EMA 3013C: Carbon Fiber Cell Phone Case

Overview:

Carbon Fiber is a composite used in material fabrication and design for many different applications in industry and academia. Composite materials are made up of two different phases (which are named the dispersed and matrix phases) that are combined to optimize the overall mechanical and material properties present in the desired application. The dispersed phase (carbon fiber) is embedded inside the matrix (epoxy) and acts to bear the load once the matrix phase eventually fails. Carbon Fiber composites are used in a vast array of applications in industry, such as wind turbines, Boeing's 787 Dreamliner, NASCAR's Formula One automobile, and sporting equipment.

Objective:

Create a Carbon Fiber iPhone 6 cell phone case using a plaster phone mold and carbon fiber lay-up method with Fiberglass Epoxy.

Hazards:

Epoxy resin and hardener can cause eye, skin, nose, and throat irritation. Special care should be taken to properly handle the Fiberglass Epoxy. Use proper gloves by consulting a glove chart and take precaution when handling and applying the Epoxy to the phone case.

Plaster Cell phone case mold:

· iPhone 6 case

· Plaster Powder (DAP or other brand)

· 3oz Dixie Paper Cups

· 16oz Plastic Solo Cup

· Cold Water

· Wooden Craft Sticks

· Glad (“Press’n Seal”) Wrap

· Saran Wrap

· Gloves

Carbon Fiber cell phone case:

· iPhone 6 Plaster cell phone case mold

· Fiberglast Epoxy (resin and hardener)

· Foam paint brush

· Vacuum bag with nozzle attachment

· Fiberglast Adhesive strips for bag edges (secure bag)

· Vacuum pump with hose attatchment

· High-gloss Carbon Fiber sheet

· 3oz Dixie Paper Cups

· 16oz Plastic Solo Cup

· Masking tape

· Wooden Craft Sticks

· Wax paper

• Obtain the iPhone 6 cell phone case
• Cover work area with saran wrap
• Lay case flat on back with the inside of the case facing up

• Completely cover the phone case with the Glad Press n' Seal Wrap
• Make sure the wrap tightly covers the entire inside of the cell phone case

• Measure out 2 parts (by volume) of DAP plaster by 1 part (by volume) of cold water in two separate 3oz Paper Dixie Cups
• Combine plaster and water in plastic solo cup and thoroughly stir with wooden craft stick

• Pour the liquid plaster into the cell phone case mold
• Make sure the entire cell phone case is filled with plaster and the liquid mold is uniform along the base and edges of the case
• Wait at least 24 hours for the plaster mold to solidify

• Cut Waxpaper to be at least 1 1/2 inches bigger than the cell phone mold all around the mold
• Similarly, cut the Carbon Fiber to be at least 1 1/2 inches bigger than the cell phone mold all around the mold

• Tape edges around the carbon fiber mold to have a place to attach the tape that will hold the cell phone case together when wrapped around the back

  Important:

  Center the phone mold on top of the wax paper and carbon fiber as shown in the figure above

  Note: If proper care is not taken to carefully tape the edges of the case, the epoxy will significantly degrade the adhesive quality of the tape. Additionally, the carbon fiber case will not be able to be detached from the tape

• Wrap the carbon fiber around the back of the mold as shown
• Tape the carbon fiber down only in the spots where tape is present
• Make sure the carbon fiber is tightly bound to the phone mold

• Mix three parts (by volume) of Fiberglast Epoxy resin and one part (by volume) of the Epoxy hardener in two separate paper Dixie Cups
• Combine the resin and hardener by pouring both slowly into a new plastic solo cup and stirring to ensure a homogenous mixture of Epoxy

Note: Optimize efficiency by reducing wasted Epoxy by either sharing with fellow carbon fiber lay-up makers or using only a small amount of resin and hardener to sufficiently saturate the cell phone case being created

• Flip the cell phone case to the back side with the carbon fiber facing up (as shown in pictures above)
• Start dabbing and brushing Epoxy on the carbon fiber
• Ensure to fully impregnate the carbon fiber with Epoxy
• Once the front side is saturated with Epoxy, turn the phone case on its back and brush around the tape
• DO NOT brush with Epoxy on the tape, as the Epoxy will degrade the adhesive (brush around)

• Place the carbon fiber cell phone case in an open area in the vacuum bag
• Make sure the phone case is placed with the taped side facing down and the flat carbon fiber side facing up

• Make sure to properly seal both sides of the vacuum bag to ensure that no leaks occur that would allow the air to "break" the vacuum seal
• Leave about 1/2 inch curl of the adhesive to properly secure the edges of the bag and firmly press down along the edges and the ends of the bag to make sure the entire vacuum bag is sealed

• Attach the vacuum hose to the center of the vacuum bag's hose nozzle
• Make sure there a tight seal and connection of the metal vacuum bag nozzle and the vacuum hose
• Stabilize the vacuum hose above the bag area using tape if needed (shown above)

• Turn on the vacuum
• Listen and look for any noticeable leaks around the bag that could break the vacuum seal
• Firmly press down the phone cases and remove any noticeable bubbles
• Allow the vacuum pump to remain on for at least one hour

• Once dry, retrieve cell phone case out of the vacuum bag

Note: Take proper care in removing the case from the bag, as well as taking off the tape. Carelessly removing materials can cause irreversible damage to the carbon fiber case through fraying or degradation of the build quality

• Clean out the plaster mold from the inside of the cell phone case
• There are many methods of completing this step, but one way is to fracture the middle of the plaster mold on the back (opening) using a hammer, and removing the multiple pieces of plaster

• Use scissors to create a wider opening for the back of the cell phone case once the fiberglass is removed

• Utilize the Dremel tools to refine and optimize the iPhone Carbon Fiber case for finer edges, as well as button and port openings

1) Use the Dremel saw tool to cut the carbon fiber case's edges to the desired form of the cell phone case

2) Use the Dremel sanding tool to refine and smoothen out the edges of the cell phone case

3) Use the Dremel carving tool to carve holes and ports for the case's camera, buttons, and charging ports

• Mix a very small batch of epoxy (about 10 ml of resin) to apply a surface-coated finish to the cell phone case

Note: Make sure to remove all bubbles and impurities once done with the surface coating process. If the bubbles are left to dry on the surface, the resulting case will have the texture of "lumpy alligator skin."

• Showcase your Carbon Fiber cell phone case with pride for all of your friends to enjoy

Considerations to make for improvement:

• Was there any fraying of the cell phone case at the bottom or at other locations along the case skin? Is there a need for an adjustment of the size of carbon fiber used?
• Was the carbon fiber wrapped tight enough around the phone mold? Did the epoxy fully impregnate the phone mold?
• Were there any bubbles present on the outer shell of the cell phone case? Porosity? How does this affect the strength and mechanical properties (as well as resistance to wear over time) of the cell phone case?
• Did the phone mold crack while applying the carbon fiber lay-up? What can be done to provide more cost efficiency and reduce waste and error in future lay-ups?