High Grinding Zone Temperature Research Articles

Enhancing grinding parameters of TC4 titanium superalloy by using hybrid eco-friendly cooling system

Grinding, a popular surface finishing operation with high dimensional accuracy is widely used for machining superalloy, ceramic, and composite materials. The trouble that arises while grinding is attributed to excessive specific energy consumption and high grinding zone temperature. This problem enhances for low thermal conductivity materials like TC4 titanium superalloy. An optimal method to minimize heat is the application of cutting fluids. However, the conventional method is inefficient and ineffective to penetrate coolant satisfactorily into the compact grinding zone. Therefore, to enhance the performance of TC4 titanium superalloy hybrid eco-friendly grinding which is the modern manufacturing process is used in this research work. Implementation of a hybrid cooling system using MQL coolant with a jet of Liquid CO2 at a higher feed rate provides a better surface morphology and eliminates biological problems. The experimental result shows that there is an eminently reduction of grinding force using a hybrid method as compared with conventional flood and MQL environmental conditions. This is generally due to better infiltration of fluid in the grinding zone and there is breakage of air turbulence which is formed around the porous grinding wheel. Moreover, MQL reduces overall manufacturing costs by reducing the amount of coolant and disposal difficulties. Significant reduction of heat flux was observed in a hybrid system which minimizes thermal-related problems and enhances the longevity of grinding wheel.[copyright information to be updated in production process]

Influence of minimum quantity lubrication on surface integrity of ground hardened H13 hot die steel

In grinding process, cutting fluids play an important role to control high grinding zone temperature. However, their use causes detrimental effect on the operator’s health and environment. On the other hand, dry grinding not only results in thermal damage to ground surface but also deteriorates the surface quality and dimensional accuracy of the ground component. The possible solution is to apply cutting fluids using minimum quantity lubrication (MQL) technique. The objective of present research work is to investigate and compare the effect of different grinding environments: dry, flood, MQL with deionized water (DIW), MQL with liquid paraffin oil (LP), and MQL with castor oil based on vegetable oil (VO) during grinding of hardened H13 hot die steel. Grinding performance was evaluated in terms of specific grinding force, specific grinding energy, grinding force ratio, surface roughness, and microhardness. Ground surface and debris morphology were also analyzed using scanning electron microscope, atomic force microscope, and energy-dispersive X-ray spectroscopy to validate the grinding performance. The results showed that MQL-VO grinding leads to minimum specific grinding force, specific grinding energy, and grinding force ratio. Further, surface roughness was considerably reduced under MQL-VO grinding, where Rɑ and Rz were 0.245 μm and 1.846 μm, respectively. AFM analysis indicated that the surface roughness of MQL-VO grinding was nearly 29.88% less as compared to dry grinding. Smooth ground surface topography, as well as long, thin, and no wear track grinding debris, were observed under MQL-LP and MQL-VO conditions. Moreover, dry grinding resulted in lower microhardness in comparison to other grinding conditions.

Grindability Improving of Titanium alloy by Using Minimum Quantity Lubrication with Pneumatic Nozzle

Major problem associated while grinding titanium alloy are high specific energy and high grinding zone temperature. To reduce temperature, grinding fluid was used but majority of them was wasted due to formation of stiff air layer around porous grinding wheel rotating at high speed which deflects grinding fluid away from grinding wheel.This paper presents an innovative improvement of MQL process by adding pneumatic nozzle. High compressed air jet from pneumatic nozzle is impinged on grinding wheel surface at an angle of 45° which suppress stiff air layer and clean machined chip, clogged wheel pores from grinding wheel surface. In this work, titanium grade I with alumina grinding wheel is ground at an infeed of 30 μm under flood cooling, MQL and MQL with pneumatic Nozzle conditions. Experimental result shows grindability of titanium grade I alloy under MQL with pneumatic nozzle proves to be an extremely efficient in order to lower grinding force, force ratio, wheel wear, wheel loading and surface roughness.

