Measurement of Friction in Drawing, Extrusion, and Rolling

1968 ◽  
Vol 90 (1) ◽  
pp. 72-80 ◽  
Author(s):  
W. Evans ◽  
B. Avitzur

In the processes of plastic forming of metals, friction between the metal and the tools (dies) plays a crucial part. Forces, flow patterns, tool wear, and surface finish of the product as well as the capacity of the equipment (in rolling), all are affected by friction. A complete analysis of any process considers the coefficient of friction as a variable. A quantitative knowledge of the value of the coefficient of friction acting during processing is desired. This work proposes an experimental procedure for the evaluation of the coefficient of friction for processes like wire drawing and rod extrusion through an open die, for hydrostatic extrusion and for rolling.

1961 ◽  
Vol 83 (4) ◽  
pp. 523-529 ◽  
Author(s):  
C. T. Yang

Split-die technique was adopted to find the coefficient of friction in wire drawing directly from experiment. Simple dynamometers with wire resistance strain gages were used for measuring separating force and drawing force instead of cumbersome equipment used by former researchers. Reasonably good results were obtained. The effect of the land or parallel portion in the die on the coefficient of friction was indicated in the results. Its importance was emphasized. A theoretical equation of the drawing stress with the effect of land considered was derived. Using the coefficient of friction obtained by the split-die method, drawing stresses were calculated from the derived equation. A comparison of the theoretical and experimental drawing stresses was made. Results were tabulated and plotted. It was concluded that including the land in the analysis of wire drawing is important and further research in analyzing the shear deformation must be pursued in order to get a close agreement between theoretical analysis and experimental results.


Author(s):  
Anirudhan Pottirayil ◽  
Pradeep L. Menezes ◽  
Satish V. Kailas

Friction can influence the quality of the finished product to a large extent in certain manufacturing processes. Sheet metal forming is a particular case, where the friction between the hard-die and the relatively soft work-piece can be extremely important. Under such conditions, topography of the harder surface can influence the resistance to traction at the interface. This paper discusses about the correlation between certain features of the surface topography and coefficient of friction based on experiments involving sliding of a few soft metal pins against a harder material. A brief description of the experimental procedure and the analysis are presented. A hybrid parameter which encapsulates both the amplitude features as well as the relative packing of peaks is shown to correlate well with the coefficient of friction.


2016 ◽  
Vol 138 (3) ◽  
Author(s):  
T. Bitter ◽  
I. Khan ◽  
T. Marriott ◽  
B. W. Schreurs ◽  
N. Verdonschot ◽  
...  

The modular taper junction in total hip replacements has been implicated as a possible source of wear. The finite-element (FE) method can be used to study the wear potential at the taper junction. For such simulations it is important to implement representative contact parameters, in order to achieve accurate results. One of the main parameters in FE simulations is the coefficient of friction. However, in current literature, there is quite a wide spread in coefficient of friction values (0.15 − 0.8), which has a significant effect on the outcome of the FE simulations. Therefore, to obtain more accurate results, one should use a coefficient of friction that is determined for the specific material couple being analyzed. In this study, the static coefficient of friction was determined for two types of titanium-on-titanium stem-adaptor couples, using actual cut-outs of the final implants, to ensure that the coefficient of friction was determined consistently for the actual implant material and surface finish characteristics. Two types of tapers were examined, Biomet type-1 and 12/14, where type-1 has a polished surface finish and the 12/14 is a microgrooved system. We found static coefficients of friction of 0.19 and 0.29 for the 12/14 and type-1 stem-adaptor couples, respectively.


Author(s):  
G. Khavin

Numerous experimental studies in the field of mechanical processing of composite materials for individual materials and tools made it possible to formulate particular models for describing tool wear, changing its microgeometry during operation and predicting durability. There are significant difficulties in measuring current wear and recalculation in mathematical models, since they include a large number of parameters. This does not allow for simple technical control of cutting edge wear and predicting tool life. The formulation of the wear-contact problem of the tool tip and the material interaction during turning of reinforced composite plastics is presented. Based on known studies, it is assumed that wear occurs along the flank of the tool, and is accompanied by an asymmetric change in the geometry of its tip. A model of abrasive wear during sliding of a tool tip rear surface with a polymer composite reinforcement material and fracture products is considered. It is assumed that the wear law is hereditary and there is a linear dependence of the wear rate on the rate of contact interaction and pressure. Shear stresses through the contact pressure and the coefficient of friction nonlinearly depend on the operating time of the tool due to the change due to wear in the geometric shape of the tool and the processing parameters of the product over time. The volumetric wear factor is a tool run time function. It reflects the fact that the interaction of the “tool-workpiece” pair with time should, as it were, forget about the running-in stage, which has a high wear rate, and the fact that the dependence of wear on the load (contact pressure) is characterized by the presence of aftereffect. A simplified relationship is obtained for the wear law under the assumption that there is no change in the coefficient of friction, temperature and contact pressure over time. Ultimately, to describe the wear law and predict the tool life, it is necessary to know a number of empirical constants, the values of which are determined by the change in the microgeometry of the tool tip during interaction during cutting.


