Karoline Healy: plastic

Showing posts with label plastic. Show all posts

I cut up the previous failed wheel into pieces so I can be easily re-metled them for the next wheel attempt to make.

First attempt at full size wheel

This is my first attempt at making a full size wheel for my kiosk. After the success of the previous test run, I continued to attempt to make a wheel out of recycled HDPE plastic. My aim was to make a wheel with a radius of 20 cm.

First step is to wash all the plastic and remove labels.

I have been collecting plastic for a while. This is what 500g of HDPE looks like.

I then weighted the plastic to that it will be enough for the size and thickness of the wheel I need.

I then put the plastic bit by bit into an oven at 180 degrees, hot enough to melt but not burn the plastic

I then put the motlen plastic blog on my tool and put the top on and pressed the MDF together.

I miss calculated the weight of the plastic so this is blob is too small for me to use.

Making Plastic wheels experiment

This is a small scale test to see if its possible to make wheels for my kiosk out of recyeld plastic.

This is the equipment I will use to form the melted plastic into a flat piece. Using 2 nuts to determine the width.

The molten blob of HPDE is pushed between the MDF boards and tightened with block nuts.

I then cut the plastic into a circle using a band saw and disc sander.

The HDPE can be planed with a wood hand plane to create a smooth more even surface .

My plastic extruding machines

2 extruding machines, 1 with a larger hole than the other. Made from copper and brass tubes soldered

together. Including a stand. Plastic is heated whilst inside and pushed down with a steel rod into some cool water.

Extrusion tests. The first one came out as a blob because I pushed the plastic out too fast,

the experiments has a better shape with a smaller holed machine and at a steadier pressure.

Oil experiments

Here I experimented with melting plastic using vegetable oil ( same method used to melt chocolate) in a bowl submerged in boiling water.) Got this idea from Thomas Thwaites

toaster project book, where he used this method to make the plastic

casing for his toaster.

My new equipment ( 240 degree sugar thermometer, small saucepan)

1st experiment : The silicone case flooded so let the plastic

free in the oil. Going back to white as it cooled down

I used silicone cupcake holders from pound-land because silicone has a very

high melting point (240 degrees)

Whereas HDPE, Polypropylene and polystyrene melt at around 130 degrees.

The plastic touching the casing is starting to melt

Quenching the whole mould in cool water to speed up the process.

A book I have read..

This is a great book from RCA graduate Thomas Thwaites, he makes a toaster completely for scratch traveling many many miles in the UK. His method of using oil to heat plastic has given me ideas for my project.

Pressure Moulding

Made these simple HDPE forms by putting a square of cylinder tube on to the metal disc

in the wooden frame and heated whilst pushing down with the steel rod. The

mould is then quenched in cold water and pushed out.

Combining plastics

Here are some experiments using different types of plastic together to see if they fuse well.

HDPE and Polypropylene fuse well together , but polystyrene doesn't stick with the

other plastics making the structure

Heat gun vs Plastic

Firstly sorting out different plastics washing and then cutting into pieces

PET bottle

HDPE milk bottle

I then made a simple mould by fly pressing aluminium and created feet by bending down the corners. I also made a tapered wooden presser.

With heat from the heat gun and pressure from the plug, I woulded the soft plastic into the mould.

HDPE plastic bag

HDPE milk bottle

All the plastics that worked with this method were PP (polypropelene), PS (polysyrene) and HDPE (high density polyethelene). The plastic that melted down the best and created the smoothest surface was PP. PS created a sort of crystal structure.