Grinding Wheel vs Flap Disc- Faster material removal

Loscaldazar · Jul 11, 2015

So which one removes metal faster on an angle grinder? A traditional grinding disc or a flap disc?

I see a bunch of welders always claiming that flap discs aren't for material removal (only finishing work), while I see several companies saying that their flap discs remove metal about 10x faster than a grinding disc.

If flap discs are so much quicker, than why do so many still use grinding discs?

rice rocket · Jul 11, 2015

Different applications.

You can use a grinder disc to perform the finishing work of a flap disc, but good luck using a flap disc to cut shapes.

The grinder disc lasts a lot longer as well.

stage20 · Jul 11, 2015

I haven't grinded everything in the world but the grinding wheel will wear less even if a flap wheel can remove it faster......you're running out of material and flap wheels are more expensive. Only time I've used a flap wheel for grinding is making roll cages. You can fine tune the pipe eaiser with a flap. Grinder eats too much away. Like mentioned, different applications or given circumstance. Grinder wheel will always outlive a flap if abused.

Strouty · Jul 11, 2015

Longevity and cost. There is no comparison between the two. If time is worth more than money, then flap discs may work better in a lot of situations. If money is worth more than time, then the grinding discs will work fine.

zkling · Jul 11, 2015

For hard materials a stone will remove material faster. Softer, especially non ferrous materials a coarse flap disk will take the lead.

Strouty · Jul 11, 2015

zkling said:
For hard materials a stone will remove material faster. Softer, especially non ferrous materials a coarse flap disk will take the lead.

I used to grease the grinding wheels with aluminum, but now I have found that the wheels made for aluminum work awesome. Just don't try and use them on steel, they disappear really quick.

Loscaldazar · Jul 11, 2015

zkling said:
For hard materials a stone will remove material faster. Softer, especially non ferrous materials a coarse flap disk will take the lead.

That is what everyone says, but there doesn't seem to be evidence from the manufacturers to support that.

https://www.youtube.com/watch?t=194&v=svB1iq4yRCE
Skip to 2:50 to see a side by side of a flap disc, grinding disc, and sanding disc. The flap disc easily and clearly outpaces the grinding disc grinding down steel.

http://www.homedepot.com/p/Diablo-4...ype-29-Conical-Design-DCX045040N01F/202830903
Both the videos there also show the same thing, the flap disc is faster on steel.

In addition, many manufacturers of flap discs actually recommend (ceramic) flap discs over grinding discs for stainless steel, titanium, and other hard alloys.

Strouty said:
If time is worth more than money, then flap discs may work better in a lot of situations. If money is worth more than time, then the grinding discs will work fine.

So it does just come down to time vs money and which do I have more of then...With Lehigh Valley flap discs only be $2 each (and they last a long time, even under heavy use), I suppose that increase in cost ($0.80 per unit) is probably worth it then. For a small time fabricator, the flap discs will probably give me great life.

I just find it odd that there is such a difference on opinion on which one is faster. Before today (when I saw those videos), I'd always assumed grinding discs were way faster (and hence only bought grinding discs because I don't care about having a smooth/glossy finish on most of what I am welding).

bcradio · Jul 11, 2015

Grinding discs last way longer

Mohawk Dave · Jul 11, 2015

I can't remember the last time I had a grinding disc on an angle grinder...90s maybe???

But then again, with plasma, bandsaws etc, we never needed to grind that much material.

I HATE GRINDING WHEELS!!!!! FLAP DISC FTW!

2oolhound · Jul 12, 2015

Loscaldazar said:
https://www.youtube.com/watch?t=194&v=svB1iq4yRCE
Skip to 2:50 to see a side by side of a flap disc, grinding disc, and sanding disc. The flap disc easily and clearly outpaces the grinding disc grinding down steel.

This video isn't that equal. Look at frames 2:59 - 3:00. At the 1/2 frame 2:59:15 (1/2 way between the 2 frames) you can see each weld by itself before the grinders block the view. The centre weld is way more uniform and it looks like it sits lower too but it's hard to tell. For sure the 2 outside welds have more high bumps to grind down. They should have used one continuous 12" weld and cut it into 3 pieces each 4" long, then done the comparison. It would also be easy to use crappy grinders against one good one. Not saying they did but...

AA/FC · Jul 12, 2015

mohawk dave said:
I HATE GRINDING WHEELS!!!!! FLAP DISC FTW

This! ^

Monkey Milk · Jul 12, 2015

I like to use grinding wheels on "thin" stuff where the flap disk could catch a corner.

sam.coll · Jul 12, 2015

Strouty said:
I used to grease the grinding wheels with aluminum, but now I have found that the wheels made for aluminum work awesome. Just don't try and use them on steel, they disappear really quick.

Fairly dangerous using a standard steel grinding disc to grind aluminum if thats what you are implying, the aluminum can clog the disc and cause it to shatter/explode.

Tim37 · Jul 12, 2015

I use a flap for prep and dressing, I use a rock for the heavy grinding.

Grinding Wheel vs Flap Disc- Faster material removal

Loscaldazar

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rice rocket

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stage20

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Strouty

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zkling

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Strouty

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Loscaldazar

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bcradio

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