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Grinding-Health and Safety continued

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Grinding-Health and Safety continued

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Controlling Exposure By Filtering Coolant

Grinding Coolant Analysis (particles per cubic centimeter)

 

Shop 1

Shop 2

 

 

Size Microns

Dirty Coolant

Dirty Coolant

Filtered 

Unused

<1

73,305

0

17,209

0

1

87,647

140,317

25,575

11

2

117,607

14,382,515

21,432

1,049

3

57,688

15,364,737

9,720

1,935

4

43,346

19,644,411

4,223

3,367

5

151,391

13,751,087

2,550

3,618

6

59,919

9,120,620

1,673

1,181

7

6,693

1,894,282

558

372

8

3,187

631,427

239

142

9

2,868

420,952

80

55

10

1,594

280,634

478

66

11

956

0

319

22

12

 

140,317

0

0

13

 

70,159

159

22

14

 

70,159

0

0

15

 

140,317

80

11

16

 

70,159

0

29

17

 

65,774

32

5

18

 

85,506

112

 

19

 

26,309

80

 

20

 

 

48

 

21

 

 

16

 

Totals

606,200

76,299,682

84,583

11,885

  

 

TCLP

 

 

 

Federal

metals

Coolant

Dirty

Filtered

Unused

disposal 

Cobalt mg/L

 

3,210

299

0.138

maybe none

Arsenic

<0.1

<.05

<0.1

<.05

<.05

Barium

0.206

<.02

0.421

0.702

0.143

Cadmium

0.086

0.06

0.038

<.003

<.003

Chromium

0.28

<.07

0.024

<.007

<.007

lead

0.12

<.04

0.09

<.04

<.04

Mercury

<0.001

<.001

<.001

<.001

<.001

Selenium

0.354

<.8

<.16

<.08

<.08

Silver

<0.01

<.07

<.014

<.007

<.007

 

 

 

 

 

 

 

 

 

 

 

 

 

 

When and Why to Filter

In grinding operations you want to filter out all the particles that are larger than 10% of the grit size of the wheel, or 10% of the tightest dimension specified.  A way to explain this is the tire and 2x4 analogy.  An automotive tire is about twenty inches in diameter.  If you run over the two-inch dimension (10%) of a 2x4 you will feel a bump. The little divider bumps (wake-up bumps, turtles) in roads are generally much less than an inch and you sure feel those.   If particles of any size come between the tool and the work it will tend to damage both the tool and the surface of the work.  The same way that a rock in your shoe will try to make a hole in both your foot and the shoe.  

Machine damage is much harder to quantify.  One way of determining acceptable particle size is to ask; what grit sandpaper you would allow to be used on the hydraulic cylinders of the machine?  As the coolant gets sprayed it gets on extended hydraulic cylinders, and is then abraded as the cylinder moves in and out.

Filtering in Carbide Tool Grinding Operations

If you use wheel grit      Wheel   grit size             Filter to this level
(Sieve) Size                         in microns                    in microns
100                                        150                              15
200                                          75                                7
400                                          38                                4
635                                          20                                2 
  
Comparison of Sumps    
  Filtered Sump Unfiltered Sump
Surface Clean 1 - 2% Tramp oil
Mixture 10% coolant 5 - 7 % coolant
Added chemicals None Bactericides & Fungicides
Growths None Bacteria colonies, Algae blooms
Sump Bottom Clean 10 - 15%  sludge
Metal Contamination All under 0.001% Arsenic, Barium,  Lead
    Cadmium, Chromium, Mercury
    Selenium, Silver 
    (Dissolved & Chelated metals)    

 

 

 

 

 

 

  

  

 

Benefits of managing coolants

 1.  Chunks of diamond and carbide - The CP 2020 removes the chunks of diamond and carbide as well as oils and grease.  If you leave the carbide and diamond in the coolant then they get between the wheel and the Carbide.  This breaks down the diamonds and the carbide. With dirty coolant there is more dressing, the grinds are worse and wheel life is shorter.

2.  Oil, grease and used coolant – New coolant is made to form very small droplets.  As the coolant gets used the droplets get bigger.  There can also be hydraulic fluid, oil off saw bodies and similar products.  These clog the diamond wheel.  They also feed bacteria which further helps to break down coolant.  The blobs of dirty coolant, oil, etc. are large enough and sticky enough to get trapped in the filters.  

The savings in proper cleanliness, general maintenance as well coolant management and filtering can be as high as 20% of the annual expenses in the following areas. 

