The symbiotic nature of the cleanroom

Smart Manufacturing

by Bruce G. Walker and Wanda R. Mattson

Analysis tools assist in performance improvements

The graphic represents a process vessel with hazardous fume potential. The station owner will note that lip exhaust is very high as represented by the perimeter bars. However, unless he is expert in exhaust management, he may fail to observe the dangerously low capture velocities at the center of the tank.
Click here to enlarge image

Convergence of man and machine is often debated. This is especially true in manufacturing where a cleanroom is not usually viewed as a convergent entity. Yet the cleanroom is a symbiotic environment of man and machine where infinitesimal actions and reactions create monumental differences.

A cleanroom is a tangled, although synergistic, web of complex systems and processes. Consider the interrelationships between personnel, facility, processing equipment, ventilation systems, alarm and monitoring systems, regulatory practices and social and environmental considerations, as well as chemical and gas delivery systems.

In this multi-tasking, multi-disciplinary environment, complex manufacturing processes occur around the clock and often within hazardous environments. Safe and best practices are the cornerstones that bind this environment into a productive operation.

The “whole factory” perspective

Globalization and e-business strategies continually challenge 'time to market' cycles. These cycle times are compressed to accomplish “fast” product development and “immediate” product introductions.

The changing manufacturing as well as regulatory environments further complicate this challenge in today's competitive arena.

Consider a litany of such items as time-to-market, engineering deadlines, conflicting schedules, budgets, price compression, manpower constraints, new processes, obsolescence, supplier selection, technology leapfrogging, quality, etc.

Computational analysis is a diagnostic tool enabling engineering resolutions to operational problems. The station shown exhibits poor exhaust performance.
Click here to enlarge image

Control of these issues begins with a “whole factory” perspective while focusing on the dynamic and symbiotic environment. Systems are implemented allowing all disciplines to be factored into the product completion equation. These disciplines may include facilities engineers, industrial hygienists, process engineers, environmental engineers, equipment technicians and operators, suppliers and safety engineers.

Communication across multiple disciplines may result in competing priorities. Cross-functional teams can sometimes resemble cross-brutalization of personnel. Added to this, numerous global standards organizations issue practices, policies, procedures and guidelines that may have conflicting requirements. Thus implementing proper factory and manufacturing protocol can be mind boggling, time consuming and fraught with contradictions.

This CFD graphic shows an exhaust system with turbulence below the deck and little fume control above the deck. Without diagnostic aids such as this, process engineers may be unable to identify high exhaust draw at the station with little fume control above the deck.
Click here to enlarge image

For example, a supervisor may be tasked to evaluate specific equipment and processes for improvement factors. The supervisor is suddenly required to thoroughly understand equipment operation and dynamics as well as be able to pinpoint areas of poor or marginal performance. This requirement may include theory of operation, air and exhaust management techniques and preventative maintenance procedures.

To implement improvement, the supervisor must review the economics of modifying or replacing the equipment. To complete this task, many cross-functional lines will be crossed, while the supervisor investigates cleanroom and equipment practices that may be beyond his practical experience. Concurrently, all tasks must be accomplished in a 'crash course' while maintaining normal production responsibilities.

Numerous engineering methodologies exist to address this complex task of organizational monitoring and control. This article addresses a simplified yet effective approach to symbiotic relationship analysis. For more comprehensive methodologies, refer to International Standards Organization's (ISO) 15704, Requirements for Enterprise Reference Architectures and Methodologies, International SEMATECH's CIM (Computer-Integrated Manufacturing) Framework, or similarly developed programs.

A symbiotic analysis: equipment exhaust and ventilation

One simplified approach, developed by Technology Performance Group (Boise, ID), addresses equipment evaluation via a Facility Air Conservation Template (FACT). This model is based on best practices developed from multiple assessment methodologies and protocols. The FACT model addresses such factors as:

  • Equipment design
  • Equipment exhaust optimization
  • Cleanroom air management

Various templates are designed for bay-chase and ballroom style cleanrooms as well as manual, semi-automated and automated equipment. In utilizing the template, beginswith a survey of the factory and the existing operational protocols and practices. Then evaluates equipment performance against the manufacturer's published specifications and operating parameters.

For this example, the published exhaust rates are evaluated against actual operating rates. An assessment is also performed to identify the equipment's dependence on laminar airflow velocities. When implementing the FACT model, the team reviews applicable environmental and safety considerations under prescribed operating practices, processes and procedures.

The FACT team generally comprises industry experts such as certified industrial hygienists, exhaust and ventilation specialists, filter balance and test experts, cleanroom component and equipment manufacturers, mechanical engineers, equipment design specialists and process professionals. Other disciplines are included as necessary to assure a 'total factory' perspective.

