CHAPTER FOUR
4.0 FABRICATION AND TESTING
The processes used in the construction of the component parts are discussed below.
4.1 MANUFACTURING PROCESS
The top plate, brackets for mounting the electric motor was welded and dampers attached to reduce vibration. These frames in which the electric motor and the trough are mounted are made of mild steel.
The first process of the fabrication of this machine was making the working diagram which serves as a guide in the course of its manufacturing. Secondly, the selection of materials for the work was considered. This was done with respect to the availability of the raw material locally and the cost implication was also considered. Next was the marking and cutting of the materials. This was done with the aid of meter rule and inscriber for marking and the work piece held on the vice while the cutting was carried out.
4.1.1 TOOLS USED DURING THE CONSTRUCTION
A machine tool is used to manufacture metal components of machines through machining, a process whereby metal is selectively removed to create a desired shape. Ranging from simple to complex pieces, machines tool can produce parts of different shapes and sizes.
Machine tools have gradually evolved over the past millennia. Today, machine tools are used to computerize numerical control (CNC) machines, which can repeat sequences with high level of precision, and produce complex pieces of various sizes and shapes.
Various techniques can be used to remove unwanted metal during the process of fabricating or shaping parts, namely; single edge cutting tools, multiple edge cutting tool, electrical discharge machining and grinding [Abrasive cutting].
Therefore, the machine tools used in the construction of this machine include:
• Milling machine: A machine tool used to machine solid materials.
• Grinding machine: A machine tool used for grinding, a process whereby an abrasive wheel is used as the cutting tool.
• Planner: A metal working machine tool that uses straight or linear movement between the work piece and a single point cutting tool to machine a linear tool path.
• Lathe: A lathe is a machine that spins a part in place while a cutting blade removes excess material to prepare it for deformation. Lathes can be used for cutting, sanding, drilling, knurling, or deforming. Cutting fluid may be used to remove the swarf (debris), and to serve as lubricant or coolant during the cutting process.
• Drills: A machine tool used for drilling or boring holes of different diameters and depth.
There are other types of tools used in the construction of this machine, which includes; saw, chisel, file, hammer, center punch, vice, etc.
4.1.2 OPERATIONS CARRIED OUT
The operations carried out in the construction of this machine include:
• Machining: The principal machining processes are classified as turning, drilling, milling. Other operations falling into miscellaneous category include shaping, planning, boring, broaching and sawing.
Milling operations are operations in which the cutting tool rotates to bring cutting edges to bear against the workpiece. Milling machine are the principal machine tool in milling.
Turning operations are operations that rotates the work piece as the primary method of moving metal against the cutting tool. Lathes are the principal machine tools used in turning.
Drilling operations are operations in which holes are produced or refined by bringing a rotating cutter with cutting edges at the lower extremity into contact with the work piece. Drilling operations are done primarily in drill presses but sometimes on lathes or mills.
Miscellaneous operations are operations that strictly speaking may not be machining operations in that they may not be swarf producing operations but these operations are performed at a typical machine tool. Burnishing is an example of a miscellaneous operation. It produces no swarf but can be performed at a lathe, mill or drill press.
• Welding: Welding is a fabrication or sculptural process that joins parent metals or materials, by causing fussion, which is distinct from lower temperature metal joining techniques such as brazing and soldering, which do not melt the base metal.
Some of the best welding methods include:
• Shielded metal arc welding: Also known as “stick weldingâ€, uses an electrode that has flux, the protectant for the puddle, around it. The electrode holder holds the electrode as it slowly melt away. Slag protects the weld puddle from atmospheric contamination.
• Gas metal arc welding: Commonly termed MIG (metal, inert gas), uses a wire feeding gun that feed wire at an adjustable speed and flows an argon-based shielding gas and carbon dioxide (CO2) over the weld puddle to protect it from atmospheric contamination.
• Electroslag welding: A highly productive, single pass welding process for thicker materials between 1 inch (25mm) and 12inches (300mm) in a vertical or close to vertical position.
