The areas of application of non-conventional manufacturing processes are as follows:
a) Chemical machining (CM): This is used for removing a layer of metal material, either shallow or deep, by means of etching using chemical compounds, like acids, bases, etc. This is a comparatively old process and it has several options: 1. chemical milling, 2. chemical blanking and 3. photo-chemical machining. Chemical milling is usually applied where larger quantities of material is to be removed from large plates or panels in the aircraft industry, space industry or cutting in depths of up to 12 mm. The process is used to make large aluminium alloy, etc. plates and sheet-metal parts lighter. Chemical blanking is used for manufacturing various scales, dials, rulers, etc. in the instrument-making industry and fine mechanical engineering industry as well as for manufacturing a variety of thin component parts in the mechanical engineering industry. The photo-chemical blanking is applied for manufacturing printed circuit boards for the electronic industry, electrical wiring, electronic chip sets and very thin component parts (depths of up to 0.0025 mm) for the aero-space industry, optics, microelectronics, instrument-making industry, printing industry, crafts – engraving metal or other material articles.
b) Electrochemical machining (ECM): This is based on “dissolving” ions of the processed material (metal) in the area around the tool, which is the electrode (-) of the DC source and the processed part is the (+), the ions thus being removed from the conductive electrolyte. This is used in wide machining applications for high-alloyed rigid steels and materials and also for manufacturing complex cutting shapes – turbine propellers, tools – stamps, moulds, dies. The technique is suitable for drilling small holes and cutting into hard materials
c) Electrochemical grinding (ECG): This process is a combination between ECM and a conventional grinding machine. The difference is in the electrical insulation provided in the machine spindle and grinding wheel and the use of an electrolyte instead of a coolant. The tool
– the grinding wheel is the (-) of the electrical source and the part being machined is the (+). The technique is applied in machining carbide tools and alloy tools, carbide steel parts, etc. alloys featuring high strength characteristics. Used for grinding, milling and drilling small holes. Not suitable for manufacturing diesл
d) Electrical discharge machining (EDM): This is a widely applied and very useful method based on the erosion of metals caused by the discharge occurring between the electrode and the processed part. The technique is applied for manufacturing tools and dies – for machining cavities and contour shaping and cutting. Used to cut and machine very hard and hardened conductor materials. Could find application in various machine engineering fields, etc. Also applied in automated processes involving CNC machining centers. Used to manufacture complex dies, for example for extrusion of aluminium component parts, etc.
e) Wire electrical discharge machining (WEDM): This is an optional EDM technique where the electrode is a continuous wire, which is used to cut the metal material similar to a band saw. Used for contour cutting of flat or curved surfaces.
The depth of the cutting plates is adjustable to up to 300mm. The tool (the wire) is usually made of copper, brass or tungsten and of outside diameter 0.25 mm.
Another optional EDM technique is the electrical discharge grinding where a conventional internal grinding machine is used the grinding stone of which is a conductor material (brass, graphite) playing the role of the electrode and the part being machined is any conductor material. Mostly used for grinding hard carbide alloys of titanium, tungsten, cobalt and tool steels; for machining fragile and brittle small-size components, surgical tools, optical devices, electronic devices, etc.
f) Laser-beam machining (LBM) is used for similar applications to those stated above – cutting, drilling, marking and for surface machining and welding operations involving various materials: metals, ceramics, plastics, leather, textiles, composite materials (in the aircraft industry, etc.).
g) Electron-beam (plasma) machining (EBM) is used in similar applications to those described for LBM but performed in a vacuum surrounding medium: precise cutting and welding of various materials.
h) Water-jet machining (WJM): This technique is used for dynamic cutting and machining various materials: plastic, rubber, foodstuffs, paper, leather, insulation materials, composite materials of up to 25mm thickness. Finds application in the food industry and the production of plastics.
i) Abrasive water-jet machining (AWJM): for “shooting” under pressure and applying dynamic action to the surface of the machined component part. Used for the same applications and materials as those described for WJM.
j) Abrasive jet(gas) machining (AJM): Applied for machining small holes, cleaning surfaces from removing sand or scale in foundry applications, stamped forgings and also for non-metal and fragile materials, as well as for deburring operations.