scholarly journals Process Limits in High Performance Peel Grinding of Hardened Steel Components With Coarse CBN Grinding Wheels

2021 ◽  
Author(s):  
Berend Denkena ◽  
Alexander Kroedel ◽  
Michael Wilckens
Keyword(s):  
Material Removal ◽  
High Performance ◽  
Hardened Steel ◽  
Wear Behaviour ◽  
Process Time ◽  
Turning Process ◽  
Grinding Wheels ◽  
Removal Rates ◽  
Grain Sizes ◽  
Very High

Abstract Recent developments in the production processes for cubic boron nitride (CBN) abrasive grains have led to commercially available grain sizes larger than lg > 300 µm. These superabrasive grains allow higher material removal rates during grinding of hardened steel components. Currently, these components are pre-machined by turning processes before being hardened and eventually finished by grinding. However, the turning process can be substituted by grinding with coarse CBN-grains since higher depths of cut are achievable when machining hardened components. This paper investigates the process behaviour of vitrified and electroplated grinding wheels with large grain sizes during the machining of hardened steel components. Process forces, wear behaviour and workpiece surface roughness are investigated for three different grain sizes and the process limits of both bond types are examined.The investigations show that the vitrified tools do not fully suit the demands for peel grinding process with very high material removal rates since wear by means of bond breakage occurs. The electroplated tools on the other hand are capable of very high material removal rates. Their wear behaviour is characterized by clogging of the chip space if the process limit is reached. Even so, both tools outperform a standard hard-turning process in terms of process time by 74 % and 94 % respectively.

scholarly journals High performance peel grinding of steel shafts using coarse electroplated CBN grinding wheels

2021 ◽  
Author(s):  
B. Denkena ◽  
A. Krödel ◽  
M. Wilckens
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Material Removal ◽  
High Performance ◽  
High Surface ◽  
Work Piece ◽  
Hard Machining ◽  
Grinding Wheels ◽  
Removal Rates ◽  
High Surface Quality

AbstractGrinding is widely known for its low material removal rates and high surface quality. However, recent developments in production processes for cubic boron nitride (CBN) abrasive grains have led to commercially available grain sizes larger than 300 µm. These superabrasive CBN-grains allow higher material removal rates during grinding of hardened steel components. Currently, these components are pre-machined with turning processes before hardening and finishing the work piece by grinding. However, the turning process can be eliminated by grinding with coarse CBN-grains since higher depths of cut are achievable when machining hardened components. This paper explores the limits of grinding wheels using grains with a size of B602 during soft and hard machining in comparison to conventional B252 grains. It is shown that the use of coarser grains leads to lower process forces, higher (tensile) residual stress and higher surface roughness. Residual stress and surface roughness are of less importance as these grains are to be used mainly in roughing operations with ensuing finishing operations for the required surface properties. Over all investigations, especially in hard machining, neither grain nor tool wear was observed for the B602 grains, whereas the B252 tool was severely clogged during the experiments. Additionally, the grinding force ratio indicates that the coarse grain tools have not yet reached their productivity limit as it increases over all investigated feeds. This indicates improving tool performance with lower amounts of rubbing for increasing feed rate during hard grinding and shows the potential for the industrial use of higher feed rates with larger grains.

Vibration-Assisted Grinding of Mild and Hardened Steel: A Novel Design Vibrating Jig and Process Performance

2012 ◽  
Author(s):  
Vaios Tsiakoumis ◽  
Andre Batako
Keyword(s):  
Material Removal ◽  
Manufacturing Sector ◽  
Hardened Steel ◽  
Surface Grinding ◽  
Grinding Wheels ◽  
Grinding Forces ◽  
Product Surface ◽  
Novel Method ◽  
Precision And Accuracy ◽  
Novel Design

Grinding is always one of the most significant processes in manufacturing sector due to its high precision and accuracy and especially nowadays where the demand for higher quality products has been raised. Its importance lies on the fact that it stands at the final stages of a component’s manufacturing chain and therefore, the possibility of errors must be at the lowest levels. Heretofore, the improvement of this process has motivated a number of researchers to develop different techniques. In the current work a novel method of vibration-assisted surface grinding of mild and hardened steel using aluminium oxide grinding wheels is examined. More specifically, the design concept along with the dynamic characteristics of a simplified vibrating jig is presented. The purpose of this jig was to accommodate and oscillate the workpiece at a certain frequency during surface grinding in order to improve the performance of the process in terms of achieving lower grinding forces and thus lower power consumption, higher material removal rates and better product surface finish. Two grinding wheels and two workpiece materials with different properties were employed during conventional and vibration-assisted surface grinding and the results are compared. The benefits of this non-conventional, advanced grinding process are also illustrated.