SELECTION OF APPROPRIATE FLUID DELIVERY TECHNIQUE FOR GRINDING TITANIUM GRADE-1 USING THE ANALYTIC HIERARCHY PROCESS

<p class="abstract">Grinding is commonly used in industry for the finishing or semi-finishing of different mechanical components. In this process, a wheel is rotated at a high speed. The wheel is made of abrasive particles known as grits. During grinding, high grinding zone temperature is experienced leading to several grinding defects. To control these thermal defects grinding fluid is usually employed mainly to cool and lubricate the grinding region. However, most of the applied grinding fluid cannot reach the grinding zone as it is deflected by the stiff air layer formed around the wheel periphery. Several attempts have been made in the past to overcome this problem in order to guarantee better fluid delivery. In this paper, two newly developed methods, a pneumatic barrier and a compound nozzle are considered to serve this purpose. Grinding experiments are conducted on titanium grade-1 specimens under four environmental conditions, which include dry, flood cooling, flood cooling with pneumatic barrier set up and cooling using a compound nozzle. Under each environment, 10 grinding passes are undertaken using 10, 20 and 30 mm infeed. Data obtained are used to optimize the grinding performance by employing the Analytic Hierarchy Process (AHP). The AHP results show compound nozzle fluid delivery at 20 mm infeed to be the appropriate condition for grinding titanium grade-1 within this experimental domain. This condition is supposed to deliver grinding fluid deep into the grinding zone thereby controlling grinding temperature effectively and may be recommended to the industry. </p>

Appropriate application of pneumatic barrier for improving grinding performance

High grinding zone temperature is the primary reason behind several grinding defects. To control thermal defects, usually large quantity of grinding fluid is employed. However, much of applied grinding fluid is reported to be wasted because of the development of a stiff air layer surrounding the rotating wheel. In the present experimental work, an indigenously introduced setup utilising a pneumatic barrier is used for controlling the adverse effect of stiff air layer formed around the grinding wheel. Different parameters of the pneumatic barrier setup are optimised by using response surface methodology (RSM). Further, experiments are performed in surface grinding with the provision of pneumatic barrier. It is observed that applying conventional grinding fluid by providing the pneumatic barrier at optimised condition, tangential and normal force components are reduced significantly, and favourable grinding chips and good ground surface is generated in comparison with the conventionally used flood cooling.

Improving grinding fluid delivery using pneumatic barrier and compound nozzle

Grinding fluid is commonly applied to control grinding defects caused by high grinding zone temperature. Delivery of fluid to the grinding zone is obstructed by the formation of a stiff air layer around the grinding wheel. This results in huge wastage of grinding fluid. In the present paper, results of using a pneumatic barrier and a compound nozzle are discussed with respect to delivering fluid deep into the grinding zone. Grinding fluid passing through the grinding wheel contact zone is measured under different modes of fluid delivery using a flood cooling, or a compound, nozzle, with or without the application of a pneumatic barrier. It is found that the system using a pneumatic barrier with flood cooling nozzle, and that employing a compound nozzle perform better than the flood cooling nozzle. A compound nozzle along with a pneumatic barrier renders substantially less wastage of grinding fluid even at a low flow rate of grinding fluid. Above a fluid discharge of 475 ml/min, the compound nozzle alone shows effective penetration of grinding fluid through the grinding zone. Reduction of grinding force, specific energy and roughness of ground surface are obtained after using compound nozzle fluid delivery system. Compound nozzle may be used instead of flood cooling nozzle as it improves grinding performance even using 52.5 % less discharge of grinding fluid.

Grinding Performance Using a Compound Nozzle Characterised by Small Discharge of Fluid

High grinding zone temperature often results in several grinding defects. For controlling this, usually large amount of grinding fluid is applied. However, synthetic grinding fluid or cutting fluid has some adverse impact on environment, and, hence, researchers are trying to reduce the application of grinding fluid. In this experimental investigation, a specially developed compound nozzle is used for delivering grinding fluid. Fluid may reach easily into grinding zone at low discharge by using this nozzle. Discharge of the nozzle is about 52% less than conventional flood cooling. Grinding results obtained under different environment are compared. It is found that better grinding performance is obtained by using this compound nozzle than conventional flood cooling grinding; as consumption of grinding fluid is substantially reduced, use of compound nozzle may be more economical and advantageous to control industrial pollution.

