Manufacturers often ask how to achieve a clean space without using a cleanroom. There are many reasons to do this, including achieving a reasonable process flow and assuring economic competitiveness. A
clean space involves basic design and structure. There is an initial capital outlay for micro-environments and facilities design.
Achieving a clean space involves coordinating engineering planning and production activities with the facilities group, the customer, and with safety/environmental professionals. Employee
practices may also have to be addressed.
The first question, albeit a semi-dramatic question, is: what
is my motivation? There are many reasons for setting up a
clean area outside of a formal cleanroom. Do you need clean
air? Clean water? Clean process chemicals? Product protection?
Worker protection? Customer satisfaction? An actual clean
area? The perception of a clean area?
BFK Solutions LLC
Pacific Palisades, Calif.
What does the customer expect?
Where particles in the air must be controlled, some sort of
HEPA filtration is required. If the customer has formal or contractual requirements for a cleanroom, building a cleanroom is
the only way to proceed. In other instances, a mini-environment
may be a more economical and technically-superior approach.1
A mini-environment where the processes are conducted by
observant, well-educated personnel can be more successful than
a stand-alone cleanroom where general employee practices are
not as well defined.
However, there are also perceptual and expectation requirements. These requirements may first appear during a site inspection by a prospective customer. One group took what appeared
to be the logical step of adopting a bench with filtered air flow for
final cleaning prior to the final finishing process. The prospective
customer was not impressed. The expectation was the presence of
a clean environment that looked like an independent room.
Aside from customer perception, it is important to define the
clean space, to define the contamination sources, to define how
the product might become contaminated; this means starting with what some may consider to be the non-glamorous,
mundane parts of cleaning and contamination control. We
often assert that contamination control starts early-on in the
assembly process. This means that, for example, the machine
shop may require clean areas and clean practices.
Initial critical cleaning
Immediate cleaning after machining is one of the most effective
paths to achieving product quality. Since cleaning involves three
steps (washing, rinsing, and drying), it is crucial to assure that
these steps are carried out promptly and effectively.
Applicators, peripherals, environmental controls
A rag is not just a rag. Handwipe cleaning often involves application of the cleaning agent using brushes, cloth, or paper towels. To achieve a clean area, you have to specify the appropriate
applicator. This is always a compromise because applicators
inherently introduce some level of particulate or chemical contamination. 2 Achieving a clean area in a shop involves specifying the applicator for the cleaning agent.
Evaluate gloves and other protective equipment. Particularly
at non-cleanroom stages of production, the Industrial Hygienist
may be in charge of specification. Of course the worker has to
be protected. However, product contamination also has to be
minimized. As an engineer or process designer, the ball has to be
in your court as well; so you may need to coordinate (i.e. negotiate) with the safety professionals.
Drying and storage
Often, parts are dried using shop air. This air may contain oil;
and the net result of attempts at drying may be deposition of
both thin film and particulate contaminants. Coordinating
with the facilities group and monitoring shop air is an important step in achieving a clean area.
Storage and transport
Parts may be machined and then stored either in the shop or in
a storage room where air quality and access are not controlled.
If parts are stored in a shop, there can be gradual accumulation
of process fluids, dust, and other soils; and there is a tendency
to move the parts from place to place. Set up a protocol for
protecting and storing the parts after they have been machined