Patent Publication Number: US-10774439-B2

Title: Methods of monitoring a plating bath

Description:
FIELD 
     The field of the present disclosure relates generally to hydrogen embrittlement, and more specifically, to methods of monitoring a health status of a plating bath. 
     BACKGROUND 
     Hydrogen embrittlement refers to a process that causes a metal or metal alloy, such as steel, to become brittle and susceptible to fracture when exposed to a quantity of hydrogen and subjected to a load. Hydrogen embrittlement generally occurs when hydrogen atoms diffuse through the crystalline structure (i.e., matrix) of a metal resulting in an increased pressure within the metal matrix. The increased pressure can adversely affect characteristics of metal, such as ductility and tensile strength. At least some known sources of hydrogen atoms are electroplating solutions, pickling solutions, phosphating solutions, paint-stripping solutions, cleaning solutions, and the like. 
     In at least some known electroplating processes, a metal substrate cathode and a plating material anode are submerged in a plating bath containing plating solution. Electric current is applied to the anode and cathode to deposit a layer of plating material on the surface of the metal substrate via the plating solution. After a desired amount of plating material has been deposited on the metal substrate, the substrate may then be heated to facilitate removing hydrogen trapped in the steel substrate beneath the plating material. Metal substrates also generally have organic surface contaminants, which if not properly cleaned prior to plating, may contaminate the plating solution. As such, prolonged use of the plating solution may affect the quality of the plated sample due to the contaminants. For example, an increased contaminant concentration in the plating solution may decrease the porosity of the plating layer, thereby limiting the amount of hydrogen removed from plated metals during the post-deposition heating process. 
     One known method of determining the porosity level of a plating solution involves periodically performing sustained load testing on select samples plated in different batches of the plating solution. Performance of sustained load testing requires the use of specialized test frames that are limited in number worldwide such that samples are typically plated and then shipped to a testing facility remote from the plating site. Sustained load testing also takes several days to complete. As such, there is significant delay between completion of a plating process and completion of a load test for a particular sample. The delay makes it difficult to detect contamination of the plating solution in a timely manner. 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     BRIEF DESCRIPTION 
     In one aspect, a method of monitoring a plating bath is provided. The method includes receiving a plurality of plated test specimens that are each plated in different batches within the plating bath, wherein the different batches are processed in a batch sequence, and wherein at least one plated test specimen is plated in each batch processed in the plating bath. The method also includes performing, at the same facility as the plating bath, a load test on each plated test specimen, wherein the load tests are initiated in a load test sequence that corresponds to the batch sequence, and determining a health status of the plating bath based on results of the load tests. 
     In another aspect, a method of monitoring a plating bath is provided. The method includes (a) plating a plated test specimen in a batch within the plating bath, (b) plating a plated production part in the batch within the plating bath with the plated test specimen, (c) performing, at the same facility as the plating bath, a load test on the plated test specimen with a test fixture, wherein the plating bath and the test fixture are at the same location, and (d) determining a health status of the plating bath based on a result of the load test. 
     In yet another aspect, a method of monitoring a plating bath is provided. The method includes receiving a plurality of plated test specimens that are each plated in different batches within the plating bath, wherein the different batches are processed in a batch sequence, and wherein at least one plated test specimen is plated in each batch processed in the plating bath. The method also includes performing, at the same facility as the plating bath, a load test on each plated test specimen as received in the batch sequence, wherein a load test duration is greater than a plating batch duration, and wherein the load test is performed on each plated test specimen with a different test fixture, such that a plurality of load tests are performed simultaneously. The method further includes determining a health status of the plating bath based on results of the plurality of load tests. 
     Various refinements exist of the features noted in relation to the above-mentioned aspects of the present disclosure. Further features may also be incorporated in the above-mentioned aspects of the present disclosure as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to any of the illustrated embodiments of the present disclosure may be incorporated into any of the above-described aspects of the present disclosure, alone or in any combination. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of an example plating and testing system. 
         FIG. 2  is a timeline of an example production and testing schedule for a plated test specimen. 
