V4 Sheets – Bending
I am researching about methods for working with the plastic sheets. I am going to share how my experience was bending different types of plastics. Currently I am only trying to do it with one method, but we are very interested in more ways to do it, so feel free to share your ways to bend the different types of plastic in this topic. Any suggestions, questions and experiences are always welcome.
You can check this topics if you are interested in this materia:
Test: Bending with the hydraulic press.
Objective: Bending different types of plastics with the hydraulic press
Material: PP, HDPE, PS
Tools: Oven, Hydraulic press and bending jig
Put the plastic in the oven enough time for getting all the interior and the exterior warm enough (1 hour has worked for my pieces of plastic). The temperature has to be just in the middle in between the softening temperature and the melting temperature. Take the piece of plastic and put it in to the hydraulic press ready to bend it. Let it cool it without releasing then pressure.
– HDPE worked the best; I was able to bend it a lot of degrees. I have just noticed a little stretch on the external area and a little excess of material in the internal area, but not a big change on the material.
– PS has shown surprisingly good results. I was not thinking that I was going to be able to bend it that good. I could reach a lot of degrees of bending before it breaks, but it reaches to bend easy until around 45º. After that it starts to break on the external surface.
– PP was the worst of them and is not easy to bend. It breaks really easy and the material starts to be stressed at the beginning of the bending. I have done it also with a higher temperature and (the material started to melt a little bit), different sources of PP (just in case it was for that PP) and I have tried with more time just in case it was not enough warm properly.
I was testing with different temperatures. In conclusion I noticed that the best temperature is the middle in between the softening temperature and the melting temperature. Colder temperatures make the plastic being too fragile, warmer temperatures make it too soft, which means that it is going to lose the strength we had when we made the sheet. Also it can start to melt or also leave some scars on the sheet when you try to press it. During the process of pressing it is important to leave it to cool at the press (It is not necessary to use an hydraulic press, it is not that strong) Then I have left the plastic cooling in the press half an hour for avoid the plastic to make an elastic bounce and come back to the beginning shape again, this happen if you try to bend the plastic without heating it first also or if you do not leave it cooling there.
Some photos of the process
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