Exp. No	Experimental data		Normalized data		Value of ∆		Grey relational coefficients		Grey relational grade
Exp. No	COF	Wear rate (mm³/m)	Norm. COF	Norm. WR	∆Value COF	∆Value WR	ξ value COF	ξ value WR	Grey relational grade
1	0.5382	0.00469	0.3292	0.2166	0.6708	0.7834	0.427	0.3893	0.40821
2	0.4417	0.0044	0.6103	0.3221	0.3897	0.6779	0.5691	0.4245	0.4932
3	0.3355	0.00481	0.9194	0.1729	0.0858	0.8271	0.8612	0.3768	0.619
4	0.5802	0.00414	0.2067	0.4153	0.7932	0.5846	0.3866	0.46106	0.4238
5	0.4989	0.00466	0.4436	0.2256	0.5563	0.7743	0.4733	0.3924	0.4328
6	0.4761	0.00381	0.51	0.5347	0.4899	0.4653	0.5051	0.518	0.51157
7	0.5963	0.00528	0.1599	0	0.8401	1	0.3731	0.3333	0.3532
8	0.5633	0.00446	0.2561	0.3004	0.7438	0.6996	0.40199	0.4168	0.4094
9	0.5128	0.00379	0.4032	0.5433	0.5968	0.4566	0.456	0.5227	0.4893
10	0.6512	0.00442	0	0.3133	1	0.6867	0.3333	0.4219	0.3776
11	0.4965	0.00385	0.4506	0.5206	0.5493	0.4793	0.4764	0.5112	0.4938
12	0.4032	0.0046	0.7224	0.24644	0.2775	0.7535	0.643	0.3989	0.5209
13	0.4617	0.00483	0.552	0.1662	0.4479	0.8337	0.5274	0.374	0.4507
14	0.3842	0.00421	0.7775	0.3896	0.2224	0.6104	0.6921	0.4503	0.5712
15	0.3078	0.00369	1	0.5764	0	0.4236	1	0.5414	0.7707
16	0.5823	0.00395	0.2005	0.4842	0.7994	0.5157	0.3847	0.4923	0.4385
17	0.5069	0.00268	0.4203	0.9451	0.57967	0.0548	0.4631	0.40135	0.6822
18	0.4803	0.00339	0.4978	0.6856	0.50218	0.3143	0.4989	0.614	0.5564
19	0.4913	0.00378	0.4657	0.5467	0.5342	0.4532	0.4834	0.5245	0.5039
20	0.4284	0.00324	0.6489	0.7396	0.3511	0.26039	0.5832	0.6576	0.6225
21	0.3685	0.00253	0.8234	0.9999	0.1766	0.000069	0.7389	1	0.8694
22	0.4922	0.00402	0.463	0.4599	0.5368	0.5401	0.4822	0.4808	0.4815
23	0.4465	0.00426	0.5962	0.3726	0.4038	0.6274	0.5532	0.4435	0.4984
24	0.3825	0.00378	0.7827	0.544	0.2179	0.4559	0.697	0.5231	0.6101
25	0.50061	0.0044	0.4386	0.3204	0.5613	0.6793	0.4711	0.4239	0.4475
26	0.4787	0.00404	0.50246	0.4498	0.4975	0.5502	0.5012	0.4761	0.4887
27	0.4635	0.00421	0.5468	0.3883	0.4532	0.6117	0.5245	0.4449	0.48716