High Performance in EDM Machining of AISI D2 Hardened Steel

2012 ◽  
Vol 500 ◽  
pp. 259-265 ◽  
Author(s):  
Faizul Ezmat Abdul Hamid ◽  
Mohd Amri Lajis
Keyword(s):  
Pulse Duration ◽  
Material Removal Rate ◽  
Electrical Discharge ◽  
Material Removal ◽  
High Performance ◽  
Electrical Discharge Machining ◽  
Removal Rate ◽  
Hardened Steel ◽  
Peak Current ◽  
Aisi D2

In this paper an attempt has been made to investigate the performance of an electrode made through powder metallurgy (PM) of copper tungsten during electrical discharge machining (EDM). Experimental results are presented on electrical discharge machining of AISI D2 hardened steel in kerosene with a copper tungsten (Cu35% - W65%) tool electrode made through PM method with a constant duty factor of 80%. In term of high performance EDM process, higher peak current (>20A) and pulse duration (>400µs) with a high machining efficiency were used. Experimental results have shown that machining at a peak current of 40A and pulse duration of 400µs yields the highest material removal rate (MRR) whereas machining at a peak current of 20A and pulse duration of 400µs yields the lowest tool wear rate (TWR). The lowest surface roughness appears at the lowest material removal rate which is at a peak current of 20A and pulse duration of 600µs. The optimum machining performance can be performed by the combination of pulse duration and peak current at 600µs and 40A respectively.

scholarly journals Special Issue on High Performance Abrasive Technologies

2022 ◽  
Vol 16 (1) ◽  
pp. 3-4
Author(s):  
Takazo Yamada ◽  
Kazuhito Ohashi ◽  
Hirofumi Suzuki ◽  
Akinori Yui
Keyword(s):  
High Precision ◽  
Ultrasonic Vibration ◽  
High Performance ◽  
High Efficiency ◽  
Hardened Steel ◽  
Textured Surfaces ◽  
Special Issue ◽  
Grinding Wheels ◽  
Creep Feed ◽  
Cutting Processes

Demand for the high-precision and high-efficiency machining of hard ceramics, such as silicon carbide for semiconductors and hardened steel for molding dies, has significantly increased for optical and medical devices as well as for powered devices in automobiles. Certain types of hard metals can be machined by deterministic precision-cutting processes. However, hard and brittle ceramics, hardened steel for molds, and semiconductor materials have to be machined using precision abrasive technologies, such as grinding, polishing, and ultrasonic vibration technologies that use diamond super abrasives. The machining of high-precision components and their molds/dies using abrasive processes is very difficult due to their complex and nondeterministic natures as well as their complex textured surfaces. Furthermore, the development of new cutting-edge tools or machining methods and the active use of physicochemical phenomena are key to the development of high-precision and high-efficiency machining. This special issue features 11 research papers on the most recent advances in precision abrasive technologies. These papers cover the following topics: - Characteristics of abrasive grains in creep-feed grinding - Quantitative evaluation of the surface profiles of grinding wheels - ELID grinding using elastic wheels - Nano-topographies of ground surfaces - Novel grinding wheels - Grinding characteristics of turbine blade materials - Polishing mechanisms - Polishing technologies using magnetic fluid slurries - Application of ultrasonic vibration machining - Turning and rotary cutting technologies This issue is expected to help its readers to understand recent developments in abrasive technologies and to lead to further research. We deeply appreciate the careful work of all the authors, and we thank the reviewers for their incisive efforts.

