Machining

Conventional Machining, one of the most important material removal methods, is a collection of material-working processes in which power-driven machine tools, such as lathes, milling machines, and drill presses are used with a sharp cutting tool to mechanically cut the material to achieve the desired geometry. Machining is a part of the manufacture of almost all metal products. It is not uncommon for other materials to be machined.

Machining is advantageous to processes like molding and casting in terms of required setup time and cost, and as such is often used in a prototyping capacity.

Processes

Machining principally consists of several basic cutting operations:

• Turning is performed on a Lathe, removes material with rotating workpiece(s) and stationary cutting tools. Note that while turning is performed in a lathe, the act of turning generally removes material from the outside diameter of the workpiece. Other operations take place in a lathe as well, such as drilling, boring, broaching, reaming, threading, tapping, grooving, knurling, honing and parting.

• Milling is performed on a Milling Machine, removes material with generally stationary workpiece(s) and rotary cutting tools. A Milling Machine is primarily similar to a drill press, with the additional element of the ability to move the workpiece along a coordinate system, to achieve feed across the tool.

• Drilling is performed on various machines, primarily Drill Presses. Drilling is also frequently performed in Milling Machines, and on Lathes.

• Boring is performed on various machines, most frequently lathes, is a method of enlarging a pre-existing hole, or inside diameter.

• Grinding is performed on various grinding machines, and removes material utilizing an abrasive wheel, most generally.

• EDM , or Electro-Discharge Machining, removes material with an electrical arc. Techniques include Plunging specifically shaped dies into the workpiece, and cutting with a wire.

• Sawing , or roughly parting material with a steel blade, such as on a metal bandsaw.

Turning

Chucks and Faceplates

Lathe chucks are used greatly for holding what is going to be machined. There are two types of chucks, an independent chuck or the universal chuck.

Milling

Workholding

to hold the work piece by the uses of face plate & clamping pads are wildly used,in some times the special purpose Equipments like fixtures,jigs,etc

Drilling

Drilling is a Metal Cutting process whereby a cylindrical tool is rotated at high speeds to reproduce a hole in the workpiece equal to the diameter of the Drill bit. Drilling is a somewhat rough operation that is often followed by a finishing operation such as Reaming, Boring or Grinding. In Drilling, a cutting tool known as a Drill Bit is secured to a Drill Press by use of a Chuck. Once fastened to the Chuck, the Drill bit is rotated to a high speed, and fed in to the workpiece.

Inspection

Measurement Tools

One of the most important aspects of Machining is the ability to accurately and consistently produce high quality work that meets required specifications. The primary way to determine whether a completed product is within specification is by measurement, either during or after a product's creation. Measurement and inspection makes it possible to maintain standardization throughout production, which is critical during the production of precise components that must be interchangeable through all other exact products, such as an Engine. The way this is achieved is through the use of Measurement tools, such as the Steel Rule, Calipers, and Micrometers. More advanced instruments and devices exist to measure product dimensions all the way out to Microns, but the standard Machine shop will need only to be measure out to 0.0001" (0.00254mm) for most jobs.

Theory

Because machining is not a single process but a group of processes, no single principle is applicable to every aspect of machining. However, all machining processes do have in common the removal of chips or "swarf" by the relative motion of a cutting tool against the workpiece or part. The means by which this motion is achieved varies by machine type, but can generally be broken down into two types of motion:

Primary motion is the result of a machine tool's speed. In the case of a simple drilling operation, this is the spinning of the drill bit. A secondary motion is provided by a tools feed. In the example of a drilling operation, this is the plunging of the drill bit into the material.

Determining optimal speeds and feeds is a major component of best machining practices. A huge number of variables are factors in determining these properties: materials of both workpiece and cutting tool, geometry of the cut, the coolant or cutting fluid used, finish and tolerance required, and the rigidity and power of the machine tool being used.