Real-time manufacturing process control monitoring method

A method of identifying unacceptable levels of defects in specific sections or work centers of a manufacturing process on a real time basis and initiating corrective action is disclosed. The system allows a user to define defect tolerances or thresholds for manufacturing work centers, tracks defects at the work centers, compares the level of faults with the tolerances, reports out of tolerance work centers, automatically initiates contact with the appropriate personnel to affect a correction to the out of tolerance work center, and maintains records of corrective actions taken.

FIELD OF THE INVENTION 
The invention relates to systems for monitoring manufacturing processes 
and, more particularly, to such systems which monitor manufacturing 
defects. 
BACKGROUND OF THE INVENTION 
There are many known systems for monitoring manufacturing processes. Such 
systems are typically computerized and vary in their level of integration 
into the manufacturing process. Some systems provide the capability to 
monitor the number of parts produced and defects or faults which are then 
reported by part. This information has proven useful in evaluating and 
improving or controlling manufacturing processes. 
However, known systems do not offer an automated way to identify 
unacceptable levels of defects in specific sections or stations of the 
manufacturing process on a real time basis and to initiate corrective 
action. For example, in currently known systems, if a particular 
manufacturing machine is out of tolerance and generates an extremely high 
rate of defective parts, current manufacturing tracking systems merely 
record the number of defective parts and may have software that can be 
utilized to generate statistical reports. However, the systems do not 
automatically indicate that there is a problem at a particular station nor 
do the systems automatically alert the proper personnel to address the out 
of tolerance machine, suggest corrections, or record corrective actions 
taken. 
For example, a manufacturing machine such as a "pick and place" which is 
used to install integrated circuit "chips" on circuit boards may be in 
need of adjustment. Certain misadjustments can cause the machine to 
repeatedly misalign the chips with the board resulting in defective parts. 
Currently defect tracking systems log and store defect data but do not 
provide the operators of the machines with information about acceptable or 
unacceptable defect rates for that step in the manufacturing process. 
Rather than alerting an operator to the fact that an excessive number of 
defects are occurring, current systems merely store the data which is then 
later analyzed and acted upon. This can result in entire product runs 
having excessively high defect rates. 
SUMMARY OF THE INVENTION 
The invention is directed to a system and method capable of identifying 
unacceptable levels of defects in specific sections or work centers of a 
manufacturing process on a real time basis and initiating corrective 
action. In one aspect of the invention, the system allows a user to define 
defect tolerances or thresholds for manufacturing work centers. The system 
then tracks defects at the work centers, compares the level of faults with 
the tolerances, reports out of tolerance work centers, automatically 
initiates contact with the appropriate personnel to affect a correction to 
the out of tolerance work center, and maintains records of corrective 
actions taken. 
A fuller understanding of the features and benefits of the present 
invention will become more fully apparent from the following description 
taken in conjunction with the accompanying drawings, in which like 
numerals refer to like parts.

DETAILED DESCRIPTION OF THE INVENTION 
The invention is directed to a system and method which in different aspects 
of various embodiments allows a user to define defect tolerances for 
manufacturing work centers, tracks defects at the work centers, compares 
the level of faults with the tolerances, reports out of tolerance work 
centers, automatically initiates contact with the appropriate personnel to 
affect a correction to the out of tolerance work center, and maintains 
records of any corrective actions taken. The system and method can be 
implemented in software in a distributed network system such as is 
depicted in FIG. 1. The software can be stored on any appropriate program 
storage device, including, for example, floppy disks, compact laser discs, 
and random access memory. 
Referring to FIG. 1, a block diagram of a manufacturing computer system in 
which the invention can be utilized is shown. Such a system may 
incorporate numerous work centers 102 which represent manufacturing 
stations and/or test stations and/or quality assurance stations. 
Typically, the work centers 102 include a computer, such as a personal 
computer ("PC") which is linked to a network through a network connection 
103. 
The server 104 for the network to which the work centers 102 are connected 
can be any of the numerous types of network servers known to those of 
ordinary skill in the art. The particular network server employed is 
chosen depending upon the performance requirements of the specific system 
using criteria such as the number of work centers on the network, and the 
amount of data to be distributed and stored. The server 104 also stores a 
database which will be described further with regard to FIG. 2. The server 
104 can also provide access to other networks such as those typically 
utilized by accounting and/or marketing departments which may exchange 
data with the manufacturing network. It is also possible that a single 
network can serve all of the departments of a small manufacturing 
facility. 