         FIG. 3  is a timeline of an example testing schedule that may be used by the plating and testing system shown in  FIG. 1 . 
         FIG. 4  is a flow diagram illustrating an example method of monitoring a plating bath. 
         FIG. 5  is a flow diagram illustrating an alternative method of monitoring a plating bath. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the drawings. 
     DETAILED DESCRIPTION 
     The implementations described herein relate to methods of monitoring a health status of a plating bath. The methods described herein include plating a test specimen along with a production part in every batch processed in the plating bath. A load test is performed on the plated test specimen plated in each batch, and the load tests are initiated in a sequence that corresponds to an order in which the test specimens are plated in the plating bath. As such, the results of the load tests are received in the sequence, which enables the health status of the plating bath to be tracked and subsequently correlated to a health status of production parts plated in associated batches. For example, if a plated test specimen plated in a predetermined batch fails its load test, processing in the plating bath is stopped, and production parts plated in the predetermined batch and in batches processed thereafter are quarantined as having been potentially plated in a contaminated plating bath. In addition, the load tests are initiated as soon as possible after a test specimen has been plated, and the load test fixtures are located at the plating bath facility such that load tests are performed at the same facility as the plating bath, to facilitate reducing an amount of delay between plating completion and load test initiation of a particular plated test specimen. As such, in facilities in which multiple batches are processed in the plating bath in an intervening period between initiation and completion of a load test that produces a failed result, the reduction in delay facilitates providing timely detection of a contaminated plating bath, thereby reducing the production of potentially defective parts in the bath. 
     As used herein, an element or step recited in the singular and preceded with the word “a” or “an” should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited. Furthermore, references to “exemplary implementation” or “one implementation” of the present disclosure are not intended to be interpreted as excluding the existence of additional implementations that also incorporate the recited features. 
       FIG. 1  is a block diagram of an example plating and testing system  100 . In the example implementation, plating and testing system  100  includes a plating bath  102  configured to process plated test specimens  104  and plated production parts  106  therein in one or more batches. Plating bath  102  includes plating solution  108 , and an anode  110  and a cathode  112  submerged within plating solution  108 . Plated test specimens  104  include a substrate  114  and a coating  116  formed on substrate  114 , and plated production parts  106  include a substrate  118  and a coating  120  formed on substrate  118 . Coatings  116  and  120  are formed from the material of anode  110 , which is deposited on substrates  114  and  118  during an electroplating process, for example. 
     Plating bath  102  is sized for plating at least one plated test specimen  104  and at least one plated production part  106  in each batch processed therein. That is, one or more plated production parts  106  are plated per batch, and at least one plated test specimen  104  is plated with the one or more plated production parts  106  in each batch. As such, plating at least one plated test specimen  104  in each batch processed in plating bath  102  facilitates monitoring the health status of plating bath  102  on a continuous basis. 
     Plating and testing system  100  also includes a plurality of test fixtures  122  for performing load tests on plated test specimens  104 . For example, the test fixtures  122  may perform a load test by applying a bending load or a tensile load on plated test specimens  104  in accordance with the ASTM International F519-Standard Test Method for Mechanical Hydrogen Embrittlement Evaluation of Plating/Coating Processes and Service Environments methodology. As such, in the example implementation, plated test specimens  104  are notched test specimens, where plated test specimens  104  are threadably, or non-threadably, engaged with test fixtures  122 , and test fixtures  122  are self-loading test fixtures, all in accordance with ASTM F519. 
     In an aspect of the present disclosure, the load test of plated test specimens  104  may require a duration of time of 200 hours up to 10 days, for example. The exemplary load test fixture  122 , which threadably, or non-threadably, engages a notched plated test specimen  104  for applying a load on the plated test specimen in accordance with ASTM International F519, is significantly smaller than large industrial load test equipment used at specialized testing laboratories. Accordingly, the load test fixture  122 , which tests at least one plated test specimen that was plated along with production parts in a predetermined batch processed in the plating bath, may be co-located with the plurality of plated production parts from the predetermined batch at the location of the facility of the plating bath where the batch was plated. Accordingly, if the plated test specimen plated in the predetermined batch fails its load test, the production parts plated in the predetermined batch that are co-located with the load test fixture  122  are readily quarantined, and identified as having been potentially plated in a contaminated plating bath. 