An investigation on surface grinding of hardened stainless steel S34700 and aluminum alloy AA6061 using minimum quantity of lubrication (MQL) technique

In grinding process, the abrasives plunge and slide against the workpiece during material removal with high specific energy consumption and high grinding zone temperature. To improve process efficiency, lubrication becomes an important requirement of the grinding fluids, along with chip removal and cooling the grinding zone. Grinding fluids have negative influences on the working environment and machining cost in terms of the health of the machine operator, pollution, the possibility of explosion (for oil), filtering, and waste disposal. The use of minimum quantity of lubrication (MQL) with an extremely low consumption of lubricant has been reported as a technologically and environmentally feasible alternative to flood cooling. This paper deals with an investigation of the grindability of hardened stainless steel (UNS S34700) and aluminum alloy AA6061 using dry, MQL, and conventional fluid techniques. One type of SiC and five types of Al2O3 wheels (corundum) as well as vegetable and synthetic ester MQL oils have been tested. The influences of wheel and coolant–lubricant types have been studied on the basis of the grinding forces, surface topography, and surface temperature. Synthetic ester MQL oil was found to give better grinding performance than the vegetable MQL oils. It was argued that the improved performance of the ester oil is caused by the formation of tribo-films on the abrasives and the workpiece, which enhances lubrication by inhibiting metal–abrasive interaction. Also, the grindability of the machined specimens was found to increase substantially by using the MQL grinding process with soft and coarse wheels. In MQL grinding of AA6061 alloy, the use of vegetable oil resulted in the lowest surface roughness, whereas using synthetic ester additives lead to highest surface roughness because of higher chip loading on the grinding wheel and consequently more redeposited material on the workpiece surface.

Investigation into the Grindability and Surface Integrity of the Nickel Base Superalloy Using Liquid Nitrogen Jet Grinding

Grinding processes are mainly technique employed widely as a finishing process in a variety of materials, such as metals, hardness and brittleness and ductile materials machining to achieve good dimensional and form accuracy of the product with acceptable surface integrity. However, grinding is associated with high specific energy requirements which may be an order higher than that required in other conventional machining processes such as turning, planning, milling etc. Therefore, in grinding process, high grinding zone temperature may lead to thermal damage to the work surface, induces micro-cracks and tensile residual stresses at the ground surfaces, which deteriorate surface quality and integrality of the ground surface. Therefore, grinding fluids are applied in different forms to control such high temperature, but they are ineffective, especially under high speed grinding conditions where the energy of the fluid is not sufficient to penetrate the boundary layer of air surrounding the wheel. Moreover, the conventional flood supply system demands more resources for operation, maintenance, and disposal, and results in higher environmental and health problems. Therefore, there are critical needs to reduce the use of cutting fluid in grinding process, and cryogenic cooling grinding is a promising solution. The work presented in this paper aims at evaluating the grind ability and surface integrity of the nickel base super alloy resulting from the application of cryogenic cooling.

Experimental and Numerical Study on Grinding Temperature during Surface Grinding with Different Cooling Methods

Grinding, characterized by its high specific energy consumption, may generate high grinding zone temperature. These can cause thermal damage to the ground surface and poor surface integrity, especially in the grinding of difficult-to-machine materials. In this paper, experimental and fem study on grinding temperature during surface grinding of Ti-6Al-4V with different cooling methods. A comparison between the experimental and numerical results is made. It is indicated that the difference between experimental and numerical results is below 15% and the numerical results can be considered reliable. Grinding temperature can be more effectively reduced with CPMJ than that with cold air jet and flood cooling method.

Analytical and Experimental Investigation of the Nickel Based Superalloy Using Cryogenic Cooling Grinding

Grinding processes are mainly technique employed widely as a finishing and difficult-to machine such as hardness and brittleness materials machining. However in grinding process, high grinding zone temperature may lead to thermal damage to the work surface, induces micro-cracks and tensile residual stresses at the ground surfaces, which deteriorate surface quality and integrality of the ground surface. The work presented in this paper aims at evaluating the grindability and surface integrity of the nickel base superalloy resulting from the application of cryogenic cooling. Grinding experiments were conducted under three different environments: dry, mineral oil and cryogenic cooling jet. The grindability results have shown that while the cryogenic cooling generates the lowest grinding temperature, no significant differences over the specific grinding force components were observed. As for the ground surface integrity, however, substantial improvements were realized. The novel process not only obviously enhances surface quality and integrality of grinding surface, but also enables retention of the wheel sharpness for a longer period and reduces pollution of grinding fluid to nature.

