Papers by Keyword: Difficult-to-Machine Material

Abstract: The large complex structure integral components composed of difficult-to-machine material (such as titanium alloy, high temperature alloy) are more and more widely applied in aerospace, weapon equipment and other industries. The material utilization rate and the processing efficiency of the milling process are very low, the cost is high. Micro copper tubes (diameter 2mm, inner diameter 1.6mm) are arranged to electrode with shape to be processed, which could cut these components with a high efficiency and low cost. The fabrication of electrode is simple and convenient, so the cost of electrode could be reduced too. The flow field design is an important problem to be solved. The model of flow field is established, and flow field of different cathodes are simulated．The analysis results show that the rectifying ring is favorable for the electrochemical machining. Finally, the cathode with rectifying ring is used in processing experiment, the edge of cutting zone is orderly, no spark and short circuit occurs. Straight line and circular hole is successfully processed. The feasibility of the scheme is proved.

Abstract: The interaction between abrasive waterjet and target is studied by computational fluid dynamics (CFD) and finite element method (FEM). The flow field inside and outside abrasive waterjet (AWJ) nozzle is obtained by CFD software. Then the pressure distribution of the fluid on the target is plotted, which is in well agreement with the force distribution of the AWJ impacting on the target and leads to the material deformation. The interaction between the AWJ and target and the fluid-solid coupling is happened. The cloud figure of the target’s deformation and stress are obtained by FEM software. The AWJ parameters such as the flow velocity, off-set and abrasive volume factor have a great effect on the material deformation and the stress distribution. The study results provide a new method to study abrasive water jet machine mechanism and help to optimize process parameters.

Abstract: This study is developing environmentally friendly cutting technologies of difficult-to-machine materials by MQL (Minimum Quantity Lubrication) cutting with Ti-B coated tools. In this research, we performed cutting experiments of difficult-to-machine materials in dry, MQL and wet conditions with non-coated tools. Cutting resistance in the MQL cutting was almost the same as that in the wet cutting. Moreover, damage of the cutting tool was not observed after the MQL cutting. Therefore the MQL cutting is expected to become an advanced cutting technology by using Ti-B coated tools because Ti-B film had high temperature lubricating properties and high wear resistance.

Abstract: Laser-assisted machining (LAM) is a hybrid cutting process in which a laser beam is used to heat and soften the workpiece locally in front of the cutting tool edge. The rapid temperature rise at the shear zone reduces the yield strength and work hardening of the workpiece, which makes the plastic deformation of difficult-to-machine materials easier during machining. LAM provides a reduction in the cutting forces/specific cutting energy, longer tool life, better surface integrity, and high productivity over traditional cutting. This paper presents the technical characteristics, material removal mechanism and the application of machining hard-to-machine material in LAM. The latest development of LAM and future scope are summarized in this paper.

Abstract: With the carbon fiber reinforced plastic(CFRP) materials more and more widely being used in aviation, aerospace and other industries, the study of the secondary processing technology of composite materials is paid attention by scholars from home and abroad. Because the composite materials has characteristics such as high hardness, high strength, light weight, anisotropic and etc, it is easy to produce hierarchical, tearing, burrs, drawing, the collapse of block and other defects in the machining process, so it belongs to a typical difficult-to-machine materials. Firstly the type and characteristics of carbon fiber composite materials were analyzed. Basing on the basic principles of composite material machining the carbon fiber composite machining defects were analyzed, and the design and optimization suggestions of the carbon fiber composite cutting tool were put forward according to its machining characteristics. The tool solutions of the drilling problems of carbon fiber composites in different areas currently facing were explored. Under the basis of theoretical research and analysis, a new type of PCD tool was designed and developed and through comparing test the optimal edge was got. Through experimental research the tool geometry parameters and cutting parameters which were suitable for machining were analyzed, and the tool life problems were analyzed too. All these laid a foundation to realize carbon fiber composite materials cutting of high efficiency and high quality.

Abstract: NC electrochemical mechanical drilling was based on NC, Electrochemical machining and mechanical grinding. It drilled with different diameter composite cathodes. This kind of drilling method took the advantages of electrochemical mechanical, so it was not restricted by parts’ strength, hardness and stiffness. The cover of cathode ensured the drilling precision. So this technology should be studied. This paper took 304 stainless steel and high temperature alloy GH710 to do study, at last the reasonable and high efficient process parameters were found in the experiment. The high quality holes of better roundness and small taper angle were drilled. The results showed that the study of NC electrochemical mechanical drilling difficult-to-machine materials was very meaningful.

Abstract: The uses of Titanium alloys have largely been increased due to the benefits which are very substantial in some specific areas. Their applications are not only limited to in aerospace industries and biomedical implants but also widely introduced in marine and automotive industries. Yet the optimum cutting conditions for those materials are still under investigation. Ti-alloys are in the group of difficult-to-machine materials due to their poor machinability. The main reasons behind their poor machinability are high chemical reactivity, low modulus of elasticity and low thermal conductivity. Here in this paper a number of literatures related to optimization of machining parameters are reviewed and the problems related to machining of these Ti-alloys including their effects are summarized.

Abstract: Stellites are cobalt based super alloys. By virtue of their excellent physio-mechanical properties, stellites are highly regarded engineering materials. Stellites posses high corrosion resistance and wear resistance properties. This study investigates the Stellite deposition process and machinability of Stellite 6 deposited on steel subtrate. Stellite 6 was deposited onto a 4140 bar using a plasma transfer arc (PTA) system and machinability was assessed on the basis of surface roughness. A series of turning operations have been carried out on a conventional lathe using coated carbide inserts and surface roughness was evaluated by Stylus type Surtronic3+ instrument. The values of surface roughness were plotted against different cutting speed, feed rate and depth of cut to display the results in graphical forms. Optimal cutting regimes were established against the best values of surface roughness.

Abstract: For the cutting of the difficult-to-machine materials, such as stainless steel and dead-hard steel, is always puzzling and restricting manufacturing, it is necessary to deeply study and search after new machining methods in respect of both theory and practice. This paper chose waved-edge milling inserts and flat-groove milling inserts of different materials to make cutting force contrast experiments on stainless steel ZG0Cr13Ni5Mo, chose ultrafine-grain inserts, YT14 inserts (local product) and CY250 inserts(foreign product) to make cutting life contrast experiments on dead-hard steel ZG35CrMo, then researched in theory the disrepair appearance, the BSE image and the granularity. The research results show that the integrated cutting capability of ultrafine grain waved-edge milling insert is excellent for difficult-to-machine materials.