Name:
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Personal Innovation
Class Default Project
TEE 229: Foam Processing
Warning: In this lab we will be using liquid resins and chemicals. These chemicals can be dangerous to
your health. When handling the chemicals, wear chemical safety gloves. Do not directly inhale chemicals.
Please follow all safety instructions.
Objectives:
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Observe and practice rudimentary foam processes
Gain understanding of foaming applications
FOAM PROCESSING
Introduction:
In this process tiny bubbles are formed within the liquid plastic resin such that when the resin solidifies
the bubbles, or at least the holes created by the bubbles, remain. The solidified bubble-containing material
can be thought of as a cellular structure. Both thermoplastic and thermoset materials are suitable for foam
processing. In this lab we will make a foam part and will also observe the differences between rigid and
flexible foam.
Procedure:
We will make foam parts using low pressure foam molding with a two-part urethane foam. Your lab TA
will give you the resin type, the mix ratio, and the total part weight while demonstrating how to create a
foam football (ex. Nurf). Record this information below:
Foam type:
Polyurethane
Mix ratio:
1.76
Parts A to
Calculate the amount of Parts A and B needed:
Total Part Weight:
357
Weight of Part A:
1
Parts B
225g
Weight of Part B:
132g___
It is important to note that the weight and density of the part can be adjusted simply by adding more or
less material to the mold. The foam will continue to expand until it fills the mold cavity. Thus, the same
material can be used to make parts over a broad range of densities.
Colorants can also be readily used in foam processes. However, the colorants must be compatible with
the material. Therefore, the same powder type colorant used in injection molding may not produce a
uniform color in a liquid resin. When used, colorants should be added as follows:
Pour the desired amount of the polyol (part B) into the cup. Add the colorant slowly to the polyol, mixing
constantly and well. Once the colorant is completely dissolved, the isocyanate may be added and stirred.
DO NOT ADD COLORANT TO MIXED POLYOL/ ISOCYANATE SOLUTIONS!!!!!!!!
Product Creation:
Step 1: List 5 areas where foam is used.
1.
2.
3.
4.
5.
Step 2: Brainstorm how you might use foam for an innovative product (extra credit) or for another product
reproduction other than the Nurf football (keep sizing reasonable – material is expensive, so not much
more than what is required by the football). If you are unsure of what to make, you can select to do the “PREAPPROVED” foam project – making the Nurf football (there is also a soccer ball). Remember the “pre-approved”
projects are “B” projects – meaning the highest grade you can receive if you select to do one of them is a B (based
on completeness, execution, and cleanliness of project, and accuracy of lab write-up).
Step 3: Sketch ideas, and have TA or professor approve. Hand in a copy of the sketches to the TA.
Step 4: Create a mold that will completely/accurately/effectively seal, that is representative of the product
you designed to make. Tools and materials to consider would be: a hardened polymer (i.e., PVC), wood,
metal, etc. Note: some mold materials will adhere to the foam, so the mold might need to be lined, and it
will need to be waxed or prepped with some non-stick material.
Step 4 Pre-Approved/Default Project (football): obtain the molds, wax the molds, measure liquids, do a
dry run clamping session, mix the part A with part B, stir vigorously, pour, into mold, quickly clamp, and
rotate. Wait 5 min. then release mold (see Step 5 for more details).
Step 5: Create foam product. Stir the polyurethane liquid, and pour it into your mold – make into two
halves if needed. Gently rock the mold halves so as to coat the mold completely. This will help to form a
skin over the mold surface. After coating the mold, and before the foaming reaction starts to accelerate,
the mold must be closed and clamped securely. Once the mold has been closed, continue to rotate the
mold slowly (5-10 rpm) for 4 minutes. At this point, the foam will have expanded to fill the mold
completely, and will have settled into a very uniform density distribution. Allow the mold to sit for an
additional 5 minutes. At this point, the mold can be opened. CAUTION: there will be pressure inside the
mold, so release the clamps gently.
When the foamed part has solidified, remove it from the mold and weigh it. Also make observations of its
surface skin (looking for cells) and any possible defects.
After the finished part is removed, allow it to sit for several minutes. This time will allow the part to cool,
and the cell walls to solidify. Record observations of the part below.
Surface Finish Observations
Write-up Questions:
1. What are some of the advantages of foamed polymers and parts? What
advantages do foamed resins have?
2. Give and explain three methods for controlling the exotherm in casting
3. Does casting have more design flexibility than other plastic manufacturing
processing? Explain why or why not.
4. You have noticed that when removed from the mold, your product tends to
collapse on one side. Give two possible causes, and solutions.
Design Problem:
Write a rapid lesson plan – outlining an idea for teaching and realistic project/activity a jr.
high or high school technology and engineering classroom could do to learn and experience foam
processing (needs to be distinctly different than what you did/we do in TEE 229). The lesson plan
should include 5 parts: anticipatory set, what will be taught, activity, material, and evaluation (how
the students will be graded).