Minimal quantity lubrication-MQL in grinding of Ti–6Al–4V titanium alloy

Titanium and its alloys are attractive materials due to their unique high strength–weight ratio that is maintained at elevated temperatures and their exceptional corrosion resistance. The major application of titanium has been in the aerospace industry. On the other hand, titanium and its alloys are notorious for their poor thermal properties and are classified as difficult-to-machine materials. The problems that arise during grinding of titanium alloys are attributed to the high specific energy and high grinding zone temperature. Significant progress has been made in dry and semidry machining recently, and minimal quantity lubrication (MQL) machining in particular has been accepted as a successful semidry application because of its environmentally friendly characteristics. A number of studies have shown that MQL machining can show satisfactory performance in practical machining operations. However, there has been few investigation of MQL grinding of special alloys like titanium alloys and the cutting fluids to be used in MQL grinding of these alloys. In this study, vegetable and synthetic esters oil are compared on the basis of the surface quality properties that would be suitable for MQL applications. The cutting performance of fluids is also evaluated using conventional wet (fluid) grinding of Ti–6Al–4V. As a result, synthetic ester oil is found to be optimal cutting fluids for MQL grinding of Ti–6Al–4V.

Experimental study on the cooling effects of cryogenic pneumatic mist jet impinging cooling method

Grinding, characterised by its high specific energy consumption, may generate high grinding zone temperature. These can cause thermal damage to the ground surface and poor surface integrity, especially in the grinding of difficult-to-machine materials. Conventional cooling methods based on large amounts of water-oil emulsions can be both ineffective and environmentally unacceptable. Here a new high efficiency cooling technology – Cryogenic Pneumatic Mist Jet Impinging (CPMJI) cooling technology is offered. It utilises the high penetrative power of fast cryogenic air jet combined with a little quantity of water of 0°C to greatly improve heat transfer effects in the machining zone. Experimental results, including heat transfer experiments and grinding experiments, indicate that CPMJI has strong cooling ability and can offer better cooling effects compared to cold air jet and traditional flood cooling method in the grinding of titanium alloy.

Research on Cryogenic Pneumatic Mist Jet Impinging Cooling and Lubricating of Grinding Processes

Grinding, characterized by its high specific energy consumption, may generate high grinding zone temperature. These can cause thermal damage to the ground surface and poor surface integrity, especially in the grinding of difficult-to-machine materials. Conventional cooling methods based on large amounts of water-oil emulsions can be both ineffective and environmentally unacceptable. Here a new high efficiency cooling technology—cryogenic pneumatic mist jet impinging cooling technology is offered. It utilizes the high penetrative power of fast cryogenic air jet combined with a little quantity of 0°C water to greatly improve heat transfer effects in the machining zone. The experimental results indicated that CPMJI could offer better machining effects compared to cold air jet and traditional flood cooling method in the grinding of titanium alloy.

Development of a simple technique for improving the efficacy of fluid flow through the grinding zone

Grinding is inherently characterized by very high-localized heating. Usually, the high grinding zone temperature is controlled by copious supply of cutting fluid. But, in reality, such cooling is not as effective as expected. The efficiency of flood cooling is very small as the coolant is obstructed from coming into actual contact with the wheel and entering into the grinding zone due to the formation of thin but stiff peripheral air boundary layer on the grinding wheel rotating at high speed in otherwise static ambient air. The increase of flow rate of coolant through the grinding zone, therefore, has become extremely essential. In the present development work, a nozzle has been designed that helps break the air layer before it reaches grinding zone, prevent air suction from the sides and at the same time force the adequate fluid towards the grinding zone. Performance of this nozzle is evaluated by separating, collecting and measuring fluid flow actually passing through the grinding zone for different nozzle locations and orientations. An attachment is designed to maneuver the nozzle for the purpose. A special work-piece-cum-fluid collecting chute is designed to measure the effective flow rate. The effective flow rate of the coolant, thus obtained, is then compared with that measured with flood cooling system originally available with the grinding machine. The developed nozzle system is found to be quite effective in enhancing the actual coolant flow through the grinding zone.

