Workpiece Rotational Speed Research Articles

The Determination of Efficient Super Finishing Conditions for the Mirror Surface Finishing of Titanium

Recently, the demands for superfinishing machines have increased, but the development of superfinishing devices and superfinishing technology remain insufficient. And titanium, with its infinite potential, is widely known as a highly ideal material. It is therefore used in various industries that require precision-machined parts, such as the automobile, chemistry and aerospace industries, due to its outstanding specific strength and corrosion resistance compared to any other alloys. In this study, a series of experiments was performed to determine the mirror surface finishing conditions of titanium as well as efficient superfinishing conditions that can be utilized practically and economically at production sites. The applied conditions were the workpiece rotation speed, the oscillation speed, the contact pressure, the roller hardness and the type of abrasive film used when superfinishing was performed using an abrasive film for titanium-based materials such as pure titanium and titanium alloy. From the experiments, it was confirmed that efficient superfinishing conditions and mirror surface finishing conditions were determined for pure titanium and titanium alloy.

A new through-feed centerless grinding technique using a surface grinder

This paper proposes an alternative centerless grinding technique, i.e., through-feed centerless grinding using a surface grinder. In the new method, a compact centerless grinding unit, composed of a guide plate, an ultrasonic shoe, a blade, and their respective holders, is installed onto the worktable of a surface grinder, and the through-feed centerless grinding operation is performed as the workpiece located on the guide plate is fed into the space between the grinding wheel and ultrasonic shoe. The ultrasonic shoe, produced by bonding a piezoelectric ceramic device onto a metal elastic body, is tilted at a small angle so as to provide sufficient force to control the workpiece rotational motion and to feed the workpiece along its axis by the ultrasonic elliptic-vibration. In this paper, the workpiece motion control tests were carried out firstly to make sure that the workpiece rotational speed and through-feed rate can be exactly controlled by the ultrasonic shoe which is essential for performing high-precision grinding operations. Then, the effects of major process parameters such as the workpiece eccentric angle, the stock removal, the ultrasonic shoe tilt angle and the applied voltage amplitude on the machining accuracy (i.e. workpiece cylindricity and workpiece roundness) were clarified experimentally. The obtained results indicate that: (1) the workpiece rotational speed can be adjusted by changing the applied voltage amplitude, whereas its through-feed rate can be adjusted by changing both the applied voltage amplitude and the ultrasonic shoe tilt angle; (2) the optimum eccentric angle is 6°, and a larger stock removal, a smaller tilt angle, or a higher applied voltage is better for higher machining accuracy; (3) the workpiece cylindricity and roundness were improved from the initial value of 16.63 μm and 14.86 μm to the final ones of 1.49 μm and 0.74 μm under the optimal grinding conditions.

Experimental Study on Reciprocating Electroplated Diamond Wire Saws Cutting SiC Wafer

The experiment that WXD170-type reciprocating rotating diamond wire saw cuts SiC wafer was studied using orthogonal test method in this paper. The influence of cutting speed of diamond wire saw, work-piece feed speed and rotating speed of work-piece on cutting process were analyzed. The optimized cutting parameters which can improve surface quality of slices and reduce tangential force were obtained. The results show that: the surface quality of slices which was cloud-shaped can be improved significantly due to the increase of the work-piece rotation. The work-piece feed speed and the rotation speed have greater impact on the tangential force than the saw wire speed; the work-piece feed speed and the work-piece rotation speed have greater impact on surface roughness than the saw wire speed. An important way to be obtained the smaller tangential force and better surface quality of slices is considering of a reasonable match among cutting speed of diamond wire saw, work-piece feed speed and rotating speed of work-piece comprehensively.

