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      If you need custom rubber parts for a medical device or aerospace application, you may need a rubber manufacturer capable of accomodating parts that require special handling. If that’s the case, chances are you may need a rubber manufacturer with a cleanroom to deliver your parts.

      What is a cleanroom, what standards are manufacturers held to and why? Here’s the rundown: everything you need to know about cleanrooms, from classification systems and standards to features and maintenance to prevent contamination. By the end of this article, you should have a clear understanding of a cleanroom’s purpose, its history, ratings, as well how contaminants are introduced and common maintenance techniques.


      First Things First: What Is A Cleanroom?

      When it comes to cleanrooms and manufacturing parts, such as rubber parts for medical devices or rubber parts for an aerospace application —manufacturers are held to stringent standards of air cleanliness. That makes sense since environmental conditions directly impact product quality. Whether it’s rubber seals or a gasket that will someday be apart of a life-saving medical device, such custom molded parts require a manufacturing environment with extremely low levels of particulates.

      That environment is a cleanroom — and the main purpose of a cleanroom is to maintain extremely low levels of dust, microbes airborne organisms and other pesky particulates that interfere with production, quality and consistency.

      Today, the levels to which cleanrooms achieve cleanliness are classified with two recognized systems.  We’ll take a look at these systems, and the different levels of classifications that exist, but let’s begin with the origin of the cleanroom.


      A Closer Look at Environmentally Regulated Rooms Through History

      Ready for a quick history lesson? Let’s step back and take a look at the beginnings of cleanroom technology.

      While it depends on who you ask, the invention of the modern cleanroom as we know it is widely attributed to Willis Whitfield in 1962.[1] But, as you can probably imagine, the concept of environmentally regulated rooms existed long before that.

      Centuries ago in the East, Chinese lacquer painters are said to have developed a sophisticated air flow system to create higher quality work. [2] In the West, 19th-century watchmakers are frequently credited as the first to create a clean, environmentally controlled environment to prevent their meticulous work from being ruined — which could happen with the tiniest speck of dirt.

      As you can see, the concept of a clean environment to promote production quality has existed for a long time. But what about the cleanroom technology we’re familiar with today? To understand that technology, let’s fast forward to the start of the 20th century.


      20th Cleanroom Manufacturing: From Surgical Cleanrooms to Production Boom

      The Great War is underway, it’s the beginning a new technological age, and Miniature Precision Bearings (MPB), a manufacturer of tiny ball bearings, identifies the quality issues they’re experiencing are due to adverse effects of airborne particulates. MPB solves the problem with air conditioning — a successful solution that eventually leads the manufacturer to later create “white rooms” with a new facility opened in 1956. Employees working in these white rooms donned smocks and caps to prevent contamination.

      Fast forward to the 1950s and the introduction of surgical cleanrooms. To be sure, cleanliness in surgical settings predates the creation of 20th-century cleanrooms. During World War II, rapidly spreading diseases in small spaces led to research and the eventual implementation of ventilation features.  The result was the introduction of high-efficiency particulate air (HEPA) filters and a clear understanding of laminar air flow, which, is, simply put, air moving in one direction.

      Move ahead to 1961. Willis Whitfield, a Sandia National Laboratory employee tasked with maintaining cleanliness in nuclear production facilities designs the first modern cleanroom we know today.[3] At this time, cleanrooms were, in essence, regularly vacuumed, sealed environments. Whitfield’s credited innovation is designing a room that circulates air through filters. In fact, the room and filtration system he designed was capable of completely and efficiently replacing all of the air in a room. “When the first cleanroom was tested, the dust counters went to nearly zero. We thought they were broken,” said Willis in an interview about cleanrooms.

      It wasn’t long before a group of 200 cleanroom experts gathered to classify and create standards for clean rooms. Once that happened, companies like RCA and General Motors contributed to the following $50 billion of global cleanroom construction based on Whitfield’s patented cleanroom design. The rest is history: Whitfield went on to help NASA with spacecraft sterilization and was known as “Mr. Clean,” thanks to Time Magazine.

      The standards established by Whitfield and other cleanroom experts were early version of the ISO ratings used today. Let’s talk about those ratings, and another important system you should be aware of for cleanrooms.


      ISO Standards and FS209E 

      As you know now, cleanrooms are rated according to their air cleanliness levels. The International Standards Organization (ISO) classification system — the primary system by which cleanrooms are are systemized today—  is organized according to how much particulate, such as dust or airborne organisms, exists per cubic meter.  While an ISO 1 rated cleanroom has the lowest amount of contamination, an ISO 9 has the maximum allowable levels.


