Particle size of powder produced by coffee grinder and its influence

Release time:

2025-11-13

Coffee grinders are widely used in our powder factory for experimental prototyping. Within seconds, they can produce dozens of grams of powder sufficient to spray several sample plates, offering rapid and convenient processing. The ground coffee powder is sieved through different mesh sizes (140,160,180, and 200) using laser particle size analyzers to measure particle distribution. These results are then sprayed onto plates for comparison with mill powder production, providing industry benchmarks. For outdoor matting powder testing, we utilize Wuhan Yincai's Outdoor Physical Matting Agent L2018C.

Particle size of powder produced by coffee grinder and its influence

Wang Yuhao, Li Zhongliang (Wuhan Yincai Technology Co., LTD.)

 

 

I. Introduction

Coffee grinders are widely used in our powder factory for experimental prototyping. Within seconds, they can produce dozens of grams of powder sufficient to spray several sample plates, offering rapid and convenient processing. The ground coffee powder is sieved through different mesh sizes (140,160,180, and 200) using laser particle size analyzers to measure particle distribution. These results are then sprayed onto plates for comparison with mill powder production, providing industry benchmarks. For outdoor matting powder testing, we utilize Wuhan Yincai's Outdoor Physical Matting Agent L2018C.

                                                 Figure 1: Coffee grinder and sampling sieve

 

 

II. EXPERIMENTAL PREPARATION

2.1 Main experimental materials

Matting agent, leveling agent, Benzoin (Wuhan Yincai Technology Co., LTD.), polyester, curing agent (TGIC), pigment (carbon black), filler (barium sulfate).

2.2 Main experimental equipment

Extruder, coffee grinder, grinder, particle size meter, spray gun, sieve mesh, oven, 60 ° gloss meter, film thickness meter.

2.3 Powder formulation

 

Table 1 matting powder raw material ratio

Name of raw material

percentage 

 Polyester 

55

TGIC

4.7

Outdoor matting agent L2018C

5.0

Benzoin L307

0.5

Leveling agent L88

1.0

 Pigment 

1.0

Matting Barium Sulfate

32

Total amount 

100

 

III. Experimental Results and Discussion

3.1 Sample preparation

Mix 1kg of the powder according to the formula from table 1. After mixing and compressing into tablets, the mixture was crushed to obtain 657g of powder. The sample was divided into four portions: Sample E (163 g), Sample F (161 g), Sample G (162 g), and Sample H (167 g). Sample E was sieved through a 140-mesh to obtain 45g of fine powder, Sample F through a 160-mesh to obtain 38 g, Sample G through a 180-mesh  to obtain 36 g, and Sample H through a 200-mesh sifter to obtain 31 g.

 

3.2 Particle size distribution of sample powder sieved by different mesh

 

Table 2: Distribution of different sieve sizes

 

 Number 

D50 um

D10 um

D90 um

Production of D90 grinding wheels

Sample E, 140 mesh

43.24

9.27

109.5

85.91

Sample F, 160 mesh

35.30

7.33

95.30

68.86

Sample G, 180 mesh

35.70

8.00

88.61

68.95

Sample H, 200 mesh

28.95

8.21

63.15

48.34

 Results and discussion ：

(1) As can be seen from the test results, the 160 mesh coffee powder sieved by grinding has a D50 of 35 microns, which is appropriate.

When we make a sample, we can use a 160 mesh sampling sieve. If we use a 180 mesh and 200 mesh sampling sieve, it will be slower.

(2) The difference between manual coffee grinding and large grinding machine grinding is mainly in D90. The coarse particle part of the powder ground by coffee grinder is significantly larger than that of the production large grinding machine, while the difference between D10 is not significant.

3.3 Spray plate inspection

Four kinds of sample powder EFGH were sprayed on three plates with different thicknesses, the film thickness was controlled at 60-70um, 70-80um and 80-90um respectively, a total of 12 plates; the oven was baked for 200℃15 minutes.

 Thickness 

 Project 

Sample E 140 mesh

Sample F 160 mesh

Sample G 180 mesh

Sample H 200 mesh

60-70um

Gloss%

leveling

12.3 Relatively flat

12.3 Relatively flat

13.0 Relatively flat

13.0 Relatively flat

70-80um

Gloss%

leveling

13.2 Leveling

13.5 Leveling

13.5 Leveling

13.8 Leveling

80-90um

 Gloss%

More flow-able

12.6 Relatively flat

12.7 Relatively flat

13.2 Relatively flat

13.2 Relatively flat

 Results and discussion ：

(1) The sieve plate of different mesh number (140 mesh to 200 mesh) has similar surface leveling.

(2) Among different film thicknesses of 60-70/70-80/80-90 um, the film thickness of 70-80 microns has better leveling than the other two.

(3) Different mesh number and different film thickness have no effect on the gloss (the slight difference in gloss in the table is normal).

(4) The above results are the conclusions drawn from the test of L2018C outdoor matting powder, which may not be suitable for other types of powder.

                                                       Figure 2: Sample diagram

 

IV. CONCLUSIONS

l For daily test and inspection, grind coffee samples into powder with a 160 mesh is suitable, which is fast to sieve.

l The powder ground by the coffee mill is similar to that of the large mill, D50 and D10 are similar, and D90 is larger, 30%-50% larger.

l For L2018C outdoor matting powder, the difference in surface leveling in different sieve mesh  is not significant, but the film thickness has a greater impact on surface leveling.

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