An engineering work station 110 is also connected by a network connection 
103 to the network served by server 104. More than one engineering work 
station may be employed depending on the requirements of the users. 
Engineering work stations may be used to analyze the manufacturing process 
and for other purposes as will be described below in further detail. The 
engineering work station includes a PC or mini-computer such as a SC 
work station. Both the computers at the work center 102 and the 
engineering work station 110 may run a windows-based operating system 
allowing for easy user interface. However, other user interface systems, 
including custom systems can be employed. 
Referring now to FIG. 2, a high level block diagram of the components of a 
manufacturing process tracking system according to the principles of the 
present invention is shown. The components can be implemented as software 
or firmware applications operating in cooperation with hardware components 
as is known to those of ordinary skill. The components depicted in FIG. 2 
may operate on the computer system depicted in FIG. 1. The Alert 
application 202 provides an interface, such as a graphical user interface 
which can be displayed at the engineering work center 110 (FIG. 1). The 
Alert application 202 allows process engineers to set manufacturing defect 
thresholds, to provide the names of the technicians that will be paged 
when the thresholds for specific work stations are exceeded and to 
identify to whom e-mails will be sent containing indications that 
thresholds have been exceeded and what corrective actions were taken. That 
information may be stored in a system database 204 which may be maintained 
in the server 104 of FIG. 1. 
A system parameter setup application 206 may also be provided. Generally 
speaking, a system parameter setup application provides an interface for 
the process engineer to input the parameters for the tracking system such 
as the types of possible defects (e.g., low solder volume, misplaced 
components), the identification of the various work centers 102 in FIG. 1, 
and other systems setup information. That information may also be 
maintained in the database 204. Such applications are usually provided as 
part of manufacturing defect tracking systems known to those of ordinary 
skill in the art. Therefore, the details of this application will not be 
provided herein as they are commercially available and known to those of 
skill in the art. 
The Track application 208 provides a user interface and receives input from 
the production operators at the work centers 102 (FIG. 1) relating to 
defects. The track application 208 transfers defect information to the 
database 204 where it is maintained. In addition, the track application 
determines when defect thresholds have been exceeded and takes appropriate 
actions in response thereto including initiating the paging of technicians 
and the sending of e-mails to the appropriate individuals as was defined 
by the Alert application 202. The e-mail and paging functions are carried 
out, in one embodiment, utilizing the Exchange software 210 from Microsoft 
Corporation. 
Turning now to FIG. 3, a more detailed description of the track application 
208 of the system will be provided. In FIG. 3, track application 208 is 
shown to include six software modules. Each of the modules will be 
described in turn. Of course, the functions of the modules of the Track 
application 208 can be divided into a different number of modules or 
combined into a single module. 
The work order entry module 302 provides a user interface to the operator 
at a work station 102 of FIG. 1 and prompts the operator to enter data 
relating to a work order. An example of a user interface which can be 
displayed on the screen of a monitor at the work center 102 is shown in 
FIG. 4. That graphical user interface, in one embodiment, prompts the 
operator to enter work order information. Such information received by the 
order entry module may be, for example, part type, customer codes work 
order ID, quantity, the employee's number and shift, the work center and 
the operation that is being performed at the work station. Alternatively, 
the foregoing information could be automatically generated or retrieved 
from an automated manufacturing station. The information work order 
information is then stored in database 204. After entering the 
information, control can be transferred to the defect entry module 304. 
The defect entry module 304 provides a graphical user interface to prompt 
the operator to enter data relating to a specific part and defect within a 
work order. In other words, the work order entry module 302 is used to 
receive information relating to an entire work order while the defect 
entry module 304 receives data for individual parts within a work order. 
An example of a graphical user interface which can be displayed on the 
screen of the monitor at the work center 102 (FIG. 1) is shown in FIG. 5. 