     In another aspect of the present disclosure, the exemplary load test fixture  122 , which threadably, or non-threadably, engages a notched plated test specimen  104  for applying a load on the plated test specimen in accordance with ASTM International F519, may be assigned an inventory location identification (ID) associated with the inventory location for the production parts in a predetermined batch that was plated in the plating bath. At the location of the facility of the plating bath, the load test fixture  122  performs the load test of at least one plated test specimen that was plated along with production parts in the predetermined batch, and is assigned an inventory location ID associated with the inventory location for the production parts plated in the predetermined batch from which the plated test specimen came. The inventory of production parts plated in the predetermined batch are withheld from use in production until completion of the load test of the plated test specimen associated with the predetermined batch. Accordingly, if the plated test specimen of a predetermined batch fails the load test on the load test fixture  122  assigned the inventory location ID associated with the inventory location for the predetermined batch of production parts, the inventory location ID readily identifies the inventory location at which to quarantine the production parts plated in the predetermined batch that have been potentially plated in a contaminated plating bath. The inventory location may be at a production facility that is remote from the plating bath facility, where the predetermined batch of production parts in the inventory location at the production facility may be withheld from use in production until completion of the load test of the plated test specimen associated with the predetermined batch. Alternatively, the inventory location may be located at the plating bath facility such that the predetermined batch of production parts are quarantined at the plating bath facility. 
       FIG. 2  is a timeline of an example production and testing schedule  124  for a plated test specimen  104  (shown in  FIG. 1 ). In the example implementation, production and testing schedule  124  includes a plating cycle  126  defined by a first duration, a heating cycle  128  defined by a second duration, a cooling cycle  130  defined by a third duration, and a testing cycle  132  defined by a fourth duration. In plating cycle  126 , plated test specimen  104  is plated in plating bath  102  to form coating  116  on substrate  114  (both shown in  FIG. 1 ). Plated test specimen  104  is then heated to facilitate hydrogen removal from substrate  114 , and cooled to enable testing cycle  132  to be initiated and a load test to be performed. Heating cycle  128  includes heating plated test specimen  104  at a first predetermined temperature. Cooling cycle  130  includes cooling plated test specimen  104  to a second predetermined temperature less than the first predetermined temperature. Plated test specimen  104  may be cooled with or without an active cooling system. Results of the load test are obtained after the fourth duration has elapsed. In one implementation, the fourth duration is up to about 200 hours, as illustrated in  FIG. 3 . 
       FIG. 3  is a timeline of an example testing schedule  134  that may be used by plating and testing system  100  (shown in  FIG. 1 ). In the example implementation, a series of load tests are performed on plated test specimens  104  (shown in  FIG. 1 ). The plated test specimens  104  are each plated in different batches within plating bath  102  (shown in  FIG. 1 ), wherein the different batches are processed in a batch sequence. Likewise, the load tests are performed in a load test sequence that corresponds to the batch sequence. 
     For example, in one implementation, the batch sequence is defined by processing a first batch, a second batch, and a third batch in plating bath  102  sequentially. As such, the load test sequence corresponds to the batch sequence in that the load test sequence is defined by initiating a first load test, a second load test, and a third load test using test fixtures  122  (shown in  FIG. 1 ) sequentially. The first load test is performed on plated test specimen  104  plated in the first batch, the second load test is performed on plated test specimen  104  plated in the second batch, and the third load test is performed on plated test specimen  104  plated in the third batch. The first, second, and third load tests are each performed for a predetermined duration, such as the fourth duration noted above. As such, results of the loads tests are received in a sequence corresponding to the load test sequence, which facilitates tracking the production of potentially defective plated production parts  106  (shown in  FIG. 1 ) in plating bath  102 . 
