TECHNICAL ARTICLE
Originally Printed in the April 2005 Issue of SMT
Magazine
SOFTWARE CONTROL EXTENDS BEYOND THE LINE
Nearly every electronics factory has some form of
“manufacturing software.” Companies often use CAD/CAM new product
introduction (NPI) tools; and business systems may track work in
progress (WIP). Software systems provided by machine vendors for feeder
setup and verification also might exist. Third-party systems are used
often across dissimilar machines for line setup and control. When spread
throughout the factory, these individual software tools can be numerous
and rarely are integrated. Individually, each may perform its specific
function properly; however, when evaluating perspective is raised above
any single area or line to view the entire factory, these disparate
tools fail to deliver a true overall business solution.
For
information-visibility requirements to span the entire factory,
traceability must include every detail of the product and process
end-to-end. Factory-wide materials and line-setup management requires
that information systems be factory-level or enterprise-level, instead
of line-level in design and scope.
Market and regulatory imperatives are driving this perspective. In several industries, traceability is a requirement; and the very meaning of “traceability” is expanding rapidly in scope and depth. For example, when lead-free and tin/lead solder are processed simultaneously, they require management of different processes running alongside one another. All tooling, chemicals and components must be managed. Risk mitigation in this environment demands electronically assured line setups.
Cost pressures also mean operations must become more efficient. This introduces issues of factory-wide materials, cart, feeder and line-changeover management to increase utilization with less overhead. Quality expectations are driving implementation of real-time statistical process control (SPC) throughout the entire process, not just at a station or machine, as well as integrating data from test. Even the simple matter of accurate, real-time component depletion data from machines and operator stations requires a factory-wide information management and tracking solution. Ultimately, this control and data acquisition is critical for manufacturing visibility to support management decision-making processes and customer reports.
Fortunately, software-system technology has advanced so that this functionality, massive data analysis and management are possible. A convergence of several factors, ranging from the maturity of factory IT infrastructure, modern production equipment intelligence, data acquisition standards and software architectures that can handle such a load, has opened a new frontier of true factory automation, beyond line automation.
Defining Manufacturing Software
The concept of “manufacturing software” is filled with an array of terms
and acronyms for many individual solutions. These terms often are
improperly applied or steered by software vendors to suit their product.
The term “MES” is applied to everything from simple
feeder/line-management tools to enterprise quality and execution
systems. For this discussion, a generally accepted categorization put
forth by a major software research group will be used, with one notable
addition.
Below enterprise resource planning (ERP) and manufacturing resource planning (MRP), a software “gap” exists at the point where these business systems stop to the detailed execution of the process, and machines and operations involved in the process. In the physical world, this gap represents the full factory floor from the stockroom through integration, test and shipment. Business systems often reach into this area to acquire product movement information, but typically handle summarized, simple information about the product, process and materials on the factory floor. The gap typically is filled with collections of data from separate systems.
A generally accepted segmentation of this gap includes four elements:
Manufacturing Execution (MES) - product tracking and performance
monitoring.
Quality Management Systems (QMS) - acquires and analyzes symptoms
and defects.
Laboratory Information Management Systems (LIMS) - manages
test-and-measurement information related to quality data.
Supervisory Control and Data Acquisition (SCADA) - provides data
streams to support everything else, and execute physical controls when
necessary.
One critical area that this segmentation omits, especially in
electronics manufacturing environments, is the issue of materials
management. In most factories, when materials leave the stockroom, they
enter an informational abyss until their return. Other disconnected
systems, such as line-setup solutions, intercept these materials. They
are aware of them when in use; however, they send them back into the
information void to be seen again at some point in the business system’s
domain. Materials management on the factory floor is critical to fill
this gap in the electronics assembly factory because it impacts
operational efficiency severely. It has direct impact on line setups and
changeover efficiency, feeder and cart management, accurate depletion
data records and a large share of the factory’s labor overhead.
Factory-wide Software Control
True factory-wide software control and information visibility is
achieved when real-time machine data acquisition and line control,
materials management, test-and-measurement management and product and
quality tracking are achieved in a seamless solution. These solutions
are based on the premise that there is a synergy between systemic
control over the processes within a factory and the software systems
providing visibility to factory information. Traceability and monitoring
are important, but without electronically assured control over 100% of
factory processes, a manufacturer may be tracing how incorrectly a
product was built. Furthermore, the software and hardware elements
involved in control systems tend to produce greater scope and depth of
information visibility.
