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80-454: A dynamo is a magnetic device originally used as an electric generator. Dynamo or Dinamo may also refer to: Dynamo Today, the simpler alternator dominates large scale power generation , for efficiency, reliability and cost reasons. A dynamo has the disadvantages of a mechanical commutator . Also, converting alternating to direct current using rectifiers (such as vacuum tubes or more recently via solid state technology)

160-403: A copper disc rotating between the poles of a horseshoe magnet . It produced a small DC voltage . This was not a dynamo in the current sense, because it did not use a commutator . This design was inefficient, due to self-cancelling counterflows of current in regions of the disk that were not under the influence of the magnetic field. While current was induced directly underneath the magnet,

240-406: A combination of series and parallel (shunt) field windings, which are directly supplied power by the rotor through the commutator in a regenerative manner. They are started and operated in a manner similar to modern portable alternating current electric generators, which are not used with other generators on an electric grid. There is a weak residual magnetic field that persists in the metal frame of

320-399: A constant metal ion level, and contribute to conductivity. Additionally, non-metal chemicals such as carbonates and phosphates may be added to increase conductivity. When plating is not desired on certain areas of the substrate, stop-offs are applied to prevent the bath from coming in contact with the substrate. Typical stop-offs include tape, foil, lacquers , and waxes . Initially,

400-402: A copper strike is used, which has good adherence to both. The pulse electroplating or pulse electrodeposition (PED) process involves the swift alternating of the electrical potential or current between two different values, resulting in a series of pulses of equal amplitude, duration, and polarity, separated by zero current. By changing the pulse amplitude and width, it is possible to change

480-424: A fast switch. Another common problem of pulse electroplating is that the anode material could get plated and contaminated during the reverse electroplating, especially for a high-cost, inert electrode such as platinum . Other factors that affect the pulse electroplating include temperature, anode-to-cathode gap, and stirring. Sometimes, pulse electroplating can be performed in a heated electroplating bath to increase

560-428: A low average power output. As with electric motors of the period, the designers did not fully realize the seriously detrimental effects of large air gaps in the magnetic circuit. Antonio Pacinotti , an Italian physics professor, solved this problem around 1860 by replacing the spinning two-pole axial coil with a multi-pole toroidal one, which he created by wrapping an iron ring with a continuous winding, connected to

640-422: A magnetic field around the rotor. This was also the discovery of the principle of dynamo self-excitation , which replaced permanent magnet designs. The dynamo was the first electrical generator capable of delivering power for industry. The modern dynamo, fit for use in industrial applications, was invented independently by Sir Charles Wheatstone , Werner von Siemens and Samuel Alfred Varley . Varley took out

720-555: A patent on 24 December 1866, while Siemens and Wheatstone both announced their discoveries on 17 January 1867, by delivering papers at the Royal Society . The "dynamo-electric machine" employed self-powering electromagnetic field coils rather than permanent magnets to create the stator field. Wheatstone's design was similar to Siemens', with the difference that in the Siemens design the stator electromagnets were in series with

800-453: A physical change is a change in the outward appearance. An example of a mechanical change is a change in tensile strength or surface hardness , which is a required attribute in the tooling industry. Electroplating of acid gold on underlying copper- or nickel-plated circuits reduces contact resistance as well as surface hardness. Copper-plated areas of mild steel act as a mask if case-hardening of such areas are not desired. Tin-plated steel

880-442: A pole passed the coil. However, the north and south poles of the magnet induced currents in opposite directions. To convert the alternating current to DC, Pixii invented a commutator , a split metal cylinder on the shaft, with two springy metal contacts that pressed against it. This early design had a problem: the electric current it produced consisted of a series of "spikes" or pulses of current separated by none at all, resulting in

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960-412: A power plant, unless either the rotor or field wiring or the mechanical drive systems are coupled together in certain special combinations. Dynamos were used in motor vehicles to generate electricity for battery charging. An early type was the third-brush dynamo . They have, again, been replaced by alternators . Dynamos still have some uses in low power applications, particularly where low voltage DC

