Lower Costs. Reduce Grinding Time: Grinding Stainless Steel with Ceramic Flap Discs

Yesterday we set up a simple grinding trial with one of our customers.  The challenge:  When grinding stainless steel, which is more cost effective?  Zirconia or Ceramic abrasive flap discs.

We wanted to compare the rate of stock removal of 60 grit Cibo abrasive flap discs on stainless steel welded test plates.  Our customer held the stop watch (it is only fair as they had travelled to come and see us!), we held the grinder.  Even though we recommend running at around 6,000 rpm when grinding stainless steel our customer wanted us to use a standard grinder at 11,000 rpm, so we did.

Test 1:  How long does it take to grind away the metal to break the test plate into two pieces along the weld seam?

Zirconia (FSC/60/115 – list price £1.86 per disc):  65 seconds

Ceramic (FTC/60/115 – list price £4.03 per disc):  35 seconds

Well that seems obvious – 53% faster work rate.  That alone is a huge labour saving, and it was also noted by our customer that less sparks and heat were generated when grinding with the FTC ceramic abrasive discs.

Test 2:  How much metal can we remove in 3 minutes of grinding.  Or put another way – does the disc continue to perform?

The same discs and test plates were used.  The result:

Metal Removed after 3 Minutes

Zirconia:                          45 grammes

Ceramic:                          75 grammes

When grinding stainless steel welds ceramics are giving a minimum 66% increase in cut rate (or reduce grinding / labour time) over zirconia abrasive discs.

Translating that into a real factory scenario:

Now don’t get us wrong.  We like how the FSC zirconia flap discs perform.  The disc kept cutting and it didn’t glaze up, but if we want to reduce grinding time and keep more heat out of the workpiece then there is clearly a better option.

Labour cost:  Assuming labour is costed at £30 per hour (typical charge out rate) there is an immediate saving of £10 per hour in labour.

Disc cost:  Ceramic discs typically outlast zirconia discs by between 3 and 4 times.  If we assume an average zirconia disc will grind for one hour (many of our competitor discs don’t) then the abrasive cost (at list price)  is

Zirconia:  £1.86 / 1 hour    = £1.86 per hour

Ceramic:  £4.03 / 3 hours = £1.34 per hour     a saving of £0.52 per hour (£4.16 per day or £20.80 per week)

Which means that FTC 60 grit discs will save a minum of £10 + £0.52 = £10.52 per hour or over £400 per week!