Experiment Research on Abrasive Belt Vibration Grinding Terminal Surface of Work Piece

In order to solve the problem of the alloy can not achieve the low surface roughness value in high-temperature, when it is grinded by abrasive disk, so that it can not meet the requirement of the craft. It uses abrasive belt grinding technology,adopts the method of fixed precise belt vibration grinding head on the CA6140 lathe and makes experiment of the impact on roughness of work piece surface from rotational speed of work piece , sand size of abrasive belt, horizontal amount of feed and process time. The result shows that the roughness value can achieve the requirement. It generalized the method of using abrasive belt grinding high- temperature alloy to make the roughness meet the requirement of craft, when guaranteed efficiency.

A new in-feed centerless grinding technique using a surface grinder

This paper deals with the development of an alternative centerless grinding technique, i.e., in-feed centerless grinding based on a surface grinder. In this new method, a compact centerless grinding unit, composed of an ultrasonic elliptic-vibration shoe, a blade and their respective holders, is installed onto the worktable of a surface grinder, and the in-feed centerless grinding operation is performed as a rotating grinding wheel is fed in downward to the cylindrical workpiece held on the shoe and the blade. During grinding, the rotational speed of the workpiece is controlled by the ultrasonic elliptic-vibration of the shoe that is produced by bonding a piezoelectric ceramic device (PZT) on a metal elastic body (stainless steel, SUS304). A simulation method is proposed for clarifying the workpiece rounding process and predicting the workpiece roundness in this new centerless grinding, and the effects of process parameters such as the eccentric angle, the wheel feed rate, the stock removal and the workpiece rotational speed on the workpiece roundness were investigated by simulation followed by experimental confirmation. The obtained results indicate that: (1) the optimum eccentric angle is around 6°; (2) higher machining accuracy can be obtained under a lower grinding wheel feed rate, larger stock removal and faster workpiece rotational speed; (3) the workpiece roundness was improved from an initial value of 19.90 μm to a final one of 0.90 μm after grinding under the optimal grinding conditions.

Performance analysis of wire electrochemical turning process—RSM approach

Electrochemical machining (ECM) has become one of the most widely spread techniques of the non-traditional processes. The main problem of ECM is that of choosing the correct working parameters to attain a high degree of accuracy under fine surface finish conditions. Recently, electrochemical turning has gained attention as a finishing process. By feeding a shaped tool into a rotating workpiece, axially symmetric turned parts can be manufactured. In this way, large symmetric workpiece can be made with small tools. This paper discusses the feasibility of using a wire as a tool in electrochemical turning process (WECT). The present study measures the performance criteria of the WECT process through investigating the effect of working parameters, namely, applied voltage, wire feed rate, wire diameter, workpiece rotational speed, and overlap distance, on metal removal rate, surface roughness, and roundness error. The experimental results are statistically analyzed and modeled through response surface methodology. The regression model adequacies are checked using analysis of variance. Furthermore, the optimal combination of these parameters has been evaluated to maximize metal removal rate and minimize surface roughness and roundness error. The study reveals the ability of using a wire as a tool in WECT and its productivity; the shape errors can be controlled through the mentioned input parameters. The results show that the increase of wire feed rate enhances the productivity of the process and improves both surface quality and roundness error. Also, the increase of rotational speed improves both the productivity of the process and geometrical error of the produced parts.

Apparent spot in circular laser hardening: effect of process parameters

Back tempering, a well known problem in laser hardening of steels, occurs when a large area is hardened by multiple overlapping passes. The overlapping passes partially temper the previous hardened material in the overlapped zone. Back tempering also occurs in circular laser hardening, a typical laser surface treatment used in case of cylindrical workpieces, since the treated starting/ending surfaces are slightly overlapped. In order to avoid the back tempering phenomenon the apparent spot (AS) technique is addressed and investigated. In case of circular laser hardening the AS technique is based on imposing a high rotational speed to the workpiece, since an apparent circular spot is generated, which contemporaneously heats all the annular surface of the workpiece. As a consequence, back-tempering is avoided. In this paper an experimental campaign is deigned to analyze the effects of the process parameters (laser power, workpiece rotational speed and workpiece diameter) on the hardened tracks in terms of width, thickness and hardness values, when the AS is applied to the circular laser hardening.