1040-417: A pulsing direct current is produced. The earliest dynamos used permanent magnets to create the magnetic field. These were referred to as "magneto-electric machines" or magnetos . However, researchers found that stronger magnetic fields — and thus more power — could be produced by using electromagnets (field coils) on the stator. These were called "dynamo-electric machines" or dynamos. The field coils of

1120-467: A range current densities along its length, which can be measured with a Hull cell ruler. The solution volume allows for a semi-quantitative measurement of additive concentration: 1 gram addition to 267 mL is equivalent to 0.5 oz/gal in the plating tank. Electroplating changes the chemical, physical, and mechanical properties of the workpiece. An example of a chemical change is when nickel plating improves corrosion resistance. An example of

1200-415: A replacement for batteries. The commutator is essentially a rotary switch . It consists of a set of contacts mounted on the machine's shaft, combined with graphite-block stationary contacts, called "brushes," because the earliest such fixed contacts were metal brushes. The commutator reverses the connection of the windings to the external circuit when the potential reverses — so instead of alternating current,

1280-407: A sample of the plating solution and an appropriate anode which is connected to a rectifier . The "work" is replaced with a Hull cell test panel that will be plated to show the "health" of the bath. The Hull cell is a trapezoidal container that holds 267 milliliters of a plating bath solution. This shape allows one to place the test panel on an angle to the anode. As a result, the deposit is plated at

1360-405: A set of rotating windings called the armature which turn within that field. Due to Faraday's law of induction, the motion of the wire within the magnetic field creates an electromotive force , which pushes on the electrons in the metal, creating an electric current in the wire. On small machines, the constant magnetic field may be provided by one or more permanent magnets ; larger machines have

1440-400: A special plating deposit called a strike or flash may be used to form a very thin (typically less than 0.1 μm thick) plating with high quality and good adherence to the substrate. This serves as a foundation for subsequent plating processes. A strike uses a high current density and a bath with a low ion concentration. The process is slow, so more efficient plating processes are used once

1520-468: Is a process for producing a metal coating on a solid substrate through the reduction of cations of that metal by means of a direct electric current . The part to be coated acts as the cathode (negative electrode ) of an electrolytic cell ; the electrolyte is a solution of a salt whose cation is the metal to be coated, and the anode (positive electrode) is usually either a block of that metal, or of some inert conductive material. The current

1600-499: Is an important parameter that provides a measure of the uniformity of electroplating current, and consequently the uniformity of the electroplated metal thickness, on regions of the part that are near the anode compared to regions that are far from it. It depends mostly on the composition and temperature of the electroplating solution. Micro throwing power refers to the extent to which a process can fill or coat small recesses such as through-holes . Throwing power can be characterized by

1680-478: Is calculated by multiplying the duty cycle and peak value of the current or potential. Pulse electroplating could help to improve the quality of electroplated film and release the internal stress built up during fast deposition. A combination of the short duty cycle and high frequency could decrease surface cracks. However, in order to maintain the constant effective current or potential, a high-performance power supply may be required to provide high current/potential and

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1760-400: Is called a hub dynamo , although these are invariably AC devices, and are actually magnetos . The electric dynamo uses rotating coils of wire and magnetic fields to convert mechanical rotation into a pulsing direct electric current through Faraday's law of induction . A dynamo machine consists of a stationary structure, called the stator , which provides a constant magnetic field , and

1840-423: Is chromium-plated to prevent dulling of the surface due to oxidation of tin. There are a number of alternative processes to produce metallic coatings on solid substrates that do not involve electrolytic reduction: Electroplating was invented by Italian chemist Luigi Valentino Brugnatelli in 1805. Brugnatelli used his colleague Alessandro Volta 's invention of five years earlier, the voltaic pile , to facilitate

1920-486: Is effective and usually economical. The operating principle of electromagnetic generators was discovered in the years 1831–1832 by Michael Faraday . The principle, later called Faraday's law , is that an electromotive force is generated in an electrical conductor which encircles a varying magnetic flux . He also built the first electromagnetic generator, called the Faraday disk , a type of homopolar generator , using

