Abstract:
An induction heating system that can be used to braze metals and that overcomes many of the disadvantages of conventional brazing systems. The induction heating system improves quality and lowers production cost for many brazing requirements. The system is designed to quickly, accurately and cost effectively heat individual parts, and to replace flame brazing procedures and batch vacuum furnaces. Because the system can braze parts in an inert atmosphere or in no atmosphere (e.g., in a vacuum), no flux or acid cleaning bath is necessary and oxidation on the part is eliminated. Further, by including a gas quenching feature, the system prevents the annealing of parts and produces high quality brazed parts that meet desired hardness specifications. In one embodiment, the induction heating system includes a vacuum chamber; a support surface located within the chamber for providing a surface onto which a part to be heated is placed; moving means connected to the support surface for moving the support surface within the chamber; a vacuum system connected to the chamber for exhausting gases from the chamber; an electrically conductive coil located inside of the chamber or located adjacent to the chamber; an induction heating unit, coupled to the coil, for providing an alternating current to the coil; a temperature sensing means for sensing the temperature of the part; an operator interface for displaying a user interface comprising one or more selectable push button icons and for receiving input from an operator; and a controller interfaced to the operator interface, the vacuum system, the induction heating unit, the moving means, and the temperature sensing means.

Description:
This application claims the benefit of U.S. Provisional Patent Application No. 60/208,091, which was filed on May 31, 2000 (status pending), and which is incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1.Field of the Invention 
     The present invention is generally related to induction heating systems, and, more specifically, to an induction heating system that can be used for, among other things, brazing applications. 
     2. Discussion of the Background 
     Brazing is a process for joining metal parts. A brazing process uses heat and a filler metal to join metals parts together. Typically, the filler metal has a melting temperature above 840° F. (450° C.), but below the melting point of the parts being joined. The filler metal is either pre-placed into the joint between the parts or fed into the joint as the parts are being heated. The application of the heat causes the filler to melt and flow into the joint, usually by capillary action, thereby joining the parts. 
     Brazing is probably the most versatile method of metal joining today, for a number of reasons. First, brazed joints are strong. Second, brazed joints are ductile; that is, they are able to withstand considerable shock and vibration. Additionally, brazing is ideally suited to the joining of dissimilar metals. 
     Conventionally, the parts to be joined and the filler metal are heated in a normal atmosphere using a conventional heat source, such as a flame. Flame brazing in a normal atmosphere causes the undesirable side effects of oxidation, scaling, and carbon build-up on the parts. To clean the parts of this carbon build-up, applications of joint-weakening flux and expensive acid cleaning baths have been required. 
     One solution to the above problem is to use a batch vacuum furnace. However, batch vacuum furnaces have significant limitations because of their large size, batch manufacturing methods, poor efficiency, and lack of quality control. 
     What is desired, therefore, is a system and/or method that overcomes these and other disadvantages of conventional brazing systems. 
     SUMMARY OF THE INVENTION 
     The present invention provides an induction heating system that can be used to braze metals and that overcomes many of the disadvantages of conventional brazing systems described above. Furthermore, the induction heating system improves quality and lowers production cost for many brazing requirements. The system is designed to quickly, accurately and cost effectively heat individual parts, and to replace flame brazing procedures and batch vacuum furnaces. 
     Because the system can braze parts in an inert atmosphere or in no atmosphere (e.g., in a vacuum), no flux or acid cleaning bath is necessary and oxidation on the part is eliminated. Further, by including a gas quenching feature, the system prevents the annealing of parts and produces high quality brazed parts that meet desired hardness specifications. 
     In one embodiment, the induction heating system includes a vacuum chamber; a support surface located within the chamber for providing a surface onto which a part to be heated is placed; moving means connected to the support surface for moving the support surface within the chamber; a vacuum system connected to the chamber for exhausting gases from the chamber; an electrically conductive coil located inside of the chamber or located adjacent to the chamber; an induction heating unit, coupled to the coil, for providing an alternating current to the coil; a temperature sensing means for sensing the temperature of the part; an operator interface for displaying a user interface comprising one or more selectable push button icons and for receiving input from an operator; and a controller interfaced to the operator interface, the vacuum system, the induction heating unit, the moving means, and the temperature sensing means. 