Rotational abrasive flow finishing (R-AFF) process and its effects on finished surface topography

The present study focus on abrasive flow finishing (AFF), a process that finishes complex internal and external geometries with the help of viscoelastic abrasive medium, while keeping in mind its low finish and material removal rates (MRR). Researchers have often strived to improve finishing rate and MRR. As an attempt to overcome the said limitations, this paper discusses rotational abrasive flow finishing (R-AFF) process wherein complete tooling is externally rotated and the medium reciprocates with the help of hydraulic actuators. In this study, preliminary experiments are conducted on Al alloy and Al alloy/SiC metal matrix composites (MMCs) at different extrusion pressures, and medium compositions are employed for finding optimum conditions of the same for higher change in roughness (Δ R a ). The same optimum conditions are used to study the effect of workpiece rotational speed on (Δ R a ), material removal (MR), change in workpiece hardness and surface topology. It is noted that as the workpiece rotational speed increases from 2 to 10 RPM, the experimental helix angle decreases from 22° to 9° and the helical path length increases from 67 to 160 mm. Based on these findings the mechanism of material removal of matrix and reinforcement in MMC using R-AFF have been proposed. Here the matrix material is removed by micro-cutting and three methods of material removal mechanisms for reinforcement are also explained. The scientific logic behind finishing mechanism of matrix and reinforcement, cross hatch patterns, helical path directions, micro-scratch (μ-scratch) width and depth variation with size, orientation and support that active abrasive grain obtains from neighboring abrasives is derived from scanning electron microscopy micrographs. Finally this study establishes that R-AFF can produce 44% better Δ R a and 81.8% more MR compared to the AFF process. Accordingly, R-AFF generates micro cross hatch pattern on the finished surface that can improve lubricant holding capabilities.

Effects of process parameters on workpiece roundness in tangential-feed centerless grinding using a surface grinder

The present authors proposed a new centerless grinding method using a surface grinder in their previous study [Wu, Y., Kondo, T., Kato, M., 2005. A new centerless grinding technique using a surface grinder. J. Mater. Process. Technol. 162–163, 709–717]. In this method, a compact centerless grinding unit composed mainly of an ultrasonic elliptic-vibration shoe is installed onto the worktable of a multipurpose surface grinder to perform tangential-feed centerless grinding operations. However, for the complete establishment of the new method it is crucial to clarify the workpiece rounding process and the effects of process parameters such as the worktable feed rate, the stock removal and the workpiece rotational speed on the machining accuracy, i.e., workpiece roundness, so that the optimum grinding conditions can be determined. In this paper, the effects of the process parameters on workpiece roundness are investigated by simulation and experiments. For the simulation analysis, a grinding model taking into account the elastic deformation of the machine is created. Then, a practical way to determine the machining-elasticity parameter is developed. Further, simulation analysis is carried out to predict the variation of workpiece roundness during grinding and to discover how the process parameters affect the roundness. Finally, actual grinding operations are performed by installing the previously constructed unit onto a CNC surface grinder to confirm the simulation results. The obtained results indicate that: (1) a slower worktable feed rate and higher workpiece rotational speed give better roundness; (2) better roundness can be also obtained when the stock removal is set at a larger value; (3) the workpiece roundness was improved from an initial value of 23.9 μm to a final value of 0.84 μm after grinding.