2000-400: Is fabricated out of perspex or glass. The Hull cell is a type of test cell used to semi-quantitatively check the condition of an electroplating bath. It measures useable current density range, optimization of additive concentration, recognition of impurity effects, and indication of macro throwing power capability. The Hull cell replicates the plating bath on a lab scale. It is filled with

2080-429: Is provided by an external power supply . Electroplating is widely used in industry and decorative arts to improve the surface qualities of objects—such as resistance to abrasion and corrosion , lubricity , reflectivity , electrical conductivity , or appearance. It is used to build up thickness on undersized or worn-out parts and to manufacture metal plates with complex shape, a process called electroforming . It

2160-698: Is referred to as flashing the field . Both types of self-excited generator, which have been attached to a large external load while it was stationary, will not be able to build up voltage even if the residual field is present. The load acts as an energy sink and continuously drains away the small rotor current produced by the residual field, preventing magnetic field buildup in the field coil. Dynamos, usually driven by steam engines , were widely used in power stations to generate electricity for industrial and domestic purposes. They have since been replaced by alternators . Large industrial dynamos with series and parallel (shunt) windings can be difficult to use together in

2240-524: Is required, since an alternator with a semiconductor rectifier can be inefficient in these applications. Hand cranked dynamos are used in clockwork radios , hand powered flashlights and other human powered equipment to recharge batteries . The generator used for bicycle lighting may be called a "dynamo" but these are almost always AC devices and so, strictly, would be called "alternators". Electroplating Electroplating , also known as electrochemical deposition or electrodeposition ,

2320-426: Is the reverse of the process of electroplating. Throwing power is an important parameter that provides a measure of the uniformity of electroplating current, and consequently the uniformity of the electroplated metal thickness, on regions of the part that are near to the anode compared to regions that are far from it. It depends mostly on the composition and temperature of the electroplating solution, as well as on

2400-474: Is used to deposit copper and other conductors in forming printed circuit boards and copper interconnects in integrated circuits. It is also used to purify metals such as copper . The aforementioned electroplating of metals uses an electroreduction process (that is, a negative or cathodic current is on the working electrode). The term "electroplating" is also used occasionally for processes that occur under electro-oxidation (i.e positive or anodic current on

2480-608: The Parthian Empire using a device resembling a Baghdad Battery , but this has since been refuted; the items were fire-gilded using mercury. Boris Jacobi in Russia not only rediscovered galvanoplastics, but developed electrotyping and galvanoplastic sculpture . Galvanoplastics quickly came into fashion in Russia, with such people as inventor Peter Bagration , scientist Heinrich Lenz , and science-fiction author Vladimir Odoyevsky all contributing to further development of

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2560-648: The 1850s. Electroplating baths and equipment based on the patents of the Elkingtons were scaled up to accommodate the plating of numerous large-scale objects and for specific manufacturing and engineering applications. The plating industry received a big boost with the advent of the development of electric generators in the late 19th century. With the higher currents available, metal machine components, hardware, and automotive parts requiring corrosion protection and enhanced wear properties, along with better appearance, could be processed in bulk. The two World Wars and

2640-507: The Greek word dynamis (δύναμις), meaning force or power) was originally another name for an electrical generator , and still has some regional usage as a replacement for the word generator. The word was coined in 1831 by Michael Faraday , who utilized his invention toward making many discoveries in electricity (Faraday discovered electrical induction) and magnetism . The original "dynamo principle" of Werner von Siemens referred only to

2720-488: The Heatley throwing power 100% × ( L − M ) / ( L − 1) , and Field throwing power 100% × ( L − M ) / ( L + M − 2) . A more uniform thickness is obtained by making the throwing power larger (less negative) according to any of these definitions. Parameters that describe cell performance such as throwing power are measured in small test cells of various designs that aim to reproduce conditions similar to those found in

2800-557: The West Side IRT subway in Manhattan into the late 1960s, and possibly some years later. They were powered by 25 Hz AC, and provided DC at 600 volts for the trains. Direct current machines like dynamos and commutated DC motors have higher maintenance costs and power limitations than alternating current (AC) machines due to their use of the commutator . These disadvantages are: Although direct current dynamos were

