In abrasive waterjet (AWJ) process, abrasive properties are of critical factors that influence machining performances. Abrasive process parameters including abrasive material, size and flow rate, ...exert a significant impact on cutting ability and quality of AWJ. In this paper, monolithic abrasive material (garnet, alumina and silicon carbide) and corresponding mixing abrasive materials are adopted to evaluate the effect of abrasive process parameters on the cutting ability and quality, respectively. Two kinds of cutting experiments are conducted with a monolithic abrasive to explore the influence of variation in abrasive material, size and flow rate on the machining performance. The cutting depth experiments for evaluating the cutting ability in terms of cutting depth are conducted with a right trapezoid aluminium alloy block. The kerf cutting experiments are taken to evaluate the cutting quality by the kerf taper angle, kerf width and surface roughness. On this basis, AWJ experiments with mixing abrasive materials are taken to probe into the composition of mixing abrasives’ effect on cutting performance. It is found that the abrasives consisting of 75% alumina and 25% garnet in mass fraction lead to a maximum cutting depth of 41.7 mm and the smallest surface roughness of
R
a
2.1 μm under the flow rate of 130 g/min.
•Mechanically alloyed magnetic abrasives have been prepared at different annealing temperatures.•Magnetic properties of these magnetic abrasives have been studied and compared.•Finishing efficiency ...of these magnetic abrasives has been studied and compared.•Schematic diagrams have been drawn to represent the cutting action of an abrasive particle.
In magnetic abrasive finishing (MAF) process, magnetic abrasives (MAs) act as a multipoint cutting tool that plays an important role in achieving the required surface finish of the workpiece. There are mainly two types of magnetic abrasives, bonded magnetic abrasives (BMAs) and unbounded magnetic abrasives (UMAs). BMAs are found to give better finishing capabilities than UMAs. Most of the previous research studies have applied the sintering technique for bonding abrasive particles with ferromagnetic particles. In this study, mechanical alloying technique, capable of producing a more homogeneous mixture and requiring lesser temperature for its preparation, is applied. The effect of annealing temperature on the magnetic properties and finishing efficiency is evaluated in finishing the internal surface of a brass tube. It has been found that MAs annealed at 950 °C give superior magnetic properties while MAs annealed at 1050 °C give superior finishing efficiency which improved the surface finish by 54.87% in just 10 min of finishing time. The minimum average surface roughness of the workpiece achieved is 0.51 µm in 60 min of finishing time. The working principle, cutting forces and the cutting mechanism has been represented by schematic diagrams for clear understanding.
New ferromagnetic abrasives are developed for use in finishing, so as to increase the productivity. Diffusional boriding of sprayed iron powder ensures high surface hardness of the powder particles, ...without loss of magnetic properties at the core. In comparison with sintered ferromagnetic powder, such powder particles have significantly greater cutting area. The productivity of magnetic abrasive machining when using diffusionally borided powders of different particle size is investigated in comparison with sintered Fe–TiC powder. The surface roughness of parts with nickel-based sprayed coatings that may be produced in machining by diffusionally borided powder is
R
a
= 0.22 µm. Experiments indicate higher productivity in magnetic abrasive machining when using diffusionally borided powders in comparison with sintered Fe–TiC powder. These results are tested industrially in finishing the components of hydraulic equipment.
A dense “boss” in the hole bottom by the conventional rotating mechanical drilling in the hard rock requires a more efficient drilling technique with great stress concentration, easy heat dissipation ...and slow bit wear. A new kind of hard rock mechanical drilling technique with the abrasive water jet assistance is developed for this issue, and the abrasive water jet is introduced to erode the “boss” for a “pilot hole” because of the lower rock tensile and shear strength compared with compressive strength. The exposed hole wall of the “pilot hole” provides a large area of free surface which can guide the cracks to the subsequent rock breaking, and promote the cutting edges to overcome the rock tensile strength to complete the tensile and shear failure of the rock around the “pilot hole”, which can reduce the drilling force and achieve the efficient drilling with low bit wear in the hard rock. By designing and manufacturing a hard rock breaking bit and a set of hard rock drilling equipment system with abrasive water jet assistance, the experiments are conducted and compared with the conventional technique. The results show that with the assistance of abrasive water jet, the drilling depth has increased by about 63%, the thrust force and torque have reduced by about 15% and 20% respectively, and the bit wear has been reduced significantly.
► Develops a new kind of hard rock mechanical drilling technique with abrasive water jet assistance. ► Designs and manufactures a hard rock breaking bit and a set of hard rock drilling equipment system. ► Conducts experiments and compares it with the conventional technique. ► Increasing extent of drilling depth and decreased degree of thrust force and torque are provided.
