Flashcards in Chapter 27 Deck (17):
Define: Electrolytic Cleaning
Also called "electrocleaning"; is a related process in which a 3-12 V direct current is applied to an alkaline cleaning solution. Results in the generation of gas bubbles at the part surface, causing a scrubbing action that aids in removal of tenacious dirt films.
Define: Sand Blasting
Form of blast finishing where grits of sand (SiO2) is used as the blasting media. Used to clean and finish a surface.
Define: Shot Peening
A high-velocity stream of small cast steel pellets (called shot) is directed a a metallic surface with the effect of cold working and inducing compressive stresses into the surface layers. Improves fatigue strength of metal parts.
Define: Mass Finishing
Involves the finishing of parts in bulk by a mixing action inside a container, usually in the presence of an abrasive media. The mixing causes the parts to rub against the media and each other to achieve the desired finishing action.
The material used in mass and vibratory finishing that are abrasive. Sometimes, media perform nonabrasive finishing operations such as burnishing and surface hardening. May be natural or synthetic materials.
Also known as electrochemcial plating, is an electrolytic process in which metal ions is an electrolyte solution are deposited onto a cathode work part (negatively charged).
Negatively charged portion of the electrochemical plating process. Often refers to the workpart being plated.
The positively charged portion of the electroplating process, usually made of metal and the serves as the source of the plate metal.
The aqueous solution in which electroplating occurs; consisting of acids, bases, or salts.
An electrolytic treatment that produces a stable oxide layer on a metallic surface. Most common applications are with aluminum and magnesium, but it is also applied to zinc, titanium, and other less common metals. coatings are used primarily for decorative purposes and provide corrosion protection.
Define: Organic Coatings
Polymers and resins, produced either naturally or synthetically, usually formulated to be applied as liquids that dry or harden as thin surface films on substrate materials. These coatings are valued for the variety of colors and textures.
Organic coatings that determine the solid-state properties of the coating, such as strength, physical properties, and adhesion to the substrate surface
Used to dissolve the binder and certain other ingredients int he liquid coating composition. Common solvents used in organic coatings are aliphatic and aromatic hydrocarbons, alcohols, esters, ketones, and chlorinated solvents.
Define: Electrostatic Spraying
Where work part is grounded electrically and the atomized droplets an electrostatically charged. This causes the droplets to be drawn to the part surfaces, increasing transfer efficiency to values up to 90%.
Define: Transfer Efficiency
The proportion of paint supplied to the process that is actually deposited onto the work surface. Some methods yield as low as 30% transfer efficiency
Involves a chemical change in the organic resin in which polymerization or cross-linking occurs to harden the coating.
Ambient temperature Curing
Elevated temperature Curing