Author(s):  
Goutam Chandra Karar ◽  
Nipu Modak

The experimental investigation of reciprocating motion between the aluminum doped crumb rubber /epoxy composite and the steel ball has been carried out under Reciprocating Friction Tester, TR-282 to study the wear and coefficient of frictions using different normal loads (0.4Kg, 0.7Kgand1Kg), differentfrequencies (10Hz, 25Hz and 40Hz).The wear is a function of normal load, reciprocating frequency, reciprocating duration and the composition of the material. The percentage of aluminum presents in the composite changesbut the other components remain the same.The four types of composites are fabricated by compression molding process having 0%, 10%, 20% and 30% Al. The effect of different parameters such as normal load, reciprocating frequency and percentage of aluminum has been studied. It is observed that the wear and coefficient of friction is influenced by the parameters. The tendency of wear goes on decreasing with the increase of normal load and it is minimum for a composite having 10%aluminum at a normal load of 0.7Kg and then goes on increasing at higher loads for all types of composite due to the adhesive nature of the composite. The coefficient of friction goes on decreasing with increasing normal loads due to the formation of thin film as an effect of heat generation with normal load.


Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4217
Author(s):  
Üsame Ali Usca ◽  
Mahir Uzun ◽  
Mustafa Kuntoğlu ◽  
Serhat Şap ◽  
Khaled Giasin ◽  
...  

Tribological properties of engineering components are a key issue due to their effect on the operational performance factors such as wear, surface characteristics, service life and in situ behavior. Thus, for better component quality, process parameters have major importance, especially for metal matrix composites (MMCs), which are a special class of materials used in a wide range of engineering applications including but not limited to structural, automotive and aeronautics. This paper deals with the tribological behavior of Cu-B-CrC composites (Cu-main matrix, B-CrC-reinforcement by 0, 2.5, 5 and 7.5 wt.%). The tribological characteristics investigated in this study are the coefficient of friction, wear rate and weight loss. For this purpose, four levels of sliding distance (1000, 1500, 2000 and 2500 m) and four levels of applied load (10, 15, 20 and 25 N) were used. In addition, two levels of sliding velocity (1 and 1.5 m/s), two levels of sintering time (1 and 2 h) and two sintering temperatures (1000 and 1050 °C) were used. Taguchi’s L16 orthogonal array was used to statistically analyze the aforementioned input parameters and to determine their best levels which give the desired values for the analyzed tribological characteristics. The results were analyzed by statistical analysis, optimization and 3D surface plots. Accordingly, it was determined that the most effective factor for wear rate, weight loss and friction coefficients is the contribution rate. According to signal-to-noise ratios, optimum solutions can be sorted as: the highest levels of parameters except for applied load and reinforcement ratio (2500 m, 10 N, 1.5 m/s, 2 h, 1050 °C and 0 wt.%) for wear rate, certain levels of all parameters (1000 m, 10 N, 1.5 m/s, 2 h, 1050 °C and 2.5 wt.%) for weight loss and 1000 m, 15 N, 1 m/s, 1 h, 1000 °C and 0 wt.% for the coefficient of friction. The comprehensive analysis of findings has practical significance and provides valuable information for a composite material from the production phase to the actual working conditions.


Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1246
Author(s):  
Stefan Valkov ◽  
Dimitar Dechev ◽  
Nikolay Ivanov ◽  
Ruslan Bezdushnyi ◽  
Maria Ormanova ◽  
...  

In this study, we present the results of Young’s modulus and coefficient of friction (COF) of Ti–Ta surface alloys formed by electron-beam surface alloying by a scanning electron beam. Ta films were deposited on the top of Ti substrates, and the specimens were then electron-beam surface alloyed, where the beam power was varied from 750 to 1750 W. The structure of the samples was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). Young’s modulus was studied by a nanoindentation test. The coefficient of friction was studied by a micromechanical wear experiment. It was found that at 750 W, the Ta film remained undissolved on the top of the Ti, and no alloyed zone was observed. By an increase in the beam power to 1250 and 1750 W, a distinguished alloyed zone is formed, where it is much thicker in the case of 1750 W. The structure of the obtained surface alloys is in the form of double-phase α’and β. In both surface alloys formed by a beam power of 1250 and 1750 W, respectively, Young’s modulus decreases about two times due to different reasons: in the case of alloying by 1250 W, the observed drop is attributed to the larger amount of the β phase, while at 1750 W is it due to the weaker binding forces between the atoms. The results obtained for the COF show that the formation of the Ti–Ta surface alloy on the top of Ti substrate leads to a decrease in the coefficient of friction, where the effect is more pronounced in the case of the formation of Ti–Ta surface alloys by a beam power of 1250 W.


2009 ◽  
Vol 35 (12) ◽  
pp. 2004 ◽  
Author(s):  
Jonathan Lee Bingham ◽  
Mariah R. Brown ◽  
Julian Ramsey Mellette

1966 ◽  
Vol 181 (1) ◽  
pp. 185-190 ◽  
Author(s):  
D. J. Lines ◽  
J. M. Lawrie ◽  
J. P. O'Donoghue

Although rotary shaft garter spring seals are widely used throughout industry, very little is known about the sealing mechanism of the lip-shaft interface. It is now generally accepted that some sort of fluid film separates the lip and the shaft. Previous workers have also postulated a relationship between the coefficient of friction and a non-dimensional hydrodynamic parameter, as in standard lubrication theory. This present paper clarifies this relationship, and shows that seals can also operate over the mixed friction, as well as the full film lubrication region. The results were obtained by accurate knowledge of the operating temperature under the sealing lip. Two types of surface thermocouple were developed to do this and these are described in full.


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