User:Julius Juanyang

MILLING

Milling is a machining process which is performed with a rotary cutter with several cutting edges arranged on the periphery /face of the cutter. This process is used to generate flat surfaces or curved profile and many other intricate shapes with great accuracy and having very good surface finish.

BASIC MILLING TECHNIQUES

Generally, there are two types of milling techniques. These are called (a) Down milling or climb milling , and (b) Up milling or conventional  milling. In up-milling, the direction of rotation of milling cutter and the direction of work piece feed are opposite to each other; whereas in down milling, they move in the same direction at the point of contact of the cutter and the workpiece. In up-milling, the thickness of chip at the start is nil and is maximum when the cutting teeth leave the surface of the work piece. In down milling, it is vice-versa.

TYPES OF MILLING PROCESSES

The milling process is broadly classified into peripheral milling and face milling. In peripheral milling, the cutting edges are primarily on the circumference or periphery of the milling cutter and the milled surface is generally parallel to cutter axis.In face milling, although the cutting edges are provided on the face as well as the periphery of the cutter, the surface generated is parallel to the face of the cutter and is perpendicular to the cutter axis. The peripheral milling cutters are supported on a long arbor. The deflection of arbor restricts the dimensional and form accuracy of this process. In face milling, the overhang of the cutter is limited resulting in better dimensional control and flatness. Peripheral milling cutters are normally used with a horizontal milling machine whereas the face cutters are used in conjunction with a vertical milling machine. The face milling can configured to be executed in either up milling or down milling as shown by the figures below. Up-hill or down-hill milling will result when the cutter is asymmetrically placed on the work piece. If the cutter is symmetrically placed on the work, the machining is carried out through both up-hill and down-hill as shown by the figure below.

In upmilling, the cutting teeth try to up root and lift the work piece from the machine table, in down milling, reverse happens. Technically, down-milling is a superior process, but up milling is commonly used. Down milling is not used unless the milling machine is fitted with a backlash eliminato

TYPES OF MILLING PROCESSES

The milling process is broadly classified into peripheral milling and face milling. In peripheral milling, the cutting edges are primarily on the circumference or periphery of the milling cutter and the milled surface is generally parallel to cutter axis.In face milling, although the cutting edges are provided on the face as well as the periphery of the cutter, the surface generated is parallel to the face of the cutter and is perpendicular to the cutter axis. The peripheral milling cutters are supported on a long arbor. The deflection of arbor restricts the dimensional and form accuracy of this process. In face milling, the overhang of the cutter is limited resulting in better dimensional control and flatness. Peripheral milling cutters are normally used with a horizontal milling machine whereas the face cutters are used in conjunction with a vertical milling machine. The face milling can configured to be executed in either up milling or down milling.