Standard Test Method for Measuring Rolling Friction Characteristics of a Spherical Shape on a Flat Horizontal Plane

Importancia y uso:

5.1 Rolling friction like sliding friction depends upon many factors. It is a system effect that involves the nature of the specimen and the rolling surface. The sliding friction force (F) is usually considered to be the sum of forces arising from deformations of surface features (F_s), from attractive forces (atomic, molecular, etc.) at contact points (F_a), and force from interaction of films and particulates on the rubbing surfaces (F_f):

The rolling friction force includes these force contributions plus effects from the relative stiffness of the contacting surfaces, the diameter (curvature) of the specimen, and other factors. Because there are so many factors involved in a rolling tribosystem, rolling resistance can best be quantified by an actual test of the specimen of interest on the intended rolling surface, as described in this test method.

5.2 There are countless applications where it is important to quantify the rolling characteristics of a particular spherical specimen on a particular rolling surface. The interlaboratory tests conducted for this test method were performed on hardened steel balls like those used in ball bearings. This test method could be used to assess the effect of different rolling surfaces on the rolling characteristics of balls for ball bearings. Conversely, it could be used as a quality control test on balls. Surface imperfections/defects/films, etc. on the balls can affect how they roll and thus the distance traveled on a common rolling surface.

5.3 Industrial applications of this test method can include assessing conveying surfaces for spherical or nearly spherical parts: check valve balls, cabinet knobs, Christmas ornaments, toilet floats, etc. Many medical devices use special shapes where rolling characteristics are a consideration. Similarly, many pharmaceutical products (pills) are spherical or nearly spherical in shape, and this test method can be used to assess rolling characteristics for conveying or other reasons such as size (mass) check.

5.4 Rolling friction of spherical specimens can be a consideration in countless sports (soccer, golf, lacrosse, etc.) and game applications (billiards, bocce, toys, etc.). This test method can be used to rank the rolling resistance of different ball compositions, masses, shapes, surface textures, design, stiffness, etc. Similarly, the test method can be used to assess the ease of rolling of balls on different playing or game surfaces.

5.5 This test method is applicable to spherical or mostly spherical food products. For example, it is common to use the rolling distance of apples, citrus fruits, nuts, etc. for size classification in marketing. These items are rolled down an angled surface and the rolling distance serves as a parameter for size determination (mass/diameter). Moreover, this test method can be used to assess the suitability of various rolling surfaces (such as carpet, metal, wood, etc.) for suitability in classification equipment. Additionally, it could also be used for food conveyance for spherical-shaped processed foods (gumballs, hard candy, meatballs, etc.)

5.6 Finally, this test method can be a valuable teaching tool for physics and tribology students. The equipment is simple, low-cost, and student proof. It can be used to demonstrate the concept of rolling friction and the factors that affect it.

Subcomité:

G02.50

Referida por:

G0115-24

Volúmen:

03.02

Número ICS:

17.040.20 (Properties of surfaces)

Palabras clave:

coefficient of rolling resistance; launch ramp; rolling friction; rolling surface; spherical specimens;