Research on Uniform Surface Roughness in Grinding of Revolving Curved Surface

When grinding the revolving curved surface with Arc Envelope Grinding Method, the different curvatures in the convex and concave surfaces make a great difference in the surface roughness. In order to solve this problem, the relationship among envelope height, feeding rate, rotational speed and curvature of workpiece was analyzed based on equal-envelope-height grinding method. The results presented that, low feeding rate of grinding wheel and high rotational speed of workpiece were helpful to obtain smaller envelope height. And the smaller the radius of workpiece curvature, the more different the surface roughness. Besides, it was an effective method to solve this problem by changing feeding rate. The feeding rate should be changed directly proportionally to radius of workpiece curvature. Then, the experimental results indicate that, the fluctuation ratio of surface roughness with variable feeding rate is reduced to 4.896% from 26.17% with constant feeding rate. It proves the validity of hypothesis.

Experimental Study of Tangential-Feed Centerless Grinding Process Performed on Surface Grinder

In our previous study, a new centerless grinding method using surface grinder was proposed. In this method, a compact unit consisting mainly of an ultrasonic elliptic-vibration shoe, a blade, and their respective holders is installed on the worktable of a multipurpose surface grinder to conduct tangential-feed centerless grinding operations. For the complete establishment of this new method, firstly in this paper workpiece rotational speed control tests were carried out to make sure that the workpiece rotational speed is exactly controlled by the elliptic vibration of shoe to achieve high-precision centerless grinding. Then, the effects of the process parameters such as the worktable feed rate, the stock removal and the workpiece rotational speed on the workpiece roundness were clarified experimentally. The obtained results showed that (1) The workpiece rotational speed can be controlled exactly by the shoe ultrasonic vibration, (2) The roundness is improved with the increases in the voltage applied and the stock removal, but the decrease in the worktable feed rate; The best roundness obtained was 0.84m.

Study on Numerical Controlled Electrochemical Turning

A preliminary study of Numerical Controlled Electrochemical Turning (NC-ECT) technology was presented in this paper. NC-ECT is suitable for machining revolving workpieces which are made of difficult-to-cut materials or have low rigidity, and it is difficult or expensive for machining these workpieces by use of traditional turning or traditional Electrochemical Machining (ECM) method. To carry out the study, an experimental setup was developed on the basis of a common lathe, and a kind of inner-spraying cathode with rectangle section outlet was designed according to the process of machining cylindrical surface. First, the NC-ECT method was simply described. Then, considering the structure of the cathode and the process of machining, the method for calculating the inter-electrode gap in machining the cylindrical surface was given. Finally, the experiments of machining the cylindrical surface were carried out. Experiments showed that the calculated inter-electrode gaps are well consistent with the actual value of the machining process, which decreases with the increase of the rotational speed of workpiece and increases almost linearly with the increase of the working voltage. Experiments also showed that the inter-electrode gap keeps a certain relationship with the working current, the inter-electrode gap can be controlled according to working current in the machining process.

Experimental investigations into rotating workpiece abrasive flow finishing

Abrasive flow finishing (AFF) is used to deburr, polish or radius surfaces and edges by flowing a semisolid abrasive medium over the intended surface to be finished. Such finishing operations play a crucial role in manufacturing process of machine parts. The cost escalates sharply when the requirement is to achieve surface roughness values near nano levels. The need for finishing is to avoid power losses due to friction, increase the wear resistance and to provide a long serviceable life to the equipment. AFF is used in the industries especially in the case of finishing complex internal and external shapes. However, AFF is a time consuming process and any effort to reduce the process time even marginally saves production time and cost of the finished product. In the present study, an effort is made towards improving the performance of AFF process by providing rotary motion to the workpiece (R-AFF: rotational abrasive flow finishing). Preliminary experimental comparative study is done on AFF and R-AFF processes to compare their process performance in terms change in R a (Δ R a) and material removal. Later complete experimental study on R-AFF is conducted using central composite rotatable design and the responses are plotted using response surface methodology. The workpiece materials used in the present study are Al alloy, Al alloy/SiC (10%) and Al alloy/SiC (15%) metal matrix composites (MMCs). The results of R-AFF are encouraging. The present study shows that rotational speed of workpiece has significant effect on output responses (Δ R a). Indigenously developed semi solid abrasive laden medium is used in the present study. Overall, the experiments have shown that R-AFF has a very promising future for the industries in terms of better finishing.

