MACHINING WITH ROTARY TOOL ME-625

SUBMITTED BY:MOHAMMED BILAL NAIM SHAIKHFAC. NO. : 15MEIM030EN. NO. : GE6168

MACHINING OPERATIONS WITH ROTATING TOOL

DRILLING OPERATION

BORING OPERATIO

N

REAMING OPERATION

TAPPING OPERATIO

N

Milling operation

Contd..

Schematic illustration of centerless grinding operations: (a) through-feed grinding, (b) plunge grinding, (c) internal grinding, and (d) a computer numerical-control cylindrical-grinding machine. Source: Courtesy of Blohm, Inc.

Schematic illustration of a horizontal-spindle surface grinder.

Counter boring & counter sinking operation

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Schematic illustration of internal grinding operations: (a) traverse grinding, (b) plunge grinding, and (c) profile grinding. Source: Courtesy of Blohm, Inc.

Schematic illustrations of various surface-grinding operations

Schematic illustration of external surface grinding

Contd..

ROTARY SAWDifferent kind of blades used in rotary saw

(c) : Composite masonry abrasive blade(b) : Composite metal abrasive blade(a) : Diamond chunk blade

ROTARY CUTTING TOOLS FOR TURNING OPERATION

Basic difference between rotary cutting and conventional cutting is the movement of the cutting edge in addition to the main cutting and feed motions.Rotary tools can be classified as either driven or self-propelled. The former is provided rotational motion by an external source while the latter is rotated by the chip flow over the rake face of the tool.Benefits provided by rotary cutting tools include 1.several hundred-fold increase in tool life 2. lower cutting temperatures 3. higher metal removal rates, 4. generation of fine surface finishes due to the circular cutting edge, and 5.improved machinability of difficult-to-cut m materials such as nickel and titanium a based alloys

NEED OF ROTARY CUTTING TOOL

Super alloys pose formidable challenges for cutting tool materials during machining; hence they are referred to as difficult-to-cut. Cutting materials such as ceramic and polycrystalline cubic boron nitride (PCBN) are recommended for turning hardened steel because of their ability to sustain the high temperature generated during the metal removal process. Hard turning with ceramic cutting tools has been a time proven manufacturing process High cutting temperatures are generated during hard turning. The generated temperatures cause thermal softening of the workpiece material, thermal damage on the machined surface as well as soften the cutting edge leading to plastic deformation . This adverse effect of heat can be reduced by using cutting fluid or by continuously supplying a fresh cutting edge, as is the case in rotary cutting tools. However, a more practical alternative includes the use of a circular shaped cutting insert which has the ability to rotate about its axis such that the engaged cutting edge is continuously fed into the tool chip interface zone. This would generate cyclical exposure of the cutting edge and rake face to the chip formation process.

ROTARY TOOL GEOMETRY

The cutting tool, known as an insert, rotates simultaneously with the workpiece in addition to its linear feed motion. The spinning action of the insert supplies the fresh cutting edge to the workpiece being machined. The cooling time for an individual cutting point on the insert is much higher than the cutting time for the same point The geometry of the rotary cutting tool is a frustum of a cone which can be orientated such that the base acts as the rake face (Type I) or with the cutting tool positioned vertically and the cone peripheral surface acting as the rake face (Type II)

PRINCIPLES OF ROTARY CUTTING

Rotary cutting principles differ from conventional cutting theories due to its unique kinematics character. Important considerations in rotary cutting are inclination angle of the cutting edge, chip flow angle and rake angle, cutting speed, chip deformation, and tool wear. The inclination angle (i) is the most important factor affecting the performance of rotary cutting. The circular cutting edge angle also varies with change in inclination angle.

Type I rotary cutting tools with (a) positive inclination angle and (b) negative inclination angle.

(a) (b)

Schematic illustration of typical SPRT turning operation

ROTARY TOOL CUTTING OPERATION

During a machining process, the rotation of a self-propelled tool is generated “naturally‟. This results in low sliding speed, pressure, and temperature at the tool-chip interface. Due to continuous motion of the cutting edge of rotary tools during machining, a long non-working period for any point on the cutting edge makes the practical cutting path of the point to be reduced by k times. The life of the rotary tool is therefore k times as long as that of a conventional round stationary tool, if other factors are not considered.

Factors Affecting Rotary Tool Life

PROBLEMS ASSOCIATED WITH ROTARY TOOL

The following may hinder the application of rotary tools in the manufacturing industry: 1. No matter how precise (or accurate) the rotating parts have been produced, a cutting edge in motion

may always generate more errors than a stationary one. 2. Severe chatter may occur due to the large tool radius and poor stiffness of the rotary system. 3. Stepped workpieces cannot be produced with rotary tools.

CONCLUSION

Rotary tool(RT) for turning achieve superior tool wear resistance and extraordinary improvement in tool life, relative to a fixed tool with identical configuration and cutting conditions, when machining difficult-to-cut materials.

There is a relation in between feed rate and rotational speed. In addition, material sticking/welding on the workpiece also promote chipping of the RT insert. Chip forms are helical with small pitch dimensions which reduces the safety and machined surface

problems associated with continuous chip formation. There is lower cutting temperatures associations with RTs during the machining, which will lowers the

generation of plastic deformation and surface hardness alterations in the workpiece material.