Solidworks Models

 These are all our parts in STL files. Click on each of them to download.
 
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Holding Part

Mike Fill

Mike Waz Shell

Teeth Fill

Thermoform Eye

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Our Monsters Are Born - Pre Manufacturing

As we begin our Monster production process, quality control is of 

Mike's Early Days

essence. Since kids will be playing with our little creatures, we cannot let any defect ruin the reconstruction of what was once a scary experience: playing with Monsters.  For this reason, we have created an injection mold and analyzed all the areas that may be imperfect.

Mold Design

The mold analyzed was produced to manufacture the holding part.  The holding part is one of most critical components that make up the yo-yo. It links one half of the yoyo to the other half of the yoyo making use of a nut, screw, and sleeve combo. The mold for this injection molded part consists of a core and cavity mold. The core mold incorporates the injector pin holes and the housing for the nut. The cavity mold incorporates the runner gate and a 1/4in hole for the screw and sleeve to slide in.

Cavity mold for the holding part. Not shown is the runner on the 1/4th centered hold.

Core mold for the holding part. Center pin-like feature is accomplished by inserting the nut, screw, sleeve combo.

Shrinkage Analysis

Correcting for Outer Diameter:

A= measured	B= measured	C= measured	D=C-B	E=100*(C-B)/B
Diameter of  Holding Part (in.)	Average Diameter of Similar Part (in.), n=16	Diameter of Mold of Similar Part (in.)	Difference (in.)	Percent Decrease
1.77in	1.785867	1.822	0.036133	1.98%

Correcting for Thickness:

A= measured	B= measured	C= measured	D=C-B	E=100*(C-B)/B
Thickness of  Holding Part (in.)	Average Thickness of Similar Part (in.), n=16	Thickness of Mold of Similar Part (in.)	Difference  (in.)	Percent Decrease
0.10	0.091733	0.094	0.002266667	2.41%

Because we saw a 1.98% decrease in diameter between the mold and the part, we increased the diameter of our cavity by 1.98%. Similarly, we increased the thickness of the cavity by 2.41%.

Step	Operation	Machine	Tool	Justification
1	Drill/Cbore	Mill	1/2"dia. 2fl End Mill	Used to create a hole for the screw, nut, and sleeve combo
2	Drill/Cbore	Mill	# 2 Center Drill	Used to create center holes to drive the #31 drill for the injector pins
3	Drill/Cbore	Mill	#31 Drill	Used to bore the injector pin holes all the way through

Manufacturing Plan for All Parts

Our manufacturing plan for the mold of any given part, such as the holding Part can be broken down into four different steps as outlined below

1. Lathe Core
2. Lathe Cavity
3. Mill Core
4. Mill Cavity

The manufacturing plan for the holding part specifically is as follows:

1.  Lathe Core

Step	Operation	Machine	Tool	Justification
1	Lathe Rough	Lathe	T1010	Used to remove large bulk of volume
2	Lathe Finish	Lathe	T1010	Used to clean the face up to a smooth finish
3	Lathe Rough	Lathe	T0808	Used to clean out the corners

2.  Lathe Cavity

Step	Operation	Machine	Tool	Justification
1	Lathe Rough	Lathe	T0101	Used to remove large bulk of volume
2	Lathe Finish	Lathe	T0101	Used to clean the face up to a smooth finish
3	Lathe Rough	Lathe	T0707	Used to clean out the corners

3. Mill Core

Step	Operation	Machine	Tool	Justification
1	Drill/Cbore	Mill	1/2"dia. 2fl End Mill	Used to create a hole for the screw, nut, and sleeve combo
2	Drill/Cbore	Mill	# 2 Center Drill	Used to create center holes to drive the #31 drill for the injector pins
3	Drill/Cbore	Mill	#31 Drill	Used to bore the injector pin holes all the way through

4. Mill Cavity

Step	Operation	Machine	Tool	Justification
1	Drill/Cbore	Mill	1/8"dia. 2fl Ball End Mill	Used to create runner
2	Drill/Cbore	Mill	# 2 Center Drill	Used to create center hole for the screw, nut, sleeve combo

Manufacturing Process and Time Estimates

The manufacturing process of these Monsters is rather long. Striving for both quantity AND quantity, we have optimized our process to take about 1345 minutes for the production of 5 Monsters broken down in the following manner:

Part	Making and Cooling Time Per Yo Yo	Duration of Process (5 Yo Yos)
Back	40min +10mins	250mins
Holding	40min+10mins	250mins
Mike fill	55min+10mins	195mins
Mikewazshell	40min+10mins	250mins
Teethfill	30min+10mins	200mins
Thermoform die	30min+10mins	200mins
Total time	245mins	1345mins

We have given 10 minutes of cooling time per part in order to let it cool enough for easy ejection of mold, but not too much for the YoYo to get stuck and shrink onto the mold.  

Given the amount of pieces we have been striving to put together since the beginning of the project, our team schedule has remained the same. We will aim to be at the lab on a daily basis starting at 8AM as we have scheduled most of our machining at that time.  By the end of this week, we strive to have all the molds ready for use. By next week, we will finish our first batch of 5 little Mikes.

Manufactured Mold Analysis

The molds manufactured so far belong to the holding.

Holding Molds of Cavity and Core, Respectively.

As depicted, the molds for the holding part contain the runner in the middle, along with a cavity for the nut, screw, and sleeve combo.  We don't expect any reworking of these parts to be needed, however, the dimensions of the molds might have to be adjusted if shrinkage doesn't align with our calculations.

Having finished the mold for the holding, we plan on finishing up the rest of the molds this week, try to produce a few parts using the finished molds, and adjust accordingly in order to get the perfect little Monsters we've all been waiting for.

Until next time!!