     Advantageously, the controller is programmed to perform a procedure in response to an operator selecting one of the selectable push button icons. The procedure includes the steps of: sending a signal to the moving means to cause the moving means to move the support surface so that the part is appropriately located with respect to the coil; sending a signal to the vacuum system to cause the vacuum system to exhaust gases from the chamber; monitoring the pressure within the chamber; after the pressure within the chamber reaches a predetermined threshold, sending a signal to the induction heating unit to cause the induction heating unit to provide to the coil an alternating current having sufficient power to heat the part to a predetermined temperature; waiting for a predetermined amount of time; and after the predetermined amount of time has elapsed, sending a signal to the induction heating unit causing the induction heating unit to stop providing the alternating current to the coil. 
     Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various embodiments of the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. In the drawings, like reference numbers indicate identical or functionally similar elements. Additionally, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears. 
     FIG. 1 is an illustration of an induction heating system according to one embodiment. 
     FIG. 2 is a block diagram of the induction heating system. 
     FIG. 3 is a figure of an exemplary coil. 
     FIG. 4 is a block diagram of one embodiment of a vacuum system. 
     FIG. 5 is flow chart illustrating the process of using the vacuum system shown in FIG.  4 . 
     FIG. 6 is a block diagram of another embodiment of the vacuum system. 
     FIG. 7 is a representation of a first user interface screen. 
     FIG. 8 is a representation of a second user interface screen. 
     FIG. 9 is a block diagram of an induction heating system having more than one chamber. 
     FIGS. 10A and 10B are a flow chart illustrating a brazing process. 
     FIGS. 11A and 11B are a flow chart illustrating an inert atmosphere brazing process. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is an illustration of one embodiment of the induction heating system  100 . As shown in FIG. 1, induction heating system  100  includes a vacuum chamber  102  sitting on top of housing  110  and an operator interface  130  for allowing an operator of heating system  100  to control all aspects and components of heating system  100 . The part to be heated is placed within vacuum chamber  102 . In one embodiment, housing  110  holds, among other things, an induction heating unit, a vacuum system, an atmospheric control system, and a master control system, all of which are shown in block diagram form in FIG.  2 . Preferably, an infrared pyrometer  120 , for measuring the temperature of the parts to be heated, is included in the heating system  100 . The master control system controls the induction heating system, the vacuum system, the atmospheric control system, the operator interface  130  and receives temperature data from the infrared pyrometer  120 . 
     In one embodiment, the vacuum chamber  102  is a metal chamber (e.g., stainless steel) with a quartz window  104 . Quartz window  104  enables an optional infrared pyrometer  120  to measure the temperature of the part being heated. In another embodiment, the vacuum chamber  102  is quartz tube. Whether vacuum chamber  102  is a metal chamber or a quartz tube depends on the application for which the heating system  100  is being used. 
     FIG. 2 is a functional block diagram which illustrates the various components of heating system  100  mentioned above. As shown in FIG. 2, a master control system  202  is interfaced with an induction heating unit  204 , a vacuum control system  206 , an atmospheric control system  208 , a servo motor  254 , operator interface  130 , a pressure sensor  269 , and infrared pyrometer  120 . As described above, the master control system  202  controls the operation of the components of heating system  100  to which it is interfaced by transmitting control signals thereto. In a preferred embodiment, master controller is the Micrologix™ 1500 programmable controller from Rockwell Automation of Mayfield Heights, Ohio (www.ab.com). However, control system  202  can be implemented with any programmable processing device, including a personal computer, a workstation etc. 
     Induction heating unit  204  functions to provide an alternating current to an electrically conductive coil  212  (e.g., copper coil). The frequency of the alternating current provided by induction heating unit  204  is in the radio frequency (RF) range. Preferably, induction heating unit  204  includes an RF power supply (not shown) connected to a tank circuit (not shown), wherein coil  212  is connected to the tank circuit. In one embodiment, the tank circuit is a parallel resonant tank circuit. By using a parallel resonant tank circuit, a low voltage coil  212  can be used. A low voltage coil is preferred because using a low voltage coil reduces the chances of arcing. 
