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Manufacturing
Execution Systems:
The One-Stop Information Source
by Joseph A. Vinhais
 Consider this scenario: The production manager of a thriving toy manufacturer needs to know when the company's popular remote-control sailboats will be available after an extensive redesign. She must verify that production has begun, determine the new manufacturing cycle time, obtain results from product testing, and check the materials inventory and projected shipping schedule.
Rather than trekking in person to various departments or even accessing several separate databases, the manager takes advantage of the company's manufacturing execution system, which not only provides the information directly to her terminal but distributes her revisions to all relevant parties.
MES technology has become a key element for enterprise solutions. The system provides a central information hub of 11 decision-based functions that link to other databases. These elements, combined with an enterprise resource planning system and a control system such as PLC, SCADA, MMI or HMI, provide the means for a paperless factory. Currently, companies in the aerospace, automotive, semiconductor, pharmaceuticals and petrochemical industries have adopted MES.
In essence, a full MES solution bridges the gap between the production/assembly floor and engineering, accounting, production control, purchasing, configuration management, quality, manufacturing engineering, process engineering, research and development, and testing. MES functions as the central depository for data distribution and collection for all other enterprise systems.
"MES uses current data to guide, initiate, respond to and report on plant activities as they occur," reports Manufacturing Execution Systems Association International, a nonprofit trade association in Pittsburgh representing MES software developers and vendors. "The resulting rapid response to changing conditions, coupled with a focus on reducing nonvalue-added activities, drives effective plant operations and processes. MES provides mission-critical information about production activities across the enterprise and supply chain via bidirectional communications."
MES and document control
Full MES solutions provide tools for document control and management. Authorizing and editing documents is controlled through an electronic engineering change notice. Hard-copy ECNs have been used for years to control revisions of engineering drawings. Today, however, companies distribute many more documents to their production and assembly departments. These documents, as well as engineering drawings, are created by electronic systems such as computer-aided design and manufacturing, word processing, spreadsheets, graphic imaging and forms tools.
When used in conjunction with MES, document control manages each document's revision and can associate the appropriate documents by part number, work center, operation, job/work order and assembly number. This ensures that an operator or assembler won't retrieve an obsolete revision to perform a specific process. Quality documents such as manuals, inspection sheets, corrective action tracking reports, control plans, warranty procedures, vendor certifications, process specifications and the like can all be controlled by an MES document control system.
MES and data collection
Many tools in today's manufacturing environment collect data -- bar coders, forms, handheld statistical process control data collectors, electronic gages and others. Typically, manufacturers invest in different devices for each implemented system. When acquiring an enterprise resource planning system, for example, manufacturers usually purchase a bar coding system to collect data associated with work orders. Bar code stations, strategically located throughout the manufacturing facility, usually cause queues of operators and assemblers logging in and out of jobs.
The bar code system primarily collects labor information. Manufacturers also must invest in a separate system to collect quality or SPC data. This usually entails creating, distributing and filling out forms. Although most SPC systems are networkable, a high percentage of them consist of stand-alone PCs with handheld data collectors.
An MES system replaces these cumbersome manual activities with electronic data collection on the shop floor, which can then be transferred to management, the front office or back to engineering.
Improving on CADs and CAMs
Several millions, if not billions, of dollars have been spent on CAD or CAM workstations and plotters. With these powerful systems, engineers create excellent electronic representations of components. Typically, they also print or plot their files, then copy and distribute them throughout the company. When engineering revises these representations, they must ensure that all distributed copies also reflect the changes. This quickly increases development costs and potential errors. An MES system eliminates these problems by automatically updating ECNs wherever they appear in the manufacturing environment.
These examples alone justify investing in an MES solution. The system allows a company's production, quality and engineering departments to provide operators and assemblers with one vehicle from which to collect, view and distribute data and documents. The single-system concept significantly reduces maintenance, training and implementation costs.
With MES, operators and assemblers have one place to go to find out what they should work on, view the appropriate documents to understand how to correctly work the process and communicate any issues or problems to the entire facility. At the same time, management can report on labor, and collect quality and SPC data.
Benefits to quality control
Think of all the data and documents that quality is responsible for: inspection sheets, sample inspection reports, control plans, key characteristic listings, process matrixes, CpK reports, nonconformance documents and tags, SPC charts, warranty documents, vendor certifications, material certifications, gage prints, inspection methods sheets, process flow diagrams and more.
A quality department uses several systems to create and edit these documents. Quality technicians usually create or edit documents electronically but distribute them manually on hard copy. They then collect the data, possibly enter it back into a system and file the hard copies for future reference or traceability. A quality department can take advantage of MES on several fronts:
 Document control -- An MES's electronic document control approach ensures that the correct revision(s) are the only ones available.
Tie-in to manufacturing -- MES in conjunction with an ERP system informs management about jobs in production, in queue or waiting to be scheduled. Jobs can be scheduled against inspectors and auditors. This allows a quality manager to view in real time any shop-floor bottlenecks and make appropriate changes.
Tool and gage management -- MES can easily show gages distributed throughout the facility that are due for calibration. Because MES is an electronic system, related documentation such as gage prints, specifications and pictures is immediately available.
Cost control -- An MES can track the quality costs associated with inspection, auditing and data collection. It also provides a mechanism for inspectors, auditors and quality engineers to track their time. Using Pareto charts, department managers can easily compare predicted costs vs. actual costs.
SPC online -- An MES system with SPC imbedded tracks production time and quantities, and can electronically flag operators when a process is due for inspection. In addition, when tied in with a company's gage tracking or management system, gage calibration can be scheduled based upon frequency of use rather than an arbitrarily specified time frame.
Tracking nonconformances -- An MES can display an electronic nonconformance document as soon as a nonconforming piece is identified, which forces the operator to identify the problem. The system can then automatically e-mail notices that a nonconformance needs to be dispositioned.
Real-time monitoring -- An MES can send an alarm throughout the network about a problem on the shop floor. The notice will even include specific information such as process, part, operation, job number, serial number and operator. With this information, quality can identify the problem right after it has occurred, rather than hearing later from manufacturing that "we had a problem today."
An MES provides all the necessary and correct information to operators or assemblers at the correct time. Quality, manufacturing and engineering data, stored in separate databases, is accessible across the network for combined reporting. An MES also allows operators to request resources from other department databases linked within the system. In short, an MES gives a quality department the means to support its internal and external customers more easily, quickly and with much more data.
About the author
Joseph A. Vinhais is president of CIMNET Inc. The company was founded in 1984 and is a leading developer, through its CIMNET-Folders, of MES solutions for discrete manufacturers. Vinhais may be contacted by fax at (610) 693-5927 or by e-mail at jvinhais@qualitydigest.com . | 