2880-421: The ability to plate items that for some reason cannot be tank plated (one application was the plating of portions of very large decorative support columns in a building restoration), low or no masking requirements, and comparatively low plating solution volume requirements. Disadvantages compared to tank plating can include greater operator involvement (tank plating can frequently be done with minimal attention), and

2960-435: The bulk solution to the electrode surface. The ideal stirring setting varies for different metal electroplating processes. A closely-related process is brush electroplating, in which localized areas or entire items are plated using a brush saturated with plating solution. The brush, typically a stainless steel body wrapped with an absorbent cloth material that both holds the plating solution and prevents direct contact with

3040-445: The case of plated solder, it is sometimes deemed necessary to have a true alloy, and the plated solder is melted to allow the tin and lead to combine into a true alloy. The true alloy is more corrosion-resistant than the as-plated mixture. Many plating baths include cyanides of other metals (such as potassium cyanide ) in addition to cyanides of the metal to be deposited. These free cyanides facilitate anode corrosion, help to maintain

3120-422: The cathode is plated, and thus the ions in the electrolyte bath are continuously replenished by the anode. The net result is the effective transfer of metal from the anode to the cathode. The anode may instead be made of a material that resists electrochemical oxidation, such as lead or carbon . Oxygen , hydrogen peroxide , and some other byproducts are then produced at the anode instead. In this case, ions of

3200-460: The cathode, the Cu is reduced to metallic copper by gaining two electrons. When the anode is made of the metal that is intended for coating onto the cathode, the opposite reaction may occur at the anode, turning it into dissolved cations. For example, copper would be oxidized at the anode to Cu by losing two electrons. In this case, the rate at which the anode is dissolved will equal the rate at which

3280-437: The coating. ASTM B322 is a standard guide for cleaning metals prior to electroplating. Cleaning includes solvent cleaning, hot alkaline detergent cleaning, electrocleaning, ultrasonic cleaning and acid treatment. The most common industrial test for cleanliness is the waterbreak test, in which the surface is thoroughly rinsed and held vertical. Hydrophobic contaminants such as oils cause the water to bead and break up, allowing

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3360-692: The commutator at many equally spaced points around the ring; the commutator being divided into many segments. This meant that some part of the coil was continually passing by the magnets, smoothing out the current. The Woolrich Electrical Generator of 1844, now in Thinktank, Birmingham Science Museum , is the earliest electrical generator used in an industrial process. It was used by the firm of Elkingtons for commercial electroplating . In 1827, independently of Faraday, Hungarian inventor Ányos Jedlik started experimenting with electromagnetic rotating devices which he called electromagnetic self-rotors . In

3440-410: The commutator to produce direct current. The first commutated dynamo was built in 1832 by Hippolyte Pixii , a French instrument maker. It used a permanent magnet which was rotated by a crank. The spinning magnet was positioned so that its north and south poles passed by a piece of iron wrapped with insulated wire. Pixii found that the spinning magnet produced a pulse of current in the wire each time

3520-598: The constant magnetic field provided by one or more electromagnets , which are usually called field coils . The commutator is needed to produce direct current . When a loop of wire rotates in a magnetic field, the magnetic flux through it—and thus the potential induced in it—reverses with each half turn, generating an alternating current . However, in the early days of electric experimentation, alternating current generally had no known use. The few uses for electricity, such as electroplating , used direct current provided by messy liquid batteries . Dynamos were invented as

3600-416: The current would circulate backwards in regions that were outside the influence of the magnetic field. This counterflow limited the power output to the pickup wires, and induced waste heating of the copper disc. Later homopolar generators would solve this problem by using an array of magnets arranged around the disc perimeter to maintain a steady field effect in one current-flow direction. Another disadvantage

3680-437: The deposited film's composition and thickness. The experimental parameters of pulse electroplating usually consist of peak current/potential, duty cycle, frequency, and effective current/potential. Peak current/potential is the maximum setting of electroplating current or potential. Duty cycle is the effective portion of time in a certain electroplating period with the current or potential applied. The effective current/potential

