Tests of the metal-polymer friction units of the transport machines

RECORD

of the tribotechnical tests

Test Purpose

To detect impact from applications the solid-film coatings and greases onto the tribotechnical properties of the metal-to-polymer friction pair

Tests Conditions

The tests are held according to ASTM G99 standard on the sphere-disk scheme (see Fig.1) at sliding friction. The method described in the standard is used in the international practice to detect friction and wear parameters.

Friction pair geometrical parameters: a sample in the shape of disk of 80 mm diameter, and 0.8 mm thickness is a spherical counterbody of 10 mm diameter

Spherical counterbody material: POM (polyoxymethylene)

Sample material: AISI 430 steel, Ra=0.5 µm

Solid-film coating of the sample: see Appendix 3

Coating thickness: 25±5 µm

Grease: see Appendix 3

Weight of the grease to be applied onto the disk: 0.25 g

Sliding rate: V=0.8 m/s

Load: F=23.0 N

Brief description of the testing technique

Tests are held on the friction machine (see Fig.2), its Certificate is given in Appendix 1. This friction machine is equipped with NI LabVIEW data controlling and registering automated system.

The spherical counterbody is set into a holder (see Fig.3) and pressed with the given force F to the disk-shaped sample rotating with frequency n=310 revolutions per minute. In process of testing sliding friction force value is continuously registered, and friction coefficient value is automatedly calculated. Tests are kept up to accumulating the given friction path L=2,880 m. After the tests, linear wear of the spherical counterbody h is measured, and dimensionless wear intensity Ih=h/L is calculated.

Fig.1. Friction scheme at testing

Fig.2. Friction machine (a – general appearance, b – testing block)

Fig.3. Holder with a spherical a counterbody set in it

Tests Results

Table 1

Experiment number	Coating name of the sample	Lubricant name on the sample	Friction path L, m	Linear wear h, µm	Wear intencity Ih	Friction coefficient in stationary mode f
1	No coating	no	2880	750	2,60E-07	0,378
2	MODENGY 1014	no	2880	140	4,86E-08	0,190
3	MODENGY 1066	no	2880	170	5,90E-08	0,300
4	MODENGY 1009	no	2880	110	3,82E-08	0,160
5	MODENGY PTFE-A20	no	2880	80	2,78E-08	0,100
6	No coating	SHRB-4	2880	710	2,47E-07	0,220
7	No coating	Pilot lubricant No.1	2880	930	3,23E-07	0,240
8	No coating	Pilot lubricant No.2	2880	590	2,05E-07	0,220
9	No coating	Pilot lubricant No.3	2880	760	2,64E-07	0,180
10	No coating	Pilot lubricant No.4	2880	520	1,81E-07	0,270
11	No coating	Pilot lubricant No.5	2880	870	3,02E-07	0,250
12	No coating	Pilot lubricant No.6	2880	260	9,03E-08	0,130
13	MODENGY 1009	Pilot lubricant No.6	2880	110	3,82E-08	0,130
14	MODENGY 1009	Pilot lubricant No.2	2880	100	3,47E-08	0,090
15	MODENGY 1014	Pilot lubricant No.6	2880	60	2,08E-08	0,050
16	MODENGY 1014	Pilot lubricant No.2	2880	80	2,78E-08	0,090
17	MODENGY 1014	SHRB-4	2880	100	3,47E-08	0,095
18	MODENGY PTFE-A20	Pilot lubricant No.6	2880	50	1,74E-08	0,067
19	MODENGY PTFE-A20	Pilot lubricant No.2	2880	100	3,47E-08	0,110
20	MODENGY 1009	SHRB-4	2880	120	4,17E-08	0,130
21	MODENGY PTFE-A20	SHRB-4	2880	70	2,43E-08	0,150
22	No coating	Pilot lubricant No.7	2880	1360	4,72Е-07	0,150
23	No coating	Pilot lubricant No.8	2880	910	3,16Е-07	0,220
24	No coating	Pilot lubricant No.9	2880	330	1.15Е-07	0,170
25	No coating	Pilot lubricant No.10	2880	950	3.30Е-07	0,230
26	No coating	Pilot lubricant No.11	196,8*	340	1.73Е-06	0,300
27	No coating	Pilot lubricant No.12	1035,0*	530	5.12Е-07	0,300
28	MODENGY 1014	Pilot lubricant No.9	2880	50	1.74Е-08	0,080
29	MODENGY PTFE-A20	Pilot lubricant No.9	2880	50	1.74Е-08	0,060

 

Notes to Table 1

* - the tests were stopped because of overriding the marginal coefficient of friction with the lubricant f=0.3.

