Ball indenter

Hardness is essentially a measure of stiffness and in principle can be related to modulus. For plastics, the term hardness refers to resistance to indentation but depending on the test method the measurement is made either with the indentation load applied or after its removal when elastic recovery has taken place. The standard methods are given in ISO 868 (Shore) [6] and ISO 2039 (Ball indentation and Rockwell) [7]. However, Vickers microhardness is more satisfactory for monitoring degradation of rigid materials. 

ISO 2039-1 2001 Plastics - Determination of hardness - Part 1 Ball indentation method ISO 2039-2 1987 Plastics - Determination of hardness - Part 2 Rockwell hardness ISO 2439 1997 Flexible cellular polymeric materials - Determination of hardness (indentation technique)... 

The pin Brinell tester takes the form of a large C damp with the ball indenter on the end of the screw. Load is controlled by a built-in shear pin. A modification of this device employs impact loading by a hammer to achieve similar results. 

The Brinell test range is limited, by the capability of the hardened steel ball indenters used, to HBN 444. This range can be extended upward to HBN 500 by using special cold work-hardened steel balls and to as high as HBN 627 by using special tungsten carbide balls. 

PC 2765-70, 1972, SEV. Gruppa 29 (CMEA, Group 29). Izmerenie tverdosti po metodu vdavlivaniya sharika (Hardness Measurements by Ball Indentation Method). 

Polymer Izod impact strength (j/m) 7f> (K) hard ness Ball indentation hardness (107 N/m2) Shore D hardness Friction coefficient (-) resistance (ASTM- D1044) (Taber) (mg/lOOOc) Abrasion loss factor (DIN 53516) (mg) Polymer ref. nr. in figures (cf. Table 13.12) ... 

Figure 16.13 Resistance against environmental stress cracking by 2-propanol (ball indentation test ISO 4600,1 h exposure)...

Contact problems have their origins in the works of Hertz (1881) and Boussinesq (1885) on elastic materials. Indentation problems are an important subset of contact problems (17,18). The assessment of mechanical properties of materials by means of indentation experiments is an important issue in polymer physics. One of the simplest pieces of equipment used in the experiments is the scleroscope, in which a rigid metallic ball indents the surface of the material. To gain some insight into this problem, we consider the simple case of a flat circular cylindrical indentor, which presents a relatively simple solution. This problem is also interesting from the point of view of soil mechanics, particularly in the theory of the safety of foundations. In fact, the impacting cylinder can be considered to represent a circular pillar and the viscoelastic medium the solid upon which it rests. 

Now we consider roller ball indentations. Let us consider first a rigid ball that does not roll but indents a viscoelastic half-space this analysis will be extended to a rolling ball. This is a typical situation in which the elastic-viscoelastic analogy is, in general, no longer applicable. 

Static-ball indenter correspond directly. The scratch test is used where indentation microhardness tests cannot be made close enough to determine local variations. Typical microhardness values for polymers are summarized by Boor (1947). 

Unhke other Rockwell scales, Rockwell parameter, R, correlates with the hardness as determined by ball indentation. Fett [1972] has shown that ... 

BS 2782 Method 365D, Determination of Hardness by Ball Indentation Method, London (1978). 

There are four major indentation hardness tests, which differ from each other in the shape of the indenter (Figure 10.23). The first of these, described in 1900, was the Brinell test, using a 10 mm steel ball indenter (Figure 10.23a), giving the Brinell hardness number, BHN. This was suitable only for metals softer than steel. In 1920 Rockwell developed a number of tests, including the B, E, F and G scales, in which the indenter is steel, and the A, C and D scales, using a conical diamond indenter with a spherical tip (Figures 10.23b and 10.23c). In the Rockwell test the difference in size between the... 

A test more frequently found in Continental Europe than in the U.K. or the U.S.A. is the ball indentation hardness test, which is standardized in ISO 2039. Part 1 [5], also dual numbered as BS 2782. Method 365D [6]. In this a 5 mm diameter hardened steel ball is pressed into the test surface under a specified load so that the indentation is between 0.07 and 0.10 mm for method A. or between 0.15 and 0.35 mm for method B. The time of application of the load is 30 seconds, and a minimum test piece thickness of 4mm is recommended. Unlike the Shore or IRHD scales, vvherc hardness is directly related to the penetration of the indentor. the ball indentation hardness is given by ... 

In ISO 2039. Part 2 [7] the Rockwell hardness test is described. This is based on the same principle as the ball indentation hardness, but due to the severity of the test in terms of the load applied and the ball diameter through which the load is applied to the test piece, the test is really only suited to the harder thermoplastics and thermosets. Several hardness scales are defined according to the ball and load used. Table 1 illustrates the defined scales in the ISO standard. 

ISO 20.79-1, Plastics—Determination of hardness—Part 1 Ball indentation hardness, 199.V... 

Hardness refers to the resistance of steel to indentation. The three important methods to determine the hardness are (1) the Brinell test, (2) the Vickers test, and (3) the Rockwell test. All these methods use the same basic principle wherein a ball or a pointed indenter is forced onto the material surface under a given load and the area of indentation thus created is measured. The Brinell test uses a 10-mm-diameter tungsten ball indenter under a load of 29,420 N. The Rockwell C hardness test uses a diamond cone indenter under a load of 1471 N. The Vickers test uses a diamond pyramid indenter, and the load varies. The greater the hardness of a material, the smaller the area of indentation. 

Vickers Ball indentation hardness) Poldi hammer... 

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