Quality standards of steel grinding balls. What to use DSTU 3499-97 or DSTU 8538: 2015?

Stas

8 years ago

01.07.2016 new standard regulating the quality of grinding balls DSTU 8538: 2015 entered into force.

In order to understand how to changed the requirements for the production of grinding balls, we decided to display them in a comparative table:

1. CLASSIFICATION AND DIMENSIONS

DSTU 3499-97

Rated diameter, mm	Nominal diameter, mm	Limit deviations from the nominal diameter, mm	Volume, сm³	Weight, кг
15 20 25	15,0 20,0 25,0	± 1,0	1,76 4,18 8,18	0,014 0,033 0,064
30 35 40 45	31,5 36,5 41,5 46,5	± 2,0	16,4 25,4 37,4 52,6	0,128 0,199 0,294 0,413
50 60 70 80	52,0 62,0 73,0 83,0	± 3,0	74,0 125,0 204,0 299,0	0,580 0,980 1,600 2,350
90 100	94,0 104,0	± 4,0	435,0 589,0	3,410 4,620
110 120	114,0 125,0	± 5,0	776,0 1023,0	6,090 8,030
Note: 1. Deviations from the ball geometric form shall not exceed limit deviations from the nominal diameter. Note: 2. Calculation of ball volume and weight is performed using values of nominal diameter provided that the steel density is 7.85 g / cm3.

DSTU 8538:2015

Claim 4

Table 1 without the calculated data that are presented in Attachment A

Rated diameter, mm	Nominal diameter, mm	Limit deviations from the nominal diameter, mm
15 20 25	15,0 20,0 25,0	± 1,0
30 35 40 45	31,5 36,5 41,5 46,5	± 2,0
50 60 70 80	52,0 62,0 73,0 83,0	± 3,0
90 100	94,0 104,0	± 4,0
110 120	114,0 125,0	± 5,0
Note. Calculated parameters – nominal mass, surface area, volume and the number of balls per one ton are given as reference in Appendix A.

2. TECHNICAL REQUIREMENTS

DSTU 3499-97

Hardness, Table 2

Ø	Group of hardness
	1	2	3	4		5
	Surface hardness	Surface hardness	Surface hardness	Surface hardness	½ R	Surface hardness	Volumetric hardness
15-70	43	49	55	55	45	65	64
80-100	40	42	52	52	40	64	62
110-120	35	38	50	50	35	63	61

Table 3

Ø	Group	Carbon,%	Equivalent,%
15-60	1,2	0,40	0,50
15-60	3,4,5	0,60	0,75
70-120	1,2	0,60	0,70
	3,4	0,60	0,75
	5	0,65	0,80

Also the balls of the 2nd, 3rd, and 4th groups can be manufactured from steel in accordance with GOST 5950.

DSTU 8538:2015

Claim 5

Hardness, Table 2

Ø	Group of hardness
	1	2	3	4		5
	Surface hardness	Surface hardness	Surface hardness	Surface hardness	½ R	Surface hardness	Volumetric hardness
15-45	45	49	55	55	45	61	57
50-70	43	48	53	53	43	60	53
80-100	39	42	52	52	40	58	48
110-120	35	38	50	50	35	56	43

The same test method should be used for monitoring of hardness between the manufacturer and the consumer.

Table 3

Ø	Group	Carbon,%	Equivalent,%
15-55	1,2	0,40	0,50
	3	0,60	0,70
	4,5	0,60	0,75
60-70	1,2	0,50	0,70
	3,4	0,60	0,75
	5	0,60	0,80
80-120	1,2	0,50	0,70
	3,4	0,60	0,75
	5	0,60	0,85

Claim 5.1.6. The balls can be manufactured from steel in accordance with DSTU 3953 (GOST 5950) and GOST 14959

Claim 5.1.8 Balls of the 4 and 5 groups of hardness can be shipped with the control impact resistance by agreement with the consumer and manufacturer. Impact resistance control procedure performed by the manufacturer.

3. ACCEPTANCE RULES

DSTU 3499-97

The repeat check allows two grinding balls do not appropriate for the hardness.

Choose 3 balls of each twentieth installment for templates to control hardness of the 5 and 4 groups

DSTU 8538:2015

Claim 8

The quality document must have information about:

– The weight of shipped products

Choose 2 balls of every installment for templates to control the hardness of 5 and 4 groups

Claim 8 4. The chemical composition of steel is determined by the incoming inspection of the steel billet or as a result of melting analysis. The chemical composition of the steel is not monitored for the grinding balls.

Claim 8 5. Quantity of balls and acceptance rules determined by the method of the manufacturer for the control of impact resistance.

4. CONTROL METHODS

DSTU 8538:2015

Claim 9

Added:

Claim 9.3.2.1. Cutting technology of grinding ball must exclude its heating above 100 ° C in order to avoid distortions of hardness measurements

Claim 9.5 Tests to control for impact resistance of grinding balls are carried out on the manufacturer’s procedure.

The table shows that in the updated quality standard appeared conception of impact resistance, which is important in the manufacturing of grinding media. Checking grinding balls to impact resistance ensures their use without the risk of splitting, which leads to an increase in the specific consumption of balls, deterioration in the quality of grinding, clogging grates and slitting the rubber mill lining.

However, DSTU 8538: 2015 contains a less stringent quality requirements for balls of 5th group of hardness because just specialists of the company “Energosteel” have managed to perform the old DSTU 3499-97 requirements for the balls of the 5th group of hardness in Ukraine.

Regarding the application of requirements the new DSTU, there is an ambiguous situation arises due to the fact that:

Firstly, DSTU 8538: 2015 is the national standard. As is known, national standards shall be solely voluntary application by reference to the new DSTU in contracts (ext. Agreements, specifications), and guidance on the quality certificates for the labeling of products.
Secondly, DSTU 8538: 2015 approved by order of the State Enterprise “UkrNIUTs” rather than the law of Ukraine, or the act of the Cabinet of Ministers of Ukraine or the central executive agency. This means that the new standard does not have the status of a technical regulation. Therefore, the compliance of products with the requirements the new DSTU is not a subject of public market surveillance.

Given all the above stated, the choice of a DSTU for supply grinding media depends on the buyer’s requirements and the manufacturer’s capabilities.

Thus, the company “Energosteel” has the ability to manufacture and supply of steel grinding balls by the old DSTU 3499-97 and by the new DSTU 8538: 2015, depending of customers needs, because the production technology and equipment of company “Energosteel” allow to produce grinding balls of the 5th group of hardness with a more and with a less strict requirements for quality of steel grinding balls for ball mills.