Glossary
Glossary
A
Abrasion: A wearing, grinding, or rubbing away by friction.
Additives: Materials added to coating to enhance certain properties.
Adhesion: The bond strength of a coating to the substrate whether metallic, nonmetallic, plastic or rubber.
Alkaline wash: Cleaning process that employs a high pH solution (caustic). A good choice for parts with little buildup of contaminants.
Aluminum oxide: Hard particulate medium used in grit blasting to clean roughen surfaces that are to be coated.
Anodizing: Creating a hard oxide surface on aluminum parts via an electric process. Unsealed anodized surfaces have porosity that makes them excellent substrates for coatings.
B
Binder: Tough polymer that acts as adhesive to join elements of matrix coatings.
Binder Break-in: Initial wear of mechanical components when large surfaces asperities can cause high friction and wear rates.
Buffing / Burnishing: Process of polishing cured coating to improve release and low friction.
C
Carrier: The liquid portion of coating (solvent or water) in which solids are dissolved or suspended.
Cold flow: Tendency of plastic materials to migrate slowly under heavy loads and /or over time.
Conductor: Material that can support flow of electrical current. Coatings are normally insulators, but can be modified with certain fillers and pigments.
Corrosion: Process of metal decomposition (oxidation) in which metal ions are united with oxygen to form metal oxides. Fluoropolymer coatings provide excellent barriers against most corrosives.
Crosslinking: Quality of thermosetting plastic resins in which polymer chains combine during curing process. In general, the greater the crosslinking, the tougher and more chemically resistant the coating.
Cryogenic: Temperatures less than -130ºC/-200ºF, Bonded dry film lubricants continue to perform at these temperatures.
Cure Test: A solvent rub testing using MEK or other solvent to test the coating for completeness of cure base on no attack of the solvent on the cured coating after a specific amount of rubs with a Q-tip.
d
Defelsko: Coating thickness gauge that can measure coatings on metallic and non-metallic substrates.
Dielectric strength: Ability of a coating to resist the passage of electric current.
Dip/spin: Coating application technique in which small parts are placed in a basket that is lowered into a coating bath, then raised and spun to remove excess coating. An economical system for coating high volumes of small parts.
Dry (solid) Lubricants: Solid materials such as PTFE, Moly Disulfide (MoS2) and graphite that have low coefficients of friction.
e
Elastomers: Any of various elastic substances resembling rubber.
Electrostatic spray: Spray application process in which the coating and part to be coated are oppositely charged; process provides excellent “wrap” of coating around the part, even on sides opposite the spray gun.
Engineering plastics: Plastic resins that have high- performance properties such as high temperature stability, hot hardness, and abrasion resistance and corrosion resistance.
Epoxy: A flexible resin, usually thermosetting, made by polymerizing of an epoxide and used chiefly in coatings and adhesives.
f
FEP (fluorinated ethylene propylene): A thermoplastic member of the fluoropolymer family, FEP has the best nonstick and nonwetting properties of these materials.
Fillers: Pigments and other solids used to alter properties of coatings.
Final Cure: The final time and temperature required to complete the final cure, sintering, melt flow or cross linking of a coating.
Flash Point: The lowest temperature at which a solvent will generate sufficient vapors to ignite in presence of flame.
Flashing: A brief subcure (at lower temperatures than the final; cure) to drive off solvents/carriers prior to full cure. This helps prevent bubbling.
Fluoropolymers: Family of engineering plastics containing fluorine, characterized by high thermal stability, almost universal chemical resistance and low friction.
Fretting: Wear phenomenon caused by vibration among tightly clamped or fastened surfaces.
Friction (dynamic): Resistance to continued motion between two surfaces: also known as sliding friction.
Friction (static): Resistance to initial motion between two surfaces.
g
Gainsharing: Incentive program aimed at improving production, quality, and attendance thru financial sharing with employees.
Graphite: Carbon-based dry lubricant that is preferred for high-temperature applications.
h
Holiday Check: A DC electric tests using a wet sponge apparatus that detects pinholes our porosity in a coating. The DC voltage of the apparatus is variable to allow for detection of pinholes at different levels with out the destruction of the coating.
Holiday CheckHot hardness: Ability of coating to retain hardness and wear resistance at elevated temperatures. Usually a catechistic of coatings based on thermosetting resin binders.
Hydrophilic: A coating that has a strong affinity for water and when wet with water its properties become extremely non-stick and slippery.
j
Job Boss: A Software package developed for job shop companies that is used to track product processing costs including labor and material. It also includes quoting functions, material management, scheduling and shop floor control. It has the capability of producing reports for final product cost review, JIT delivery performance.
m
Matrix coating: One in which some ingredients, such as the lubricant (PTFE), which is soft, is enveloped in others (the matrix, such as harder, more wear-resistant binders).
Micro Inch / μ inch: One micro inch, a millionth of an inch.
Micrometer:
- A device for measuring very small measurements.
- Unit of length equal to one thousandth of a millimeter (10 to the -3 e) or one millionth of a meter (10 to the -6 e).
Micron / μ: One micron, a millionth of a meter. Also expressed as a μm, or micrometer (.001 mm).
Migration (of lubricant): Characteristic of any fluid lubricant to move away from bearing area.
Moly, moly disulfide, and molybdenum disulfide, MoS2: Four names for the same naturally occurring substance that has good low-friction and load bearing properties.
n
Noise damping: The absorption of sound vibrations. Xylan coatings form good noise damping surfaces.
o
Oleophobic: Repels Oil. Oil does not wet out on the surface of coating but beads up on it.
