Casting machines

Fire-Resistant Hydraulic Fluids. Fire-resistant hydrauhc fluids are used where the fluid could spray or drip from a break or leak onto a source of ignition, eg, a pot of molten metal or a gas flame (17). Conditions such as these exist in die-casting machines or in presses located near furnaces. Specific tests for fire resistance are conducted by Factory Mutual in the United States. 

Fig. 10. Schematic of casting machine used to make microporous membranes by watervapor imbibition. A casting solution is deposited as a thin film on a moving stainless steel belt. The film passes through a series of humid and dry chambers, where the solvent evaporates from the solution, and water vapor is absorbed from the air. This precipitates the polymer, forming a microporous membrane that is taken up on a collection roU (25).

Fig. 11. Schematic of Loeb-Sourirajan membrane casting machine used to prepare reverse osmosis or ultrafiltration membranes. A knife and trough is used to coat the casting solution onto a moving fabric or polyester web which enters the water-filled gel tank. After the membrane has formed, it is washed...

Urethanes are processed as mbber-like elastomers, cast systems, or thermoplastic elastomers. The elastomer form is mixed and processed on conventional mbber mills and internal mixers, and can be compression, transfer, or injection molded. The Hquid prepolymers are cast using automatic metered casting machines, and the thermoplastic peUets are processed like aU thermoplastic materials on traditional plastic equipment. The unique property of the urethanes is ultrahigh abrasion resistance in moderately high Shore A (75—95) durometers. In addition, tear, tensUe, and resistance to many oUs is very high. The main deficiencies of the urethanes are their resistance to heat over 100°C and that shear and sliding abrasion tend to make the polymers soft and gummy. 

Fig. 12. Development of casting machines where S is the end of the supported length and C the cutoff 2one circles represent roUs. A is a vertical mold B a vertical mold with bending C a vertical mold with progressive bending D a curved mold with straightening and E a curved mold with progressive...

After leaving the casting machine, the slab is cooled by water sprays to 180—240°C and fed into the mill, which is generally of the four-high roU type, where a 60% reduction is taken in one pass. The strip is then coiled and, when the casting mn has been completed, is fed back through the mill and roUed at a temperature of 80—90°C, with a reduction up to 50%, to give the required final thickness, finish, and properties. 

The end product is either cast as anodes for electrolytic refining or, rarely, as ingots for sale as fire-refined copper. A horizontal casting wheel with 12—32 horizontal molds is normally used for anode casing. Using continuous casting machines, the copper is cast as a continuous strip to be cut to the required anode shape (28). 

In a continuous casting machine, molten steel is poured into a reservoir at the top of the machine. It passes at a controlled rate into a water cooled mold where the outer shell of the steel becomes solidified. The steel is drawn down into a series of rolls and water sprays, which ensure that it is both rolled into shape and fully solidified at the same time. At the end of the machine, it is straightened and cut to the required length. Fully formed slabs, blooms, and billets emerge from the end of this continuous process. 

Figure 6 76 inch diameter E. B. Blue Co. rotational casting machine... 

Steel sheets, widely used in thousands of products, are produced Irorn slabs from a slabbing mill, continuous casting machine, or pressure-poured molils. These pieces are hot-rolled in a hoi strip mill, descaled bv pickling in an acid solution, and then cold-rolled and tempered m a cold-reduction and temper mill. Tlte cold-tolled snip may he marketed in coil form, or carried to a side-trimming and sheet shearing line, where it is customized lor speeilie user needs. 

---