Efficiency Of Grinding Process Research Articles

Nickel-based super alloy grinding optimisation using a hybrid multi attribute decision making method based on entropy, AHP and TOPSIS

ABSTRACT Nickel-based superalloy grinding, as well as selecting the appropriate operational parameters, is one of the major challenges in machining engineering. The conducted research consists of two sections. The first section presents a systematic experimentation, which has been carried out to qualitatively and quantitatively investigate nickel-based superalloy grinding. Vitrified CBN grinding wheels, along with a rotary diamond cup dresser, were utilised to conduct the experiments with the workpiece of Inconel 738. Specific grinding energy, G-ratio and surface roughness were indicated as three major machining outputs, while the inputs were the dressing conditioning and grinding parameters. In the following, the effects of different operational parameters were relatively ranked according to their weighted impact on the grinding performance using hybrid multi-attribute decision-making (MADM) methods. For this purpose, a combination of three techniques: Analytic Hierarchy Process (AHP), Entropy and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was utilised to select the most appropriate grinding conditions, while considering the conflicting effect of the different dressing and grinding parameters. The results indicate that specific energy can be an important criterion for evaluating the process efficiency. The changes in G-ratio and surface roughness have the same trends, as opposed to specific grinding energy mutation. The grinding parameters are summarised in equivalent chip thickness. Our findings show that dresser cross feed rate, along with equivalent chip thickness, has the greatest impact on the grinding process efficiency.

Improving the Efficiency of Grinding Process Using the Rubber-Pasted Grinding Wheel

Abstract This paper studies the efficiency improvement of AISI 4140 steel external cylindrical grinding process. Experiments were carried out with two types of grinding wheels, a conventional and the rubber-pasted grinding wheels. With each type of the wheel, nine experiments were performed. Cooling fluid, spindle speed, feed rate and depth of cut are variables in the experiments. Two outcomes used to evaluate grinding efficiency are surface roughness and material removal rate (MRR). Experimental results demonstrate that the surface roughness achieved in the grinding operation using the rubber-pasted grinding wheels is smaller than using the conventional wheel. The Data Envelopment Analysis-based Ranking (DEAR) method was applied to determine the optimal values of the input parameters for the “minimum” surface roughness and “maximum” MRR in the cases of using each grinding wheel. It is found that the optimization of the input parameters in this circumstance are equal. Several grinding experiments for examining the values of the variables were also performed for both the wheels. The results also confirm that the surface roughness in the grinding process with the rubber wheels is about 19.42% smaller than the conventional wheels.

The Prospects of Abrasive Treatment of Tough-To-Machine Materials

Abstract In current conditions, great attention is paid to the quality of parts, which is in many ways determined by finishing operations of mechanical treatment, with surface grinding being the most widespread. Grinding process efficiency, abrasive tool wear intensity, machined surface quality and other features of grinding process depend on properties of the environment, where the cutting process takes place. Forced changing of conditions of this environment is one of the ways to control and optimize the grinding process, which can be reached due to finding new technological decisions. One of the most promising directions to solve this problem is the process of face grinding with discontinuous grinding tool and supply of cooling fluid or air in the cutting zone directly. Carried analysis of features of face grinding has shown that heat density can be decreased by the usage by grooved wheels with vortex air cooling or by supply of cooling-lubricant technological fluid. Obtained dependences of temperature field of part surface during grinding establish the influence of the length of working shoulders and grooves, vortex tubes number, outflow rate, temperature and flow rate of cold vortex flow of air. These data provide conscious control over the process of discontinuous face grinding by changing wheel grain size and grinding speed.

THEORETICAL STUDY OF THE EFFECT OF GEOMETRICAL PARAMETERS AND LOCATION OF ROTOR IMPACT ELEMENTS OF AN IMPACT-CENTRIFUGAL GRINDER ON SPEED AND ANGLES OF CRUSHED PARTICLES FLIGHT