The graphical user interface shown in FIG. 5 is generated by the defect 
entry module 304 to prompt the user to enter defect related information 
for a specific part. For example, the user may be prompted to enter the 
serial number of the part, a code or description of the defect and the 
disposition of the part with the defect. In addition, the graphical user 
interface can display totals or counts for selected defects or reject 
codes for the current order being processed. The threshold or maximum 
number of defects permitted can also be shown. In addition, this graphical 
user interface can also display the defect count by defect location. This 
would be applicable where a specific location on the part may have more 
than one defect that could be associated with it but the threshold of 
permissible defects per order can be set in terms of defects per location 
and not just total defects by type of defect. 
Shown in the upper right quadrant of the graphical user interface shown in 
FIG. 5 is a bar chart representing the total defects for the work order. 
Defect limits can be set by defect or fault code, total defects, and 
defects by location. The process that is initiated when any of the 
thresholds is exceeded is describable with reference to FIG. 7. The test 
entry module 306 provides a graphical user interface for entering and for 
transmitting that data to the database 204. 
An example of a graphical user interface which can be displayed on the 
screen on a monitor at a work center 102 (FIG. 1) is shown in FIG. 6. As 
shown in FIG. 6, the graphical user interface displayed by the test entry 
module 306 prompts the operator to enter an employee number, a shift 
number, the test operation and part number. The operator can then enter 
the quantity from the present lot that failed the identified test. Each 
part that failed the test is identified by serial number. This information 
is then transmitted by the test entry module to the database. The 
information stored in the database is used by the defect entry module 304, 
discussed above, to determine defect counts, defect location counts, and 
total defect counts. 
The process control module 308 maintains defect counts, determines whether 
defect count thresholds have been exceeded and initiates the notification 
procedures when the defect thresholds have been exceeded. As indicated in 
FIG. 3, the process control module communicates with the defect entry 
module 304 and database 204. A more detailed description of the process 
control module can now be provided with reference to FIG. 7. 
FIG. 7 is a flow chart which represents the functions carried out by the 
process control module 308. At step 702 data received by the defect entry 
module as input from an operator in response to the graphical user 
interface depicted in FIG. 5, is utilized by the process control module to 
increment the defect arrays or counts with new values. The defect 
information from the defect entry module may be stored in database 204 and 
accessed by the process control module 308 or, alternatively, it can be 
transferred from the defect entry module 304 to the process control module 
308. The defect arrays correspond to the various defect counts maintained 
in database 204 and displayed on the graphical user interface depicted in 
FIG. 5. The defect arrays can include counts by defect code, defect 
location, and total defects by part type. 
Next, at Step 704 the process control module determines whether the serial 
number for the board or part is a duplicate. Typically, a serial number 
would be a duplicate in a situation where a second or additional defect 
has been entered in a system for the same part. If the serial number is 
not a duplicate, the window size of the graphical user interface depicted 
in FIG. 5 is increased so that the additional part number can be displayed 
as indicated in Step 706. At Step 708, the process control module 
determines whether the window size of the portion of the window displaying 
the serial numbers of the defective parts at the work station exceeds the 
maximum size permissible for the window. If the maximum size is exceeded, 
the oldest serial number is removed from the defect arrays for that work 
center, as indicated as Step 710. In this manner, the definition of the 
window size can be used to define the size of the set upon which the 
defect thresholds are based. In other words, if the window size, for 
example, is set to a maximum of listing 20 parts, then the defect 
thresholds would be set based upon a group of 20. 
Next, at Step 712, the process control module increments the defect group 
arrays. These arrays are the current count of defects (for example, by 
part number, by location, by defect code) for the work center. Next, at 
Step 714, the process control module determines the applicable thresholds 
for the defect arrays. The thresholds may be stored and retrieved from 
database 204. Next, at Step 716, the defect group arrays may be sorted to 
display the arrays in order according to which is closer to its threshold. 
Then, at Step 718, the defect count or arrays are compared against the 
thresholds to determine if any of the thresholds have been exceeded. As 
indicated at Step 720, if none of the thresholds have been exceeded, the 
information for graphically displaying the status for each of the defect 
arrays is determined at Step 722. 
An example of a manner of displaying the defect counts is shown in FIG. 5. 
As an example, if the defect count is greater than 75% of the threshold 
value, the graphical representation can be in red in order to alert the 
operator that the defect threshold is close to being violated. If the 
defect count is between 50% and 75% of the threshold, the graphical 
representation can be presented in yellow. Finally, the graphical 
representation can be presented in green if the defect count is less than 
50% of the threshold value. 
