A core is a preformed baked sand or gren sand aggregate inserted in a mold to shape the interior part of a casting which cannot be shaped by the pattern.
A core box is a wood or metal structure, the cavity of which has the shape of the desired core which is made therein.
A core box, like a pattern is made by the pattern maker. Cores run from extremely simple to extremely complicated. A core could be a simple round cylinder form needed to core a hole through a hub of a wheel or bushing or it could be very complicated core used to core out the water cooling channels in acast iron engine block along with the inside of the cylinders.
Dry sand cores are for the most part made of sharp, clay-free, dry silica sand mixed with a binder and baked until curred, the binder cements the sand together. When the mold is poured the core holds together long enough fort he metal to solidify, then the binder is finely cooked, from the heat of the casting, until its bonding power is lost or burned out. İf the core mix is correct fort he job, it can be readily removed from from the castings interior by simply pouring it out as burnt core sand.
(C.W. Ammen, The Complete Handbook Of Sand Casting,1st edition, page 80)
Face mill
Face milling is a machining operation that controls the height of the machined part. For most applications, face milling is a relatively simple operation, at least in the sense that it usually does not include any difficult contouring motions. The cutting tool used for face milling is typically a multi tooth cutter, colled a face mill, although end mills may also be used for certain face milling operations, usually within small areas. The top sufaces machined with a face mill are generally perpendicular to the axis of the facing cutter. In CNC programming, the face milling operations are fairly simple, although two important considerations are critical:
a) selection of the cutter diameter
b)inital starting position of the tool in relation to the part
(Peter Smid, CNC Programming handbook, second edition, page227)
End mill
End mills are the most common tools used for peripheral milling. There is a wide selection of end mills available for just about any conceivable machining application. Traditional end mills come in metric and english sizes, variety of diameters, styles number of cutting flutes, numerous flute designs, special corner designs, shanks, and tool material compositions.
Some of the most common machining operations that can be performed with an end mill – HSS, cobalt, solid carbide or an indexable insert type:
Peripheral end milling and contouring
Milling of slots and keyways
Channel groves, face grooves and recesses
Open and closed pockets
Facing operations for small areas and thin walls
Counterboring
Spotfacing
Chamfering
Deburring
(Peter Smid, CNC Programming handbook, second edition, page275)
Low-pressure die casting
The low pressure die casting process involves holding the molten metal to be cast in a crucible around which are the heateing elements necessary to keep the metal molten. The crucible and elements are contained inside a sealed pressure vessel in the top cover of which is a riser tube whose lower end is immersed in the molten metal. Low pressure air (0.75 bars to 1.0 bar) is introduced into the crucible above the surface of the molten metal and forces the metal up the riser tube and out through the top end. This top end is attached to the bottom or fixed half of the die, which is designed to allow air to escape as the molten metal enters. When the metal has solidified in the die, which is aircooled, the air pressure is released and the remaining molten metal in the riser tube drops.
(Bruce J. Black,Workshop Processes, Practices and Materials, Third Edition,page 291)
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