3760-472: The deposition rate, since the rate of most chemical reactions increases exponentially with temperature per the Arrhenius law . The anode-to-cathode gap is related to the current distribution between anode and cathode. A small gap-to-sample-area ratio may cause uneven distribution of current and affect the surface topology of the plated sample. Stirring may increase the transfer/diffusion rate of metal ions from

3840-459: The desired strike thickness is obtained. The striking method is also used in combination with the plating of different metals. If it is desirable to plate one type of deposit onto a metal to improve corrosion resistance but this metal has inherently poor adhesion to the substrate, then a strike can be first deposited that is compatible with both. One example of this situation is the poor adhesion of electrolytic nickel on zinc alloys, in which case

3920-410: The device when it is not operating, which has been imprinted onto the metal by the field windings. The dynamo begins rotating while not connected to an external load. The residual magnetic field induces a very small electrical current into the rotor windings as they begin to rotate. Without an external load attached, this small current is then fully supplied to the field windings, which in combination with

4000-401: The dimensionless Wagner number : Wa = R T κ F L α | i | , {\displaystyle {\text{Wa}}={\frac {RT\kappa }{FL\alpha |i|}},} where R is the universal gas constant , T is the operating temperature , κ is the ionic conductivity of the plating solution, F is the Faraday constant , L is

4080-506: The direct current generators which use exclusively the self-excitation (self-induction) principle to generate DC power. The earlier DC generators which used permanent magnets were not considered "dynamo electric machines". The invention of the dynamo principle (self-induction) was a major technological leap over the old traditional permanent magnet based DC generators. The discovery of the dynamo principle made industrial scale electric power generation technically and economically feasible. After

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4160-545: The electric current less sensitive to voltage), and raising the solution conductivity (e.g. by adding acid ). Concurrent hydrogen evolution usually improves the uniformity of electroplating by increasing | i |; however, this effect can be offset by blockage due to hydrogen bubbles and hydroxide deposits. The Wagner number is rather difficult to measure accurately; therefore, other related parameters, that are easier to obtain experimentally with standard cells, are usually used instead. These parameters are derived from two ratios:

4240-453: The equivalent size of the plated object, α is the transfer coefficient , and i the surface-averaged total (including hydrogen evolution ) current density. The Wagner number quantifies the ratio of kinetic to ohmic resistances. A higher Wagner number produces a more uniform deposition. This can be achieved in practice by decreasing the size ( L ) of the plated object, reducing the current density | i |, adding chemicals that lower α (make

4320-569: The first electrodeposition. Brugnatelli's inventions were suppressed by the French Academy of Sciences and did not become used in general industry for the following thirty years. By 1839, scientists in Britain and Russia had independently devised metal-deposition processes similar to Brugnatelli's for the copper electroplating of printing press plates. Research from the 1930s had theorized that electroplating might have been performed in

4400-447: The first source of electric power for industry, they had to be located close to the factories that used their power. Electricity could only be distributed over distances economically as alternating current (AC), through the use of the transformer . With the 1890s conversion of electric power systems to alternating current, during the 20th century dynamos were replaced by alternators , and are now almost obsolete. The word 'dynamo' (from

4480-510: The growing aviation industry gave impetus to further developments and refinements, including such processes as hard chromium plating , bronze alloy plating, sulfamate nickel plating, and numerous other plating processes. Plating equipment evolved from manually-operated tar -lined wooden tanks to automated equipment capable of processing thousands of kilograms per hour of parts. One of the American physicist Richard Feynman 's first projects

4560-643: The heart of all modern dynamos. Charles F. Brush assembled his first dynamo in the summer of 1876 using a horse-drawn treadmill to power it. Brush's design modified the Gramme dynamo by shaping the ring armature like a disc rather than a cylinder shape. The field electromagnets were also positioned on the sides of the armature disc rather than around the circumference. After dynamos and motors were found to allow easy conversion back and forth between mechanical or electrical power, they were combined in devices called rotary converters , rotating machines whose purpose