Fig.4. Samples with MODENGY 1014 coating on them before (on the left) and after (on the right) the tests

Fig.5. Samples with MODENGY 1009 coating on them before (on the left) and after (on the right) the tests

Fig.6. Samples with MODENGY PTFE-A20 coating on them before (on the left) and after (on the right) the tests

In Appendix 2, graphs of friction coefficient changing during the tests.

Experiment No.6 (see Table 1) is considered as the basic variant to be compared with – it’s the sample without any coating, SHRR-4 lubricant. The test results that exceed the basic variant on friction and wear factors in complex are gathered together in the Table 2 to make comparison them with it more convenient. Values of linear wear h, µm, and friction coefficient in stationary mode f are given in the table cells in the h/f format.

Table 2. Tests results assessment in comparison with the basic variant.

Grease Name	Coating Name
	No coating	MODENGY 1014	MODENGY 1009	MODENGY PTFE-A20
no	750/0,378	140/0,190	110/0,160	80/0,100
SHRB-4	710/0,220	100/0,095	120/0,130	70/0,150
Pilot lubricant No.2	590/0,220	80/0,090	100/0,090	100/0,110
Pilot lubricant No.6	260/0,130	60/0,050	110/0,130	50/0,067
Pilot lubricant No.9	330/0,170	50/0,080	-	50/0,060

Conclusions

The following has been established as the tests result:

1. Replacement SHRB-4 basic grease for the pilot lubricants No.2, 6, 9 enables to reduce wear of the counterbody by 1.2 to 2.7 times, and friction coefficient by down to 1.7 times;
2. Use of the solid-film coatings pointed in Table 2 on the sample instead of SHRB-4 grease enables to reduce wear of the counterbody by 5.1 to 8.9 times, and friction coefficient by 1.2 to 2.2 time depending on the coating name;
3. Use of the solid-film coatings pointed in Table 2 on the sample in addition to SHRB-4 grease enables to reduce wear of the counterbody by 5.9 to 10.1 times, and friction coefficient by 1.5 to 2.3 times depending on the coating name;
4. While being used in addition to SHRB-4 grease, the best on criterium of wear reduction is MODENGY PTFE-A20, and on friction reduction is MODENGY 1014;
5. It has been remarked that the solid-film coatings give more significant impact on improving friction and wear values in comparison with greases (see. points 1,2, 3);
6. By selecting optimal combination of a solid-film coating and a grease, it is possible to achieve wear reduction by up to 14.2 times (for example, MODENGY 1014 coating and Pilot lubricant No.9), and friction coefficient reduction by up to 4.4 times (for example, MODENGY 1014 coating and Pilot lubricant No.6).

Appendix 1

Appendix 2

Graphs of friction coefficient changing during the tests

Experiment No.1

Experiment No.2

Experiment No.3

Experiment No.4

Experiment No.5

Experiment No.6

Experiment No.7

Experiment No.8

Experiment No.9

Experiment No.10

Experiment No.11

Experiment No.12

Experiment No.13

Experiment No.14

Experiment No.15

Experiment No.16

Experiment No.17

Experiment No.18

Experiment No.19

Experiment No.20

Experiment No.21

Experiment No.22

Experiment No.23

Experiment No.24

Experiment No.25

Experiment No.26

Experiment No.27

Experiment No.28

Experiment No.29

Appendix 3

Performances of the greases under test

Grease Name	Basic oil type	Basic oil viscosity at 40°С, mm2/s	NLGI	Colour	Thickener	Lower limit of service temperatures, °С	Upper limit of service temperatures, °С	Anti-corrosive properties (EMCOR method)
SHRB-4	Mineral	32	2	Brown	Complex barium soap	-30	130	no data available
Pilot lubricant No.11	PAO	120	2	White	Calcium sulfonate	-40	140	0 - 1
Pilot lubricant No.12	PAO	50	2	Light brown	Compex aluminium soap	-45	170	0 - 1
Pilot lubricant No.9	PAO	25	2	Beige	Lithium soap	-60	120	0 - 1
Pilot lubricant No.3	PAO	48	1 - 2	Beige	Compex aluminium soap	-30	140	0 - 1
Pilot lubricant No.4	PAO	400	1 - 2	Beige	Polyurea	-30	180	0 - 0
Pilot lubricant No.2	Mineral	160	2	Black	Lithium soap	-20	120 ( 140)	0 - 0
Pilot lubricant No.6	PAO	32	2	Beige	Lithium soap	-50	140	no data available

Performances of the solid-film coatings under test

Coating Name	Polymerization Mode	Color	Fillers	Service temperatures °С	Corrosion resistance (hours in neutral salt mist acc. to ISO 9227)
MODENGY 1014	40 min. at 180°С	Grey	MoS2, PTFE	-75…+255	> 670
MODENGY 1009	30 min. at 120°С	Matt Black	PTFE	-100…+250	> 300
MODENGY PTFE-A20	30 min. at 20°С	Translucent White	PTFE	-50…+130	> 160