Effects of Friction Plate Hardness and Surface Orientation on the Frictional Properties of Cereal Grain

Table 3

The angle of static friction of cereal kernels and the significance of differences in angle values.

Cereal species	Plate hardness HV30	Angle of static friction (°) of cereal kernels on plates with different surface orientations
		Parallel			Perpendicular
		min.	max.	Average	min.	max.	Average
Barley	311	13.3	20.7	16.9^aAB	20.0	27.3	23.5^bC
	380	14.3	18.7	16.2^aA	19.0	25.3	22.0^bB
	478	15.0	23.0	17.3^aBC	17.7	23.7	21.1^bA
	554	14.3	24.0	16.6^aA	17.0	28.7	20.8^bA
	611	14.7	26.3	17.7^aC	16.7	26.0	20.8^bA
	655	14.7	20.0	16.3^aA	18.0	26.7	21.3^bA
Oats	311	13.7	18.7	16.4^aA	17.7	26.3	22.7^bAB
	380	14.0	19.7	16.1^aA	19.7	27.7	23.0^bB
	478	15.0	20.7	17.2^aB	17.7	27.0	22.0^bA
	554	13.7	28.0	17.4^aBC	18.7	27.0	22.1^bAB
	611	15.3	23.0	18.1^aC	19.3	34.3	22.3^bAB
	655	14.0	25.7	17.4^aBC	19.3	31.7	22.2^bAB
Rye	311	13.7	20.3	17.6^aD	20.7	28.3	23.4^bD
	380	14.7	21.7	16.9^aC	18.3	26.3	22.1^bC
	478	14.3	22.7	16.6^aBC	18.0	24.7	20.8^bAB
	554	13.3	23.7	16.1^aAB	18.3	25.3	20.6^bAB
	611	14.0	18.0	16.0^aA	17.7	28.3	21.3^bB
	655	14.0	19.6	16.6^aBC	17.3	24.7	20.3^bA
Wheat	311	15.0	23.3	18.1^aE	18.7	25.7	21.5^bB
	380	13.0	19.0	16.0^aB	19.3	25.3	21.5^bB
	478	14.3	22.7	17.3^aD	17.7	27.0	20.9^bB
	554	13.3	21.3	16.1^aBC	16.3	24.7	19.5^bA
	611	14.0	19.7	16.7^aC	19.7	27.7	22.3^bC
	655	13.7	19.3	15.4^aA	20.7	33.0	24.1^bD

^a,bSignificant differences between the average angle of static friction of cereal kernels on friction plates with identical hardness and different surface orientations are marked with different letters; ^A,B,C,D,Esignificant differences between the average angle of static friction of cereal kernels on friction plates with an identical surface orientation and different hardness are marked with different letters.