DESIGN AND ANALYSIS OF FORM TOOL

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1 DESIGN AND ANALYSIS OF FORM TOOL Volume 5, Issue 1 NOV BIKUMALLA SRUTHI, 2 M ANIL KUMAR 1 Pg Scholar, Department of MECH, MLR INSTITUTE OF TECHNOLOGY, Ranga Reddy, Telangana, India. 2 Assistant Professor, Department of MECH, MLR INSTITUTE OF TECHNOLOGY, Ranga Reddy, Telangana, India. Abstract A form tool is precision-ground into a pattern that resembles the part to be formed. The form tool can be used as a single operation and therefore eliminate many other operations from the slides (front, rear and/or vertical) and the turret, such as box tools. A form tool turns one or more diameters while feeding into the work. Before the use of form tools, diameters were turned by multiple slide and turret operations, and thus took more work to make the part. In this Project we model a form tool using CATIA V5. The advantages of form tools are (a) cycle time, (b) it works as POKA YOKA (mistake proofing) (c) maintains relation between operation (d) cost optimization. This tool is designed based upon the component drawing supplied by the customer, spindle power and rpm of CNC machine on which this tool is proposed. This tool is modeled by using a 3D modeling software. In this the design of form tool is carried out using CATIA modeling software, analyzed using FEA software ansys workbench. Keywords tool, single point cutting tool, designing, modeling, simulation, structural simulation, stress, strain, deformation I INTRODUCTION Designing a forming tool is one of vital factor of tool engineering, which must be known by every design engineer. Forming a tool means giving a particular and useful shape with required dimensions to the part. The part formed by forming operation is generally takes the shape of the dir or punch. In the forming operation, the metal flow is not uniform and localized to some extent, depending upon the shape of the work piece. Bending along a large radius in a straight line may also be referred to as a forming operation. It is difficult to distinguish between a bending and forming tools. Forming operation may be simple and extremely complicated. A form tool is precision-ground into a pattern that resembles the part to be formed. The form tool can be used as a single operation and therefore eliminate many other operations from the slides (front, rear and/or vertical) and the turret, such as box tools. A form tool turns one or more diameters while feeding into the work. Before the use of form tools, diameters were turned by multiple slide and turret operations, and thus took more work to make the part. For example, a form tool can turn many diameters and in addition can also cut off the part in a single operation and eliminate the need to index the turret. For single-spindle machines, bypassing the need to index the turret can dramatically increase hourly part production rates. On long-running jobs it is common to use a roughing tool on a different slide or turret station to remove the bulk of the material to reduce wear on the form tool. There are different types of form tools. Insert form tools are the most common for short- to medium-range jobs (50 to 20,000 pcs). Circular form tools are usually for longer jobs, since the tool wear can be ground off the tool tip many times as the tool is rotated in its holder. There is also a skiving tool that can be used for light finishing cuts.

Form tools can be made of cobalt steel, carbide, or highspeed steel. Carbide requires additional care because it is very brittle and will chip if chatter occurs.

2 Form tools can be made of cobalt steel, carbide, or highspeed steel. Carbide requires additional care because it is very brittle and will chip if chatter occurs. A drawback when using form tools is that the feed into the work is usually slow, " to " per revolution depending on the width of the tool. Wide form tools create more heat and usually are problematic for chatter. Heat and chatter reduces tool life. Also, form tools wider than 2.5 times the smaller diameter of the part being turned have a greater risk of the part breaking off. When turning longer lengths, a support from the turret can be used to increase turning length from 2.5 times to 5 times the smallest diameter of the part being turned, and this also can help reduce chatter. Despite the drawbacks, the elimination of extra operations often makes using form tools the most efficient option. THEORY OF FORM TOOL: Flat or blocked tools are further classified according to the setting of tool with respect to the work piece, viz. radialfed tools and tangential-fed tools. Further, form tools are also classified with respect to orientation of tools with respect to the work piece axis VARIOUS TYPES OF FORMING TOOLS: Flat Form Tool:Straight and flat form tools have a square or rectangular cross-section with the form being along the side or end. These tools are similar in appearance to the turning tools. These are usually set centrally so that they will cut their contour which is identical to the desired contoured of the work piece. A typical example of V-notch tool is shown in Figure. This type of tool is suitable for making deep straight-sided form grooves. The cutting is restricted type due to the mixed chip flow. Because of the existence of the good surface finish, this type of tool must be operated at very low cutting speed. PURPOSE OF FORMING TOOLS: A form tool is defined as a cutting tool having one or more cutting edges with well defined profile or contour that is reproduced as the desired form on the work piece surface. Form tools utilized for turning applications are classified according to type of cross section. The classification is shown in the tree diagram of Figure Design of Metal Shaping Tools: Figure shows a typical flat form tool without rake angle. It is necessary to compute x to be machined in the tool in

