Frictional Behavior in Metalworking Processes

1970 ◽  
Vol 92 (4) ◽  
pp. 535-542 ◽  
Author(s):  
M. B. Peterson ◽  
F. F. Ling

Frictional behavior in metalworking processes between the tool and the workpiece for unlubricated condition is discussed. The primary aim of the work was to develop means to predict frictional behavior in terms of which metal flow can be better understood. Experimental and theoretical work has been carried out to determine the important variables of metal working friction. It was found that friction is dependent upon the strength of the workpiece, the pressure, the surface adhesion, and the surface roughness. The pressure-dependence of shear strength based on experimental data is also discussed. Finally, although techniques are available to predict friction, they are dependent upon the ability to predict interface surface temperature.

2011 ◽  
Vol 486 ◽  
pp. 262-265
Author(s):  
Amit Kohli ◽  
Mudit Sood ◽  
Anhad Singh Chawla

The objective of the present work is to simulate surface roughness in Computer Numerical Controlled (CNC) machine by Fuzzy Modeling of AISI 1045 Steel. To develop the fuzzy model; cutting depth, feed rate and speed are taken as input process parameters. The predicted results are compared with reliable set of experimental data for the validation of fuzzy model. Based upon reliable set of experimental data by Response Surface Methodology twenty fuzzy controlled rules using triangular membership function are constructed. By intelligent model based design and control of CNC process parameters, we can enhance the product quality, decrease the product cost and maintain the competitive position of steel.


Author(s):  
Klaus Medeiros ◽  
Kyle Chavez ◽  
Fernando S. Fonseca ◽  
Guilherme Parsekian ◽  
Nigel G. Shrive

Finite element models were developed to assess the influence of several parameters on the load capacity, deflection, and initial stiffness of multi-story, partially grouted masonry walls with openings. The base model was validated with experimental data from three walls. The analyses indicated that the load capacity of masonry walls was considerably sensitive to the ungrouted and grouted masonry strengths and mortar shear strength; moderately sensitive to the vertical reinforcement ratio and aspect ratio; slightly sensitive to the axial stress; and almost insensitive to the opening size, reinforcement spacing, and horizontal reinforcement ratio. The deflection of the walls had well-defined correlations with the masonry strength, vertical reinforcement, axial stress and aspect ratio. The initial stiffness was especially sensitive to the axial stress and the aspect ratio, but weakly correlated with the opening size, and the spacing and size of the reinforcement.


2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Karl Niklas Hansson ◽  
Stig Hansson

The surface roughness affects the bone response to dental implants. A primary aim of the roughness is to increase the bone-implant interface shear strength. Surface roughness is generally characterized by means of surface roughness parameters. It was demonstrated that the normally used parameters cannot discriminate between surfaces expected to give a high interface shear strength from surfaces expected to give a low interface shear strength. It was further demonstrated that the skewness parameter can do this discrimination. A problem with this parameter is that it is sensitive to isolated peaks and valleys. Another roughness parameter which on theoretical grounds can be supposed to give valuable information on the quality of a rough surface is kurtosis. This parameter is also sensitive to isolated peaks and valleys. An implant surface was assumed to have a fairly well-defined and homogenous “semiperiodic” surface roughness upon which isolated peaks were superimposed. In a computerized simulation, it was demonstrated that by using small sampling lengths during measurement, it should be possible to get accurate values of the skewness and kurtosis parameters.


2017 ◽  
Vol 261 ◽  
pp. 267-274
Author(s):  
Pantelis N. Botsaris ◽  
Chaido Kyritsi ◽  
Dimitris Iliadis

In this paper, there is an attempt to monitor and evaluate machining parameters when turning 34CrNiMo6 material under different cooling and lubrication conditions. The machining parameters concerned are temperature of the cutting tool and the workpiece, level of vibrations of the cutting tool, surface roughness of the workpiece, noise levels of the turning process and current drawn by the main spindle motor. Four different experimental machining scenarios were completed, specifically: conventional wet turning process, dry cutting and two additional modes employing cooling by cold air. Experimental data were acquired and recorded by an optimally designed network of sensors. Experimental data were statistically analyzed in order to reach conclusions. According to the research that has been done, although, overall, minimum cutting tool and workpiece temperatures were observed under wet machining, cold air cooling is capable of achieving comparable cooling results to wet machining. The lowest values of surface roughness were achieved by wet machining, whereas the lowest level of cutting tool vibrations were observed under cold air cooling.


Author(s):  
Sayed A. Nassar ◽  
Ramanathan M. Ranganathan ◽  
Saravanan Ganeshmurthy ◽  
Gary C. Barber

This experimental study investigates the effect of tightening speed and coating on both the torque – tension relationship and wear pattern in threaded fastener applications. The fastener torque – tension relationship is highly sensitive to normal variations in the coefficients of friction between threads and between the turning head and the surface of the joint. Hence, the initial level of the joint clamp load and the overall integrity and reliability of a bolted assembly is significantly influenced by the friction coefficients. The effect of repeated tightening and loosening is also investigated using M12, Class 8.8, fasteners with and without zinc coating. The torque – tension relationship is examined in terms of the non-dimensional nut factor K. The wear pattern is examined by monitoring the changes in surface roughness using a WYKO optical profiler and by using a LECO optical microscope. A Hitachi S-3200N Scanning Electron Microscope (SEM) is used to examine the contact surfaces, under the fastener head, after each tightening/loosening cycle. Experimental data on the effect of variables and the tightening speed, fastener coating and repeated tightening on the nut factor are presented and analyzed for M8 and M12, class 8.8, fasteners.


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