Tool Forces Research Articles

A comparison of flood cooling, minimum quantity lubrication and high pressure coolant on machining and surface integrity of titanium Ti-5553 alloy

Ti-5553 alloy is considered as a next generation aerospace alloy, however, it is also considered as difficult-to-machine material due to its thermal and mechanical properties. As limited research work presented in literature on machining process of this alloy, more research is needed to determine appropriate machining strategies for this alloy. Thus, this study presents extensive experimental work to asses the machining performance of this next generation aerospace alloy in a wide range of cutting speeds by utilizing high pressure coolant (HPC) delivery, minimum quantity lubrication (MQL), and flood cooling. Machining performance measures are tool wear rate, force components, and chip breaking. Surface and subsurface characteristics of machined parts were evaluated focusing on surface topography, dimensional accuracy, microhardness and XRD analysis. The obtained results showed that high pressure coolant delivery remarkable improved machining performance of this alloy at higher cutting speeds as compared to flood cooling and MQL. Considering surface integrity characteristics, surface and subsurface hardness shows decreased trend in all conditions and cutting speeds as compared to hardness of as received material resulting from thermal softening. XRD analysis illustrated that alfa and beta peaks shows noticeable broadening and reduced intensity but no phase transformation is observed.

Real-Time Sclera Force Feedback for Enabling Safe Robot-Assisted Vitreoretinal Surgery.

One of the major yet little recognized challenges in robotic vitreoretinal surgery is the matter of tool forces applied to the sclera. Tissue safety, coordinated tool use and interactions between tool tip and shaft forces are little studied. The introduction of robotic assist has further diminished the surgeon's ability to perceive scleral forces. Microsurgical tools capable of measuring such small forces integrated with robotmanipulators may therefore improve functionality and safety by providing sclera force feedback to the surgeon. In this paper, using a force-sensing tool, we have conducted robotassisted eye manipulation experiments to evaluate the utility of providing scleral force feedback. The work assesses 1) passive audio feedback and 2) active haptic feedback and evaluates the impact of these feedbacks on scleral forces in excess of aboundary. The results show that in presence of passive or active feedback, the duration of experiment increases, while the duration for which scleral forces exceed a safe threshold decreases.

Formation of Built-Up Layer on the Tool in Turning Operation of Magnesium Alloys

The present work highlights some factors which affect formation of a protective built-up layer (BUL) on the rake face of the cutting tool when cutting magnesium alloys. This work suggests that BUL can positively affect tool life, surface roughness, cutting speed and tool forces. The BUL is formed in cutting magnesium alloys with the PCD tool inserts at cutting speed range from 500 to 2500 m/min and at the carbide tool inserts at lower cutting speed range around 550 m/min. It has been found that deposit layers primarily have similar chemical composition as MnAl inclusions which are incorporated in the structure of the examined AZ91 magnesium alloys.

Investigation of the Effect of Soil Moisture Content, Contact Surface Material and Soil Texture on Soil Friction and Soil Adhesion Coefficients

Abstract Soil friction and soil adhesion increase the implement draft force and energy consumption particularly in the tools that have larger contact area with soil. The main ways of lowering the total draft force of the tillage tools include the use of proper materials in tools structures as well as application of the tools in appropriate soil moisture content condition. This paper investigates the effects of soil moisture content, contact surface material and soil texture on soil friction and soil adhesion coefficients. To measure the coefficients of soil friction and soil adhesion, a measurement system was developed at the University of Mohaghegh Ardabili. Experiments for each soil texture were performed at five levels of soil moisture content and four contact materials of steel, cast iron, rubber, and teflon with three replications. Results have shown that in all soil types, the effects of soil moisture content and contact materials had a significant effect on the coefficient of both soil friction and soil adhesion at the probability level of 1%. The coefficient of friction increased with soil moisture content increment and reached its maximum and then had a drop in the fluid phase. Results have shown that the mean values of soil friction and soil adhesion coefficients were significantly different from the studied soils.