For example, a factory-wide feeder, cart and consumables-control system that includes on-line machine setup control and an end-to-end MES system yields tremendous traceability information when joined with real-time data streams from machines and line-based product scanners. Without materials control, or end-of-process MES records, more than half of the traceability data depth collapses. To illustrate the business impact of this scenario, consider a traceability tool involving SMT assembly machines. If the tool is unaware of activities at the repair stations and test, data has no assurance of accuracy if components were replaced later in the process with different lot codes. In a regulatory area where exactness is key, this is a serious liability. This is a small example of the synergistic relationships of software connections across a factory that are required to fill the informational gap. This is why a singular solution aware of all factory-wide functions is effective.
Factory-wide solutions such as these have two goals. First, they bring control to operations, materials, setup of lines and stations and the assembly process. Once materials and setup control is complete and the process begins executing, control moves to a real-time mode in which SPC applied to any data set emerging from the process can induce alarms and physically stop lines anywhere.
Routes are controlled at a granular station level. Test-and-repair loops
are automated fully. These processes generate great volumes of data from
tracking devices, machines and test-and-inspection sources. The analyzed
sum of this information results in visibility, which takes several
forms. One common form is a comprehensive traceability report (CTR) for
a unit, or its inverse, the ‘where used’ lookup for a lot across all
products. Others include real-time performance and quality diagnostics,
instantaneous job status and location views, or historical quality and
performance metric reports in unlimited forms. In a singular factory
solution, these outputs are derived from one database; and reporting and
analytics inherently exceed the capability of disparate solutions. These
outputs support management decisions and quality improvement direction,
while providing customers with the information they demand. The synergy
of control systems to visibility is powerful. If the link is broken, the
risk of viewing reports on a product that was manufactured improperly
exists.
Factory-wide Benefits
Few manufacturers willingly choose to embark on the selection of a
factory-wide data management system. The traditional strategy has been
to identify point solutions and delay integration, or spend a great deal
of time attempting it. The risk of selecting the wrong point solution
often is considered less than that of selecting one massive solution.
Therefore, the reason these systems currently are entering factories is
not necessarily through a desire of manufacturers to have these
solutions - it is an imperative brought on by the regulatory and market
environments. For manufacturers servicing markets such as military,
medical and automotive, it is a necessity. There are a few specific
capabilities that are difficult to achieve with separated systems, but
singular solutions can deliver them elegantly.
Regulatory - Traceability Historically, traceability would be a report of the reference designators mapped to a component-lot number for each component on a serialized product. Today, this is a minor element of what is considered a CTR. Some markets demand CTRs containing upper and lower assemblies; all test, inspection, measurement data with SPC metrics; defects down to pin; all operator records; WIP stations and timing; false positives; rework records and components replaced with old/new lots; every error from every machine it passed through; every tool/chemical/consumable at each station; and process parameters such as data from ovens and printers at the time the unit was within each process. A single, medium-sized PCB can produce a CTR of over 50 printed pages. Considering the different areas of the factory, user interfaces and machine connections required to obtain the data in a CTR, it is apparent that modern traceability cannot be achieved from line-level tools. On the contrary, it requires real-time, detailed data connections to every step of the process, as well as knowledge of all materials movement.
Regulatory - Lead-free Control In factories where lead and lead-free will run in parallel, electronically assuring proper use of consumables and components is critical. Comprehensive material management, not merely on line-level, assures this control.
Cost Driver - Risk Mitigation Through Materials and Setup Control
The CTR requires comprehensive knowledge of the tooling,
components, feeders and chemicals used on the floor, as well as where
and when they were used. This is the visibility side of the equation.
The control side involves risk mitigation. When carts and materials
reach the lines, the system eliminates risk by stopping lines
automatically until proper feeders, tooling and chemicals are setup at
each station. Guidance of operators, risk elimination in setups and
comprehensive cart-and-feeder management factory-wide all support CTR
data.
Cost Driver - Line Utilization and Operational Productivity. In larger
facilities, centralized and guided feeder loading to the lines as
required for upcoming changeovers can reduce operational overhead
dramatically and improve line utilization. A factory-wide system
provides visibility to feeders loaded on every cart and every machine,
ensuring that machines are not waiting for components.