Using the FACT process, a value-added analysis of the cleanroom environment is conducted to address: cleanroom laminar airflow management; equipment exhaust; consumables (water, gases, etc.); equipment effluent (liquid, solid, vapor); exhaust energy evaluation; and cost of ownership.

The FACT team will:

  • Review client data
  • Perform limited data acquisition (as required)
  • Complete a FACT evaluation
  • Evaluate equipment theory of operation
  • Audit operator procedures and preventative maintenance schedules
  • Survey objectives
  • Reveal improvements by application of best practices
  • Identify excessive exhaust usage by equipment and/or component
  • Verify safe practices per applicable compliance requirements
  • Evaluate balancing reduced laminar air flow velocities with tool exhaust performance

Click here to enlarge image

Once an analysis is complete, the FACT team prepares a prescription to identify and list candidates for exhaust reduction, specify equipment profile program, describe computational evaluation of improvements (supported by empirical data), determine the solution set for exhaust reduction, prescribe a solution set for reduced laminar air flow velocities, and recommend improvements for environmental health and safety.

The implementation phase is dedicated to:

  • Characterizing subject equipment with empirical and computational data
  • Defining reduced laminar airflow performance
  • Designing changes for best practices solution set

    Cleanroom air management and exhaust performances are synergistic partners in the fab environment formula. Dependent upon that synergism are people, processes and productivity.

    Unbalancing the synergistic partnership by changing laminar airflow without balancing exhaust performance can have a negative effect on the total cleanroom environment. Harmony of the total factory environment is the goal. An added benefit is achieved when items are identified that can be permanently added to equipment design specifications leading to continuous improvement as well as concurrent product development.

    The final phase requires developing this material into training programs to assist all personnel in the continuous evaluation of operational states. Now a factory's multidisciplinary team can continually monitor goals while understanding the dynamics of the total factory environment.

    Adding complexity to analysis: factory construction

    Consider the previous equipment exhaust and ventilation example. Now add the complexity of the facility viewed from a construction standpoint. Here, applicable codes are derived from Uniform Building Code (UBC).

    Furthermore, UBC represents just one of the numerous bodies of codes that must be addressed when building, remodeling or operating any manufacturing facility. Other regulations and agencies to consider include OSHA, ASHRAE, ISO, NEC, EPA, local authorities and numerous others.

    From a facilities engineering management perspective, they must coordinate construction activities, install equipment and assure a production-ready operation amidst a myriad of other tasks while meeting all code and compliance issues.

    This plot represents capture velocity across the surface of the process tank from back to front. Both leading edge velocity and trailing edge velocity fail to achieve critical capture velocity.
    Click here to enlarge image

    Returning to our exhaust example. While efforts to reduce airflows in processing equipment reduce energy consumption at the factory level, no equipment manufacturer can ship equipment that is not in full compliance with UBC, nor can equipment be installed without compliance to all applicable codes and regulations.

    Add to this complexity, the concurrent introduction of a new material, process or technology. The review, acceptance and signoff processes must now include all disciplines while considering the impact to the product as well as process, total manufacturing facility and personnel. Returning to the “whole factory” approach, view all aspects from people and practices to equipment design, selection, installation, usage, maintenance and obsolescence and/or replacement.

    Benchmarking activities across industries and disciplines often result in the development of numerous best practices programs in environmental health and safety, monitoring programs and building construction advancements, just to name a few.

    Along with benchmarking, a common practice among many manufacturers is to validate a technology, process or program and then replicate it across the entire company as well as throughout the supplier chain as applicable. This approach assists in disseminating best practices and proven technologies. The question, however, is whether it can be accomplished quickly enough to meet the shortened time-to-market and new technology development cycles faced by all manufacturers.

    Synergistic manufacturing is tied to dynamic markets. Information is abundant and overwhelming. The essential element is tying that information into working knowledge. The tie may be viewed as a bridge that is forever under construction.

    Plan, collect data, analyze, report and adapt. Mature factories are moving toward total predictive manufacturing where capital expenditures versus capacity and costs are predictive. Certainly, future manufacturing entities will utilize the experience and reasoning capabilities of man with the advancements of machine to create future “smart factories.”

    Bruce Walker is president of Technology Performance Group Inc., of Boise, ID.

    Wanda Mattson is chief executive officer of Technology Performance Group Inc., of Reno, NV.


Easily post a comment below using your Linkedin, Twitter, Google or Facebook account. Comments won't automatically be posted to your social media accounts unless you select to share.