A New Method for Production of Double-Curvature Dome-Shaped Part: Statistical Analysis of the Effects of Process Parameters on the Radius of Curvature of Obtained Dome Shape

A New Method for Production of Double-Curvature Dome-Shaped Part: Statistical Analysis of the Effects of Process Parameters on the Radius of Curvature of Obtained Dome Shape

Numerical simulation of laser preheating of friction stir welding of dissimilar metals

ABSTRACTFriction stir welding, FSW, of harder metal alloys is difficult to perform, like here dissimilar welding of titanium alloy to stainless steel in butt joint configuration. One major limitation is tool wear which can be reduced by preheating with a laser beam. A mathematical model to calculate the tool forces during FSW was developed further. The calculations show that the laser beam reduces forces at the pin and shoulder of the FSW-tool, accompanied by reduced heat generation through the tool. Within its operating limits, the process has low sensitivity on the lateral position of the leading laser beam. The model supports the understanding and optimisation of the complex interaction zone of forces and heat around the FSW-tool.

Finite element simulation and Experimental verification of Incremental Sheet metal Forming

Incremental sheet metal forming is now a proven manufacturing technique that can be employed to obtain application specific, customized, symmetric or asymmetric shapes that are required by automobile or biomedical industries for specific purposes like car body parts, dental implants or knee implants. Finite element simulation of metal forming process is being performed successfully using explicit dynamics analysis of commercial FE software. The simulation is mainly useful in optimization of the process as well design of the final product.This paper focuses on simulating the incremental sheet metal forming process in ABAQUS, and validating the results using experimental methods. The shapes generated for testing are of trapezoid, dome and elliptical shapes whose G codes are written and fed into the CNC milling machine with an attached forming tool with a hemispherical bottom. The same pre-generated coordinates are used to simulate a similar machining conditions in ABAQUS and the tool forces, stresses and strains in the workpiece while machining are obtained as the output data. The forces experimentally were recorded using a dynamometer. The experimental and simulated results were then compared and thus conclusions were drawn.

Study on the variable pressure CCOS polishing technology

In grinding and polishing of the aspherical and freeform surface, the CCOS technology is widely used. It commonly uses constant pressure during polishing, and thus the desired amount of material to be remove depends on the dwell time. This paper focuses on the variable pressure CCOS polishing technology. It adds one more degree of freedom to the polishing process, in which the desired amount of material to be removed is controlled by both the polishing pressure and the dwell time. Firstly, a mathematical model was established for the variable pressure polishing process. Then, the stability and response speed of the output force of the polishing tool, and the stability of removal function was measured and analyzed. Finally, a material removal experiment that applied sinusoidal force was carried out on a K9 material mirror. Results show that frequency of the measured force is the same as that of the ideal sinusoidal polishing force, with a standard deviation of the force error being about 0.35 N. Its effect on PV and RMS of the finish surface is less than 9%. The spatial period of the measured surface profile is the same as that of surface profile obtained by simulation of the sinusoidal polishing process. The surface profile error is within 17%. In this paper, variable pressure polishing was achieved, and its effectiveness for optical processing was verified.

Investigations into tilt angles and order of cutting sequences for cutting head design of roadheaders

This paper explains optimum arrangement of gauge tools and corner cutting picks for cutting head design of roadheaders. Full-scale simulation of roadheaders cutting heads of practical types with a wide range of tilt angles was carried out through laboratory linear cutting experiments. The trials showed that optimum tilt angle for corner cutting picks was approximately equal to the half breakout angle of the rock, and corner cutting picks acted as gauge tools after this value. Tilt angles greater than the optimum value were not recommended for both gauge and corner cutting picks, due to poor cutting efficiency and tool holder problems. Higher specific energy was found when the order of cutting sequences of unparalleled axis tools (the gauge tools) was arranged to start cutting from nose side of the cutting head than that of the opposite direction. The parallel axis tools on roadheaders cutting heads were, however, understood to be not affected by the order of cutting sequences. Furthermore, the effective area method which was previously suggested for tool force calculation of parallel axis tools was also verified for unparalleled axis tools investigated in this research study.

