DIY Sandblasting: Blasting Plastics

[kat.rawlings]

I read the DIY Sandblasting section on this website (>>>paint>>>stripping and blasting>>>shot blasting) and thought somebody might be able to help me with my research.

I am currently looking into shot blasting plastics as I work for a plastics engineering company. My goal is to use shot blasting on materials such as acrylic and polypropylene to achieve a better surface finish before laser welding.

I was just wondering if anybody has any experience in shot blasting plastics and the types of abrasives that can be used?

Thanks

Kat

 

[rtbcomp]

Welcome to the forum, should be an interesting topic.

I grit blasted some plastic items, as an experiment, with J-Blast Supafine, but the results were raggy, like someone had torn bits off the surface. IIRC the material was ABS.

I really wonder wether shot blasting would be the thing to do, quite a bit of heat is generated which could soften the plastic and cause scarring and embedding of the media into the workpiece.

 

[brightspark]

I read the DIY Sandblasting section on this website (>>>paint>>>stripping and blasting>>>shot blasting) and thought somebody might be able to help me with my research.

I am currently looking into shot blasting plastics as I work for a plastics engineering company. My goal is to use shot blasting on materials such as acrylic and polypropylene to achieve a better surface finish before laser welding.

I was just wondering if anybody has any experience in shot blasting plastics and the types of abrasives that can be used?

Thanks

Kat

give guysons a ring and ask there advice. they sell a whole range of difrent media . if they cant help no one can they sell plastic media thats not so abrasive and probably will clean the surfaces u require without damage

 

[Shedendman]

Dry Ice blasting is the way to go,but boy the setup cost is.....................
Do a search on the net for it might give you a few ideas

 

[Monster966]

I use guyson saftigrit 180/220. Works fine so long as you don't hold the gun too close or for too long. Also used honite, can't remember what size, it gives a finer finish.

 

[kat.rawlings]

Thanks for your advice everyone. I will be looking at purchasing some equipment this week so that testing can begin. I'll let you know how it goes!

 

[kat.rawlings]

If anybody has any other ideas please let me know. I have ordered a gun, somebody is making a cabinet for me, and I have got saftigrit 180/220 and honite 13 glass bead from Guysons. I have also ordered 20/30 and 30/40 acrylic.

Thanks

 

[kat.rawlings]

Initial Testing........................

We have purchased a Sealey gun (SG10E), made a cabinet and started testing. We have used 3 different abrasives; Saftigrit (Aluminium Oxide) 180/220, Honite 13 glass bead and “Blasting Grit” that came free with our gun. Does anybody know what “Blasting Grit” actually is because it doesn’t say on the container or on the website??? Nylon 66, White PVC, Clear PVC, PE, PC and PP were all tested and the gun was held so that the nozzle was 100mm from the samples.

We have found that the Honite is too soft and fine and doesn’t really modify the surface. The aluminium oxide gives a smooth, even finish but it discolours the plastic. The blasting grit is a bit too course and also discolours the surface.

I would therefore like to purchase something of a similar hardness to aluminium oxide (Saftigrit 180/220) that won’t discolour the surface of the plastic. I was thinking white aluminium oxide could work? Any other suggestions? We would also like to purchase something slightly rougher than the Saftigrit, any ideas?

Thanks

 

[Shox Dr]

Have you inspected the surface for media inclusion, just because it doesn't discolour the surface doesn't mean in hasn't embedded. Does it matter if it has?

 

[brightspark]

try a bag of kiln dried sand only a few quid from wickes or b and q worth a try nowt to loose

 

[kat.rawlings]

@ Shox Dr
Thanks for your reply, so many things to consider! I'm sure some of the material will have embedded, and yes it will matter if we are using it for medical applications because surface contamination will definately be a problem. I'm sure it won't matter for certain applications but there are a few medical products in the pipeline that would benefit from the surface finish we are achieving. Any ideas on how we would test for contamination? Or how we could make sure we have removed the abrasive e.g. dissolving in a chemical? Polypropylene is quite chemically inert so I was thinkin this might be a possibility.

 

[kat.rawlings]

@ brightspark
Thank you, I bought some kiln dried sand from B&Q for £3.76! I'll have to update you when I have tested it.

 

[rtbcomp]

I think you'll find most blasting media is pretty inert too.

I'm with Stalwart on this one, given the application dry ice would seem to be the safest bet. Can you arrange a demo of someone?

 

[Shox Dr]

I think you'll find most blasting media is pretty inert too.

I'm with Stalwart on this one, given the application dry ice would seem to be the safest bet. Can you arrange a demo of someone?

Must have missed that post.


Yep got to agree Dry Ice, especially now we Know it's for "medical applications" everything else is going to embed to A greater or lesser Degree

 

[shed or dead]

Kat, if you are new to sand blasting please read up on the health implications of kiln dried sand and free silica.

What surface do you wish to achieve? Surely there's a chemical treatment appropriate to your objective, acid for glass etching or similar. The benefit of a chemical is that there is always (almost) another known chemical to remove unwanted residues.

I'll also add that I'm fairly new to this too and many of the other respondents have years of experience. It's all a learning curve.

 

[dougy.t]

plastic blasting

try using baking soda. its very gentle and does not create as much heat. look for baking soda madia on ebay.

 

[Ratty]

Interesting...presume you meant media dougy, still no luck but did find this
Also some info on this site - http://www.soda-blast.co.uk/

 

[Monster966]

Pay close attention to what shed or dead said, you don't want silicosis!

The saftigrit should be white, if it's not it's just standard aluminium oxide & will defo discolour your workpiece. Can't remember if they do a coarser version of it. I'd talk to Guyson & tell them what you're trying to achieve & any special requirements like your medical application, they're pretty knowledgeable & will normally have covered something similar in the past.

 

[kat.rawlings]

try a bag of kiln dried sand only a few quid from wickes or b and q worth a try nowt to loose

Did some testing on PP, PC, nylon 66, cast acrylic, PE, clear PVC and white PVC and it didn't work very well. It would therefore make sense to use aluminium oxide instead, which gave a better surface finish. Because of this and also for safety reasons I have decided to give up on the kiln dried sand! Thanks for your help though, it's always good to know what works and what doesn't and it only cost less than £4!

 

[kat.rawlings]

I think you'll find most blasting media is pretty inert too.

I'm with Stalwart on this one, given the application dry ice would seem to be the safest bet. Can you arrange a demo of someone?

Thanks I will have a look into dry ice blasting, I don't know anything about it. Is is expensive? Do you know who I could arrange a demo from?