Burcu Atay, 140060029, 7th week

Adhesive

Adhesives are polymers used to join other polymers, metals, ceramics, composites, or combination of these material. The adhesives are used for a variety of applications. The most critical of these are the " strıctural adhesives", which find use in the automative, aerospace, appliance, electronics, construction, and sporting equipment areas.
Chemically Reactive Adhesives These adhesives include polyurethane, epoxy, silicone, phenolics, anaerobics, and polymidies. One-component systems consist of a single plymer resin cured by exposure to moisture, heat, or- in the case of anerobics- the absence of oxygen. Two-component systems (such as epoxies) cure when two resins are combined).
Evaporation or Diffusion Adhesives The adhesive is dissolved şn either an organic solvent or water and is applied to the surfaces to be joined. When the carrier evaporates, the remaining polymer provides the bond. Water-base adhesives are preferred from the standpoint of environmental and safety considerations. The polymer may be completely dissolved in water ır may consist of a latex, or a stable dispersion of polymer in water. A number of elastomersi vinyls an acrlics are used.

Hot-Met Adhesives These thermoplastic polymers and thermoplastic elastomers melt when heated. On cooling, the polymer solidifies and joins the materials. Typical melting temperatures of commercial hot-melts are about 80°C to 110°C, which limits the elevated-temperature use of these adhesives. High-performance hot-melts, such as polyamides and polyesters, can be used up to 200°C

Pressure-Sensitive Adhesives These adhesives are primarily elastomers or elastomer copolymers produced as films or coatings. PRessure is required to cause the polymer to stick to the substrate. They are used to produce electrical and packaging tapes, labels, floor tiles and wall coverings, and wood-grained textured films.

Conductive Adhesives Apolymer adhesive may contain a filler material such as silver, copper, or aluminum flakes or powders to provide electrical and thermal conductivity. In some cased, thermal conductivity is desired but electrical conductivity is not wanted; alumina, beryllia, boron nitride, and silica may be used as fillers to provide this combination of properties.

(Askeland,D.R,The Science and Engineering of Materials,3rd Edition, pg.514-515)

Flushing

The single most important factor in successful EDM work is flushing: the removal of metal particles from the gap. Good flushing provides a good machining conditions. If the flushing is poor, metal will be removed erratically, time to machine will increase, and costs will increase. Sometimes, when the overcut is 0.0015’’ or smaller, a vacuum flush will be used. Sometimes a combination methods will be used.
(Brown, J.A., Modern Manufacturing Processes,Industrial Press. Inc., pg. 74)

Flat honing

Flat honing is designed to correct out-of-flatness and out-of-parallelism, as well as improve the surface finish and produces a desired thickness. Typical surface conditions prior to flat honing are: over size, out-of-parallel, bowed, and rough. Usually a lapped or honed surface is a baseline from which important dimensions are taken; there are places where 0.0001’’ out-of-flatness or out-of parallelism could ruin an assembly, for example, a hydraulic seal or ball bearing race.
(Brown, J.A., Modern Manufacturing Processes,Industrial Press. Inc., pg. 225)

Solid Solution Strengthening
Large additions of chromium, molybdenum, and tungsten and smaller additions of tantalum, zirconum, niobium, and boron provide solid solution strengthening. The effects of solid solution strenghthening are stable and, conswquently, make the alloy resistant to creep, particularly when large atoms such as molybdenum and tungsten (which diffuse slowly) are used.
(Askeland,D.R,The Science and Engineering of Materials,3rd Edition, pg.402)