Returning to Step 720 of FIG. 7, if a threshold has been exceeded, then at 
Step 724 the process control module initiates the actions to page the 
technician responsible for the particular work center. The pager 
information (e.g., pager number) for the technician responsible for the 
work center can be stored in the database 204. Next, in Step 726, the 
process control module displays a corrective action screen, in the form of 
a graphical user interface, to the operator at the work center Such a 
graphical user interface is depicted in FIG. 8. The corrective action 
screen can display the name of the technician being paged, the threshold 
that has been exceeded, and other relevant information. The corrective 
action screen can also request the operator to enter the root cause of the 
defect which exceeded the threshold and a description of the corrective 
action taken at the work center to address the problem. In addition, it is 
possible to display suggested corrective actions or a course of action to 
be followed by the operator to attempt to determine if there is a fault at 
the work center which is causing an excessive number of defects. 
At Step 728, the information entered in response to the corrective action 
screen is sent by e-mail to an engineer and/or other parties to review and 
analyze. The list of e-mail recipients can be stored in the database 204. 
Next, the process control module proceeds to Step 722 to display the 
defect parameters as described above. 
The foregoing process described with reference to FIG. 7 is carried out 
each time a defect is entered by the defect entry module 304. 
The Alert application 202 shown in FIG. 2, functions to establish the 
defect thresholds for work centers. The Alert application 202 also 
generates the e-mail lists and paging lists which are utilized when a 
threshold is exceeded. Referring to FIG. 9, a description of the operation 
of the Alert application will be provided. FIG. 9 is a functional flow 
chart representing the functions carried out by the Alert application 202. 
Generally speaking, the functions performed by the Alert application can 
be divided into two groups, functions relating to part types and functions 
relating to work centers. The functions relating to part types will be 
described first. 
The Alert application maintains a part list 902 in database 204 (see FIG. 
2). The Alert application includes the functionality of removing items 
from the part list as represented by box 904. That function can be 
accomplished by a graphical user interface allowing a user to 
interactively delete part types from the part type list. In addition, an 
add function 906 allows for the addition of new part types to the part 
type list. That function can also be carried out through a graphical user 
interface, allowing a user to interactively add part types. Part types can 
be added from an available parts type list or a completely new part type 
can be added. 
In a similar manner the Alert application can also provide the capability 
to add, delete or edit the pager list maintained in data base 204 as 
represented by box 901. 
Information associated with each part type in a part type list can be 
edited utilizing the edit function 908. Associated with each part type may 
be a list of work centers at which those parts are manufactured or tested 
and an e-mail list of individuals to be notified when defect thresholds 
are exceeded for that part type. Associated with each work center by part 
type is defect threshold information. Therefore, work centers can be 
removed from association with a part type as indicated by process 910, or 
can be added in association with a part type as represented by process 
912. In addition, e-mail addresses can be added or removed from 
association with a part type. 
When a work center is added to a part type, defect information can then be 
associated with the work center for that part type. As represented at box 
914, defect thresholds for a part type at a specific work center can be 
set for total defects, defect code or type, and defect by location. In 
addition, the defect code and defect by location thresholds can be set 
based upon defects per window (window defines a specific number of parts) 
or defects per board or defects per location on a board. Thresholds can be 
entered into the database by defect code ("detail") 916 and/or by location 
on the product 918. In addition, functionality is provided for adding, 
editing and removing each of these types of thresholds as represented by 
box 920. In addition, the functionality for setting up exception 
conditions 922 for each of the thresholds is provided. This would permit 
the thresholds to be ignored in selected circumstances. 
As indicated by the foregoing description, various embodiments of the 
invention provide a system and method which can automatically indicate 
that there is a problem at a particular work center, automatically alert 
the proper personnel to address the problem, suggest corrections, and/or 
record corrective actions taken. Such systems and methods can increase 
manufacturing efficiency, reduce down time and thereby reduce 
manufacturing costs. 
The invention may be embodied in other specific forms without departing 
from its spirit or essential characteristics. The described embodiments 
are to be considered in all respects only as illustrative and not 
restrictive and the scope of the invention is, therefore, indicated by the 
appended claims rather than by the foregoing description. All changes 
which come within the meaning and range of equivalency of the claims are 
to be embraced within their scope.