours     17 minutes 16 seconds

Part Assumptions:

Bow Tie: We are trying to mold two bow ties at once.  We assume that the surface area of the mold is not too great for the injection molding machine.  If it is an issue, we will modify the mold, blocking one of the channels and reducing the apparent surface area.

Retaining Ring: We are assuming that the constant thickness will cause the mold to cool at the same rate at all parts of the ring. Because of the small thickness, there should be no need to a small draft angle to help the ring be ejected from the mold. Because of the lathe and small amount of mill work, creating this mold will take very little time. We also assume there will be approximately 2% shrinkage with this part, based on measurements of model parts in the lab classroom. Thus, the mold dimensions are 2% larger than our final goal dimensions.

Thermo-form Window: We are assuming that the thickness of the thermoformed part remains roughly constant, so that the upper profile of the part is an offset of the lower profile. We are expecting a variation in thickness of within 10% throughout the part.

Yo-yo body: We have assumed a 2% shrinkage of the body upon cooling, and so we have scaled the molds by 102% to accommodate that.

Injection Mold Assumptions:

We are going to create 210 molds for each part to ensure that all molds fall into our tolerance range and do not have any deformations.

The bow tie, a complex but thinner part, will take about 15 seconds for each body to cool. The bow tie mold can complete two bow ties at a time, therefore waiting 15 seconds gets two bow ties done at once. This is why only 105 runs are required to create 210 bow ties.

The retaining ring is the thinnest part, thus we assume it will only take 8 seconds per part to cool.

 The thermo-formed window is a bit slower than injecting molding because of the heating of the plastic, thus will take 35 seconds.

The yo-yo body is the thickest part, thus it will take the longest to cool. We will assume it takes about 20 seconds for each body to be made.

Because it takes about 10 minutes for the set-up of each molding process (warming up of plastic, loading G-code, etc), an extra 40 minutes must be added onto the fabrication process. We estimate that it will take 4 hours, 7 minutes, and 30 seconds to fabricate all of the plastic parts to make our yo-yo.

Once all of the parts are created, we need to press fit together all of the parts. For each yo-yo, it will take about 3 minutes to assemble one yo-yo. This includes press fitting parts together, screwing in one side of the yo-yo into the other, and checking for errors. By using all six group members, we can create an assembly line to put together yo-yos in about 5 hours.

Conclusions:

The time schedule above dictates how our team will spend our time in lab. Our team must set time aside during the week to come to lab to manufacture parts. It is also important to complete all parts by a particular date to begin the assembly of our entire yo-yo. If any part needs to be re-done, using the table determines how long we need to spend in lab to fix mistakes. As parts are changed, our group will edit the time table to keep an accurate time table of fabrication time.