One of efficiency indicators of grain grinders is grain granulometric composition. The basis of mixed fodder is crushed grain, the particles of which must have a leveled granulometric composition for subsequent mixing and obtaining a high-quality feed mixture. In agricultural production, hammer crushers are widely used, in which the destruction of grain occurs due to the impact of a hinged hammer. The main disadvantage of these crushers is that not the entire surface of the hammers is involved in grinding, thus reduces grinding process efficiency. A slightly different principle of material destruction is laid down in the basis of the proposed design of the shock-centrifugal grinder. Main work is performed by flat impact elements located on the rotor, which serve to accelerate crushed particles with subsequent impact of them on the bump elements. An important step in the design of new constructions of shock-centrifugal grinders is to determine size and location of the impact elements on the rotor, without which the grinding process is not possible. In the calculation method presented, the dependencies for determining the velocities and angles of a single particle flight from the surface of a flat impact element for its specified dimensions are proposed. Two variants of an impact element location on the rotor are considered and analyzed: radial and at an angle in the direction of rotor rotation. As a result of research carried out, it is noted that in the case of inclined position of an impact element on the rotor an increase in flight speed and flight angles change in crushed particles, which gives the opportunity to have a positive effect on grinding process.

Аналіз технологічних умов підвищення ефективності процесу шліфування

Аналіз технологічних умов підвищення ефективності процесу шліфування

The effect of steric and activation factors antagonism upon grinding process efficiency

The effect of steric and activation factors antagonism upon grinding process efficiency

Behaviour of steel with the metastable austenite during segmental grinding

The methods of the grinding process efficiency evaluation have been presented in this paper basing upon the temperature in the workpiece tool contact area. The technique of determining this temperature has also been given as a combination of analytical and experimental process. These are especially useful by properties and phase transformation investigations in the metastable austenite steels.

Optimizing the Dry Grinding Process on the Basis of Bond Materials

In order to decrease the negative environmental impacts of the cutting fluids (for example, disposal of grinding sludge) and also to reduce the manufacturing costs and the required space for the machines the dry grinding can be a conceivable alternative for the conventional grinding processes. Nevertheless, dry grinding has not been widely introduced into industry because of the high temperature generated in the grinding zone and difficulties of heat transfer without coolants. Selection of the proper grinding wheel bonds, grit sizes and concentration has significant effect on the grinding performance and the generated heat in the contact zone. This paper addresses the effects of the grinding wheel bond and the concentration on the dry grinding process efficiency through comparing the results of the carried out experiments with three resin bonded cBN-cup-wheels, each consisting different bond components. For this purpose, surface roughness and thermal damages during dry and wet grinding (utilizing grinding oil) by three different resin bonds were measured. The results show almost identical surface roughness values for dry and wet grinding. Furthermore, using the resin-kryolith-graphite bonded wheel leads to a reduction in thermal damages on the workpiece. Through different experiments, it was shown that the different bonds, used in this study, have significant influence on the chip loading of the grinding wheels. This is contributed to the different chip formation mechanisms and induced grinding temperatures when grinding by the different wheel bonds.

An Experimental Study on the Dynamic Behavior of Grinding Wheels in High Efficiency Deep Grinding

The design and material of the grinding wheel hub determine its static and dynamic behaviors which, in turn, play significant roles in grinding performance. This can be of special interest in high efficiency deep grinding (HEDG) process, in which the wheel is subjected to extremely high centrifugal and grinding forces. On the other hand, controlling the dynamic behavior of the grinding wheel through an in-process monitoring and a post-process measurement seems an appropriate approach to optimize the grinding process. This paper addresses the effects of the Carbon fiber-reinforced polymer (CFRP) hub body on the grinding process efficiency through comparing the results of the experiments carried out by two CBN vitrified bonded wheels with different hub materials, CFRP and steel. The experiments were conducted using a new in-process measurement system. It was proved that the dynamic behavior of grinding wheels can affect the chip removal mechanism, and in turn, influences the finished surface roughness. Furthermore, using the CFRP as the hub material leads to a reduction in the wheel radial expansion during the operation and grinding forces. High amplitudes and frequencies have been measured when using the steel grinding wheel, while they can be damped by employing CFRP hub material.

ボールミル粉砕による超微粉砕の可能性

In general, it had been well known that the energy efficiency of grinding process decreases with decrease of produced particle size or with increase of grinding time or with increase of input energy.In this study, we defined the size reduction energy as the elastic strain energy which is stored up to fracture in the solids. The relationship between particle size and fracture energy or impact velocity required for fracture quantitative based on the single particle crushing was referred.As a result, it was found that the increase of probability of collision between particles and grinding media is effective for ultrafine grinding. The above has been verified experimentally by the ball milling.