The Cooling Effects of Cryogenic Pneumatic Mist Jet Impinging in Grinding of Titanium Alloy

Grinding is inherently characterized by high specific energy requirements, a high grinding zone temperature. Many methods have been employed in grinding high grinding zone temperature. But all have their shortfalls, both in cooling environmental pollution. Here a new high efficiency cooling technology—cryogenic mist jet impinging (CPMJI) cooling technology is offered. In this technology, coolant is carried by high-pressure cryogenic air (–20°C) and reaches the machining form of mist jet to enhance heat transfer in machining zone. This paper mainly cooling effects of CPMJI in surface grinding, compared with grinding with compressed flood cooling. CPMJI seems to have better effects than other cooling methods.

Performance Improvement of Grinding of SiC Using Graphite as a Solid Lubricant

Grinding is a widely employed finishing process for different materials. It is inherently characterized by its high specific energy requirement unlike other machining processes. This leads to a high grinding zone temperature, which impairs the workpiece quality by inducing thermal damage in the form of surface and subsurface cracks, phase transformations, tensile residual stresses, etc. The microcracks and residual stresses induced in the surface of the ceramics during grinding can severely limit the application of ceramic components. This article deals with an investigation on using graphite as a solid lubricant to reduce friction and thereby improve the surface integrity of ground silicon carbide (SiC). An experimental setup has been developed, and experiments have been conducted to study the effect of using a graphite lubricant on the surface roughness, grinding forces, and specific energy while grinding SiC material. Results indicate that there is a considerable improvement in the performance of grinding SiC using graphite as a solid lubricant when compared with dry grinding in terms of specific energy requirements, surface roughness, and damage. The employment of graphite as a solid lubricant in ceramic grinding makes the process more economical and reliable.

Determination and control of grinding zone temperature under cryogenic cooling

Grinding processes, though employed widely as a finishing process, have their own share of problems, like high grinding zone temperature which may lead to thermal damage to the work surface, like induction of tensile residual stresses, development of microcracks, enhanced risks of wheel loading and excessive wheel wear. Grinding fluids are applied in different forms to control such high temperature, but they are partially effective within a narrow working range; recent studies also indicate their polluting nature. cryogenic cooling, if employed properly, could control the grinding zone temperature more effectively by intensive removal of heat from the grinding zone. The present study deals with the effect of cryogenic cooling on grinding zone temperature for five commonly used steels both experimentally and computationally. Results indicate that the effectiveness of cryogenic cooling is substantial throughout the experimental domain.

The effect of cryogenic cooling on grinding forces

Grinding forces are important parameters to judge the performance of any grinding process. Cryogenic cooling in grinding is a new concept to control the high grinding zone temperature without polluting the environment. The paper presents a hypothesis on the mechanics of grinding under cryogenic cooling. Experiments have been carried out to study the effect of cryogenic cooling on grinding forces and to check the validity of the hypothesis. The results indicate substantial reduction in the grinding forces under cryogenic cooling over range of infeed and dressing procedure for different commonly used steels.

Effects of cryogenic cooling by liquid nitrogen jet on forces, temperature and surface residual stresses in grinding steels

Grinding is a widely employed finishing process for different materials such as metals, ceramics, glass, carbides, rocks, etc. to achieve good geometrical (form) and dimensional accuracy with acceptable surface finish and surface integrity. However, it is inherently characterized by high specific energy requirements, unlike other conventional machining processes such as turning, milling, etc., which lead to a high grinding zone temperature and poor surface integrity. Many methods have been investigated to control this high grinding zone temperature, but all have their shortfalls, both technological and environmental, in exchange for controlling the grinding zone temperature. This paper briefly discusses the results obtained with regard to grinding forces, specific energy, grinding zone temperature and surface residual stress when using cryogenic cooling and compares them to the results from dry grinding and grinding with soluble oil. Cryogenic cooling seems to have the edge over other coolants in terms of controlling the temperature, residual stresses and grinding forces, and it is also environment friendly.