4640-409: The inability to achieve as great a plate thickness. This technique of electroplating is one of the most common used in the industry for large numbers of small objects. The objects are placed in a barrel-shaped non-conductive cage and then immersed in a chemical bath containing dissolved ions of the metal that is to be plated onto them. The barrel is then rotated, and electrical currents are run through

4720-402: The invention of the alternator and that alternating current can be used as a power supply, the word dynamo became associated exclusively with the ' commutated direct current electric generator', while an AC electrical generator using either slip rings or rotor magnets would become known as an alternator . A small electrical generator built into the hub of a bicycle wheel to power lights

4800-406: The item being plated, is connected to the anode of a low-voltage direct-current power source, and the item to be plated is connected to the cathode . The operator dips the brush in plating solution and then applies it to the item, moving the brush continually to get an even distribution of the plating material. Brush electroplating has several advantages over tank plating, including portability,

4880-409: The metal to be plated must be replenished (continuously or periodically) in the bath as they are drawn out of the solution. The plating is most commonly a single metallic element , not an alloy . However, some alloys can be electrodeposited, notably brass and solder . Plated "alloys" are not "true alloys" (solid solutions), but rather they are tiny crystals of the elemental metals being plated. In

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4960-481: The operating current density . A higher throwing power of the plating bath results in a more uniform coating. The electrolyte in the electrolytic plating cell should contain positive ions (cations) of the metal to be deposited. These cations are reduced at the cathode to the metal in the zero valence state. For example, the electrolyte for copper electroplating can be a solution of copper(II) sulfate , which dissociates into Cu cations and SO 4 anions. At

5040-423: The production plating bath. The Haring–Blum cell is used to determine the macro throwing power of a plating bath. The cell consists of two parallel cathodes with a fixed anode in the middle. The cathodes are at distances from the anode in the ratio of 1:5. The macro throwing power is calculated from the thickness of plating at the two cathodes when a direct current is passed for a specific period of time. The cell

5120-412: The prototype of the single-pole electric starter, both the stationary and the revolving parts were electromagnetic. Around 1856, six years before Siemens and Wheatstone , Ányos formulated the concept of the dynamo, but did not patent it as he thought he was not the first to realize the idea. Instead of permanent magnets, his dynamo used two electromagnets placed opposite to each other in order to induce

5200-516: The ratio M = m 1 / m 2 of the plating thickness of a specified region of the cathode "close" to the anode to the thickness of a region "far" from the cathode and the ratio L = x 2 / x 1 of the distances of these regions through the electrolyte to the anode. In a Haring-Blum cell, for example, L = 5 for its two independent cathodes, and a cell yielding plating thickness ratio of M = 6 has Harring-Blum throwing power 100% × ( L − M ) / L = −20% . Other conventions include

5280-445: The residual field, cause the rotor to produce more current. In this manner, the self-exciting dynamo builds up its internal magnetic fields until it reaches its normal operating voltage. When it is able to produce sufficient current to sustain both its internal fields and an external load, it is ready to be used. A self-excited dynamo with insufficient residual magnetic field in the metal frame will not be able to produce any current in

5360-529: The rotor, but in Wheatstone's design they were in parallel. The use of electromagnets rather than permanent magnets greatly increased the power output of a dynamo and enabled high power generation for the first time. This invention led directly to the first major industrial uses of electricity. For example, in the 1870s Siemens used electromagnetic dynamos to power electric arc furnaces for the production of metals and other materials. The dynamo machine that

5440-410: The rotor, regardless of what speed the rotor spins. This situation can also occur in modern self-excited portable generators, and is resolved for both types of generators in a similar manner, by applying a brief direct current battery charge to the output terminals of the stopped generator. The battery energizes the windings just enough to imprint the residual field, to enable building up the current. This

5520-501: The same time. The size and mass of the rotor was made large so that the rotor would act as a flywheel to help smooth out any sudden surges or dropouts in the applied power. The technology of rotary converters was replaced in the early 20th century by mercury-vapor rectifiers , which were smaller, did not produce vibration and noise, and required less maintenance. The same conversion tasks are now performed by solid state power semiconductor devices . Rotary converters remained in use in

