The Akron abrasion test is a standardized laboratory method for determining the abrasion resistance of vulcanized rubber by measuring the volume lost when a rotating rubber wheel is rubbed against an abrasive grinding wheel under a controlled load and slip angle. Conducted in accordance with GB/T 1689 and comparable international abrasion standards, the test delivers quantitative abrasion volume data that support compound development, quality control, and material qualification for tires, conveyor belts, footwear, and other rubber products. This article explains the test principle, specimen requirements, operating parameters, calculation method, and typical industrial applications of Akron abrasion testing.
Technical Overview
The Akron abrasion test evaluates the resistance of vulcanized rubber to abrasive wear under rolling-sliding contact conditions. In this method, a wheel-shaped rubber specimen is mounted with its axis inclined at a defined angle relative to the axis of a driven abrasive grinding wheel. The specimen is pressed against the grinding wheel under a specified load, and because the two axes are not parallel, a controlled degree of slip is generated at the contact interface. This slip produces progressive abrasion of the rubber surface, simulating the wear mechanism experienced by many rubber products in service.
The primary result of the test is the abrasion volume, calculated from the mass lost by the specimen during the test and the density of the rubber compound. A smaller abrasion volume indicates higher abrasion resistance. In China, the method is specified in GB/T 1689, which defines the apparatus, specimen geometry, test conditions, and calculation procedure. The Akron method is complementary to other internationally recognized abrasion tests, such as the rotary drum (DIN-type) method described in ISO 4649, GB/T 9867, and ASTM D5963, the Pico abrasion method in ASTM D2228, and the NBS ribbon abrader method in ASTM D1630. Because the contact geometry and wear mechanism differ between these methods, results are not directly interchangeable, and the test method must always be reported together with the result.
Key operating parameters of a typical Akron abrasion test include an inclination angle of 15 degrees between the specimen axis and the grinding wheel axis, an applied load of approximately 27 N (2.75 kgf), and a specimen wheel speed of approximately 76 revolutions per minute. The abrasive wheel is dressed at defined intervals to maintain a consistent cutting surface, and specimens are pre-ground before the measured run to remove surface skin and stabilize the wear condition.
Testing Samples
Molded Vulcanized Test Wheels
The standard specimen for the Akron test is a wheel-shaped test piece, typically about 68 mm in outer diameter with a width of approximately 12.7 mm, vulcanized directly onto or securely fastened to a metal hub. The wheel is molded from the rubber compound under test using the compound's established curing time and temperature. The running surface must be smooth, free of porosity, blisters, cracks, and mold defects, and concentric with the axis of rotation to ensure uniform contact pressure during abrasion.
Specimens Taken from Finished Products
Material cut from finished goods such as tire treads, belt covers, or footwear soles can also be evaluated, provided that sufficient thickness of dense rubber is available. Cut material is ground to the required wheel geometry and bonded or clamped to a hub. Where the original product surface is of interest, the as-received surface may be retained; otherwise, a defined amount is removed by pre-grinding so that the bulk compound is tested rather than surface contamination or finish layers.
Specimen Conditioning
Before testing, specimens are conditioned in a standard laboratory atmosphere, typically 23 °C ± 2 °C and 50% ± 5% relative humidity in accordance with GB/T 2941 / ISO 23529. Specimens are protected from light, heat, and ozone contamination. The density of each compound is determined separately, usually in accordance with GB/T 533 / ISO 2781, because density is required to convert the measured mass loss into abrasion volume.
Testing Items
The Akron abrasion test and its associated test program commonly include the following reported items:
- Abrasion volume (volume loss), expressed in mm³ or cm³, often normalized to a reference travel distance of 1.61 km
- Mass loss of the specimen over the measured test run
- Abrasion resistance index or relative abrasion resistance, comparing the test compound with a reference compound tested under identical conditions
- Comparative abrasion ranking of multiple compounds or batches
- Visual assessment of the abraded surface, including checks for abnormal wear patterns, tearing, or smearing
Testing Methods
Apparatus and Test Conditions
The test is performed on an Akron abrasion machine consisting of a specimen wheel spindle, a driven abrasive grinding wheel of specified grit and grade, an inclination adjustment mechanism, a loading system, a revolution counter, and a dressing device for renewing the abrasive surface. Typical test conditions per GB/T 1689 include an inclination angle of 15°, an applied load of approximately 27 N, and a specimen wheel speed of approximately 76 r/min. The test run length is expressed in revolutions of the specimen wheel and is selected according to the standard and the expected wear rate of the compound. An analytical balance with a resolution of 0.001 g is used for all mass determinations.
Test Procedure
The general sequence of an Akron abrasion test is as follows:
- Prepare or obtain the conditioned wheel specimen and record its identification, compound, and cure details.
- Dress the grinding wheel to restore a fresh, uniform abrasive surface.
