Casting process is the most direct method of producing a product from the chosen material.
Though products in all the three major classes of materials, metals, ceramics and polymers
can be produced by this method, casting of metals is by far the most widely used process.
The basic steps in the casting process are preparation of the material in the liquid state,
transferring the liquid material into a shaping mold, allowing the transformation of liquid
material in the mold into a solid form.
The story of metal casting is as glamorous as it is ancient, beginning with the dawn of human civilization and interwoven
with legends of fantastic weapons and exquisite artworks made of precious metals. It was and is involved in the two main
activities of humans since they began walking the earth: producing and defending wealth. Civilization as we know it
would not have been possible without metal casting. Metal casting must have emerged from the darkness of antiquity first
as magic, later to evolve as an art, then as a technology, and finally as a complex, interdisciplinary science....
Defects, the scourge of the metalcaster. These can be as simple as broken or loose sand,
or more complicated like gas bubbles. In any case, it doesn't look good, and it may make
the casting useless.
Now, I'm pretty good at casting , so I don't make many mistakes... but here's one that
got by me:
This casting shows a very common defect, flash. This is where the
mold somehow seperated enough to allow metal between the halves,
along the parting line. (See also the trivet for more flash.) You can
see the inside circle here is nearly completely filled in with flash. ...
Solvent casting property for the scaffolds preparation is very simple, easy and inexpensive.
It does not require any large equipment; it is totally based upon the evaporation of some
solvent in order to form scaffolds by one of the two routes. One method is to dip the mold
into polymeric solution and allow sufficient time to draw off the solution; as a result a layer
of polymeric membrane is created. Other method is to add the polymeric solution into a
mold and provide the sufficient time to evaporate the solvent that create a layer of
polymeric membrane, which adhere to...
Particulate leaching is one of the popular techniques that are widely used to fabricate
scaffolds for tissue engineering applications (Ma & Langer, 1999; Lu et al, 2000). Salt, wax or
sugars known as porogens are used to create the pores or channels. Here salt is grounded
into small particles and those particles that have desired size are poured into a mold and
filled with the porogen. A polymer solution is then cast into the salt-filled mold. After the
evaporation of the solvent, the salt crystals are leached away using water to form the pores
of the scaffold.
All surfaces are rough. The world of the engineer is made of solids whose surfaces acquire
their texture as the result of a great variety of processes. In some cases it is merely a byproduct
of forming the bulk shape, for example, in casting, molding, or cutting. More often a separate process affecting only the surface layers is applied after the part has been formed to its bulk dimensions. Some treatments remove material, as in grinding and etching. Others,such as plating, flame spraying, and sputtering, add it. ...
This standard is issued under the ﬁxed designation C 59/C 59M; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the Department of Defense.
Polymer micromolding is a common way to ma
microchannels, because of the ease of processing, low co
and bio-compatibility. Molds with micron-scale featur
may be made from photosensitive polymers (e.g., SU-8)
by DRIE silicon micromachining. Poly(dimethylsiloxan
(PDMS) is often chosen as the microstructural materi
. PDMS is spin cast onto the mold, cured and peel
off. A short exposure in an oxygen plasma activates t
PDMS surface and results in instant bonding to oth
PDMS or glass surfaces.