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Eliminate sanding before polishing aluminium

July 22, 2009

We are polishing forged aluminium. Before polishing we are using 600 grit sanding to remove the machining lines. Now we are looking to eliminate sanding completely.

If anybody have any solution please answer my question. The solution may be in the form of Polishing compound, Buff or a innovative sanding machine which will reduce the sanding time drastically.

Regards,

Anbalagan Elavarasan
Assistant Engineer - Chennai, Tamil Nadu, India

Hi, Anbalagan. Your question is somewhat similar to asking if you can omit the power shovel step when digging the foundation for a building; yes you can, you can dig the foundation with a teaspoon if you want -- but you'll still have just as much dirt to move :-)

In general we use the expression 'sanding' to cover the rough heavy cut, 'polishing' to cover the medium cut, and 'buffing' to describe the final fine cut. To try to do the rough cut with a finer abrasive is going in the wrong direction. But that does not mean that the exact sequence of sanding cloths, polishing compounds, and buffing compounds you are presently employing is the ideal one. Yes, there are automated sanding and polishing machines, and another reader may be able to name the style of machines you could consider. Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
July 22, 2009

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July 27, 2009

Dear Ted Mooney,

Thanks for your reply to my question. Now I understand your concept. I am requesting you to suggest me the ideal sequence of sanding clothes, polishing compounds, and buffing compounds for polishing forged aluminium wheel.

Looking forward to your valuable suggestion.

Thanks,

Anbalagan Elavarasan
Assistant Engineer - Chennai, Tamil Nadu, India

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Anbalagan,

My shop also does sanding and polishing. Depending on the final cosmetic appearance you are looking for you might be able to omit sanding. If you are looking for a mirror finish at the end then you have to remove the lines. You can try bright dipping the parts or you can use a vibratory finisher. Many suppliers have proprietary bright dip formulations or you can try one from the Metal Finishing Guidebook.

Tim Hamlett, CEF
- West Palm Beach, Florida, USA
July 27, 2009

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August 1, 2009

Thanks for your valuable input. Can I know what is the solution you are using in bright dipping to remove the machining lines.
And I also request you to recommend any vibratory polishing suitable for aluminium truck wheels(forged aluminium)

Regards,
A. Elavarasan

ANBALAGAN ELAVARASAN
wheels - Chennai, Tamil Nadu, India

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August 17, 2009

Dear sir,
We are using 600 grit manual sanding before polishing aluminium alloy truck wheel to remove the machining lines. Sanding time for one full wheel takes more than 60 min. Now we are looking to simplify sanding. Anybody have any solutions please.

Regards,

Anbalagan Elavarasan
Assistant Engineer - Chennai,Tamil Nadu, India.

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First of two simultaneous responses --

Years ago there was a commercial that ended with" you can pay me now or you can pay me later".
You could improve your machining to significantly reduce the machining lines.
You could partially automate the sanding operation.
I would not go into the electropolish for aluminum without seeing one in operation. It is a nasty process and can be very obstinate at times.
You could go to cheaper help for initial sanding operation.
IE: there is no really great ideas.

James Watts
- Navarre, Florida
August 17, 2009

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Second of two simultaneous responses --

If you have any major volume of parts and you like the finish you are now getting by hand, you should look into automating that with a robotic system.

AF Kenton
retired business owner - Hatboro, Pennsylvania
August 18, 2009

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August 22, 2009

Dear Sir,
Thanks for your reply. We have already automated our polishing line with robot. But the prepolishing activity is what killing us (sanding). We are spending more manpower and time in sanding to remove the machining lines from the aluminium wheel. If you have any solutions to simplify the sanding operation or eliminating the same please tell us.

Regards,

ANBALAGAN ELAVARASAN
- Chennai, Tamil Nadu, India

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Dear Anbal,

As none of the above suggestions have worked for you, please look at machining alternatives and try to avoid the machining lines in the first place. With alternative tools the possibilities are endless.

Khozem Vahaanwala
Saify Ind

Bengaluru, Karnataka, India

August 25, 2009

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First of two simultaneous responses -- August 26, 2009

Two things
1. See what you can do to improve parts/molds?
2. Run parts through mass finishing to improve finish prior to robotic polishing.Rough guidelines: For speed use a fast cut ceramic media. If you have better than a 35 RMS maybe use plastic media. If parts are 25 RMS use medium cut media. If parts are 20 or better use fine cut media.

AF Kenton
retired business owner - Hatboro, Pennsylvania

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Second of two simultaneous responses --

Dear sir,
Thanks for your view. Currently we are using PCD inserts for finishing the aluminium wheel in CNC machine. But still we were not able come out of the machining line problem.
Can you please give any tooling related solutions to overcome this.

Regards,
A. Elavarasan.

ELAVARASAN
- Chennai, Tamil Nadu & India
August 27, 2009

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August 28, 2009

The tech services group at the OEM for your inserts should be able to help you, as it appears that your local vendor is unable to.
Normally, with a proper insert, you have a problem with the feed rate. I assume that you have the speeds correct.
Diamond turning on steel has the capability to be quite close to a rough grind or better.

James Watts
- Navarre, Florida