Micromachining of aluminum pipes using magnetic abrasive finishing

The demand for highly finished surfaces has increased dramatically in recent years. There are obstacles toward fulfilling the requirements for creating such finished parts. Disability of traditional surface finishing methods, which is due to particular shape and geometry of work pieces, and tool inaccessibility to every feature of work pieces are samples of such obstacles. This has lead to innovating new finishing processes. One of these methods, which uses moving abrasive particles in magnetic field, is called magnetic abrasive finishing of machined surface roughness, an approach to optimize the principles of this process. In this research, some effective parameters on surface roughness such as magnetic flow density, process time, amount of magnetic abrasive powder, and rotational speed of work piece have been tested and roughness sensation against these parameters has been studied. According to the results, using permanent magnets of 1T, the amount of 8g of ilmenite powder of mesh 150, rotating speed of 750rpm, and 30–40min of process time, will result into a surface roughness of 0.45μm Ra from the original value of 2μm Ra under other conditions kept on their best values.

Investigation into magnetorheological abrasive honing (MRAH)

A scheme to finish external curved surfaces, by imparting rotation while the abrasive-mixed magnetorheological fluid (or abrasive-mixed MR fluid) is pushed up and down, is presented in this paper. Since the relative motions resemble those present in conventional honing, the proposed method is named as ‘Magnetorheological Abrasive Honing’ (MRAH). This paper outlines the design and development of magnetorheological abrasive honing setup. A DC electromagnet with cylindrical pole faces is used and measurement for magnetic flux density is done. Experiments are conducted with aluminum and austenitic stainless steel workpieces to understand the effect of magnetic field. Effect of initial roughness, workpiece rotation and process duration on finishing was investigated with ground austenitic stainless steel workpieces. It is observed that the improvement in finish is better for rougher surface and higher rotation speed of workpiece and a reduction in roughness is consistent with process duration.

Synchronous finishing processes using a combination of grinding and electrochemical smoothing on end-turning surfaces

A new finishing mode has been utilized as an effective finishing tool design with an electrode and a nonconductive grindstone to execute grinding and electrochemical smoothing synchronously. This mode can be used for various end-turning operations. Through simple equipment attachment, grinding and electrochemical smoothing can follow the cutting process on the same machine. Among the factors affecting electrochemical smoothing, grinding performance combined with electrochemical smoothing, is primarily discussed. In the experiment, different types of electrodes are used with continuous and pulsed direct current. The control factors include die material, chemical composition, and concentration of the electrolyte. The experimental parameters are finish tool and workpiece rotational speed, flow rate of electrolytes, gap width between electrode and workpiece, electrical current density and pulsed period, and finishing tool geometry. High workpiece and electrode rotational speed produces a better finish. A thin electrode is associated with higher current density and provides larger discharge space for a better finish. Pulsed direct current can promote the effect of electrochemical finishing. Decreasing the height of the finish tool to a partial-form tool is associated with less restricted electrolyte flow and more discharge space, which creates better finishes than the full-form tools. The grindstone, with an adequately convex shape, also appeared to have an adequate initial gap width between the electrode and workpiece, which matches enough current density and obtains a better finish. The most effective geometric design for the finishing tool and the advantage of the low-cost equipment in electrochemical smoothing, following end-turning, is investigated in this study.

Design of continuity processes of electrochemical finishing and grinding following turning

A newly designed finishing process utilizing an effective electrode and a grinding tool to execute the continuous electrochemical finishing and grinding processes following turning is described in this paper. The proposed process can be used for a variety of turning operations. Electrochemical finishing and grinding can be performed following the finishing process on the same machine by using a simple attachment. The factors affecting electrochemical finishing, grinding performance, and electrochemical finishing are discussed. The electrode was tested with both continuous and pulsed direct current. A higher work piece rotational speed produced a better finish. Changing the electrode design from a semicircle to a wedge form with a small end radius caused the electrolytic products and heat to dissipate more rapidly and provided the best finishing. Pulsed direct current finishing was slightly better than using continuous direct current finishing. However, the use of pulsed current would increase machining time and cost.