KEMPER C688

Alloy Digest ◽  
2017 ◽  
Vol 66 (12) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Physical Properties ◽  
Tensile Properties ◽  
Copper Alloy ◽  
High Performance ◽  
High Conductivity ◽  
Bend Strength ◽  
Very High

Abstract Alloy C688 is a high-performance copper alloy with very high conductivity. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and bend strength. It also includes information on corrosion resistance as well as forming and joining. Filing Code: Cu-867. Producer or source: Gebr. Kemper GmbH + Company KG Metallwerke.

KEMPER KHP7025

Alloy Digest ◽  
2017 ◽  
Vol 66 (10) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Physical Properties ◽  
Tensile Properties ◽  
Copper Alloy ◽  
High Performance ◽  
High Conductivity ◽  
Bend Strength ◽  
Very High

Abstract Alloy KHP 7025 (UNS C70250) is a high-performance copper alloy with very high conductivity. Uses include connector springs, tabs, contact springs, switches, relays, and leadframes. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and bend strength. It also includes information on corrosion resistance as well as forming, machining, and joining. Filing Code: Cu-865. Producer or source: Gebr. Kemper GmbH + Company KG Metallwerke.

Use of activated carbon to remove undesirable residual amylase from refinery streams

2017 ◽  
pp. 96-103 ◽  
Author(s):  
Gillian Eggleston ◽  
Isabel Lima ◽  
Emmanuel Sarir ◽  
Jack Thompson ◽  
John Zatlokovicz ◽  
...  
Keyword(s):  
Activated Carbon ◽  
High Temperature ◽  
High Performance ◽  
Activated Carbons ◽  
Amylase Activity ◽  
Sugar Industry ◽  
End User ◽  
Customer Complaints ◽  
Carry Over ◽  
Very High

In recent years, there has been increased world-wide concern over residual (carry-over) activity of mostly high temperature (HT) and very high temperature (VHT) stable amylases in white, refined sugars from refineries to various food and end-user industries. HT and VHT stable amylases were developed for much larger markets than the sugar industry with harsher processing conditions. There is an urgent need in the sugar industry to be able to remove or inactivate residual, active amylases either in factory or refinery streams or both. A survey of refineries that used amylase and had activated carbon systems for decolorizing, revealed they did not have any customer complaints for residual amylase. The use of high performance activated carbons to remove residual amylase activity was investigated using a Phadebas® method created for the sugar industry to measure residual amylase in syrups. Ability to remove residual amylase protein was dependent on the surface area of the powdered activated carbons as well as mixing (retention) time. The activated carbon also had the additional benefit of removing color and insoluble starch.

Relations between carbon removal rates, biofilm size and density of a novel anaerobic reactor: the inverse turbulent bed

2000 ◽  
Vol 41 (4-5) ◽  
pp. 253-260 ◽  
Author(s):  
P. Buffière ◽  
R. Moletta
Keyword(s):  
Removal Rate ◽  
Removal Rates ◽  
Carbon Removal ◽  
Biofilm Growth ◽  
Loading Rates ◽  
Biomass Activity ◽  
High Turbulence ◽  
The One ◽  
High Level ◽  
Very High

An anaerobic inverse turbulent bed, in which the biogas only ensures fluidisation of floating carrier particles, was investigated for carbon removal kinetics and for biofilm growth and detachment. The range of operation of the reactor was kept within 5 and 30 kgCOD· m−3· d−1, with Hydraulic Retention Times between 0.28 and 1 day. The carbon removal efficiency remained between 70 and 85%. Biofilm size were rather low (between 5 and 30 μm) while biofilm density reached very high values (over 80 kgVS· m−3). The biofilm size and density varied with increasing carbon removal rates with opposite trends; as biofilm size increases, its density decreases. On the one hand, biomass activity within the reactor was kept at a high level, (between 0.23 and 0.75 kgTOC· kgVS· d−1, i.e. between 0.6 and 1.85 kgCOD·kgVS · d−1).This result indicates that high turbulence and shear may favour growth of thin, dense and active biofilms. It is thus an interesting tool for biomass control. On the other hand, volatile solid detachment increases quasi linearly with carbon removal rate and the total amount of solid in the reactor levels off at high OLR. This means that detachment could be a limit of the process at higher organic loading rates.

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