5600-418: The stator were originally separately excited by a separate, smaller, dynamo or magneto. An important development by Wilde and Siemens was the discovery (by 1866) that a dynamo could also bootstrap itself to be self-excited , using current generated by the dynamo itself. This allowed the growth of a much more powerful field, thus far greater output power. Self-excited direct current dynamos commonly have

5680-644: The technology. Among the most notorious cases of electroplating usage in mid-19th century Russia were the gigantic galvanoplastic sculptures of St. Isaac's Cathedral in Saint Petersburg and gold-electroplated dome of the Cathedral of Christ the Saviour in Moscow , the third tallest Orthodox church in the world . Soon after, John Wright of Birmingham , England discovered that potassium cyanide

5760-429: The various pieces in the barrel, which complete circuits as they touch one another. The result is a very uniform and efficient plating process, though the finish on the end products will likely suffer from abrasion during the plating process. It is unsuitable for highly ornamental or precisely engineered items. Cleanliness is essential to successful electroplating, since molecular layers of oil can prevent adhesion of

5840-479: The water to drain rapidly. Perfectly clean metal surfaces are hydrophilic and will retain an unbroken sheet of water that does not bead up or drain off. ASTM F22 describes a version of this test. This test does not detect hydrophilic contaminants, but electroplating can displace these easily, since the solutions are water-based. Surfactants such as soap reduce the sensitivity of the test and must be thoroughly rinsed off. Throwing power (or macro throwing power )

5920-406: The working electrode), although such processes are more commonly referred to as anodizing rather than electroplating. One such example is the formation of silver chloride on silver wire in chloride solutions to make silver/silver-chloride (AgCl) electrodes . Electropolishing , a process that uses an electric current to selectively remove the outermost layer from the surface of a metal object,

6000-467: Was a better path for the magnetic flux , by filling the space occupied by the magnetic field with heavy iron cores and minimizing the air gaps between the stationary and rotating parts. The Gramme dynamo was one of the first machines to generate commercial quantities of power for industry. Further improvements were made on the Gramme ring, but the basic concept of a spinning endless loop of wire remains at

6080-500: Was a suitable electrolyte for gold and silver electroplating. Wright's associates, George Elkington and Henry Elkington were awarded the first patents for electroplating in 1840. These two then founded the electroplating industry in Birmingham from where it spread around the world. The Woolrich Electrical Generator of 1844, now in Thinktank, Birmingham Science Museum , is the earliest electrical generator used in industry. It

6160-483: Was developed consisted of a stationary structure, which provides the magnetic field, and a set of rotating windings which turn within that field. On larger machines the constant magnetic field is provided by one or more electromagnets, which are usually called field coils. Zénobe Gramme reinvented Pacinotti's design in 1871 when designing the first commercial power plants operated in Paris . An advantage of Gramme's design

6240-704: Was not to provide mechanical power to loads but to convert one type of electric current into another, for example DC into AC . They were multi-field single-rotor devices with two or more sets of rotating contacts (either commutators or sliprings, as required), one to provide power to one set of armature windings to turn the device, and one or more attached to other windings to produce the output current. The rotary converter can directly convert, internally, any type of electric power into any other. This includes converting between direct current (DC) and alternating current (AC), three phase and single phase power, 25 Hz AC and 60 Hz AC, or many different output voltages at

6320-409: Was that the output voltage was very low, due to the single current path through the magnetic flux. Faraday and others found that higher, more useful voltages could be produced by winding multiple turns of wire into a coil. Wire windings can conveniently produce any voltage desired by changing the number of turns, so they have been a feature of all subsequent generator designs, requiring the invention of

6400-455: Was used by Elkingtons . The Norddeutsche Affinerie in Hamburg was the first modern electroplating plant starting its production in 1876. As the science of electrochemistry grew, its relationship to electroplating became understood and other types of non-decorative metal electroplating were developed. Commercial electroplating of nickel , brass , tin , and zinc were developed by

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