Manufraturing Processes

Introduction

Manufacturing Processes are used to create items that we humans use day to day. Anything from toys for kids to gearbox gears. The general definition of manufacturing process is a process of transformation of input materials into usable articles. The vast amount of materials used in these processes are metals, plastic, ceramics, and glass. Engineering processes are sorted by two groups: Deformation processes and Machining processes.

Deformation processes are processes which modify the shape/form of a solid by applying the right amount forces and/or heat. A few examples are :

-Forming

- Forging

- Moulding

- Rolling

- Many more.

Then, Machining processes is a processes where the needed shape is created by removing excess material in chips from the work piece. A few examples are :

- Cutting

- Punching

- Laser cutting

-Many more.

In this report, we will look further into:

- Precision CNC Machining

- Electro Discharge Machining

- Centreless Grinding.

For each giving a brief overview of these 3 manufacturing processes with examples where these processes are used to produce products . And explain why the chosen item is made by using this certain procedure.

Precision CNC machining

Before CNC, there was NC which was Numerical control, a form of programming automation in which a machine is controlled by code, called a part program. The first NC system was developed in 1952 in Massachusetts Institute of Technology.

There is three main parts in a NC System :

- Program of instructions

- Machine control Unit

- Machine tool

Then CNC came along. CNC is an NC system which uses a dedicated computer with part programs within the machine control unit. This makes the system more easier to read/ write code, reliable and easier to maintain plus lowering the cost of purchase.

There is a massive range of tools that work with CNC variants. Here are just a few :

- Drills

- EDMs

- Lathes

- Milling machines

- Wood routers

With the use of computer-aided design (CAD) and computer-aided manufacturing (CAM) programs makes yours work more accurate and precise.

Main applications of CNC Machining include: brackets, levers, joints, nuts, bolts, clamps, handlebars and many more.

Another application of CNC machining is Medical and Dental supplies. For example Titanium artificial Heart pump components, Pacemaker adaptors and connections. With CNC this allows the company to make these Heart pump components with +-0.004mm Tolerances.

For this application, CNC would be the best bringing these characteristics:

- Increased productivity

-High accuracy and repeatability

- Reduced production costs

- Reduced indirect operation costs

- Greater Flexibility

- Lower operator skill requirements

- Can be in operation for 24hours a day.

The only problems when thinking of using CNC for your company is the high initial cost of the system and the high maintenance requirements.

Electro Discharge Machining

Electric discharge machining (EDM) is a manufacturing process whereby a desired shape is obtained using electrical discharges (sparks). Material is removed from the work piece by a series of rapidly recurring current discharges between two electrodes, separated by a dielectric liquid and subject to an electric voltage.

In 1770, English physicist Joseph Priestley studied the erosive effect of electrical discharges. The EDM process was invented by two Russian scientists, Dr. B. R. Lazarenko and Dr. N. I. Lazarenko, in 1943. Later on, Seibu developed the first CNC wire EDM machine 1972.

These are a few types of EDM:

- Wire EDM

- No-Wear EDM

- Electrical discharge Grinding

- Ultrasonic EDM

- Sinker EDM

The two main types are:

Sinker EDM.

Sinker EDM, also called cavity type EDM or volume EDM, consists of an electrode and workpiece submerged in an insulating liquid such as oil. The electrode and work piece are connected to the correct power supply. The power supply generates an electrical potential between the two parts. As the electrode approaches the work piece, dielectric breakdown occurs in the fluid, forming a plasma channel and a small spark jumps. These sparks then melt/heat the metal, when it keeps happening it gradually shapes the form of the electrode.

Wire EDM

In Wire ED, a thin single-strand metal wire, usually brass, is fed through the workpiece, submerged in a tank of dielectric fluid, typically deionized water.

Wire-cut EDM is typically used to cut plates as thick as 300mm and to make punches, tools, and dies from hard metals that are difficult

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