289 research outputs found
The minimum quantity of lubricant technique in grinding of steel using a wheel cleaning system
The application of minimum quantity of lubricant (MQL) for metal cutting has emerged
as an alternative for reducing the abundant flow of cutting fluids, thus achieving cleaner
production. Although considered an innovative technique in grinding operations, the
widespread application is hindered mainly due to the high heat generation and the
clogging of wheel pores caused by machined chips, harming the final product quality
and increasing tool wear. This study sought to improve MQL use in grinding. Thus,
besides the conventional MQL injected at the wheel/workpiece interface, a
compressed air jet was also added, in order to clean the clogged wheel pores from the
mixture of MQL oil and machined chips. Experiments were conducted using external
cylindrical plunge grinding on AISI 4340 quenched and tempered steel, and a vitrified
cubic boron nitrite (CBN) wheel. The lubri-refrigeration methods employed were the
conventional with abundant flow, conventional MQL (both without any cleaning air jets)
and MQL with the cleaning jet, directed at the surface at different angles of incidence.
The main goal of these experiments was to verify the viability of replacing traditional
abundance flow with MQL with wheel cleaning. The analyses were conducted by
measuring the following output variables of the process: workpiece surface roughness,
roundness, diametrical wear of the wheel. Results show the possibility of implementing
the cleaning jet technique as a technological improvement of the minimum quantity of
and grinding, in order to reduce the usage of cutting fluids. The MQL technique with
cleaning compressed air jet, for a specific angle of incidence (30°) proved to be
extremely efficient to obtain improved surface quality and accurate workpiece shape,
as well as to reduce wear wheel and to prevent thermal damage, when compared to
the other lubri-refrigeration methods tested (without cleaning jet).Special thanks to FAPESP (State of São Paulo Research Assistance Foundation)
(process 2009/51440-5 (Research Assistance) and 2009/51439-7 (Scientific
Initiation)) for the financial resources made available for this study, and to the Schaeffler Group (INA brand) for the support offered in conducting metallographic
analyses
Experimental and Numerical Analysis of the Surface Integrity resulting from Outer-Diameter Grind-Hardening
AbstractBesides conventional heat treatment operations, an innovative approach for surface hardening is the grind-hardening process. During this process the dissipated heat from grinding is used for a martensitic phase transformation in the subsurface region of machined components. Additionally, compressive residual stresses are induced in the grindhardened surface layer. However, for the implementation of grind-hardening into industrial production extensive experimental tests are required to achieve iterative results of hardening depth. This paper focuses on the identification of parameter sets for a sufficient grind-hardening in outer-diameter grinding. On the one hand, grinding tests were conducted supported by metallographic investigations; on the other hand, a finite-element-based model was used to predict the surface integrity resulting from grind-hardening
Development of Multi-grit cBN Grinding Wheel for Crankshaft Grinding
A crankpin, part of a crankshaft, has a complex profile that is difficult to grind. The process often causes challenges such as excessive heat on the crankpin sidewall and wheel wear on the radius, causing reduced dressing interval. Different solutions were proposed to overcome these challenges, mainly focusing on the process, i.e. grinding strategies. However, the work presented in this thesis is concerned with optimising the superabrasive grinding wheel.A novel analytical assessment framework was developed for evaluating grinding wheel performance that can account for the effects of grit properties and dressing conditions on the wheel topography and, in turn, grinding performance. Based on the model of cutting and sliding grinding force components, a set of performance indicators were derived and then used to evaluate the effect of the wheel topography on the grinding process. Results showed that grit toughness, thermal stability, size and concentration affect the intrinsic specific grinding energy via grit protrusion and sliding component via wear flat area. On the other hand, the grit shape only affects the wear flat area but maintains the intrinsic specific grinding energy regardless if the grit has a higher or lower aspect ratio (blockier or elongated). To complement grinding performance information, wear was evaluated via grinding and lapping tests. The analyses revealed that wheels containing grits with a higher aspect ratio (elongated grits), lower toughness, lower concentration, or smaller size generate lower grinding forces; however, they wore faster. On the other hand, wheels featuring grits with a lower aspect ratio (blocky grits), higher toughness, higher concentration or coarser grit had the opposite effect. They generated higher forces and wore slower, exhibiting longer tool life. Findings from laboratory-based trials resulted in two crankpin wheel designs. One aimed to reduce heat generation, while the other targeted less wheel wear. Industrial tests at the end user demonstrated that the favourable design contained elongated and smaller grits at a lower concentration, because it reduced heat generation despite the higher wheel wear. This was confirmed via the Barkhausen noise measurements, which showed a 20% reduction in intensity compared to the reference wheel and a 30% reduction in intensity compared to the wheel design containing blockier and larger grit at higher concentration
An environmental impact analysis of grinding
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (leaves 39-40).This thesis was intended to investigate the environmental impact of grinding in the United States manufacturing industry. Grinding is an ideal method for producing parts with a fine surface finish and high dimensional accuracy and for shaping hard or brittle workpieces. There are a wide variety of different types of grinding machines, each with different applications and slightly different energy requirements. Workpieces are generally flooded with a stream of coolant while being ground or placed in a spray of coolant mist. Coolant recycling systems are used to filter ground off chips out of coolant and to remove foreign oils and bacteria which pose health hazards. Oil mist collectors both clean mist coolant and prevent the toxic coolant from being inhaled by machinists. In total, 63 *10¹⁵ joules of energy are consumed per year by grinding in manufacturing, 57% of which is directly used in material removal. A total of 1.5*10¹⁰ pounds of scrap chips, spent grinding wheels, and used filters are produced each year as a result of grinding, over 99% of that being scrap chips. About 2.3 million gallons of fluids per year of grinding fluids are incinerated. Grinding creates a significant environmental footprint, creating a need for methods to reduce energy use in grinding and for ways to recycle solid waste that would otherwise be sent to landfills or incinerated.by Beth Baniszewski.S.B
Texturing methods of abrasive grinding wheels: a systematic review
Creating textures on abrasive wheels is a strategy that allows a significant improvement in grinding operations. The reduction of the internal stresses in the workpiece and the temperature during the grinding operation generates an increase in the dimensional accuracy of the workpiece and a longer tool life. Textured abrasive wheels can be produced in many different ways. Depending on the processing method, the dimensional accuracy of the tool and its applicability is changed. Some methods can produce tools with three-dimensional grooves; there are also methods that are employed for the re-texturing of grooves after the grooved zone wears out. In the literature, the benefits of textured grinding wheels over traditional wheels have been extensively discussed. However, information on the particularities of texturing methods is still lacking. To clarify the advantages, limitations, and main advances regarding each of the groove production methods, the authors of this article carried out a systematic review. The objective of this work is to establish the factors that are affected by groove production methods and the technological advances in this area. The benefits and drawbacks of various grooving techniques are then reviewed, and potential study areas are indicated.This research was funded by FCT national funds, under the national support to R&D
units grant, through the reference projects UIDB/04436/2020, UIDP/04436/2020, UIDB/00690/2020,
UIDP/00690/2020, and SusTEC (LA/P/0007/2020). This work is within the scope of the Sharlane
Costa Ph.D. degree in progress, financially supported by the Portuguese Foundation for Science and
Technology (FCT) through the PhD grant reference 2021.07352.BDinfo:eu-repo/semantics/publishedVersio
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