Rheological properties of powdered milk

USE

Provides nutritional supplement for babies up to 12 months.

TEST EQUIPMENT

Instrument: powder flow tester (PFT)

Tray: 230 cc, 6 inches in diameter

Lid Type: Pallet Lid, 304 s / s, 33 cc, 6 inch diameter (Flow Function)

Wall cover, 304 s / s, 2B finish, 6 inch diameter (wall friction)

Test Type: Flow Function Test, Wall Friction Test

Temperature: Room temperature (70-72 ° F)

Humidity: 24 %

TEST METHOD

A Brookfield Powder Flow Tester, equipped with Powder Flow Pro software for automated instrument control and data acquisition, was used to test this branded infant formula. The formula was put into the trough and the scraping tool was then used to evenly distribute the powder throughout the trough. After recording the sample weight and entering it into the software, a standard flow function test and then a wall friction test were performed. The time required for each test was 35 minutes and 20 minutes, respectively.

MEASURED PARAMETERS

Fluidity Very cohesive to fluid

Wall friction 16.5º

Bulk density 440 kg / m³ (filling density) to 620 kg / m³ (12.5 kPa)

TO ANALYSE

Hopper shape Conical arc

Flow factor 1.40

Critical Arch Dimension 5.456 inches (136.4 mm)

Rat hole diameter Depending on the diameter of the tank

RESULTS

Figure 1 shows the fluidity of infant formula at different levels of consolidation stress. These results show that infant formula generally flows easily, except at low levels of consolidation stress where it begins to fall in the cohesive and very cohesive range (less than 3 kPa).

Figure 1: Baby Formula Flow Function

Figure 2 shows the friction angles of the walls at different levels of normal stress. Wall friction angles represent the friction between the sliding powder and the wall of the hopper or chute at the start of flow. In this test, a stainless steel cover was used, illustrating what the friction would look like if the formula were in a stainless steel hopper. The effective wall friction angle for this powder remained at a static value of 16.75 ° at all normal stress levels.

Figure 2: Friction of the wall of formula milk

Figure 3 shows the bulk density of the material at different levels of consolidation stress. This graph tells us that infant formula has a filling density of about 440 kg / ³ and amounts to about 620 kg / m³ at about 12.5 kPa of consolidation stress. In general, a free flowing powder will show very small changes in bulk density, while a cohesive or low flowing powder will generally show a large increase in bulk density.

Figure 3: Bulk density of infant formula

CONCLUSION

Baby formula is a very cohesive to cohesive powder at low levels of consolidation stress and flows easily at high levels of consolidation stress. This means that the formula may have problems with flow when the hopper empties. Possible issues include camber (when the powder forms a cohesive bridge over the outlet) and ratholing (when the powder only flows out of the center, leaving the rest of the material static against the walls). The critical arch dimension of 5.456 inches (136.4 mm) provides a conservative estimate to prevent arching, provided the minimum outlet dimension of the hopper exceeds this value. The critical dimension of the perforation depends on the diameter of the tank. Powder Flow Pro can automatically calculate the diameter of the rathole once the diameter of the bin is entered.