     In the embodiment shown in FIG. 2, coil  212  is placed within vacuum chamber  103 . However, in other contemplated embodiments, such as the embodiment in which vacuum chamber  102  is implemented with a quartz tube, the coil is not placed within vacuum chamber  102 , but is placed in proximity thereto. Induction heating unit  204  and coil  212  are commonly available and can be purchased from Ameritherm, Inc. of Scottsville N.Y. as well as other vendors of induction heating equipment. Additionally, an induction heating unit that could be used with heating system  100  is described in U.S. patent application Ser. No. 09/113,518, filed Jul. 10, 1998, entitled “RF Power Supply”, which is assigned to the assignee of the present invention and which is incorporated herein by this reference. 
     FIG. 3 illustrates an exemplary embodiment of coil  212 . As shown in FIG. 3, in one embodiment, coil  212  has a first winding  302  and a second winding  304 . A part  310  to be heated or brazed is placed between first winding  302  and second winding  304 . As described above, induction heating unit  204  provides an alternating current to coil  212 . An electromagnetic field emanates from the coil as the alternating current flows through the coil. It is this electromagnetic field that is used to heat the part  310 . As the coil design is influenced by the shape of the part  310  to be heated, the invention is not limited to any specific coil design. 
     Vacuum system  206  functions to remove gases from chamber  102 , thereby reducing the pressure within chamber  102  (assuming the temperature and volume of the chamber do not change). FIGS. 4 and 6 each illustrate an exemplary embodiment of vacuum system  206 . One skilled in the art should understand that the invention is not limited to any specific vacuum system embodiment and that FIGS. 4 and 6 are provided merely for illustration and do not serve to limit the invention. 
     As shown in FIG. 4, in one embodiment, vacuum system  206  includes a “roughing” pump  402 , a molecular diffusion pump  404 , a three-way valve  406 , and a gate valve  408 . Master controller  202 , chamber  102 , roughing pump  402 , and diffusion pump  404  are all connected to three-way valve  406 , whereas only master controller  202 , diffusion pump  404  and vacuum chamber  102  are connected to gate valve  408 . FIG. 5 illustrates a process  500  performed by master controller  202  to create a vacuum (i.e., to reduce the air pressure) within vacuum chamber  102  using the vacuum system illustrated in FIG.  4 . 
     Process  500  begins in step  502  where master controller  202  sends to roughing pump  402  a signal that causes roughing pump to begin pumping. At the same time, master controller  202  configures three-way valve  406  such that the gases within chamber  102  will be removed therefrom by the pumping action of roughing pump  402  (step  504 ). While roughing pump  402  is removing the gases from chamber  102 , master controller  202  determines the pressure within chamber  102  (step  506 ) by reading the output of pressure sensor  269 . In step  508 , controller  202  compares the pressure determined in step  506  with a predetermined pressure value. If the determined pressure is less than or equal to the predetermined value, then control passes to step  510 , otherwise control returns to step  506 . In step  510 , controller reconfigures valve  406  such that roughing pump  402  will pull air from diffusion pump  404  instead of from chamber  102 . Next (step  512 ), controller opens valve  408  and sends a signal to diffusion pump  404  to cause it to begin exhausting the gases within chamber  102 . 
     FIG. 6 illustrates another embodiment of vacuum system  206 . As shown in FIG. 6, vacuum system  206  includes roughing pump  402 , a turbo molecular pump  602  (“turbo pump”), and a gate valve  604 . Roughing pump  402  is connected to turbo pump  602  which is connected to chamber  102  through gate valve  604 . The turbo pump  602  functions to pump gases out of chamber  102 , and roughing pump  402  functions as a backing pump to the turbo pump  602 . That is, roughing pump  402  pumps gases out of the turbo pump  602 . The process performed by controller  202  to reduce the air pressure within chamber  102  is straightforward process. The process begins with controller  202  sending a signal to roughing pump  402  and turbo pump  602  that causes both of them to begin pumping. At or about the same time, controller  202  opens gate valve  604  such that gas molecules and other molecules within chamber  102  are exhausted by the pumping action of turbo pump  602 . While the pumps are activated, controller  202  monitors the pressure within chamber  102 . 