     For example, if it is determined that plated test specimen  104  plated in the first batch has failed its load test, the results of the load test are used to determine the health status of plating bath  102  at times corresponding to when certain batches are processed therein. The health status of plating bath  102  is determined to be normal if plated test specimen  104  passes the load test, and is determined to be abnormal if plated test specimen  104  fails the load test. If plated test specimen  104  plated in the first batch fails its load test, the failed test results may be correlated to the health status of plating bath  102  at a time corresponding to the first batch, and at a time corresponding to batches processed after the first batch. The health status of plating bath  102  may then be correlated to a health status of plated production parts  106  plated in plating bath  102 . 
     For example, upon receiving the results of the failed load test of plated test specimen  104  plated in the first batch, plating in plating bath  102  is stopped and all plated production parts  106  plated in the first batch and in batches processed thereafter are quarantined. An investigation may then be performed to validate the results of the failed load test. In one implementation, a first plated test specimen and a second plated test specimen are plated in each batch, and load test results for the second plated test specimen are evaluated if the first plated test specimen fails its load test. Alternatively, if plated test specimen  104  plated in the first batch fails its load test, the load test result of plated test specimen  104  plated in the second batch is evaluated to validate the results of the failed load test. 
     The health status of plated production parts  106  may either be normal or abnormal. If the results of the failed load test are validated, the health status of plated production parts  106  plated in the first batch and in batches processed thereafter is determined to be abnormal. As such, it is determined that the plated production parts  106  may be defective and/or unusable for their intended purpose. 
     In some implementations, plating bath  102  is used continuously or semi-continuously such that more than one batch is processed in plating bath  102  per day. Accordingly, more than one load test may be initiated per day to facilitate continuous or semi-continuous monitoring of plating bath  102 . For example, as illustrated in  FIG. 3 , the second load test is initiated after the first load test is initiated, but before the first load test is complete. In addition, the load tests for plated test specimens  104  are initiated as soon as possible after plating is completed to facilitate reducing delay between plating completion and load test completion. For example, in one implementation, the load test of a particular plated test specimen  104  is initiated immediately after cooling cycle  130  (shown in  FIG. 2 ) is complete and plated test specimen  104  is at the second predetermined temperature. That is, the first load test is initiated at a first interval after processing of the first batch is initiated. The first interval is approximately equal to a sum of the first duration, the second duration, and the third duration. In addition, the second load test is initiated at a second interval after the first load test is initiated. The second interval is approximately equal to the first duration. As such, delay in receiving the load test results is reduced. 
     The delay is further reduced by performing the load tests with test fixtures  122  positioned at the same location as plating bath  102 . As such, the load tests may be performed without having to ship plated test specimens  104  offsite, thereby eliminating shipping delay and reducing the delay between plating completion and load test completion. 
       FIG. 4  is a flow diagram illustrating an example method  200  of monitoring a plating bath. Method  200  includes receiving  202  a plurality of plated test specimens that are each plated in different batches within the plating bath. The different batches are processed in a batch sequence, and at least one plated test specimen is plated in each batch processed in the plating bath. Method  200  also includes performing  204 , at the same facility as the plating bath, a load test on each plated test specimen. The load tests are initiated in a load test sequence that corresponds to the batch sequence. In addition, in one implementation, a load test duration is greater than a plating batch duration, and the load test is performed on each plated test specimen with a different test fixture, such that a plurality of load tests are performed simultaneously. Method  200  further includes determining  206  a health status of the plating bath based on results of the load tests. 
       FIG. 5  is a flow diagram illustrating an alternative method  208  of monitoring a plating bath. Method  208  includes (a) plating  210  a plated test specimen in a batch within the plating bath; (b) plating  212  a plated production part in the batch within the plating bath with the plated test specimen; (c) performing  214  a load test on the plated test specimen with a test fixture, wherein the plating bath and the test fixture are at the same location; and (d) determining  216  a health status of the plating bath based on a result of the load test. Steps (c) and (d) are repeated  218  for a plurality of plated test specimens and a plurality of plated production parts plated in each batch of the plating bath. 
     This written description uses examples to disclose various implementations, including the best mode, and also to enable any person skilled in the art to practice the various implementations, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.