Twin shaft machines

Blending and mixing are important unit operations in the polymer blend industry. Hancock patented the first internal mixer in 1923. Freyburger in 1876 improved the device to a more efficient counter-rotating twin-shaft machine. The Banbury mixer is a modification of this patent. The Parrel Co. introduced two-roll mills, then the Ram extruder surfaced in 1797. Screw machines that were capable of manufacturing... 

Working load. The efficiency drops off quickly as the load decreases. The more the load is decreased from 100% rated capacity, the steeper is the decline in the machine performance. The decline in performance depends on the machine and the control system. For example, at 70% of full load, the ratio of the part-load efficiency to the efficiency at full-load might vary typically between 0.95 and 0.85, depending on the machine and the control system. Twin-spool machines have a better part-load performance than single-shaft machines. Part-load performance depends on the size of the machine. 

Flow laminations, laminations caused by inner gliding surfaces, and cutting laminations, all can be distinguished to varying degrees in the extrusion of plastic bodies, independent of the extrusion method employed, e.g. piston extrusion presses, single-shaft extruders, twin-shaft extrusion machines or rotory-type extruders. 

Mixing. The oldest processing operation is mixing. The first patent on an internal mixer, an annular container with a spiked rotor, was granted to T. Hancock in 1823. A more efficient, coimter rotating twin shaft internal mixer was patented by Freyburger in 1876, and its modified versions by P. Pfleiderer [1882] and B. F. Banbvuy [1916]. The two-roll mill was invented by E. M. Chaffe [1836], and manufactured by Farrel Foundry and Machine Co. 

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