Electronic problem lists: a thematic analysis of a systematic literature review to identify aspects critical to success.

Problem list data is a driving force for many beneficial clinical tools, yet these data remain underutilized. We performed a systematic literature review, pulling insights from previous research, aggregating insights into themes, and distilling themes into actionable advice. We sought to learn what changes we could make to existing applications, to the clinical workflow, and to clinicians' perceptions that would improve problem list utilization and increase the prevalence of problems data in the electronic medical record. We followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to systematically curate a corpus of pertinent articles. We performed a thematic analysis, looking for interesting excerpts and ideas. By aggregating excerpts from many authors, we gained broader, more inclusive insights into what makes a good problem list and what factors are conducive to its success. Analysis led to a list of 7 benefits of using the problem list, 15 aspects critical to problem list success, and knowledge to help inform policy development, such as consensus on what belongs on the problem list, who should maintain the problem list, and when. A list of suggestions is made on ways in which the problem list can be improved to increase utilization by clinicians. There is also a need for standard measurements of the problem list, so that lists can be measured, compared, and discussed with rigor and a common vocabulary.

Using RSM Technique for Modeling and Optimization the Influence of Cutting Parameters on Tool Wear and Cutting Forces in Turning Operation

This study is an attempt to investigate the effect of cutting parameters on the cutting force and tool wear during turning of AISI 304 steel using tungsten carbide tool (WC). The first aim of present work was to employ the Response Surface Methodology (RSM) technique to obtain the influence of input machining parameters, such as cutting feed, cutting speed and cutting depth on the cutting force and wear of tool. Experiments were carried out in a 20 runs experimental matrix by a CNC machine according to the design matrices established by Design of Experiment (DOE) software 'version 8' with RSM technique. Cutting force was measured using a lathe dynamometer and tool wear with the help of an optical microscope. The relationships between parameters of machining and the responses (cutting tool wear and cutting force) were modeled and analyzed by RSM technique. ANOVA analysis was applied to study the impact of machining parameters on the outputs (responses) and to establish empirical equations for these responses in terms of input machining parameters. Significant quadratic models were developed with a probability (p-value ≤ 0.05) for both tool wear and cutting force. Results showed that the depth of cut is the most significant factor affecting the cutting force, closely followed by feed and cutting speed, whereas only the important parameter influencing the tool wear was appeared to be the cutting depth. Also, the results manifested that the optimum value for minimum tool wear and minimum cutting force was found at (80 m/min) cutting speed, (0.2 mm/rev) feed and (0.4 mm) cutting depth. A good agreement was found between the experimental and predicted results with a maximum error of 8%.

TOOL FORCES AND SPECIFIC ENERGY PREDICTION MODELS IN THE PROCESS OF SANDSTONES CUTTING BY USING CONICAL PICKS

In this study, unrelieved rock cutting experiments were conducted at the linear rock cutting machine and the characteristics of tool forces were discussed. The correlations among tool forces, specific energy, cutting depth, and rock strength were analyzed using single factor regression analysis method. Based on multiple non-linear regression method, the models of tool forces and specific energy were developed considering the rock strength and cutting depth. The results indicate that models of tool forces have the superior performance. When the model of specific energy is analyzed using the compressive strength of the rock, it was seen that the correlations are weak compared to the model related to tensile strength of rock. In conclusion, it is emphasized that the proposed models presented in this study are particularly recommended for performance prediction of soft and medium-hard strength sandstones in case conical picks are employed.

