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1. INTRODUCTION

Computer Numerical Control (CNC) Milling is the most common form of CNC. CNC

mills can perform the functions of drilling and often turning. CNC Mills are classified

according to the number of axes that they possess. Axes are labelled as x and y for horizontal

movement, and z for vertical movement. CNC milling machines are traditionally

programmed using a set of commands known as G-codes. G-codes represent specific CNC

functions in alphanumeric format. During CNC milling, the computer translates the design

into instructions on how the drill needs to move to create the shape. Typically, the drill can

move up down, or tilt at an angle, and the table moves the part laterally. For complex parts,

the part may need to be rotated at some point in the milling process. Because the process is

run by a computer, high resolutions, and greater throughput are possible.

2. RAW MATERIALS

All cutters that are used in milling can be found in a variety of materials, which will

determine the cutter's properties and the workpiece materials for which it is best suited. These

properties include the cutter's hardness, toughness, and resistance to wear. Milling can be

performed on workpiece in variety of materials, including most metals and plastics. The

materials that are used in this milling is aluminium alloy 2024. Aluminium alloy 2024 is an

aluminium alloy, with copper as the primary alloying element. It is used in applications

requiring high strength to weight ratio, as well as good fatigue resistance. It is wieldable only

through friction welding, and has average machinability. This material has a dimension of

100mm x 100mm x 26mm and weight of 2 kg.

Figure 2.1 Material use; Aluminium Alloy 2024

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3. PROCESS TOOLS

Milling cutters are cutting tools typically used in milling machines or machining

centres to perform milling operations. They remove material by their movement within the

machine or directly from the cutter's shape. Milling cutters come in several shapes and many

sizes. There is also a choice of coatings, as well as rake angle and number of cutting surfaces.

Cutting tool in CNC milling such as flat End mill, counter drill, drill, face mill, slab mill,

counter bore, and countersank.

Figure 3.1 Milling cutter tools

i. End milling-An end mill makes either peripheral or slot cuts,-determined by the step-over distance, across the workpiece in order to machine

specified feature, such as a profile, slot, pocket, or even a complex surface contour.

Figure 3.2 End Mill Toolpath

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ii. Drilling-A drill enters the workpiece axially and cuts a hole with a diameter equal to that

of the tool.

-produce a blind hole, which extends to some depth inside the workpiece, or a

through hole which extends completely through the workpiece.

Figure 3.2 Drilling Toolpath

iii. Chamfer milling- A chamfer end mill makes a peripheral cut along an edge of the workpiece or

a feature to create an angled surface.

-A 45 degree angle, can be machined on either the exterior or interior of a part

and can follow either a straight or curved path.

iv. Face milling-A face mill machines a flat surface of the workpiece in order to provide a

smooth finish.

-The depth of the face, typically very small, may be machined in a single pass

or may be reached by machining at a smaller axial depth of cut and making

multiple passes.

Figure 3.3 Chamfer Mill Toolpath Figure 3.2 Face Mill Toolpath