Cutting Edge Preparation - World Research Library

CUTTING EDGE PREPARATIONVARUN RAMESHB.E Student, Mechanical Engineering, Bangalore Institute of TechnologyE-mail: Varun.chalak@gmail.comAbstract- Proper selection and application of cutting tool edge preparation is considered one of the basic ingredients for asuccessfully manufactured and correctly performing hardmetal-cutting tool. It is widely known it's also called, of cutting tooledges can significantly increase the life of cutting tools by as much as 300% or more! Other benefits may include reducedcycle times of the cutting operation for the end user as a result of less chipping and a cooler running tool. Additionally, abetter surface finish is obtained on the material being cut, thus the possibility of further cost & time reductions to the toolend user. The discussion is aimed at the process of Nylon Abrasive Filament brush honing and how it affects the tool as anend product. It also identifies some of the manufacturing related pitfalls and the problems that can drive manufacturing costs.Keywords- Adhesion, Bristles, Honing and Micro-topography.(notchedness) and the micro-structuring of the faceand flank of the tool. The consideration of thesecutting preparation aspects influences the cuttingprocess causing improvements in tool life, toolreliability and work-piece quality.I. INTRODUCTIONIn the last decade the research works on cutting edgepreparation have increased due to its importance inmicro-machining applications, and equally for theobserved influence of the cutting edge preparation indifferent aspects of the machining process, mainly inwear development and tool life, cutting forces andmoments, distribution of the temperature, chipformation, chip flow and transportation, stress andstrain held during the cutting process, surfaceintegrity of the work piece, precision and accuracy inthe geometry of the work piece and the coatingquality of the cutting tool in terms of adhesion anduniformity. The application of the edge preparationprocess seeks to solve this problem by means of theelimination of defects and irregularities and by thegeneration of a defined edge geometry and bymodifying the micro-topography of the edgeII. IMPORTANCE OF CUTTING EDGEPREPARATIONA. ComparisonThe systemic and controlled application of the cuttingedge preparation process has several main purposesto add strength to the cutting edge, minimizes theedge chipping, eliminate previous defects of thecutting edge, increases tool life, prepares the toolsurfaces for coating deposition, improves part quality(accuracy, surface finish). The comparison of Sharpedge and prepared edge could be described as shownin the figure:Fig1: Comparison between a SHARP edge and PREPARED edgeProceedings of 30th The IIER International Conference, Beijing, China, 26th July 2015, ISBN: 978-93-85465-57-426

Cutting Edge PreparationB. ImportanceThe application of new cutting strategies to improveproductivity in the machining process and quality ofwork pieces requires the development of modernprecision cutting tools.For an integral and systemic development of aprecision cutting tool, four related aspects areconsidered: Cutting tool material (substrate); economicallyviable and meeting the requirements of a specificapplication. Coating technology; economically viable inenhancing the properties of the substrate. Macro-geometry; technologically adequate for chiptransportation, chip breaking, tool gripping andhandling.Fig. 2: Influence of the cutting edge preparation on themachining process Cutting edge preparation; precise, repeatable,controllable and compatible with a specificapplication and subsequent coating.IV.PROCESSPREPARATIONThe control of each of these aspects affects thequality and reliability of the cutting tool that issubjected to extreme conditions in modern cuttingtechnology; with local pressures between tool andwork-piece material between 100-10000 N/mm2,temperatures between 300-1200 C and velocitiesbetween 100-6000 m/min.III. INFLUENCE OF CUTTINGPREPARATION IN MACHININGFORCUTTINGEDGEThere are different technological possibilities forcarrying out the cutting edge preparation of precisioncutting tools. The considered processes utilize avariety of energy sources for removing the requiredmaterial for the cutting edge preparation. Some of themost frequently used processes are shownschematically in Figures 3 and 4, grouped accordingto the energy source used (mechanical, thermal andchemical processes).EDGEThe cutting edge preparation process generates thecontour of the cutting edge, changes the microtopography of the cutting edge, and also modifies themicro-structuring of the surfaces in the vicinity of theedge. These aspects of the cutting edge preparationinfluence the cutting process. As a resultconsequences on the tool performance and workpiece quality are observed.The cutting edge preparation geometry influences thethermo-mechanical aspects of the cutting process: Shape of deformation zones Distribution of temperatures in cutting Cutting forces Distribution of stresses in cuttingThese effects in turn affect: Chip formation and chip flow Surface integrity of the workpiece (e.g. residualstress) Surface roughness of the workpiece Tool wear resistanceV. EXPERIMENTAL SETUPA. Priniciple of with abrasive filaments forcutting edge preparationInfluence is portrayed in the following figure:Proceedings of 30th The IIER International Conference, Beijing, China, 26th July 2015, ISBN: 978-93-85465-57-427