Quality Driver - Real Continuous Improvement When data streams from all factory equipment are being automatically acquired by a single database that is maintaining a large amount of factory information, SPC rules can be applied to any measurement or attribute data emerging from the process. As an improvement over point-solutions at test/inspection stations, this allows emerging issues detected in one area of the process to cause line stops and alarms at a root point in the process. SPC can enable based upon rules for equipment errors, rather than upon fixed schedules.
Cost Driver - Inventory Management Real-time machine
data integration merged with materials and feeder control provides
automatic depletion of component quantities. This is useful when data is
flushed back to business systems.
Software Technology Framework
Considering the functions and capabilities of factory-wide solutions,
the data sources and data volume involved are staggering. From an IT
standpoint, it is a data-storage challenge and a transaction-rate issue.
From a commercial viability standpoint, it is an issue of generic and
broad plug-and-play compatibility with a wide range of machine sets on
the factory floor.
Standards, such as IPC CAMX for uniform XML message definitions from various categories of equipment, have made the idea of plug-and-play factory integration possible. Most major machine vendors already are compatible with xLink for the communication of CAMX data, making these machines connectable to any software system capable of subscribing to XML/SOAP messages. The use of XML/SOAP messaging lends itself to building scalable, high-availability systems for reliably processing large volumes of data.
This type of broad system bears responsibility in the factory and cannot fail. The criticality of its role requires a system design that is scalable to any transaction load and can guarantee high availability, even in the event of server failures. Multi-layer distributable web-service-based solutions are the optimal means for achieving both goals. A factory-wide solution should prove lateral and vertical scalability by design. It should allow separation of business logic from the database and user interface, preferably allowing separation of various areas of the business logic for the largest deployments. This enables IT departments to add additional servers within a farm when system load becomes too great. They could increase server power traditionally, however; this is expensive and does not provide redundancy. Lateral scalability is difficult to achieve in the design of a system, but provides the user with redundancy and automatic fail-over when servers fail, offering uninterrupted service.
Data acquisition systems must provide for assured data retention, integrity and time synchronization - even if the machines to which they are connected are disconnected from the network for a significant period of time. This is critical to traceability and other visibility functions dependent on machine data streams.
A system should supply out-of-the-box interactive display, report and
charting capabilities, as well as preconfigured reports. However, all
companies require the construction of their own output. Customized
reporting must be the most flexible and forward-looking area of the
system. Reporting should be achieved through an isolated layer in the
system, not through direct database access, as direct access can fail
over time when the vendor changes the data structure to accommodate new
versions and features. The use of web-service layers that generate XML
from the database is a modern and forward-compatible way to safely
present data to reporting engines. Users can rely on this for future
custom reports and data outputs.
Cost Efficiency
Moving from multiple line-level solutions to a comprehensive solution
that fills the manufacturing information gap has psychological
challenges for most companies. However, there also are significant
functional and cost benefits. Most companies maintain a combination of
commercial line-level software systems in addition to in-house software
or solutions from their business system providers or third-party
vendors. These tend to be integrated with one another in complex and
sub-optimal ways over time. Contemplating a replacement of these mixed
systems that a company depends upon for their daily operations is never
a desirable event. When these systems reach their functional limit,
however; and if a company analyzes how much maintenance of these systems
costs, the decision becomes simple.
System consolidation tends to increase elegance, reliability,
simplicity, data outputs and control. It also reduces IT maintenance and
service-contract costs across multiple vendors. Perhaps most
significant, it reduces the cost of continual integration and repairs
between systems. A unified solution offers a single customer/vendor
relationship to maintain, simplified IT maintenance and a single,
predictable on-going cost.
Conclusion
Comprehensive factory-wide automation with software is a reality for
electronics facilities. With new regulatory requirements and
ever-increasing cost and quality demands, electronics manufacturers will
be compelled to move toward a more complete automation model, such as
those used in surrounding industries. Equipment and processes are not
the impediment to this maturation. Adoption of factory-wide information
visibility and process control is an evolutionary step that should be
taken.
Author Information:
Jason Spera, Chief Executive Officer
Aegis Industrial Software Corporation
220 Gibraltar Road, Suite 100
Horsham, PA 19044