Development of an Imaging System and Its Application in the Study of Cutting Fluid Atomization in a Turning Process

Airborne inhalable particulates in the workplace can represent a significant health hazard, and one of the primary sources of particles is mist produced through the application of cutting fluids in machining operations. One of the principal mechanisms associated with cutting fluid mist formation is atomization. Atomization is studied by applying cutting fluid to a rotating workpiece such as found in a turning process. In order to properly study the atomization mechanism, an imaging system was developed. This system extends the size measurement range typically achievable with aerosol sampling devices to include larger particles. Experimental observations reveal that workpiece rotation speed and cutting fluid flow rate have significant effects on the size of the droplets produced by the atomization mechanism. With respect to atomization, the technical literature describes models for fluid interaction with the rotating workpiece and droplet formation via drop, ligament, and film formation modes. Experimental measurements are compared with model predictions. For a range of rotation speeds and fluid application flow rates, the experimental data are seen to compare favorably with the model predictions.

Effect of hybrid electrochemical smoothing–roller burnishing process parameters on roundness error and micro-hardness

In this paper, a novel finishing process, which integrates the merits of electrochemical smoothing (ECS) and roller burnishing (RB) for minimizing the roundness error and increasing surface micro-hardness of cylindrical parts, is proposed. Through simple equipment attachments, electrochemical smoothing–roller burnishing (ECS–RB) can follow the turning process on the same machine. To explore the optimum combinations of the ECS–RB process parameters in an efficient and quantitative manner, the experiments were designed on the basis of the response surface methodology technique. The effect of ECS–RB parameters, namely, burnishing force, applied voltage, inter-electrode gap, and workpiece rotational speed on the roundness error and surface micro-hardness was studied. From the multi-objective optimization, the optimal combination of parameter settings are burnishing force of 350 N, applied voltage of 8.2 V, inter-electrode gap of 2.75 mm, and rotational speed of 970 rpm for achieving the required lower roundness error and higher surface micro-hardness. Surface micro-hardness considerably increases about 31.5% compared to the initial surface micro-hardness, and about 2.32 μm roundness error can be achieved using the optimum combination of process parameters. Therefore, the combination of ECS and RB is a feasible process by which it potentially reduces roundness error and surface micro-hardness of axis-symmetric parts improving their reliability and wear resistance.

Design of Surface Finish Using Compound Processes of Grinding and Electrochemical Finishing Following Turning

A new finish method uses an effective electrode connecting with a nonconductive grinding tool to execute the design of compound processes of electrochemical finishing and grinding following turning is investigated. The submitted processes can be used for various turning operations. Through simple equipment attachment, electrochemical finishing and grinding can follow to execute the finishing process on the same machine. Among the factors affecting electrochemical finishing the performance of grinding combined with electrochemical finishing is primarily discussed. In the experiment, the electrode is used with continuous and pulsed direct current. The grinding tool moves following the electrode and grinds the workpiece surface. The experimental parameters are electrical current rating, feed rate of electrode and grinding tool, rotational speed of workpiecel, pulsed period, and geometry of finish-tool. The results show that pulsed direct current with longer off-time can slightly improve the finish effect for its dregs discharge mobility. Using an adequate rotational speed of workpiece with high rotational speed is advantageous to the finish effect. A thinner plate-form electrode with a smaller end radius is associated with larger discharge space and produces higher current density and provides faster feed rate and a better finish effect. The grinding can effectively increase the finish effect. An effective and a low-cost finish process through the design electrode and using the grinding assistance in the electrochemical finishing after turning process make the surface of workpiece smooth and bright.