Oğuzhan Paçal, 030070031, 8th week

Alkaline Surface Cleaning:
The most used industrial cleaning method is alkaline surface cleaning, the action which is basically physical as well as chemical, aided by combination of surfactants, emulsifiers, separating agents, saponifiers, and wetting agents all attacking the part to be cleaned.The solution may be heated or agitated in motion by stirring.
Dissovable particles of dirt are washed away. Solid particles are seperated from the part and allowed to either settle in the form of sludge to the bottom or be floated away and removed from the solution by means of filtering similar devices.
(Ivana Suchy, Handbook of Die Design 2nd Edition, p668)

Organic solvent cleaning:
Organic solvent cleaning consists of an application of solvents to the organic contaminants such as oils or grease, in an attempt to remove them from the surface of parts. Sometimes this cleaning method has to be followed by an alkaline wash, in order to remove the solvent itself from the part surface. This type of cleaning may also be used for removal of water from electroplated parts.
Solvents may be either petroleum-based or chlorinated hydrocarbons or alcohols. Other solvents include but are not restricted to benzol, acetone, and toluene.
The mechanism of cleaning is applicable mainly to contaminants of organic origin, such as grease or oils. These impurities may be easily solubilized and removed, or washed off the part's surface
(Ivana Suchy, Handbook of Die Design 2nd Edition, p669)

Metallizing:
Plastics are nonconductors of electricity, which allows them to be used in many unique applications, such as electronic devices, protective housings, and advanced military systems (stealth vehicles). There are many applications that demand plastic materials to be electrically conductive or highly reflective. Compact discs, automotive lightning systems, and chrome-like decorative surfaces for auto and truck grills have unique demands for plastic materials, and all of these applications require a metal layer to be somehow applied to the surface of the plastic. The use of metallizing is categorized as follows:

• Functional: Used to reflect or conduct energy, such as light or electricity, in electromagnetic interference (EMI) reduction and radio frequency interference (RFI) reduction
• Decorative: Used to create an appearance, such as auto/truck grills
• Both: Provides both a functional and decorative service

Although there are many ways to achieve functional and decorative metallization of plastics and plastic products, the main mathods include hot stamping, printing and coating, vacuum metallizing, electroless plating, and electrolytic plating.
(Edward A. Muccio, Decoration and Assembly of Plastic Parts, p. 161)

Acid Cleaning (About Surface Treatments):
Acid cleaning uses various solution containing organic acids, mineral acids, and acid salts,
combined with a wetting agent and detergent for cleaning of iron and steel. Such a cleaning
method may be used to remove oil, grease, oxide, and other contaminants without additional
application of heat.
Acid cleaning and acid pickling are quite similar processes, with acid pickling being
much more aggressive treatment, used for removal of scale from forgings or castings and
from various half-finished mill products.
Mineral acids and salts are numerous, forming either inorganic (mineral) acid solutions
or solutions of acid salts or acid-solvent mixtures. Organic components of these cleaning
solutions may be oxalic, tartaric, citric, acetic, and other acids, with acid salts such as
sodium acid sulfate, bifluoride salts, or sodium phosphates. Solvents used in this process
may be ethylene glycol or monobutyl (and other) ethers.
(Ivana Suchy, Handbook of Die Design 2nd Edition, p. 669)