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Improving Surface Roughness of Polypropylene and Measuring Surface Roughness
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Posted by: kat.rawlings

01/27/2011, 05:29:45

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Hi everyone,

I was just wondering if anybody can offer me any tips or advice for a project I am working on at the moment. We have been carrying out shot blasting using various abrasives to improve the surface roughness of some polypropylene parts that we are making for the medical industry (1m to 2.5m diameters). Various abrasives have been tested such as garnet, glass bead AB 177-297 and 801 AC, brown aluminium oxide 80/100 and 180/220, white aluminium oxide 70, 120 and 180/220, kiln dried sand, blasting grit (came free with the Sealey shot blasting gun), Honite 13 glass bead, Type 2 plastic media (Urea Formaldehyde) and Type 5 plastic media (20/30 and 30/40 acrylic).

White aluminium oxide 180/220 and acrylic blast media gave us the best results. However, when an electron microscope was used to find the surface roughness of some polypropylene samples that had been blasted with aluminium oxide 180/220, we found that the surface roughness was around 2.5 microns Ra, when it needs to be 0.8 microns Ra.

We therefore still need to improve the surface finish considerably. Does anybody have any suggestions of how we can do this? We are currently carrying out more shot blasting testing with aluminium oxide and plastic media. We are also looking into dry ice blasting.

Also, we would like to be able to measure the surface roughness of our samples on-site while we are carrying out trials. I am therefore looking into hiring/buying a surface roughness testing machine. Can anyone recommend UK companies who might be able to help with this?

Thanks

Kat








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: Improving Surface Roughness of Polypropylene and Measuring Surface Roughness -- kat.rawlings
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Posted by: Kelly Bramble

01/27/2011, 08:06:14

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Measuring surface roughness is not a technological leap.

Search the internet for "Profilometer" and less expensive "Surface Roughness Comparator".

Engineers Edge sells a wide variety of Surface Roughness Comparators.

See: www.engineersedge.com/catalog/index.php/cPath/38








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Posted by: RWOLFEJR

01/29/2011, 10:06:08

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Might want to try crushed walnut shells...? Also might need to take two steps to get there. One media blast followed by a second.






Modified by RWOLFEJR at Sat, Jan 29, 2011, 10:07:13


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Posted by: kat.rawlings

02/02/2011, 04:51:53

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Kelly Bramble: We are measuring Ra to 0.8 microns so I was just asking for recommendations about the cheapest way to do this. I am aware there is lots of surface measuring equipment available from many companies. The main problem I am having is achieving such a fine surface finish in the first place.

RWOLFEJR: Thanks for your help. I will look into natural abrasives. It might be possible to blast with the al oxide first and then something much finer to give a smoother finish. It appears as though natural abrasives are the softest abrasive available so this might be our solution. Thanks.








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