Cutting Edge PreparationBrushing with nylon abrasive filaments (BNAF)uses a brush with abrasive filaments formed by anylon matrix and particles of hard abrasive(aluminium oxide, silicon car- bide, cubic boronnitride and diamond) as filling material toremove material by abrasion. The experimentalset-up for cutting edge preparation by BNAF isillustrated in Fig. 5 and Fig. 6.B. Cutting edge preparation geometries:To specify the form of the cutting edge, tooldesigners and manufacturers provide variouspossibilities of tool edge geometries, which arecommonly referred to as tool edge preparation.Fig. 7 illustrates the major types of edgepreparation design that are used in mostcommercial precision cutting tools.In general there are three types:Round,Waterfall, Trumpet/Reverse waterfall Therounded edge can have variants depending onthe form of the profile that connects A and A .If the curvature of the rounded profile, that joinsAα and A , is relatively uniform without strongvariations along the profile, a nominal singleradius is considered. On the other hand, if therounded profile has a strong curvature variation,two geometries are considered: waterfall ortrumpet form.In the waterfall form, the curvature is bigger atthe end of the profile that connects with the toolflank Aα and the curvature is smaller at the endof the profile that connects with the face A .In contrast, in the trumpet geometry, thecurvature is bigger at the end of the profile thatconnects with the tool face A and the curvatureis smaller at the end that connects the tool flankAα.Fig. 5: Diagram of the equipment for BNAFThe cutting tool to be prepared is mounted in afixture on a table that has movement in twoorthogonal horizontal directions, one to adjustthe penetration depth of the filaments and otherto approximate the cutting tool to the brushbefore applying the alternating feed movementof the table. The brush is mounted with the axisin horizontal position coupled to a electric motorwith controlled rotational speed and with thepossibility of changing the rotational directionduring the process cycle.Fig. 7: Different Edge Preparation ProfilesC. Comparison between Radial and WaterfallProfiles:The geometric shape of the edge hone affectstool performance just as much as hone size does.The radius-shape hone is, overwhelmingly, thepreferred choice. More than 80 percent of honedcutting tools receive a radius hone, which iscentrally located on the cutting corner of thetool.This hone forms a true circular shape that blendsequally with the top surface of the tool and thetool’s flank, or side. With a waterfall-shapedhone, the edge prep is skewed toward the topside of the tool. The ratio of the top side of theFig. 6: Principle of Abrasive Brushing edge preparationProceedings of 30th The IIER International Conference, Beijing, China, 26th July 2015, ISBN: 978-93-85465-57-428

Cutting Edge Preparationedge to its side is normally 2:1. The main benefitof a waterfall hone is that the honing processleaves more tool material directly under thecutting edge, which further strengthens thecorner.Waterfall hones are mostly used for very roughmachining applications, such as those involvinginterrupted cuts or removing scale from aworkpiece. In most heavy cutting applications, atool with a waterfall hone will outperform onewith a radius hone. However, for most standardcutting.Fig. 9: Comparison Between Round And Rectangular BrushesFor Average Edge Rounding ValuesApplications—those that warrants a radiusedge—the use of a waterfall edge would increasetool pressure and shorten tool life.CONCLUSIONMachine was studied in detail, calculated fewsamples and compared with the actual workingof the brushes on machine with optimumoperating parameters. The study of bothrectangular and round brushes were conducted inorder to acheieve the Waterfall profile, wherethe variations in the edge roundness value of theinserts were more, so that a forecast would beestablished for Inserts as the profile and theEdge Roundness values are within permissiblelimits.A waterfall hone is achieved around the 4 to4:30 o’clock position. The Hone size can beadjusted by adjusting the brush speed. Decreasethe brush rotation speed to decrease the honesize and increase the brush rotation speed todecrease the hone size. In and out movement ofthe brush will affect the size of the hone.Movement of the brush towards the insert willincrease the size of the hone and moving thebrush away from the insert will decrease the sizeof the hone. There are two kinds of brushes Thestudy of both rectangular and round brusheswere conducted in order to acheieve theWaterfall profile, where the variations in theedge roundness value of the inserts were more,so that a forecast would be established forInserts as the profile and the Edge Roundnessvalues are within permissible limitsA sample of 15 inserts were inspected underRound-Bristles Brushes wherein the averageedge roundness value variations was found to be27.15 microns. Further, after a thoroughevaluation of the samples under observation anddiscussions with the Production Team andcounterparts, it was brought into considerationthat Rectangular-Bristles Brushes should be usedin place of Round-Bristles Brushes. A sample of120 inserts were tested under Rectangularbristles brushes and it was seen that the averagevariations in the Edge-Roundness values of theinserts was brought down by 3.67microns.VI. RESULTS AND DISCUSSIONSComparing the Round and Rectangular bristlesgives us a better view of Waterfall profile usedwith different bristle brushes. The comparison ofthese bristle brushes are shown in Fig. 7 and Fig.8.Further, the profiles of the inserts were verymuch similar to the international standards. Thisreplacement of Round Brushes with theRectangular Brushes has enhanced theproduction of Inserts as the Waterfall profile andthe Edge Roundness values are withinpermissible limits.The time study of the EDGE HONING operationgave experience to the real time exposure ininteracting with the operator and understandingthe operation and behaviour the workmen withinthe organisation.Fig. 8: Comparison between Round and Rectangular brushesreadingsProceedings of 30th The IIER International Conference, Beijing, China, 26th July 2015, ISBN: 978-93-85465-57-429