Make more money 
1.         Longer Machine Life
2.         Longer time between rebuilds
3.         Less downtime
4.         Less equipment replacement
5.         Faster operation 
6.         Faster cycle times
7.         Fewer tool replacements
Better quality 
9.         Measured as the smoothness of the worked surface
9.         Measured in SPC consistency 
10.        Produce better overall quality work
11.        Reduced rework
12.        Reduced scrap
13.        Tighter tolerances
Greater Lubricity with clean coolant
14.        No burning
15.        Clean coolant will also help prevent problems with heating of the tools.
16.        Less heat during machining therefore less change in surface condition 
17.        Smoother cuts and grinds
Reduced consumable costs 
18.        Longer tool run life per sharpening
19.        Longer tool life
20.        Longer coolant life
21.        Longer grinding wheel life
22.        Less dressing required
23.        More parts per dollar of raw material
Reduced Labor 
24.        Less machine maintenance
25.        Less tool maintenance
26.        Less finishing required
Cleaner workplace
27.        Perhaps increased operator safety  
28.        Retards bacteria growth
29.        Eliminate smells
30.        Help eliminate noise
Fewer problems than shops that use dirty coolants.   
31.        Less OSHA exposure
32.        Less EPA exposure
33.        Less waste
34.        Cleaner waste
35.        Lower coolant disposal or recycling costs
36.        Reduces non-coolant waste and waste disposal costs

 

Reduce Diamond Wheel Costs  save $3,000 to $10,000 per year

A good grinding operation will still dump huge amounts of oil and grease into the sump. We ran a test on a high production machine. In twenty-two days of double shift we pulled out about ten pounds of oil and grease.  This oil and grease clogs the wheel. Clogged wheels mean slower grinds, worse quality, and shorter wheel life. Clean coolant increases diamond wheel life by at least 30% overall, and as much as 50% depending on the wheel and the application. This is a saving of 25% to 35% in annual diamond wheel cost. Removes oils and greases. 

Longer Coolant Life - Save $1,000 a year per machine + the saving in labor.

If you filter your coolant, you will get much longer life. In actual tests we see coolant last six months and it is still doing an excellent job. This saves you on coolant costs, and the maintenance of sump cleaning and coolant changing.  

West Coast Saws in Tacoma, WA has been running our filter units for three years on five machines with a unit full time on each machine. They estimate that they save $5,500 a year in coolant costs not counting the tremendous saving in labor from fewer cleanings and coolant changes. 

Increase Machine Life - Save $2,000 to $8,000 per year

The big advantage in clean coolant is that it protects the machine. Dirty coolant can shorten machine life by 5% to 7% a year. Saw and tool grinding generates a huge amount of very small, very abrasive particles. These particles get into the coolant and then are sprayed all over. 

These particles get into controls, cylinders, rods and bearings where they increase wear and reduce quality. The CP 2002 removes particle down to one micron, and removes them with incredible efficiency. 

Removing Cobalt (free & chelated) From Saw Grinding Coolant 

Test of Cobalt remover

The cobalt remover looks and flows about like honey.  It removes metals chemically as well as physically binding very fine particles into a larger, filterable mass.  You will want to use it before a filter change as it plugs up filters.   However it I easily removed and will not cause problems with the new filters.   

Background: Coolants typically dissolve the cobalt matrix out of tungsten carbide during saw sharpening.    This situation can be greatly improved by coolant filtering.  However coolant filtering also means that coolants will only be changed once or twice a year.  

Laboratory tests show that there can be considerable coolant chelated (dissolved) in coolant after six months.  This is also visible with clear coolants as the cobalt typically imparts a reddish tinge.  

Test Procedure:  We took 1 liter of coolant that had been filtered constantly at the grinder using a 25-micron bag followed by a ten-micron cartridge filter.  We filtered this with a vacuum filtration setup using a filter paper in the 1 - 2 micron range and got a good coating of grit on the filter paper.  We then added the cobalt inhibitor and filtered using a 30-micron filter.  We got a huge amount of material out.  The filter cake was about as thick as a penny.  Finally we filtered the coolant with a filter in the 1 - 2 micron range and got a nice covering on the filter paper.  

We received one liter of coolant that the saw mill said was “used but clean”.  First, we filtered it and got 2.4 grams of sludge.  Then we added cobalt remover and filtered again.  We got another 6.8 grams.  Finally we used a fine filter (equivalent to our CP 2002 series filter units and got another 2.3 grams. 

The saw mill said the coolant was “Used but clean.”   We filtered out 11.5 grams from 1 liter.   9.1 grams of that came from the use of cobalt remover. 

Test Results: The first filtering got out all the very fine grit.  The cobalt inhibitor extracted the cobalt from the coolant and formed it into large, sticky clumps that could be readily filtered out.  The results are very visible.


b2b lead generation