Investigation on the characteristic of forces of the tool edge in finish machining of titanium alloys

In order to tackle the problems during processing titanium alloys, 2D orthogonal cutting mechanics models are proposed in this paper. In particular, models are based on the classical orthogonal force model with the consideration of the blunt tool edge and the chamfering tool edge when the force is less than the tool edge radius. Moreover, simulations and experiments have been carried out to investigate the characteristic of forces of the tool edge. The model describes the relationship between the tool edge and forces. In addition, it can accurately predict the initial flow of the chip under the action of the tool edge. Substantially, the theoretical basis for optimizing the design of the tool edge can be provided.

Assessment of Postural Sway in Individuals with Multiple Sclerosis Using a Novel Wearable Inertial Sensor

Balance impairment is common in individuals with multiple sclerosis (MS). However, objective assessment of balance usually requires clinical expertise and/or the use of expensive and obtrusive measuring equipment. These barriers to the objective assessment of balance may be overcome with the development of a lightweight inertial sensor system. In this study, we examined the concurrent validity of a novel wireless, skin-mounted inertial sensor system (BioStamp®, MC10 Inc.) to measure postural sway in individuals with MS by comparing measurement agreement between this novel sensor and gold standard measurement tools (force plate and externally validated inertial sensor). A total of 39 individuals with MS and 15 healthy controls participated in the study. Participants with MS were divided into groups based on the amount of impairment (MS_Mild: EDSS 2–4, n = 19; MS_Severe: EDSS ≥6, n = 20). The balance assessment consisted of two 30-s quiet standing trials in each of three conditions: eyes open/firm surface, eyes closed/firm surface, and eyes open/foam surface. For each trial, postural sway was recorded with a force plate (Bertec) and simultaneously using two accelerometers (BioStamp and Xsens) mounted on the participant’s posterior trunk at L5. Sway metrics (sway area, sway path length, root mean square amplitude, mean velocity, JERK, and total power) were derived to compare the measurement agreement among the measurement devices. Excellent agreement (intraclass correlation coefficients >0.9) between sway metrics derived from the BioStamp and the MTx sensors were observed across all conditions and groups. Good to excellent correlations (r >0.7) between devices were observed in all sway metrics and conditions. Additionally, the acceleration sway metrics were nearly as effective as the force plate sway metrics in differentiating individuals with poor balance from healthy controls. Overall, the BioStamp sensor is a valid and objective measurement tool for postural sway assessment. This novel, lightweight and portable sensor may offer unique advantages in tracking patient’s postural performance.

Comparative Studies on Machinability of MCLA Steels EN19 and EN24 Using Taguchi Optimization Techniques

Medium carbon low Alloy steels are commonly used for manufacturing of automotive components such as gears, spindle, shafts and aerospace components etc. In order to improve the mechanical properties of steel, forging and annealing operations are carried out. Machinability and surface roughness test was carried in order to find the optimum parameters of the EN Steels. Machinability is the ability of material, with ease of removal. Machining of material effects on the Tool Forces, power consumption and Surface Roughness. The present work focuses on Comparative Studies on Machinability of Forged and annealed EN19 and EN24 MCLA Steels, using Taguchi Optimization Technique. For machinability test, the Design the experiments is carried according to Taguchi L9 orthogonal array. Machinability Test is performed on the centre lathe, and the parameters studied are the cutting Speed, Feed and Depth of Cut. Also, the surface roughness is carried for the machinability samples to optimize the parameters for surface roughness using Taguchi’s experiment.

Influence of graphite nanoadditives to vegetable-based oil on machining performance when MQCL assisted hard turning

The current study demonstrates through experiment, the effect of solid lubricant assisted minimum quantity cooling lubrication (MQCL) when turning tempered (~60 HRC) alloyed steel Uddeholm Caldie with cemented carbide tools on the process performance. In MQCL application, nanosized graphite nanoplatelets (GnP) solid lubricant powder was dispersed (0.2% vol.) in rapeseed oil based lubricant “ECOLUBRIC”. The effect of cutting parameters at dry machining and with MQCL lubrication on the machined surface finish, tool forces, tool wear and vibrations generated were studied.