     Referring again to FIG. 2, the atmospheric control system (ACS)  208  will be described. In one embodiment, ACS  208  includes a gate valve  270  for connecting a gas source  272  to vacuum chamber  102 . Gate valve  270  is controlled by controller  202 . That is, controller  202  can open and close valve  270 . The gas provided by gas source  272  is used to quench (i.e., cool) the part(s) that was/were heated. That is, in some applications it is necessary to cool the part immediately after it has been heated. One example of such an application is the copper brazing of steel components. To cool the part, the controller  202  configures valve  270  such that a large amount of the gas provided by source  272  will flow into the chamber, thereby quenching the part that was heated. Preferably, gas source  272  provides an inert gas, such as Argon or Helium. 
     In another embodiment, ACS  208  further includes a second gate valve  280  for connecting a second gas source  282  to vacuum chamber  102 . The gas provided by gas source  282  is used to provide an inert atmosphere in which to heat or braze parts. Some applications, such as the brazing of silver, copper, steel or brass alloys, should be performed in an inert atmosphere, while others, such as brazing nickel alloys with nickel, should be performed in a near vacuum environment. Therefore, depending on the type of material that is being heated, gas source  282  may or may not be needed. In those applications where gas source  282  is needed, controller  202  is preferably programmed to direct vacuum system  206  to remove the air from chamber  102  and, once most of the air is removed, to configure valve  280  to allow the gas from gas source  282  to flow into chamber  102  before activating induction heating unit  204 . In this manner, the part will not be heated until the chamber contains only the gas provided from gas source  282 . 
     Still referring to FIG. 2, in one embodiment, heating system  100  includes a support surface (e.g., a table)  250  that is provided within chamber  102 . Support surface  250  is connected, through a rotary/linear vacuum feedthrough  252 , to a servo motor  254 , which is interfaced with controller  202 . Servo motor  254  functions to move support surface  250  upwards and downwards and/or to rotate support surface  250 . 
     Controller  202  uses servo motor  254  to move the part to be heated into position within the coil. That is, a number of parts or assemblies can be loaded on to support surface  250  and controller  202  can move support surface  250  so that each part can be heated in turn. For example, after a part on the support surface  250  has been heated as required, controller  202  can direct motor  254  to move support surface  250  so that the next part to be processed is placed in the appropriate location with respect to coil  212 . Once this part is in the correct location with respect to the coil  212 , controller  202  will direct induction heating unit  204  to provide the alternating current to the coil  212 , thereby heating the part. This automatic process can continue until all the parts that have been placed on the support surface  250  have been processed as required. 
     Also shown in FIG. 2 is a thermocouple feed-through  290  for allowing a thermocouple (not shown) to be placed inside of chamber  102  to measure the temperature of the part(s) being heated. The thermocouple can be used in place of the infrared pyrometer  120  or it can be used to periodically calibrate the infrared pyrometer  120 . 
     Referring now to the operator interface  130 , operator interface  130  provides a graphical user interface to operator  201 . The user interface enables operator  201  to issue commands to, and receive information from, controller  202 . In one embodiment, operator interface  130  is a touch-screen display. In other embodiments interface  130  includes a standard computer display monitor in combination with a keyboard and/or mouse or other input device. FIGS. 7 and 8 illustrate a main menu screen  700  and a manual control screen  800 , respectively, both of which are displayed to the operator  201  via operator interface  130 . 
     When controller  202  is powered on, main menu screen  700  is displayed on interface  130 . Referring to FIG. 7, Screen  700  includes three sections. A top center section  702  displays current system operational status. In this section, the operator may take one look to determine exactly what is occurring in the system. A middle section  704  has real-time bar graphs showing the key process characteristics: (1) temperature of the part being processed, (2) pressure level in the chamber  102 , and (3) power output from the power supply within induction heating unit  204 . A left section  706  of screen  700  includes push button icons for starting an automatic process performed by controller  202  and for stopping the automatic process. That is, activating a particular push button causes operator interface  103  to send a predetermined signal to controller  202 . In response to receiving the predetermined signal, controller  202  performs a series of predefined steps. For example, in response to the predetermined signal, the controller  202  could be programmed to send control signals to any one or more of the various components shown in FIG. 2 to which controller  202  is interfaced so as to perform a brazing process such as the one shown in FIGS. 10A and 10B or FIGS. 11A and 11B. 
