MILLING OPERATION TYPE

                                                        MILLING OPERATION TYPE

MILLING OPERATION

v  Depending on the geometry of the cutter and the motion between the cutter and work piece , some basic type of milling operation are

ü  Up milling

ü  Down milling

ü  slab milling

ü  Face milling

ü  End milling

ü  Straddle milling

ü  Form milling

Up milling

•       Up milling is also referred  to as conventional milling. the direction of the cutter rotation opposes the feed motion. In this case the table moves towards the cutter, opposing the cutter direction.
  

Down Milling

• Down milling is also referred to as climb milling. the direction is some as the feed motion. For example, if the cutter rotates counterclockwise, the workpiece is fed to the right in down milling.
   
  
  

§                             The chip formation in down milling is opposite to the chip formation in the up milling

Slab Milling

• In slab milling , also called peripheral milling, the axis of cutter rotation is parallel to the workpiece surface to be machined. The cutter generally made of high speed steel, has a number of teeth along its circumference ,each tool acting like a single point  called a plain mill.

  Face Milling

•    It is often necessary to create a flat face on the large part. This can be done best using face milling. In face milling, the cutter is mounted on a spindle having an axis of rotation perpendicular to the workpiece surface.

 End miling

q  The cutter in end milling generally rotates on the axis vertical to the workpiece. Flat surface as well as various profile can be produced by end milling. The end faces of some end mills have cutting teeth, and these can be used as a drill to start a cavity.

Straddle Miling

• Two or more cutter are mounted on an arbor and are used to machine two parallel surface on the workpiece.

Form Miling

• Cutters with specially shaped teeth are used to produce curved  profiles, such cutters are also used for cutting gear teeth.

MILLING

                                        MILLING PROCESS

Milling is a machining operation in which a work piece is fed past a rotating cylindrical tool with multiple cutting edges. The axis of rotation of the tool is perpendicular to the feed direction. The tool is called the milling cutter and the cutting edges are called teeth. Mostly plane surfaces are created through milling. It’s an interrupted cutting operation; the teeth of milling cutter enter and exit work piece during each revolution. So, the tool material and cutter geometry must be chosen carefully to withstand cycles of impact forces and thermal shock.

Milling is used in the metal work industry and defined as the process of cutting, shaping and finishing a piece of metal. It is one of several metal working processes that include turning, welding, and fringing. Milling is used when more complex metal shape are desired. The process is used to create a number of metal parts and structures and everything from rings and bracelets bridges and freight ships . Typically, milling involves cutting away pieces of metal to create dovetails, threads, bevels, slots, and ridges. The grooved edges of coins are a simple example of the milling process.

Milling is the machining operation in which material is removed from the surface by using the multipoint rotating cutting tool known as milling cutter. milling cutter is known as multipoint cutting tool because it has equally spaced cutting teeth. This machine is most widely used due to fast production, high accuracy and good surface finish.

Milling process is one of the most fundamental and commonly encountered material removal operations in manufacturing process. The surface roughness is one of the important properties for evaluating the work piece quality during the end milling process. The surface roughness plays a great part in fatigue strength and corrosion resistance, surface friction, light reflection, ability of holding a lubricant, electrical and thermal contact resistance, appearance, cost, etc .High quality of the surface after end milling makes further machining of the surface not necessary, which brings about decreased power consumption and environment load. However, optimization of surface roughness is consistently challenged by its uncertainty of prediction model as well as various influencing parameters, which can be divided into controlled and non-controlled parameters. Main parameters of the first type includes spindle speed, feed rate, and depth of cut. And vibrations, tool wear, machine motion errors, and material non-homogeneity of both the tool and work piece, chip formation belong to the non-controlled parameters. The non-controlled cutting parameters are hard to reach and their interactions cannot be exactly determined.

It the process of cutting away material by feeding a work piece past a rotating multiple tooth cutter. The cutting action of many teeth around milling cutter provide a fast method of machining. The machined surface may be flat, angular, or curved. The may also be milled to any combination of shapes. The machine for holding the work piece, rotating the cutter, and feeding it is known as milling machine.

Milling is one of the basic machining processes.  Milling is a very versatile process capable of producing simple two dimensional flat shapes to complex three dimensional interlaced surface configurations.