YOLETTE'S COMPONENTS:
Each Yolette will be comprised of six different parts: a
core, a faceplate numerical insert, a roulette ball, a clear cover, an acorn
nut and a retainer ring. The core, faceplate and retainer ring will be
injection molded out of polypropylene, the clear cover will be thermoformed and
the roulette ball and acorn nut will be bought from McMaster. The yoyo will be
held together via the traditional 10-24 setscrew, spacer and nut assembly as
described in lab.
Core: The core will be manufactured via a traditional, two part
mold process. We will locate the ejector pins in the surface that is buried
underneath the numerical insert faceplate to improve the appearance. We will be
injection molding the part using a brown coloring for the resin but have been
researching options to paint the yoyo and give it a mahogany finish. Before
initiating each injection cycle a nut will be placed inside each core, within
the structure that keeps the acorn nut in place (center of the roulette wheel)
via the screw and nut method but will ensure a cavity through the whole part by
pressing against the cavity mold. This is a very important step in our
manufacturing process as it will provide us with a way to assemble the yoyo
together and will ensure a location for the acorn nut which plays a key role in
creating a roulette within the yoyo’s face.
Faceplate: The faceplate or numerical insert will be comprised of the
gray/gold plate and the black and red slots. This is a two part process, where
we will employ two different sets of molds, one to create the slots, one black
and one red for each face of the yoyo and another mold that assembles the two
slot sets and allows for the injection molding of the gray/gold area. The slot
mold will have an outer ring that constitutes the runner and allows for the
placement of the slots in the faceplate mold. This process was described in lab
and we are very interested in applying it to our design. We believe that if
successful, it will reduce the time required to assemble each individual yoyo
when compared to options such as laser cutting the individual slots or coloring
them in.
Retainer Ring: The retainer ring snap fits on the core of the yoyo, lamping
the thermoformed clear cover in place. The design follows the instructions
stipulated in lab for the snap fits including the one sided tolerances on mold
manufacturing for the internal and external diameter features and the length of
engagement of 0.150”.
Clear cover: The clear cover will be thermoformed out of clear 0.030”
high impact polystyrene and will have a donut shape with a perforation in the
center so that the setscrew can go through and screw into the acorn nut. Due to
the draping methodology employed in its manufacturing we will need to focus our
attention into the locations of the vacuum perforations and control the
stresses on the sheet of polystyrene. The cover will be held in place by the
retainer ring and will serve the purpose of holding the ball inside the body
part.
Acorn Nut: Click here to see details of the acorn nut in the McMaster website.
Roulette Ball: Click here to see details of the roulette ball in the McMaster website.
TABLE OF SPECIFICATIONS:
GANTT CHART:
Click here to see the detailed schedule with the timeline and description of each major task.
Posted by: David D'Achiardi and Jose M. Linares
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