3 order that the depth BC is correct profile. This distance x is to be planned by a fly cutter or planning tool and is measured normal to the clearance face. The amount of x is less than actual depth of form AB produced on the work piece because of the clearance angle α. From the geometry of the figure x = AB cos(α) Figure shows a flat form tool with rake angle. The wedge angle is given by (90 γ α). Using geometry of the figure, the depth x to be ground or machined can be determined in the following manner: The circular form tool is circular in shape. It has depth x or projection of distance x produced all around the diameter in the form of annular grooves. The outside diameter of circular form tool is determined in accordance with the height of profile to be turned. The graphical method is recommended for this purpose. Circular form tool is shown in Figure. Introduction of rake angle to facilitate cutting action modifies the profile on the tool. GRAPHICAL METHOD OF DETERMINING PROFILE OF FORM TOOL: Design of Forming Tools: STRESSES ACTING ON A FORM TOOL: Types of stress to which tools are exposed: Circular Form Tool: The types of tool load sustained in a range of non-chip forming manufacturing techniques, are shown in figure.

The bottom die is exposed to pressure and is subjected to mainly sliding friction (wear).

4 The upper die of cutting tools is exposed to shock-like compressive and bending loads. The cutting and the lateral area is affected by wear strain as a result of friction between the work piece and the tool. The bottom die is exposed to pressure and is subjected to mainly sliding friction (wear). The face of the upper die and the surface of the lower die should have as high a friction co-efficient as possible, whilst the lateral area of the upper die should have a low friction co-efficient so that the sheet does not move during the cutting operation. The situation in deep drawing operations is similar. Here, the upper die is exposed mainly to pressure and only to a low level of bending load, the lower die is exposed mainly to friction and to a lesser degree to pressure. As in the cutting operation, care must be taken to ensure that the sheet does not flow at the upper die area. The friction coefficient should therefore be as high as possible at the rounding of the upper die but low at the rounding of the drawing ring. In forward extrusion operations, compressive and temperature stresses occur at the upper die and compressive, tensile, friction and thermal stresses at the lower die. Thermal load also develops in cold extrusion operations as a result of the inner friction during material flow. TOOL DAMAGE AND WEAR: Types of damage The types of damage shown in Fig., occur as a result of the types of stress previously described. These may render the tool unfit for use and include: - Wear - Mechanical crack formation - Thermal crack formation - Plastic deformation. The situation in the case of reverse extrusion is similar, although the upper die is additionally affected by bending and friction stresses. The types of stress listed, also occur in varying degrees in other processes such as extrusion, forging, pressure casting and shell casting. The high operating temperatures are particularly liable to cause stresses which are generally masked in forging operations by additional shock stress. CAUSES OF DAMAGE AND THEIR MECHANISMS

This is because in the vast majority of cases, a number of causes interact and combine to cause wear in the tribo-technical systems in industrial practice, The most important wear mechanisms and

