Friction Test Method Research Articles

The influence of tool geometry on friction behavior in sheet metal forming

Friction test for the several tool radius is carried out and the influence of tool geometry on the friction behavior is studied. Using the testing results the numerical simulation of sheet metal forming is also carried out. The result of numerical simulation shows that the present friction test method is very efficiency to evaluate the friction behavior of sheet metal forming process.

ゴムの摩擦 ゴムの摩擦試験方法

ゴムの摩擦 ゴムの摩擦試験方法

ゴムの摩擦挙動および摩擦試験法に関する研究 （１） 各種試験機による特殊ゴムの摩擦特性の評価

ゴムの摩擦挙動および摩擦試験法に関する研究 （１） 各種試験機による特殊ゴムの摩擦特性の評価

Tribologische Prüfung

Round robin for development of standardised tribology test-methods. To develop accepted friction and wear test methods for hard thin coatings an international round robin test with 27 participating laboratories from twelve countries was performed. A German round robin with twelve participants was startet for fretting wear of thin coatings. A compilation and first valuation of the reported results for titanium nitride coatings reveals the still existing difficulties and limits of reproductibility of such tests. Although all participants got identical test samples and performed the tests according to an identical test procedure the scattering of the reported friction and wear values were great as well for the test repetitions of the same laboratory as between the mean values for the different laboratories

摩擦，摩耗 摩擦・摩耗試験方法の動向

摩擦，摩耗 摩擦・摩耗試験方法の動向

An experimental comparison of three documented test methods for the evaluation of friction sensitiveness

Abstract Several different test methods can be used to determine the sensitiveness of an explosive or energetic material to initiation by friction. In this paper we examine the results for seven explosives obtained using three commonly used friction test methods. The suitability of each method as a means of quantifying friction sensitiveness is discussed, and the advantages and disadvantages of the individual techniques are highlighted.

Evaluation measures of lubricity by means of compression-twist type friction testing machine.

A compression-twist type friction testing machine has been developed to establish the fundamental friction testing method for metal forming. This machine has been devised to change easily contact pressure, sliding velocity, sliding distance and combination of friction pairs. Two indenter types, that is, ones with different contact length along sliding direction and a ring-shape-indenter, are employed and several mineral oils are tested using mild steel and alloy tool steel SKD 11 as the friction pairs. Surface appearances of testpiece and tool during sliding are observed by a SEM and a profile projector. The variations of friction coefficient during sliding are understood based on the surface appearance. Thus, new measures to evaluate lubricity in boundary lubrication, oil film strength and antiweldability are proposed.

Development of friction tests for lubrication in model-material experiments

Frictional conditions between the tool and the specimen are important in the plastic working of materials, influencing the flow of the material and being a decisive parameter for tool/specimen interface pressure and for deformation force: the selection of the “right” lubricant for the model-material simulation is therefore a matter of importance. The method chosen in this work is to use friction-testing methods based on geometrical changes in order to adjust the frictional conditions in the simulation to the conditions of the real process. Friction-testing methods for general forging, cold forging, and rolling have been examined, and recommendations are advanced. It is demonstrated that combinations of vaseline/kaolin or zinc stearate/kaolin will cover the whole range of friction coefficients — as measured by the ring test — from 0 to 0.577.

Seizure Mechanism in Cold Extrusion and Forging

To examine the seizure mechanism in cold extrusion and forging, a bifurcating extrusion type friction testing machine has been manufactured by the authors. This friction testing method was devised to simulate the frictional surface in the process accompanied with a remarkable surface expansion which influences markedly the seizure phenomena in extrusion and forging. Using a commercially pure aluminium as the workmetal, the frictional characteristics, and in particular the seizure mechanism, have been investigated under a lubricated condition with a mineral oil of higher viscosity and a dry frictional condition. Under the lubricated condition, the frictional surface was remarkably expanded more than 26 times; nevertheless no seizure was observed throughout the extruded travel. On the other hand, under the dry frictional condition, the seizure is initiated at the region where a virgin surface is exposed or the relative slip displacement exceeds a critical value. It was observed that even in the dry frictional condition, a smooth burnished metal surface could be obtained if the surface expansion ratio and the relative slip displacement are lower than a critical value.