Keiichi Onishi

MAS.863 How to Make (Almost) Anything

Composites

This week's assignment was "Design and make a 3D mold (~ft2), and produce a fiber composite part in it."

Overall progress

I wanted to make something useful, and decided to make a plate to put fruits such as oranges and apples. Making composites consists of three steps. First, I designed mold using SolidWorks. As plate is simple design, I chose to design single and open mold. Second step is milling form based on the mold design. Third step is putting burlap and epoxy (epoxy plus hardner) on mold, put it in a bag, and vacuum it. Even though plate is simple, I should have created two molds to compress material easily. Strength of the product could have been improved.

  • What: Fruits plate
  • Components: Burlap, epoxy, hardner, and form for mold
  • Design tool: Solidworks
COMP 02
Step 1: Design Plate

I designed simple mold for a plate using SolidWorks. I have gotten familiar with SolidWroks!!!

COMP 03
Step 2: Milling form to make a mold

I milled form to make a mold. I generated tool path using Shopbot 3D using 1/4" ball end endmill. As I thought resolution of the burlap should be quite rough, I used 1/4" for both rough and finish cut. Total processing time was less than 20 minutes. I wrapped the mold using plastic wrap.

COMP 04
Step 3: Mixing epoxy and hardner

I used clear epoxy that needs 24 hours cure time. I mixed epoxy and hardner with the ratio of 100:43 in weight.

COMP 05
Step 4: Applying epoxy to burlap; Curing

I applied epoxy to three layers of burlap. I wasn't sure about how much epoxy I should have applied, so I put as much epoxy as possible but not excess. Then I put red film as peel ply on burlap, and cotton to absorb excess epoxy. I put the mold with peel ply and cotton to a vaccum bag, then vacuum it.

COMP 06
Step 5: Demolding

Approximately afte 24 hours, I took out the plate from the vacuum bag. Thanks to peel ply, it was quite easy to demold product. The composite didn't reflect tight R corner due to the vacuum bag couldn't maintain vacuum. I should have used two mold compressing material between those mold. Also I would add at least two layers of burlap next time to increase strength.

COMP 01
Step 6: Final product

Perfectly the plate worked as fruits plate!!