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15. Wildcard week

During this week how I planned I will make my Final project bags / legs . For that I am going to use vacuum forming with several different materials. The first material is EVA Foam - from this I wanted to make protective layer for my items inside the bags. The second layer will be PVC - for durability and waterproofing. And also I will use a sponge for the outer layer because I intend to place the desk on different surfaces including the bed.

Design

For this task I first modeled the 3D of the last layer the fabric. After that, layer by layer, taking into account the thickness of the materials, i designed other. first fabric then sponge , pvc , and EVA foam.

Here you can see a sectional view.

Molding

And since I was going to get this with the help of vacuum forming, I designed a form on which I would tighten the materials layer by layer.

For this task, I chose 18mm diameter cutters with a flat head for roughing and a rounded head for finishing.

After designing with Fusion 360 I generated g-code, since we didn’t have a long cutter I decided to make it in two parts and then glue them together.

The height of the first layer was 60 mm, 2x30 MDF, the second MDF 30 mm.

During the process I also added two holes to help position the two pieces exactly. And then I glued them together and sanded them.

This is what I got in the end.

Vacuum Forming

At that time, our laboratory did not have a professional vacuum forming machine, but it so happened that Mkhitar (many thanks to him) made a homemade vacuum forming machine for the Fabric Academy Bootcamp .

It measures 60 x 60 cm and does not have a built-in heating plate. But for my whole ones it’s ok.

EVA Foam

And so let’s start, the first layer should have been EVA foam (this is a wonderful material, it is used for various purposes, for example in the production of shoes or in cinema to create various sets and props, it is very flexible, it can be heat treated, etc.) And I chose it as a protective layer for the future storage space for my laptop items.

First, I cut the blank 60 by 60 and attached it to the frame.

And since the machine did not have a heating system, I had to do this using heating gun. So I heated the workpiece and turned on the machine.

As you can see during the process I also used the heating gun to soften the material and the result was better.

And here are the results: very good quality and a very smooth surface. After forming I cut the Object from the frame and it came off the mold very well.

PVC

The next material is PVC with a thickness of 2 mm. Since my product has several layers that are located inside each other, I decided not to create a separate shape for each layer, but to do it like this: Since at the first stage it was impossible to predict the shrinkage of the material. Once the foam piece was ready, I decided to cut it out of the frame and put it back on the mold I made from MDF, so I increased the mould as long as needed, taking into account shrinkage.

As for molding PVC, I did everything the same as with EVA foam, first heated the PVC, then put it on the mold, at first everything was very good, but it turned out that the PVC hardens very quickly and I began to soften it. in the process using a hot air gun.

My material cracked during the molding process. And that’s because I used a hot air gun and not a built-in heater. The reason is that when I use a hot air gun, I heat the material unevenly, and the molding processes create different stresses, and the wall thickness also becomes uneven.

Anyway, to fix all this, I decided to put reinforced tape over the holes to continue forming.

And since this layer will be an intermediate layer and I will glue a sponge onto it in the future, I decided to still use it, despite the flaws.

3D Printing

Since I needed two products that were mirror images of each other, I decided to 3D print the second one and compare it to each other.

I also designed frames for my piece with built-in magnets so that I could attach them to my final project in the future.

Upholstery

After all this I covered it with sponge and upholstery fabric.

Result

Here is the result of my efforts.

Conclusion

In conclusion, I can say that vacuum forming is a very interesting process, it is a good technology for various reasons, but you need to follow some rules, and since I used a hot air gun, I was not able to achieve an ideal result, because the material must be heated evenly and the process must be fast, after you have heated it, it must immediately be pulled onto the mold. I also made a similar product on a 3D printer using PLA and, having compared them, I can say that when vacuumed, the product turned out to be lighter and in no way inferior in strength to the printed one, and also had much better characteristics in terms of properties such as elasticity and softness.