Final Design

_______________________________________________________________________________________________________________________

Primary Design Choices

Material

Plastics are given recycling numbers, or resin codes. The plastics that are usually considered “safe” for food applications have the resin codes 1, 2, 4, and 5 that correspond to Polyethylene Terephthalate (PET), High Density Polyethylene (HDPE), Low Density Polyethylene (LDPE), and Polypropylene (PP) respectively. Therefore, these four types of plastics were considered as possible materials for the baby tray. A comparison of these options can be seen below in Table 1.

Table 1 | Summary of pros and cons for PET, HDPE, LDPE, and PP

_______________________________________________________________________________________________________________________

Suction Cup

There are many different kinds of suction cups on the market. Suction cup materials considered included nitrile (Buta-N), silicone, rubber, and vinyl. In the end, it basically came down to a decision between a silicone suction cup versus the other materials because silicone was food grade and could withstand the high temperatures of a dishwasher, but was significantly more expensive than the other solutions. A comparison of pros and cons suction cup material can be seen below in Table 2.

Table 2 | Summary of pros and cons for suction cup material selection

Two types of suction devices were considered, vacuum cups and suction cups. Vacuum cups are used in conjunction with machinery to handle and move items on the production line in a factory. As shown in Figure 1 below, these typically have metal housings and a hole that goes through the center of the suction cup (for air to be drawn through by the machinery). Vacuum cups in the food industry are often made out of silicone. Suction cups, seen in Figure 2, are the run-of-the-mill regular suction devices used in everyday applications like hanging a shower caddy on the wall or a planter off a window. A comparison of these two options can be seen in Table 3.

 Table 3 | Summary of pros and cons for vacuum cups and suction cups

_______________________________________________________________________________________________________________________

Shape and Form Factor

There were two major design approaches considered for the baby tray. The first approach (referred to as the Circular/Penguin Shape) was having a shape based around circular eating area with a matching circle-shaped lid. The circular eating area would be the basis for various shapes; thus, many designs could easily be made without having to change the lid feature or the eating area as seen in Figure 3.

Figure 3 | Different shape designs centered on the same circular eating area

The second design approach (referred to as the Abstract/Car Shape) was to have the eating compartments integrated into the design of the shape. For example, shown in Figure 4 below, the windows and wheels on the car baby tray and the wing sections on the butterfly baby tray are the eating compartments. Despite the cool factor, this was a high risk idea mainly due to the difficulty in designing a lid to fit the abstract shaped eating areas. Also, certain eating areas might not be appropriately sized for baby feeding.

Figure 4 | Car and butterfly baby trays utilizing abstract shaped eating areas

 Table 4 | Comparison of the two design approaches

 _______________________________________________________________________________________________________________________

Description of Final Design

Material

Polypropylene was decided as being the material for the baby tray. It meets all the functional requirements for being lightweight, durable, dishwasher safe, child safe, and injection moldable. It is not the most readily recyclable material, but it is recycled and has a greener image than some other plastics. Many other food packaging and baby feeding products already are being made with polypropylene. Though it is slightly more expensive than other plastics, it is worth the cost. Two possible grades of polypropylene that can be used for the baby tray are ProFax 6523 and FHR P5M6K-048.

_______________________________________________________________________________________________________________________

Suction Cup

Figure 5 | Current 60 mm vacuum suction cup used in prototype

The current suction cups used in the baby tray prototypes were 60 mm silicone vacuum suction cups purchased for $10 each in person from a distributor in Irvine, CA. Silicone was chosen as the material of choice because of its resistance to deformation at high temperatures (dishwasher safe) and being food grade. The final design requires a suction cup that does not have a hole all the way through the suction cup like the ones in the prototypes because the hole requires extra effort to create an airtight seal under the suction cup (using Loctite or Teflon tape) and this is not feasible for the final retail product. The silicone suction cup used in the final design will have to be custom molded as research did not yield desired suction cups that could be purchased off the shelf at a reasonable price point (costing $10-25). Since the baby tray hopes to retail at around $19.99, the unit price for the suction cup must be below $3. A baby tray design was considered where two suction cups were used instead of just one suction cup to help prevent the rotation and sliding of the baby tray while affixed to a tabletop, but the second suction cup added unwanted cost and perceived extra hassle in having to release an additional suction cup when removing the baby tray from the table.

_______________________________________________________________________________________________________________________

Shape and Form Factor

The circular shaped tray and the abstract shaped tray developed into the penguin and car tray respectively. Two alternative versions of the final penguin design were done. One version had a surface that extended all the way around the baby tray so that the bottom edges would sit flush against the table. The other version did not have this feature to remove any crevices for food to get stuck on the back side of the tray. These two designs of the circular penguin tray can be seen in Figures 6 and 7.

  igure 6 | Penguin tray with flush bottom feature. Left—front view. Right—back view.

Figure 7 | Penguin tray without flush bottom feature. Left—front view. Right—back view.

Both versions of the penguin tray had a lid feature borrowed from OXO’s line of baby feeding products. The tray itself has a slightly raised rim that goes all the way around the inside edge of the circular feeding area; the lid has an indented groove that fits onto the rim of the tray. The user snaps the lid into place and uses the tab to help remove the lid.

Figure 8 | Lid feature on the penguin trays

The final version of the car baby tray shown in Figure 9 did not have a lid because a viable lid solution for the abstract shape was not found. Therefore, the car tray shown is very simple in design. One existing issue is that the wheel eating areas are a little bit on the smaller side (67 mm in diameter). Making them bigger would result in scaling up the overall size of the baby tray and a finger would not be able to reach through the finger hole and release the suction cup. A possible solution is to remove the walls like the penguin tray in Figure 7, but this may detract from the aesthetics of the tray when the overall car shape goes from 3D to 2D.

Figure 9 | Abstract shaped car tray without lid. Left—front view. Right—back view.

_______________________________________________________________________________________________________________________