Every picture tells a story: Grinding stainless steel welds
Which flap disc should I use to grind stainless steel? A common enough question. We recently had a staff training session on this very question and below you can see the results.
5 stainless steel folded and welded samples were ground for 30 seconds. Machine speed: 6,000rpm. Operating at high pressure.
Disc 1: FSC 80 grit zirconia 115mm flap disc
It cut reasonably well. Enough to remove light welds but under high pressure it quickly began to generate more heat and sparks. Note: P80 abrasive flap discs are not designed for high metal removal applications.
Use for light weld removal and at lower pressure.
Disc 2: FSC 60 grit zirconia 115mm flap disc
The FSC 60 grit zirconia disc was removing weld at a reasonable rate and also generating a high volume of sparks. When used on stainless steel, at high pressure, significant weld discolouration will be generated.
Use for general purpose weld removal where a good finish is needed and where lifetime of the disc is less important.
Disc 3: FSC 40 grit zirconia 115mm flap disc
The FSC 40 grit zirconia flap disc was removing weld at a good rate and generating less heat than the P60 discs which left less weld discolouration.
Use for good general purpose stock removal.
Disc 4: FTC 40 grit 115mm flap disc
The FTC Ceramic P40 grit flap disc was removing weld at a high rate and also generating very few sparks, indicating a much cooler cut. Note the significantly reduced metal blueing discolouration. The ceramic FTC disc was the only able to succesfully grind away the complete weld within the trial period.
- For low volume production and light fabrication work use Zirconia FSC 40 and FSC P60 flap discs. They will effectively grind away significant volumes of stainless steel weld.
- Where high disc life and speed of cut are required use Ceramic FTC 40 and FTC 60 grit flap discs.
N.B. Although many metal fabricators do not currently use variable speed grinders we conducted this test at 6,000 rpm (approximately half fixed speed grinder speed). There is no doubt that the performance of all abrasives on an angle grinder will be significantly improved by working at lower speeds. Conversely the above trial variations would only be increased at 11,000 rpm.