Efficiency and precision are two key indicators in the magnetic abrasive finishing (MAF) process. This paper presents the design of a core-shell structured magnetic abrasive particles (MAPs) with ...enhanced magnetic saturation rate and improved morphology. In addition, a processing roughness model based on indentation theory was developed by determining the number of active abrasive particles within the MAPs. The evolution of the MAF mechanism during the elastic and plastic deformation of processing material is clarified to realise high MAF efficiency and precision on slender tube surfaces. The grooves that slot on magnetic poles drive the maximum magnetic force on the MAPs. The simulation results from both the theoretical model of magnetic force and the active abrasive particle number theory are consistent with the actual experimental parameters, which effectively predict and explain the MAF phenomenon and mechanism. As to the zirconium alloy tube, the maximum improvement of five MAF passes on surface roughness
Ra
using the designed MAP is 63.38%, with the roughness
Ra
reaching 0.119 μm.
This paper discusses the manufacturing process of magnetic-field-assisted abrasive sensing for electroplated diamond cutting wires. The study uses a magnetization device to partially magnetize the ...piano wire and coat diamond abrasives around it. A magnetic field sensing coil is used to measure the magnetized area and a pair of needle-type vertical coil electromagnets are used for partial magnetization. The magnetic field that can be measured ranges between 9.44 and 375 mT. The study found that the distribution of diamond abrasives on the diamond cutting wire and its rigidity are crucial factors that affect the cutting performance and service life.
Brushing with bonded abrasives is a finishing process used for deburring, edge rounding, and roughness reduction. However, due to the complex motion, chipping, and wear behavior of abrasive ...filaments, industrial brushing processes have historically relied on empirical knowledge. To gain a better understanding of filament interactions, a physical model based on the discrete element method was developed to simulate process forces and contact areas. Filament patterns of round brushes were determined through the use of laser line triangulation and image processing. These filament patterns showed interlocked filaments and yielded more accurate results when used in brushing simulations than the oversimplified square patterns, which were used in previous research. Simulation confirms the occurrence of filament interactions, distinguishes between sweeping and striking filament motions, and reveals dynamic behavior at high brushing velocities that may increase undesirable tool wear.
Ultra-fine diamond grains are used to prepare agglomerated diamond (AD) abrasives that are, in turn, applied to make fixed agglomerated diamond abrasive (FADA) pads. The as-prepared pads demonstrated ...very low removal efficiency along with a poor processing stability，which limits the applicability of ultra-fine diamond grains in fixed abrasive tools. In this reported research, mixed-size agglomerated diamond (MAD) abrasives with a combination of ultra-fine diamond grains and coarser diamond grains were employed to make FADA pads for lapping BK7 glass. Three types of FADA pads were manufactured with ultra-fine AD abrasives, coarser AD abrasives and MAD abrasives, respectively, for maximizing the process efficiency and stability of fixed abrasive pads consisting of ultra-fine diamond abrasives while improving the surface quality of the lapped glass substrates. The results showed that a FADA pad with MAD abrasives exhibited higher material removal rate (MRR) than a pad with AD abrasives of ultra-fine diamond grains only and lower surface roughness Ra and better surface microstructure than a pad with AD abrasives of coarser diamond grains. The distinct lapping feature of MAD abrasives was that the coarser diamond grains mainly accelerate the lapping efficiency while the ultra-fine diamond grains improved the surface quality of workpiece.
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•A concept of mixed-size agglomerated diamond (MAD) abrasives is prompted and applied in fixed abrasive (FA) pads.•Material removal rate (MRR) and self-sharping of MAD abrasives are better than the ultra-fine AD abrasives in FADA pads.•For the MAD abrasives, coarser diamond grains and ultra-fine diamond grains play different roles in FMADA pad.•Coarser diamond grains of MAD abrasives improve the exposure height of abrasives in FMADA pad.
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•A novel magnetic field-assisted mass polishing (MAMP) process and device is presented.•The MAMP process can implement fast polishing a number of freeform surfaces with nanometric ...surface roughness.•The effect of key parameters to the material removal characteristic are analyzed.•The MAMP process can respectively utilize the bonded and loose magnetic abrasives for the rough and fine polishing.
This paper presents a novel magnetic field-assisted mass polishing (MAMP) technology for high-efficiency finishing of a number of freeform components simultaneously. The MAMP makes use of a rotational magnetic field applied outside an annular chamber which drives the magnetic abrasives to impinge on and remove material from the workpiece mounted inside the chamber. The influence of the magnetic field on the material removal characteristics is analysed by the finite element method. The factors affecting surface generation were studied through polishing experiments. Experimental results show that MAMP is effective for polishing of a number of freeform surfaces with nanometric surface finish.