     There is also provided a push button icon  710  for switching to a manual mode of operation. When push button icon  710  is selected, manual control screen  800  is displayed. Manual control screen  800  may be used for process development and/or trouble shooting. Included in screen  800  are bar graphs  804  for providing real-time feedback of the temperature of the part being processed and the pressure level in the chamber  102 . 
     Every function is available to the operator through a number of push button icons  802  displayed on the screen  800 . Thus, the operator can configure all the valves, start and stop the pumps, activate the induction heating system, etc. merely by activating the appropriate push button icon. Upon activating a push button icon, the operator interface  130  sends to the controller  202  a signal that indicates which push button icon was activated. In response to receiving the signal, controller  202  performs some action depending on which push button was activated. For example, if the activated push button is labeled “Heat On”, controller  202  sends a control signal to induction heating unit  202  that causes the unit  202  to heat the part by providing alternating current to the coil  212 . 
     If a very large number of parts need to be processed in a short amount of time, it is possible to expand heating system  100  to include more than one chamber  102 . Such an expanded heating system  900  is shown in FIG.  9 . The advantage of expanded heating system  900  is that it can process more parts per minute than heating system  100 . Heating system  900  is shown having three chambers ( 902 ,  904 , and  906 ), however, heating system  900  is not limited to this number of chambers. Although not shown in FIG. 9, there is a pressure sensor associated with each chamber for measuring the pressure in the chamber. 
     Advantageously, heating system  900  does not require more than one vacuum system  206 . This is because vacuum system  206  is coupled to each of the chambers  902 - 906  by a valve system  930 , which includes one or more valves. Similarly, heating system  900  only requires one induction heating power supply  910 , one quench/atmosphere gas source  272 , one controller  202 , and one operator interface  130 . Power supply  910  is coupled to each coil  932 ,  933 , and  934  through a contactor  920  and an optional tank circuit  922 . Gas source  272  is coupled to each chamber  902 - 906  by valve system  940 , which includes one or more valves. 
     At the start up of heating system  900 , a part(s) are loaded into chamber  902  and the automatic process for chamber  902  will initiate. The automatic process includes the steps of: (1) moving the part(s) to be processed close to the coil  932 , (2) pumping down the chamber  902  (i.e., removing the air and other molecules from chamber  902 ) to reach the desired pressure level, (3) introducing an inert gas into the chamber  902  (this step is optional), (4) configuring contactor  920  such that the alternating current created by power supply  910  is provided to coil  932  to create an electromagnetic field (EMF) for heating the part(s), and (4) quenching the part using a quenching gas after the part has been heated as required for the particular application. After completion of step (2), controller  202  configures valve system  930  so that the pumping action of vacuum system  206  will exhaust the gas within chamber  904 . After valve system is so configured, the automatic process for chamber  904 , which is similar to that of chamber  902 , will initiate. 
     Similarly, after the pressure in chamber  904  has reached the desired level, controller  202  configures valve system  930  so that the pumping action of vacuum system  206  will exhaust the gas within chamber  906 . After valve system is so configured, the automatic process for chamber  906 , which is similar to that of chambers  902  and  904 , will initiate. In this manner, a number of parts can be processed in parallel, thereby increasing the number of parts that can be processed in a given amount of time. 
     Heating system  100  and heating system  900  can be used in a wide variety of heating applications. In particular, heating system  100  and  900  are well suited for brazing application. Such brazing applications included brazing silver, brass alloys, copper, steel, and nickel components using silver, copper or nickel alloys as the filler metal. 
     Because heating system  100  and  900  include programmable controller  202 , almost any heating application can be automated by programming the controller  202 . That is, with a single push of a button, an entire brazing process can be carried out and handled by the controller. 
     FIGS. 10A and 10B illustrate a process  1000  for brazing parts using heating system  100  and using as the filler metal a paste, such as a nickel alloy paste. One skilled in the art of computer programming can program controller  202  to perform one or more of the steps of process  1000 . 
