Ads
related to: moulding sand refractoriness
Search results
Results From The WOW.Com Content Network
The cope and drag (top and bottom halves, respectively) of a sand mold, with cores in place on the drag. Two sets of castings (bronze and aluminium) from the above sand mold. Sand casting, also known as sand molded casting, is a metal casting process characterized by using sand—known as casting sand—as the mold material. The term "sand ...
Friability: As the casting or molding cools, the core must be weak enough to break down as the material shrinks. Moreover, they must be easy to remove during shakeout. Good refractoriness is required as the core is usually surrounded by hot metal during casting or molding. A smooth surface finish. Minimum generation of gases during metal pouring.
The history of molding sand is difficult to study, as much of the origins of the practice predate writing. Molding sand was used exclusively for bronze casts, which was pioneered by the ancient Chinese. The next major advancement came in India in 500 B.C. when cast-crucible steel was created.
Refractoriness is the property of a refractory's multiphase to reach a specific softening degree at high temperature without load, and is measured with a pyrometric cone equivalent (PCE) test. Refractories are classified as: [2] Super duty: PCE value of 33–38; High duty: PCE value of 30–33; Intermediate duty: PCE value of 28–30
In casting, a pattern is a replica of the object to be cast, used to form the sand mould cavity into which molten metal is poured during the casting process. Once the pattern has been used to form the sand mould cavity, the pattern is then removed, molten metal is then poured into the sand mould cavity to produce the casting.
The pattern is a model of the desired casting. Talcum powder is often dusted over the pattern to aid in the removal of the pattern. Sand is sifted over the pattern until the model is covered by a few inches of sand. More sand is then dumped into the drag, and rammed with a wooden wedge, or mechanically vibrated to pack the sand down.
A molding sand mixture, usually green sand or bentonite, is blown into a rectangular steel chamber using compressed air. The molding sand is then squeezed between two patterns, which are on the two ends of the chamber. After squeezing, one of the chamber plates swings open and the opposite plate pushes the finished mold onto a conveyor.
Permeability is a property of foundry sand with respect to how well the sand can vent, i.e. how well gases pass through the sand. And in other words, permeability is the property by which we can know the ability of material to transmit fluid/gases. The permeability is commonly tested to see if it is correct for the casting conditions. [1]