DIY Sandblasting: Blasting Plastics

[kat.rawlings]

That is definately a possibility and we have already tried a few combinations of blast media that haven't been very successful. We are waiting for a finer grade of aluminium oxide to arrive and we will be carrying out some more testing using 2 stages of blasting with different media.

 

[pidgeon chit welder]

Now for a 180 degree thought .. can you make ( mill out ) and polish out a master mould / split mould and then cast in clear de bubbled liquid acrilic or injection mould it etc instead.

I though of this when I was in Minehead looking at some resin casts which were ultra smooth .
Making a mould would solve subsequent problems once and for all , it may also be cheaper in the long run if numerous discs were required

 

[kat.rawlings]

Sounds like that would work and would give a better surface finish but it would be far too expensive for us to do. We are making small quantities of this product, maybe about 20 a year, and these will be different sizes so we would need several moulds. We will be sticking to the original process and milling these products so we are just looking at improving surface finish as a final stage to the process.

 

[Shox Dr]

At this point I would be revising, the material choice and either the people and or machine used.

It's all getting a bit daft you should be able to get a far better finish without all this faff and extra work

 

[kat.rawlings]

At this point I would be revising, the material choice and either the people and or machine used.

It's all getting a bit daft you should be able to get a far better finish without all this faff and extra work

I know what you're saying and your probably right but after speaking to my manager it looks like a lot of effort has gone into choosing the process in the initial stages and it seems as though it is restricted due to us needing small quantities and these are different sizes. Molding will cost millions which is why this company has come to us instead of a molding company. If we don't make it this way then we do not have any other processes at my company that will work. There is a lot of money involved so we don't want to turn away the contract. We can achieve the desired surface finish if somebody sits and sands down this product by hand which will take a few days. Rather than turn away the contract and tell our customer to use a different process we may as well do this. I have just been asked by my manager to have a look into a technique that might be better than this. If we don’t find one then I guess some unlucky person has to sit and sand them all.

 

[Shox Dr]

Arrrr the old we've spent xyz on this bloody project, lets just keep throwing more at it.

I'm glad I work for myself. Good luck Kat

 

[kat.rawlings]

At least we have a back up plan if I don’t find a better solution. Working on some other projects too so it’s not all bad and grit blasting was a success in frosting clear acrylic so at least we solved this problem. We have learnt loads about grit blasting plastics, which might end up helping with other projects so I don’t feel like it as been a waste of time. This thread has been really helpful to me throughout the testing that we have carried out so thanks everyone.

 

[pidgeon chit welder]

Several companies have cnc plastic film moulding machines
They use a cnc plastic particle UV moulding machine and simply set up the cnc prog then the machine sprays a clear film of the of the required plastic mixture which is melted in place by a UV light , many passes later in about four or five hours later the item which can be as complex as a human skull etc is finished and is wash clean with warm water and then polished out where / if needed

Complex moulds /castings forms are now done in hours rather than weeks and are apparently very very cheap