5 Since wear is the most important type of damage, it makes sense to investigate its causes in more detail. There is no one material characteristic which provides a conclusive indication in itself, as to the level of wear resistance of that material. This is because in the vast majority of cases, a number of causes interact and combine to cause wear in the tribo-technical systems in industrial practice, The most important wear mechanisms and means of reducing wear, are therefore discussed briefly in the following These include: - Adhesion - Abrasion - Surface break-up and - Tribo-chemical reaction Wear inhibiting coatings are frequently equated with hard coatings. This may be true in the case of abrasive wear, in which there is a correlation in many cases between surface hardness and wear resistance. However, this does not apply to other types of wear or to a combination of stresses, since factors other than hardness, such as surface design, toughness etc. are also important. Adhesive wear: Occurs when bonding forces in the area of the atomic lattice take effect between two metallic materials. The prerequisite for this is that the lattices of the bodies concerned, are structurally similar and that they approach one another until there is only a short distance between them. Furthermore, the more the lattice structures of the materials concerned differ; the lower is their susceptibility to adhesive wear. Abrasive wear: Occurs when the harder of the two bodies involved in the wear process, has pronounced roughness beaks, which tear particles of material from the surface of the softer body. Materials which are resistant to abrasive wear, have outstanding hardness in comparison with the abrading material. When there is surface breakdown, the crystal and the structural condition is damaged irreversibly as a result of alternating stresses and which depend on the duration and level of stress involved. Surface breakdown is reduced when the strength of a material is high, whereas stress peaks and notch effects result in an increase. Tribo-chemical reactions: Occur when the wear processes take place only in the outermost boundary layer of the bodies involved. This boundary or interfacial layer

can be formed by reactions between the material and the surrounding medium. Consequently, the wear characteristics of the base material itself have no influence on this process.

equal degree by the material and by the surrounding medium. Consequently, the lubricant is the primary determining factor.

6 can be formed by reactions between the material and the surrounding medium. Consequently, the wear characteristics of the base material itself have no influence on this process. It is not possible to specify any particular material behavior in order to avoid the tribo-chemical reaction, since the formation and characteristics of the outer boundary layer are determined to an equal degree by the material and by the surrounding medium. Consequently, the lubricant is the primary determining factor. The various types of damage sustained by tools, are illustrated in Fig by the example of a forging die. In 70 % of all cases in which tools become unfit for use, wear is the underlying cause. Mechanical cracking occurs in 25 % of all cases. Requirements to be met by the base material and the subsurface layer: In contrast, plastic deformation and thermal cracking very rarely mark the end of tool life. These results cannot be transferred directly to other forming operations but wear will be the most common type of wear there too, since shock and temperature stress are generally lower in these operations than in forging. Tool materials for extrusion tools MODELING & ANALYSIS: BASE MATERIAL AND BOUNDARY LAYER: Requirements to be met by forming tools: Due to the types of stress listed, there are a number of special requirements which must be met by the base material and the boundary layer of tools. These are shown in Fig. The focus in the following is on the requirements to be met by the wear and strength characteristics.

7 CREATING POCKET TO CREATE COUNTER OF A TOOL BASIC CROSS SECTIONAL PROFILE OF FORM TOOL CREATING SLOT CREATING SHAFT CHAMFERING THICKNESS CREATING POCKET

The shown mesh method was called Tetra Hydra Mesh. Meshing is used to deconstruct complex problem into number of small problems based on finite element method.

8 MESHING: Poisson's Ratio: 0.28 DRAFTING OF FORM TOOL Meshing for FORM TOOL GENERATED DRAWING LINES FINATE ELEMENT ANALYSIS: The above image showing the meshed modal, Default solid Brick element was used to mesh the components. The shown mesh method was called Tetra Hydra Mesh. Meshing is used to deconstruct complex problem into number of small problems based on finite element method. APPLYING LOADS: Imported model from CATIA to the format of IGES DEFINING THE MATERIAL PROPERTIES HSS OR HIGH SPEED STEEL Yield strength: 250MPa Density: 7.7e-006 kg mm^-3 Bulk Modulus: e+005 Shear Modulus: Poisson's Ratio: 0.28 SILICONIZED SILICON CARBIDE Density: 3.1e-006 kg mm^-3 Bulk Modulus: e+005 Shear Modulus: e+005 Rotational velocity of FORM TOOL Force acting on FORM TOOL

been observed that the maximum stress developed is 48.957MPA.

