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Compression molded out of oven (MDF molds?)

This topic contains 2 replies, has 3 voices, and was last updated by  Donald Hugens 4 days ago.

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Christian Henriod chenkus

Compression molded out of oven (MDF molds?)

16/05/2019 at 07:59

Hello!

I have been researching on this page for a couple of weeks now and each time I am closer to know what I want to do with the information of this community.
I will make a compression machine and I have seen some different ways to use the molds:

#1. The one Dave shows in his videos: heat the oven, put the plastic in the mold and use the press built into the machine.
#2. Another technique I have seen is to heat the plastic in the open mold, then take out the mold and use a press to mold the piece.
#3. And the other is to heat the plastic in a tray and pour the half melted plastic to a mold outside and exert pressure with a machine.

While the first 2 methods are made with metal molds, in the last I have seen a video (https://vimeo.com/josecamachopd/pplastic) where they make MDF molds.
I wanted to know, according to your experience, the pros and cons of these different types of finishes. I suppose that in the technique #3 the molds are more economical, and in addition, you can heat the plastic in a conventional oven (not the PP machine).

What can you tell me about these techniques, in terms of finished products and production times or something else.

Thank you!

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16/05/2019 at 20:37
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Not sure. MDF is fabricated at temperatures comparable to the  plastic temperature. I don’t know what is released at that point. If you look at section VI of a typical MSDS http://www.hardwoodweb.com/architectural/docs/MSDSUltraStock.pdf it talks about some of what can be released during thermal decomposition (without specifying a temperature). I would research it a bit before a lot of use.

As far as using it, I’ve used wood molds with my injection machine. I use aluminum tape on the contact surfaces to avoid sticking, and make sure all the thicknesses are robust enough to handle the pressure. For a limited number of runs it works well.

helper
18/05/2019 at 10:10
0

Heating MDF might indeed not be the healthiest way to go, at least not indoors, without ventilation and a mask, but the same goes for working with the plastics so the point could be made that if using MDF as a mould is not safe nor is melting the plastic!

 

Combining the techniques (MDF with tape/foil) also might improve both.

 

 

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