Machining current

Direct-current motor fields are on the stator. The rotor is the armature. The magnetic field does not rotate like the field in ac machines. Current in the armature reacts with the stator field to produce torque. 

Washing machines currently on the market are constructed almost exclusively with drums and laundry tubs of corrosion-resistant stainless steel or with an enameled finish that is inert to alkaline wash liquors. Nevertheless, various machine components are made of less detergent resistant metals or alloys. To prevent corrosion of these parts, modern detergents contain corrosion inhibitors in the form of sodium silicate. The colloidal silicate that is present, deposits as a thin, inert layer on metallic surfaces, thereby protecting them from attack by alkali. 

Finally, metal objects can sometimes be fabricated in their entirety by electrodeposition (electroforming), with much the same considerations as electroplating. Conversely, portions of a metal specimen can be selectively electrolyzed away (electrochemical machining). This technique is especially useful where the metal to be shaped is too hard or the shape to be cut is too difficult for conventional machining. The sample is made the anode, a specially shaped tool the cathode, and electrolyte solution (e.g., aqueous NaCl) is fed rapidly but uniformly over the surface to be machined. Current densities may reach several hundred amperes per square centimeter across the electrolyte gap of a millimeter or so. Excellent tolerances can be achieved in favorable circumstances.16... 

Tablets have been produced for more than 150 years. The first tableting machine, developed by Brockedon in 1972 [1], was a manually operated single-punch machine. Currently high-speed tableting machines can produce more than a million tablets per hour.

Particle-producing machines currently used Nuclear reactor Cyclotron Cyclotron (for deu-terons) Cyclotron or proton synchrotron Electron synchrotron or linear Heavy ion accelerator Proton synchrotron ... 

FIGURE 2.14. Electrochemical surface machining current density distribution (left) and resulting hole (right). (See color insert.)... 

To bring the ECM technique in practice for industrial applications, controlled metal removal with high accuracy is needed. To achieve this, the ECM setup requires electrical power system for supplying machining current to the electrodes, arrangements for forced electrolyte circulation between the tool and workpiece, and mechanical structure for controlled movement of tool toward the workpiece. Figure 2.2 shows the basic subunits of the ECM setup. 

Hence, for EMM, total machining current as well as effective machining time are reduced due to charging and discharging of the double layer. Considering this factor, metal removal in the case of EMM cannot be estimated theoretically utilizing only Faraday s laws of electrolysis, which is normally utilized in the conventional ECM. 

In EMM, voltage is normally considered in the range of below 10 V for moderate material removal and higher accuracy [10]. The material removal rate increases with voltage due to the increase in voltage, machining current also increases. Faraday s law states that the material removal rate is proportional to... 

Types and the number of ions available in the electrolyte determine the magnimde of conductivity. The conductivity of the electrolyte depends on the concentration of the electrolyte. A concentrated electrolyte offers low resistance to flow of machining current due to the presence of higher number of ions. The concentration of electrolyte is expressed in different ways such as weight of the solute per unit weight of solution (w/w), weight per unit volume of solution (w/v) or gram-molecules, or moles, of solute per liter of solution (M). 

Many machines currently meet noise specification because manufacturers have responded to the need to cut noise. Some equipment like saws, however, can t be made to run any quieter, so proper hearing protection is a must. 

Most injection moulding machines currently available can be operated either manually, semi-automatically or automatically. The source of power is invariably electricity, but drives are based on mechanical, hydraulic or even compressed air modes of operation. 

Material is removed from the surface with a shaped diamond tool, hence the name. Accuracies to one microinch ( th lm) are achievable. Size is limited by the machine, currently about 2 m. 

A number of injection moulding machines currently produced in Europe and the USA can be supplied already modified for LSR and provide, together with the meter-mix units, virtually a turn-key operation. Mould design is generally straightforward and duplicates many existing techniques used for rubber and plastics. Runner systems and gates can be much smaller than usual and this reduces material waste. 

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