Oleophobic Orange Peel: The varying degrees surface roughness or finish similar to that of an orange.
p
Partial cure: Process sometimes utilized when multiple layers of fluoropolymer coatings are to be applied. The first coat is incompletely cured. The second coat is applies and both are fully cured together.
PFA (perfluoroalkoxy): The thermoplastic member of fluoropolymer family of engineering plastics, one characterized by excellent release and low friction.
Phenolic: A resin or plastic, usually thermosetting, made by condensation of a phenol with an aldehyde and used for molding, insulating, coatings and adhesives.
Phosphating: Surface pretreatment used on ferrous parts that provide a very thin crystalline film that enhances both corrosion resistance and adhesion.
Pinhole: A tin hole in a coating as if made by a pin that allows potential exposure or leak path to the substrate beneath the coating.
Polyamide-Imide (PAI): A high strength plastic with the highest strength and stiffness of any thermoplastic up to 275°C (525°F). It has outstanding resistance to wear, creep, and chemicals- including strong acids and most organics—and is ideally suited for severe service environments.
Polyarylsulfone (PAS): A thermally stable thermoplastic resin consisting mainly of phenyl and biphenyl groups linked by ether and sulfone groups (3M Company). The material is resistant to high and low temperatures and has good impact, chemical and solvent resistant, and electrical insulating properties.
Polyethersulfones (PES): Highly resilient thermoplastic plastics. Materials made of polyethersulfones are transparent or slightly transparent (high light transmission and refractive index), resistant to hydrolysis, and provide excellent chemical resistance to mineral lubricants, aliphatic hydrocarbons, acids and alkalis. The thermoplastic polyethersulfone has a melting range or glass transition temperature of approximately 220°C and can be processed to form a finished product with up to 30% inorganic fillers, fiberglass or carbon fibr-ers in an extrusion (extruded profiles) or injection moulding process. Due to their optimum electrical insulating properties, polyethersulfones have applications in the electronics and automobile industries. Polyethersulfones are also used in the medical sector, the food sector (membrane technology), as well as in aircraft cabins.
Polymer fume fever: 24-hour flu-like symptoms (with no long-term effects) cause by inhaling the gasses released during the decomposition of fluoropolymers.
Porosity: Pinholes or minute pores in a coating that allows potential exposure or leak path in the coating to the substrate, one reason for the failure of chemical, electrical or corrosion resistant coating. Can be detected with a spark check test or holiday checker.
Postcure: A second cure at high temperature to enhance specific properties such as release and nonwetting.
Powder metal: Material formed by compressing particles and heating (sintering) to solidify and strengthen them
Preheating: Warming of parts prior to application of coating, recommended when adhesion is critical and when parts are being coated in humid atmospheres. In some cases, this technique can be used to achieve higher-than- normal film builds.
Pressure Spraying: Coating technique similar to siphon spraying, except that the coating is delivered from a pressurized pot to the spray nozzle under positive pressure. Generally used for high-volume production.
Pretreatment: Processes for cleaning and conditioning a substrate to be coated. Next to the choice of coating, this maybe the most important factor in the use of high -performance coatings.
PTFE (polytetrafluoroethylene): A thermoplastic member of the fluoropolymer family of plastics. PTFE has the lowest coefficient of friction of any known solid and the highest temperature resistance of the fluoropolymers.
PVDF (Polyvinylidene fluoride): High -molecular weight thermoplastic of vinylidene fluoride with greater strength, wear resistance and creep resistance than FEP, PFA, or PTFE.
r
Resistance (electrical): The opposition offered by a coating to the passage through it of an electric current.
s
Salt fog: ASTM B-117 test procedure that simulates the corrosive environment caused by road salt and marine spray.
Sand blasting (also grit blasting): Surface cleaning and roughing process that provides a mechanical “tooth” to aid the coating adhesion. Media include aluminum oxide, even crushed walnut shells. The medium must be chosen to match the substrate and foreign material on the substrate to be removed.
Siphon spraying: Most common technique for applying coatings, also known as “conventional” coating is drawn from a reservoir into an atomizing air nozzle and propelled toward the surface to be coated.
Spark Check: An DC electrical test that can be used detect pinholes or porosity in a coating. The DC voltage is variable to allow for different levels of testing. The testing voltage is anywhere from 50 to 5000 VDC depending on the coating and the application or specification requirements.
Static electricity: Buildup of stationary electrical charge on a coated surface.
Stick-slip (chatter): Unstable sliding condition in which movement of one part over another starts and stops, caused by temporary over coming of static friction.
Substrate: Any surface to be coated. This can include metals such as steel, cast iron, bronze, brass, aluminum, stainless steel, chromium, and (with special precautions) nickel. Paper, most plastics, wood, leather fabrics and glass can also be coated.
t
Tape Test: An ASTM method D3359-02 for measuring the adhesion of a coating to a substrate using a specific tape and technique.
Thermoplastic: Plastic resin that softens when reheated.
Thermoset: Plastic resin that crosslinks during cure so that it does not soften when reheated.
Transfer efficiency: The amount (percentage) of a coating that actually reaches and stays on the part being coated. Some coating methods give far higher transfer efficiency than others.
w
Wear: Deterioration by friction (abrasion, spalling, cutting, fretting).