Comparison of Two Subsoiler Designs Using the Discrete Element Method (DEM)

Abstract. Subsoiling is an essential tillage practice for loosening soil and enhancing water infiltration. In this study, a discrete element model was developed and validated to simulate soil-tool interactions. The validated model was then used to evaluate two design alternatives of subsoiling tool: a non-winged tool (NW) and a winged tool (WW). The performance indicators used for the evaluation included draft force and soil disturbance area at different rake angles (ranging from 23.0° to 40.5°) and working depths (ranging from 225 to 350 mm) at a constant travel speed of 0.8 m s-1. The results showed that the WW tool required more than twice the draft force and disturbed more than twice the soil area when compared to the NW tool, regardless of rake angle and working depth. The draft force of the NW tool had no variation over the range of rake angles tested, whereas the WW tool had the lowest draft force at 26.5°. The soil disturbance area did not show any particular trend for both design alternatives at the rake angles studied. With the increase in working depth, the soil disturbance area of the WW tool decreased; however, no change was observed for the NW tool. Considering both draft force and soil disturbance area, both the NW and WW tools should be operated at the shallowest possible depth, and the recommended rake angle was 33.5° for the NW tool and 33.5° to 40.5° for the WW tool. Keywords: DEM, Design, Disturbance, Force, Soil, Subsoiling, Tool.

Online Monitoring of Tool Wear and Surface Roughness by using Acoustic and Force Sensors

This paper explores the effect of tool wear and surface roughness during the CNC turning of D2 steel by using acoustic emission and force sensors. The values of the forces were measured by using a Kistler 9257B dynamometer while the acoustic emission sensor was fixed upon the tool shank. The machining process was carried out until the flank wear was found to approach the critical value of 0.3mm. Tool wear plays a decisive role in any machining process since it contrarily affects tool life and forces. This has a direct impact on surface quality of the machined surface. Therefore, methods for sensing cutting tool wear are crucial in view of optimum use of cutting tools with effective monitoring system. As the wear increases, the radial forces and the surface roughness were found to shoot up considerably. The acoustic emission was analyzed and parameters were found to increase proportionally with tool wear.

Simulation of incremental forming processes of a pyramidal ring made of two materials

Incremental forming is one of the most well-known forming processes for complex and asymmetric parts. This method uses a CNC machine, simple forming tool, and a die. This study focused on effects of some parameters such as the material, feed rate, pitch, rotational speed and movement strategy of tool on the dimensional precision, forming force, thickness distribution and fracture in the welding area. The results showed that single point incremental forming (SPIF) led to a better thickness distribution with lower tool force, whereas two-point incremental forming led to better dimensional accuracy. Rotational speed does not have any significant impact on the forming process while decreasing the feed rate partially reduced the forming force. According to the results, although dimensional precision in double point incremental forming is better than SPIF, when it comes to the thickness distribution, forming force, and economic issues, SPIF is in favor. The results also showed that by connecting two materials, different parameters for the two materials could be investigated simultaneously in one simulation process.

Effect of cutting depth and line spacing on the cuttability behavior of sandstones by conical picks

Various types of conical picks in different shapes are produced and widely employed on mechanical excavators. Depending on the mechanical and abrasivity properties of rocks, appropriate shape of pick is selected. In order to obtain maximum efficiency from the pick during excavation, the interaction between the pick and rock and the cutting mechanism play very important role. In this context, linear cutting tests were conducted by using a conical pick at the cutting depths between 3 and 18 mm and also at the various line spacings on sandstones exhibiting different mechanical properties. The results indicated that cutting depth and line spacing have significant influences on the tool forces acting on the pick, the ratio of normal to cutting force, and the specific energy. Accordingly, strong correlations and empirical models were developed. In conclusion, the empirical models proposed for estimating the forces and specific energy would be used for producing the conical bits and also designing the cutter heads of mechanical excavators on soft and medium-hard strength sandstones.