     Process  1000  begins in step  1002  where the part to be heated is placed onto the support surface  250  in the chamber  102 . The support surface  250  is then positioned so that the part is located in a predetermined location with respect to the coil  212  (step  1004 ), and the chamber is sealed (step  1006 ). Next, the vacuum system  206  is activated (step  1008 ). Activation of the vacuum system  206  causes gas molecules within the chamber  102  to be removed therefrom, thereby lowering the pressure within the chamber  102 . 
     Next, the pressure within the chamber is determined (step  1010 ) by measuring the output of pressure sensor  269 . The pressure determined in step  1010  is compared to a predetermined pressure value (step  1012 ). In one embodiment the predetermined pressure value is about 5×10 −5  torr. If the pressure determined in step  1010  is less than or equal to the predetermined pressure value, control proceeds to step  1014 , otherwise control returns to step  1010 . In step  1014 , the induction heating unit  204  is used to heat the part to X degrees as measured by infrared pyrometer  120 . X can range between 400 and 1000 degrees. However, X should not be so high that it is high enough to melt the filler metal. X need only be high enough to evaporate the binder that is in the braze paste and/or out-gas the part being heated. Preferably, X is about 700 degrees Fahrenheit. 
     Next, the pressure in the chamber  102  is determined (step  1016 ). The pressure determined in step  1016  is compared to a second predetermined pressure value ( 1018 ). In one embodiment the second predetermined pressure value is about 1×10 −6  torr. If the pressure determined in step  1016  is less than or equal to the second predetermined pressure value, control proceeds to step  1020 , otherwise control returns to step  1016 . In step  1020 , the induction heating unit  204  is used to heat the part to Z degrees, wherein Z is greater than X. Preferably, Z is a high enough temperature to melt the filler without melting the parts being brazed (e.g., Z is between 1000 and 3000 degrees Fahrenheit). In one embodiment, Z is about 2100 degrees Fahrenheit. 
     The next step is to simply wait for a predetermined amount of time (step  1022 ). In one embodiment, the predetermined amount of time is 300 seconds. After the predetermined amount of time has elapsed, the induction heating unit  204  is directed to cease heating the part (step  1024 ) and a “quenching” gas is introduced into the chamber  102  to cool the part ( 1026 ). Next, the vacuum system  206  is de-activated (step  1028 ) and the part is removed from the chamber  102  (step  1030 ). 
     FIGS. 11A and 11B illustrate a process  1100  for brazing a part in an inert atmosphere. One skilled in the art of computer programming can program controller  202  to perform one or more of the steps of process  1100 . 
     Process  1100  begins in step  1102  where the part to be heated is placed onto the support surface  250  in the chamber  102 . The support surface  250  is then positioned so that the part is located in a predetermined location with respect to the coil  212  (step  1104 ), and the chamber is sealed (step  1106 ). Next, the vacuum system  206  is activated (step  1108 ). Activation of the vacuum system  206  causes gas molecules within the chamber  102  to be removed therefrom, thereby lowering the pressure with the chamber  102 . 
     Next, the pressure within the chamber is determined (step  1110 ). The pressure determined in step  1110  is compared to a predetermined pressure value (step  1112 ). In one application, the predetermined pressure value is about 1×10 6  torr. If the pressure determined in step  1110  is less than or equal to the predetermined pressure value, control proceeds to step  1114 , otherwise control returns to step  1110 . In step  1114 , a “low” flow of inert gas is introduced into the chamber  102  to produce partial pressure (e.g., 10 torr in one embodiment). Preferably, the inert gas flows directly across the part. After the pressure in the chamber  102  reaches the predetermined partial pressure as a result of introducing the inert gas into the chamber, control proceeds to step  1116 . 
     Referring now to step  1116 , the induction heating unit  204  is used to heat the part to X degrees as measured by pyrometer  120 . X usually ranges between 800 and 3000 degrees Fahrenheit, depending on the application. Preferably, X is a high enough temperature to melt the filler without melting the parts being brazed. The next step is to hold the temperature at X degrees for a predetermined amount of time (step  1118 ). After the predetermined amount of time has elapsed, the induction heating unit  204  is directed to cease heating the part (step  1120 ), and the amount of inert gas flowing across the part per a given amount of time is increased so as to “quench” (i.e., cool) the part (step  1122 ). Lastly, the part is removed from the chamber  102  (step  1124 ). 
     While various embodiments/variations of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.