      Prior to the creation and implementation of the ISO standards, the U.S. General Service Administration’s classification system, known as Federal Standard 209E (FS 209E), was the gold standard for cleanroom ratings and used across the globe.[4] But demand for an international classification system increased and precipitated the implementation of the ISO standards.

      With the FS209E classification system, the number in “class 10,000 cleanroom” represents the number of particles of size .5mm or larger allowed per cubic foot of air.[5] While FS209E was canceled and superseded by the ISO standards in 2001, it’s classification system is still in wide use today.[6] For example, with our 5,000 square foot, low particulate cleanroom molding facility, we let customers know our room is rated as both ISO Class 7 and class 10,000.

      These are the two systems of cleanroom standards in use today. With a clear understanding of these systems and levels, let’s turn our attention to cleanroom design features.


      How Cleanroom Airflow Works

      When it comes to air filtration for cleanrooms, there are two common types in use: HEPA and ULPA (ultra low particulate air) filters. Through laminar air flow or turbulent air flow (which we’ll talk more about in a moment), HEPA and ULPA filters remove over 99% of a room’s microparticles.


      Now let’s turn our focus to the laminar and turbulent methods of airflow. Laminar air flow cleanrooms, or unidirectional airflow cleanrooms as they are also known, do exactly what the latter name suggests: create air that flows in a single, unobstructed path. This is maintained with laminar air flow hoods that focus air jets into a straight path. In addition, the architectural features of the cleanroom contribute to minimized turbulence of airflow.  With laminar flow, air moves through HEPA filters, which cleans air entering the environment. These filters are often made of stainless steel to minimize contaminant entry.

      With turbulent airflow systems, a non-unidirectional airflow model is used. Random, non-specific velocity filters, along with laminar flow design, keep cleanroom air contaminante-free. While it may seem counterintuitive, this random movement is central to getting particles from the air through the filter. [7]


      Down and Dirty: How Cleanrooms Get Contaminated

      Now that we understand the systems by which cleanrooms are classified, let’s talk about how contaminants and maintenance. The maintenance of a cleanroom requires a multi-pronged approach. When it comes to contamination, particles are introduced primarily in two ways.

      The first way is contaminants are introduced is through employees. To put it bluntly, since there is no way to bring an end to the continuous shedding of dead skin or human hair, employees are required to wear hazmat-like protective gowns to ensure the room’s target number of air particles are maintained.

      The second way contaminants are introduced is simply through the manufacturing process. And this is what’s so great about the modern cleanroom’s airflow design features in its ability to filter out contaminants introduced in the actual plastic or rubber part manufacturing process.[8]


      Cleanroom Maintenance Techniques

      Regarding cleanroom maintenance, there are a number of important techniques. First, it’s important that interior surfaces are wiped down every day, and the cleanroom floor regularly cleaned as well. All points of contact, like doorknobs, handles and equipment used for operation, should be thoroughly cleaned as well. In addition, filters associated with the HEPA system must also be changed frequently, or certified. It’s also important for proper air flow tests and leak checks are performed routinely.  These are just a few of the basic requirements needed to maintain a cleanroom.[9]

      Our team at  Da/Pro Rubber is proud to custom design and manufacture a wide range of custom plastic and rubber parts in our ISO 7 / Class 10,000 cleanroom. In fact, our cleanroom and our proprietary process are what truly set us apart. From custom compounding for material to molding, washing, quality inspection, customer-specified processing, sub-assembly, and special packaging, our cleanroom accommodates a wide range of applications for custom plastic parts and molded rubber.

      In addition, our cleanroom processes include compression transfer molding, automated (vision) inspection, quality control and inspection, special packaging, ultrasonic washing and slitting (if needed), as well as sub-assembly.

      The possibilities are limitless when it comes to applications for custom plastic or rubber parts manufactured in cleanrooms. No matter what your applications call for, we look forward to identifying and meeting your cleanroom needs — and above all, exceed your standards.


      [1] https://www.tested.com/science/608153-history-cleanroom/

      [2] https://electroiq.com/1999/03/a-brief-history-of-cleanrooms/

      [3] https://www.tested.com/science/608153-history-cleanroom/

      [4] https://www.terrauniversal.com/cleanrooms/iso-classification-cleanroom-standards.php

      [5] https://www.cleanairtechnology.com/cleanroom-classifications-class.php

      [6] http://www.iest.org/Standards-RPs/ISO-Standards/FED-STD-209E

      [7] https://www.thomasnet.com/articles/automation-electronics/Cleanroom-Air-Flow-Principles

      [8] https://angstromtechnology.com/cleanroom-classifications-standards/

      [9] https://www.cleanairproducts.com/documents/How%20to%20spec%20a%20cleanroom.pdf