9 been observed that the maximum stress developed is MPA. Equivalent Elastic Strain Distribution MATERIAL of SISIC Fixed Support of FORM TOOL RESULTS AND DISCUSSIONS Figure shows the equivalent elastic strain distribution of form tool when the load is applied onto the contact surface. It has been observed that the maximum strain developed is mm/mm. Stress Distribution of SISIC MATERIAL Figure shows the total stress distribution of FORM TOOL when the load is applied onto the contact surface. It has been observed that the maximum stress developed is MPA. Equivalent Elastic Strain Distribution of HSS MATERIAL Stress Distribution of HSS MATERIAL Figure shows the total stress distribution of FORM TOOL when the load is applied onto the contact surface. It has Figure shows the equivalent elastic strain distribution of form tool when the load is applied onto the contact surface. It has been observed that the maximum strain developed is mm/mm.

Second mode shape of FORM TOOL Third mode shape of FORM TOOL TOTAL DEFORMATION of HSS MATERIAL Figure shows the total deformation of form tool when the load is applied onto the contact surface.

10 TOTAL DEFORMATION of SISIC MATERIAL Figure 4.5 shows the total deformation of form tool when the load is applied onto the contact surface. It has been observed that the total deformation developed is mm. Second mode shape of FORM TOOL Third mode shape of FORM TOOL TOTAL DEFORMATION of HSS MATERIAL Figure shows the total deformation of form tool when the load is applied onto the contact surface. It has been observed that the total deformation developed is mm. Fourth mode shape of FORM TOOL MODAL ANALYSYS The element type and various material properties such as young s modulus, density and Poisson s ratio are mentioned, and they are as Young s modulus: 2.35e+005Mpa Density: 7.7e-006 kg mm^-3 Poisson's Ratio: 0.28 MODAL ANALYSYS OF HSS MATERIAL: First mode shape of FORM TOOL Fifth mode shape of FORM TOOL

11 The following conclusions are drawn from the present work 1. The Von mises stresses of HIGH SPEED STEEL are obtained in static analysis is MPA Mpa and Sixth mode shape of FORM TOOL Results: Static analysis Von mises stresses of SISIC is MPA 2. The deformation in HIGH SPEED STEEL is mm in static analysis and deformation in SiSiC is mm. 3. The Stain Distribution in HIGH SPEED STEEL is mm/mm and strain distribution in SiSiC Modal analysis is mm/mm 4. The Eigen values (natural frequencies) of HIGH SPEED STEEL are mm and Eigen values of SiSiC is mm CONCLUSION: In this project we modeled a form tool according to customer drawing/ requirement using CATIA V5. The form tool reduces the waste as errors due to operator fatigue, interruptions and production planning. The form tool mainly used to reduce the machining time and analyzed and stresses are using FINITE ELEMENT ANALYSIS with SISIC material as compared to High Speed Steel material From above stress, strain, total deformation we can observe that both HSS and SiSiC materials gave accurate results for form tool but according to cost HSS material is best. References m 5. nical.htm

12 6. m Bafv8wftlJO4Dg&gws_rd=ssl#q=cnc%20form%20to ols%20wikipedia 9. Bafv8wftlJO4Dg&gws_rd=ssl#q=cnc+milling+machi ne+form+tool 10. Brown & Sharpe, Automatic Screw Machine Handbook p. 11. Jump up^ Hartness, James (1910), Hartness Flat Turret Lathe Manual, Springfield, Vermont, USA: Jones and Lamson Machine Company, 12. Jump up^ Kanigel, Robert (1997), The One Best Way: Frederick Winslow Taylor and the Enigma of Efficiency, Viking Penguin, ISBN

Modeling and Analysis of a Surface Milling Cutter Using Finite Element Analysis

International Journal of Engineering Research and Development e-issn: 2278-067X, p-issn : 2278-800X, www.ijerd.com Volume 4, Issue 10 (November 2012), PP. 49-54 Modeling and Analysis of a Surface Milling