Indirect process condition monitoring

Abstract

Disclosed is a method of controlling the production of a bulk-solidifying amorphous alloy by providing a set point control system, run in conjunction with a continuous smart feedback process control system that continuously monitors the processing conditions during manufacture, and continuously updates the smart feedback control system thereby enabling the control system to learn as the process is running.

What is claimed is: 
     
         1 . A method of controlling the manufacture of a bulk-solidifying amorphous alloy comprising:
 modifying one or more process conditions selected from the group consisting of vacuum level, viscosity of melt, temperature of melt, temperature of core, cooling rate, mold dwell time, and plunger rate, and determining the physical characteristics of the bulk-solidifying amorphous alloy, wherein the physical characteristics are selected from one or more of the group consisting of degree of crystallinity, hardness, elongation, and yield strength;   establishing set points for at least two process conditions selected from the group consisting of vacuum level, viscosity of melt, temperature of melt, temperature of core, cooling rate, mold dwell time, and plunger rate;   establishing criteria for determining when a product is considered a failure based on one or more of the physical characteristics, and performing a multi-variable statistical analysis to determine which process condition, or combination of process conditions indicate a product failure;   controlling the method of manufacturing a bulk-solidifying amorphous alloy by rejecting a part that was fabricated when at least one process condition is outside the set point, and at the same time continuously monitoring the at least two process conditions, and if the process conditions indicate a product failure even though within the set points, tagging the product or products made using those process conditions, measuring the physical characteristics of at least one of the products, and updating the process conditions that indicate a product failure depending on the results of measuring the physical characteristics of the tagged product or products.   
     
     
         2 . The method of  claim 1 , wherein set points are established for at least three process conditions selected from the group consisting of vacuum level, viscosity of melt, temperature of melt, temperature of core, cooling rate, mold dwell time, and plunger rate. 
     
     
         3 . The method of  claim 1 , wherein set points are established for at least four process conditions selected from the group consisting of vacuum level, viscosity of melt, temperature of melt, temperature of core, cooling rate, mold dwell time, and plunger rate. 
     
     
         4 . The method of  claim 1 , wherein the vacuum is within the range of from about 1.0×10 −4  to about 0.02 psi, 
     
     
         5 . The method of  claim 1 , wherein the plunger rate is within the range of from about 5 in/sec. to about 500 in/sec. 
     
     
         6 . The method of  claim 1 , wherein the viscosity of the melt is within the range of from about 0.1 poise to about 10,000 poise. 
     
     
         7 . The method of  claim 1 , wherein the temperature of melt is within the range of from about 650 to about 1300° C. 
     
     
         8 . The method of  claim 1 , wherein the cooling rate is within the range of from about 1 C/s to about 1,000 C/s. 
     
     
         9 . The method as claimed in  claim 1 , wherein the bulk-solidifying amorphous alloy is described by the following molecular formula: (Zr, Ti) a (Ni, Cu, Fe) b (Be, Al, Si, B) c , wherein “a” is in the range of from 30 to 75, “b” is in the range of from 5 to 60, and “c” is in the range of from 0 to 50 in atomic percentages. 
     
     
         10 . The method as claimed in  claim 1 , wherein the bulk-solidifying amorphous alloy is described by the following molecular formula: (Zr, Ti) a (Ni, Cu) b (Be) c , wherein “a” is in the range of from 40 to 75, “b” is in the range of from 5 to 50, and “c” is in the range of from 5 to 50 in atomic percentages. 
     
     
         11 . The method of  claim 1 , wherein the method is controlled to produce a bulk-solidifying amorphous alloy having an amorphicity greater than 95%. 
     
     
         12 . The method of  claim 1 , wherein the method is controlled to produce a bulk-solidifying amorphous alloy having a yield strength within the range of from about 150 ksi to about 750 ksi, 
     
     
         13 . The method as claimed in  claim 1 , wherein the method is controlled to produce a bulk solidifying amorphous alloy that can sustain strains up to 1.5% or more without any permanent deformation or breakage. 
     
     
         14 . The method of  claim 1 , wherein the method is controlled to produce a bulk-solidifying amorphous alloy having a Vickers hardness within the range of from about 300 HV-1000 g to about 1,500 HV-1000 g. 
     
     
         15 . The method as claimed in  claim 1 , wherein updating comprises removing the criteria that indicate a product failure if measuring the physical characteristics of the product results in an acceptable product at least three consecutive times for the same criteria. 
     
     
         16 . The method of  claim 1 , further comprising periodically measuring the physical characteristics of products indicated as acceptable by the control system due to their process conditions, and if the physical characteristics reveal the product as unacceptable, then updating the process conditions that indicate a product failure to include those process conditions that produced the failed product. 
     
     
         17 . The method of  claim 1 , wherein updating comprises rejecting products made by the criteria that indicate a product failure if measuring the physical characteristics of the product results in a failed product at least three consecutive times for the same criteria.