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DEFORMing TEST AND CAM SIMULATION FOR a designed end milling tool with CERAMIC insertsFrcel Ionu-Ctlin1 ABSTRACT: Cutting tools with ceramic inserts are increasingly being used in machining of super alloys typically used in aerospace industry. The ceramic inserts make higher cutting speeds possible due to the higher temperature resistance compared to carbide inserts. However, the success of the process is very sensitive to the right selection of process parameters. Ceramic inserted tools has been introduced to enhance surface finish and reduce cutting forces. This paper describes also a simulation method for NC programs. The simulation uses a virtual CNC milling machine as a basis for the simulation of the generated NC program.1 INTRODUCTION

The majority of modern cutting tools are complex structures comprising a hard body, wear resistant cutting inserts which are supported by a shank or holder generally manufactured from low or medium alloy steel. The insert, with which the actual cutting operation takes place, is generally kept as small as possible in order to reduce the cost and may be made in a variety of hard materials, commonly cemented carbide at different grades.Ceramic inserts represent economic advantages over other type of inserts since higher material removal rate (MRR) is possible owing their high heat resistance and gradual entry to the cut. Besides, power consumption and tool life are dependent on cutting force magnitudes.In the next sections, geometry of the end milling tool with ceramic insert is described. Ceramic inserts are quadratic form, with drafted walls.Nowadays highly complex work pieces, mostly in large varieties, are manufactured on CNC-controlled machine tools. These complex manufacturing processes need to be checked thoroughly before running at a real machine tool. Nowadays most NC programs are created via computer aided manufacturing (CAM) tools. However, these kinds of software only consider the work piece and the tool. 2 TOOL GEOMETRYThe general information of the designed tool are described in Fig. 1. The body of tool is from carbon steel and inserts from ceramic. The inserts are clamped of body with special screws.

Fig. 1. Tool geometry

1 University Lucian Blaga of Sibiu, Engineering Faculy, Emil Cioran 4, 550025, Sibiu, RomaniaE-mail: ionut.farcasel@ulbsibiu.ro.2.1 Tool body The tool body is from carbon steel, an metalalloy, a combination of two elements, ironandcarbon, where other elements are present in quantities too small to affect the properties. The only other alloying elements allowed in plain-carbon steel are: manganese(1.65% max), silicon (0.60% max), andcopper(0.60% max). Steelwith a low carboncontenthas the same properties as iron, soft but easily formed. As carbon content rises the metal becomes harder and stronger but less ductileand more difficult toweld. Higher carbon content lowers steel's melting point and its temperature resistance in general.AISI 1045 steel is a medium tensile steel supplied wich has a tensile strength of 570 - 700 MPa and Brinell hardness ranging between 170 and 210. AISI 1045 steel is characterized by good weldability, good machinability, and high strength and impact properties in either the normalized or hot rolled condition. AISI 1045 steel has a low through-hardening capability with only sections of size around 60 mm being recommended as suitable for tempering and through-hardening. However, it can be efficiently flame or induction hardened in the normalized or hot rolled condition to obtain surface hardnesses in the range of Rc 54 - Rc 60 based on factors such as section size, type of set up, quenching medium used etc.AISI 1045 steel lacks suitable alloying elements and hence does not respond to the nitriding process.A simplified representation of the tool is shown in Fig. 2, overall dimensions are represented.

Fig. 2 Dimensions

2.2 Ceramic insertsCeramic milling typically runs at 20 to 30 times the speed of carbide, although at lower feed rates (~0.1 mm/tooth), which results in high productivity gains. Due to intermittent cutting, it is a much cooler operation than turning. For this reason, speeds of 2297-3280 mm/min when milling are adapted, compared with 656-984 mm/min for turning. Ceramics have a high tendency for notching, which is why round inserts are primarily used to ensure a high lead angle. Never use coolant.

Ceramics have a negative effect on the surface integrity and topography, and are therefore not used when machining close to the finished component shape. Ceramic inserts are NOT recommended in titanium. Cutting fluid should NOT be used with ceramic inserts.

3 Deforming test3.1 General informations

Deforming test evaluates the effect that load has on the shape of a sample. It is the measurement of a sample material to withstand a permanent deformation and/or the ability of the sample to return to its original shape after deforming. Deformation is measured as the percent change in height of a sample, under a specified load, for a specified period of time.This end milling tool was designed in Catia V5 software and has a simple construction with four slots for ceramic inserts. The machining diameter is 30 milimeters.3.2 ClampingTo clamp this tool is necessary an aligning bar with Morse taper, an conical adapter and a slotted nut. Clamping operation is shown in Fig. 3.

Fig. 3 Clamping3.3 Constraining and forcesThe tool is constrained on the outside diameter (that have 20 miliimeters) and the resultant forces press on the flanks where are fixed the inserts. All of these are shown in Fig. 4.

Fig. 4 Constraining

To show the deforming of the tool, was simulated a analysis in Catia V5 software, wich present the material tendency to deform. To simulate this, were taked in consideration only the static forces, not and those dynamic forces wich appears during the machining process.In Fig. 5 is presented the tool before starting the analysis .

Fig. 5 Tool before

In Fig. 6 is presented the tool after the analysis. Must to specify that the analysis was simulated only on a flank of the tool.

Fig. 6 Tool after3.4 Von Mises stressVon Mises stress is widely used by designers to check whether their design will withstand a given load condition. Von Mises stress is considered to be a safe haven for design engineers. Using this information an engineer can say his design will fail, if the maximum value of Von Mises stress induced in the material is more than strength of the material. It works well for most cases, especially when the material is ductile in nature.For this tool also was simulated a stress analysis in Catia V5 software. The result is presented in Fig. 7.