- Pre-grind the specimen for a preliminary period to remove the molded surface layer and stabilize the contact condition, then brush off all debris.
- Weigh the specimen accurately and record the initial mass m1.
- Mount the specimen on the machine, set the inclination angle and applied load, and run the test for the specified number of revolutions.
- Stop the machine, allow the specimen to cool to ambient temperature, remove loose debris, and reweigh to obtain the final mass m2.
- Repeat the test on replicate specimens, commonly three, and report the median result.
- Dress the grinding wheel between specimens or at the intervals specified by the standard to control abrasive sharpness.
Calculation of Abrasion Volume
The abrasion volume is calculated from the measured mass loss and the density of the rubber compound using the relationship V = (m1 − m2) / ρ, where V is the abrasion volume, m1 and m2 are the initial and final specimen masses in grams, and ρ is the compound density in g/cm³. The result may additionally be normalized to a reference travel distance of 1.61 km where required by specification. Where a reference compound is tested in parallel, the relative abrasion resistance is calculated as the ratio of the reference compound's volume loss to the test compound's volume loss, frequently expressed as a percentage index. The test report should identify the standard used, the test conditions, the specimen description, the density value applied, individual and median results, and any deviations observed during testing.
Applications
Tires and Automotive Rubber Components
Akron abrasion data are widely used to evaluate tread compounds, sidewall compounds, and other wear-exposed automotive rubber parts. Abrasion resistance correlates strongly with tread wear life, making the test a key screening tool for compound formulation, filler selection, and batch-to-batch consistency control in tire manufacturing.
Industrial Rubber Goods
Conveyor belt cover compounds, V-belts, hoses, rubber rollers, bushes, and seals are frequently qualified using Akron abrasion results. For conveyor belts in mining and bulk material handling, cover abrasion resistance directly affects service life and maintenance intervals, and abrasion limits are commonly written into product specifications.
Footwear and Consumer Products
Outsole and heel compounds for footwear are routinely ranked by abrasion volume to support durability claims and material selection. Other consumer and industrial products, including gaskets, diaphragms, and protective rubber linings, benefit from the same quantitative wear characterization.
Research, Development and Quality Control
In research and development, the test enables rapid comparison of polymer grades, carbon black and silica loadings, crosslink density, and process variations. In production quality control and incoming material inspection, abrasion volume serves as an acceptance criterion. Manufacturers, specifiers, and accredited third-party laboratories also use Akron abrasion data for product certification, supplier qualification, and failure analysis of returned parts.
FAQ
What is the Akron abrasion test used for?
The test measures the abrasion resistance of vulcanized rubber by abrading a wheel-shaped specimen against a grinding wheel under a defined load and slip angle. The resulting abrasion volume is used to compare compounds, qualify materials, and predict wear performance in products such as tires, belts, and footwear soles.
Which standard governs the Akron abrasion test?
The method is specified in GB/T 1689, which covers the apparatus, specimen, procedure, and calculation for vulcanized rubber. Related but methodologically different abrasion tests include ISO 4649, GB/T 9867, and ASTM D5963 for the rotary drum (DIN-type) method, ASTM D2228 for the Pico abrader, and ASTM D1630 for the NBS ribbon abrader.
How does the Akron test differ from the DIN or rotary drum abrasion test?
In the Akron test, a wheel-shaped specimen is inclined against a grinding wheel, and the slip generated by the inclination angle drives the abrasion. In the rotary drum (DIN-type) method, a small cylindrical specimen is pressed against and traverses a rotating drum covered with abrasive cloth. The contact geometry, abrasive medium, and slip conditions differ, so numerical results from the two methods are not directly comparable.
What sample is required for Akron abrasion testing?
A wheel-shaped vulcanized specimen, typically about 68 mm in outer diameter and 12.7 mm wide, is required. It can be molded directly from the compound under test or machined from a finished product, provided sufficient dense rubber thickness is available. Multiple specimens, commonly three, are usually tested to obtain a representative median result.
How should Akron abrasion results be interpreted?
A lower abrasion volume indicates better abrasion resistance. Because results depend on the exact apparatus, abrasive condition, and procedure, comparisons are only valid between tests performed under the same conditions on the same machine, and the test standard and conditions must always accompany the reported value.
Can soft, foam, or thermoplastic materials be tested by the Akron method?
The method is intended primarily for dense vulcanized elastomers. Cellular or very soft materials may deform excessively or tear under the applied load, and thermoplastic elastomers can be tested only if they can be fabricated into a stable wheel specimen. In such cases, alternative wear test methods are often more appropriate.
How long does Akron abrasion testing take?
The machine run itself is short, typically lasting from several minutes to about an hour per specimen depending on the specified revolutions. Overall laboratory turnaround, including molding and vulcanization of specimens, conditioning, density measurement, and replicate testing, is commonly a few working days.