Fig. 7 Von Mises stress

In Fig. 8 are presented the zones were actually the tool is supposed to stress.

Fig. 8 Stress zone

According to these simulations, must to do real cutting tests to see exacly how this tool react to real machining conditions.

Varying machining conditions are encountered in adaptively controlled machining situations where operating conditions such as the feedrate and spindle speed are adjusted continuously to achieve desired objectives.4 caM simulation4.1 General informations

Computer Aided Manufacturing (CAM) is defined as the use of a computer system in the planning, control and management of operations, directly or indirectly through any interface between the computer and production resources.Indirect CAM applications include computer is designed to support manufacturing operations. In this kind of applications, the computer is not connected directly to the production process being used "off-line" for meeting planning activities, generating programs, instructions and information through the company's production resources can be managed more efficiently.4.2 CAD-CAM simulation

Nowadays most NC programs are created via computer aided manufacturing (CAM) tools. However, these kinds of software only consider the work piece and the tool. Yet, the increasing complexity of product and part demands higher security regarding the process functionality and virtual verification based on digital data. The highly complex parts are made using highly complex processes such as mill-turning on multi axis machines. Therefore new methods such as machine simulations have been developed and are widely used. These machine simulations check the functionality of the NC program either regarding processability or the compatibility with the CNC (Fig. 9).

Fig. 9 Simulation

The compatibility with the CNC are commonly checked with hardware in the loop simulations. However, a collision free NC program with correct CNC usage is not the only goal to be achieved during process planning. Surface quality and maintaining tolerances are crucial parts as well. The combination of a hardware in the loop machine simulation and a high resolution simulation of the process could be the right way to increase the expressiveness and usefulness of virtual prototypes. This is especially true for manufacturers who are producing small lots of parts and have to change their production process very often. 4.3 NC programs

Newly generated NC programs coming from the CAM software are usually tested thoroughly before going to the actual machine tool and prior to the actual chipping process. Therefore, common CAM software has an integrated simulation of the chipping process by simulating the material removal at the work piece. However the CAM integrated simulation shows only the chipping process between the tool and the raw work piece.In Fig. 10 is presented the CAD-CAM chain, starting in the CAD system where usually the target work piece was created.

Fig. 10 CAD-CAM chain

After the simulation with the machine simulator, the user is aware of all problems, e.g. collision cases with the clamping device within the working area and can correct them .4.4 Catia V5 machiningFor the designed end milling tool was simulated a machining process in Catia V5 software. That started from an paralelipipedic steel preform (Fig. 11). For this simulation was designed also in Catia a end milling tool to approximately dimensions as tool used for tests.

Fig. 11 Steel preform

This simulation describes two simple operations, with the same end milling tool :1- face milling (Fig. 12),

Fig. 12 Face milling

2- profile conturing (Fig. 13).

Fig. 13 Profile conturing

Catia V5 can also generate NC programs easy and efficient. For example, for the simulation above, using Sinumerik 840D postprocessor, was generated the NC program. A part of this NC code is presented in Fig. 14. These program is easy to understand and modify, is generated in ISO format so can function on every milling machine wich have that interface.

Fig. 14 NC code

Because all of the functions that Catia V5 disposes, these research was easier to achieve.5 ConclusionsAend millis a type ofmilling cutter, acutting toolused in industrialmillingapplications. It is distinguished from thedrillin its application, geometry, and manufacture. While a drill can only cut in the axial direction, a milling can generally cut in all directions, though some cannot cut axially.

End mills are used in milling applications such as profile milling, tracer milling, face milling, and plunging.The designed tool was computer tested to static deformations, tested to stress in machining process. To simulate the milling process by means of material removal at the virtual work piece, a solution was presented that uses machining functions.6 REFERENCES

http://ac.els-cdn.com/S2212827113004289/1-s2.0-S2212827113004289-main.pdf?_tid=1f3fbfc6-9027-11e4-8f1e-00000aacb35f&acdnat=1419946023_8ad903ed2ea4d8c02f23fea37898b9c2http://ac.els-cdn.com/S2212827114002741/1-s2.0-S2212827114002741-main.pdf?_tid=49ba67d8-9027-11e4-a7f0-00000aacb360&acdnat=1419946094_5698f1141b75e886761baf35b0e686c0http://ac.els-cdn.com/S1018363911000365/1-s2.0-S1018363911000365-main.pdf?_tid=656b514a-9027-11e4-91ae-00000aab0f02&acdnat=1419946140_e3c0b85c8caff96a1a49bc319ce0333ehttp://www.lmtfettetools.com/catalogs/Milling%20Tools%20and%20Inserts/Milling%20Tools%20and%20Inserts%202004.pdfhttp://www.azom.com/article.aspx?ArticleID=6130http://en.wikipedia.org/wiki/Carbon_steelhttp://www.sandvik.coromant.com/en-us/knowledge/milling/getting_started/milling_different_materials/hrsa_and_titanium_milling/pages/ceramic-inserts-cutter-for-roughing-hrsa.aspxhttp://www.learnengineering.org/2012/12/what-is-von-mises-stress.htmlhttp://www.chatillon.com/test-solutions/test-types/deformation-testing.aspxhttp://manufacturingscience.asmedigitalcollection.asme.org/article.aspx?articleid=1447125

http://en.wikipedia.org/wiki/End_millR8 milling cutter

6ACADEMIC JOURNAL OF MANUFACTURING ENGINEERING, VOL. 7, ISSUE 1/2009 5ACADEMIC JOURNAL OF MANUFACTURING ENGINEERING, VOL. 7,ISSUE 1/2009