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Twin Screw Extruders

CLEXTRAL

BIVIS TECHNOLOGY: PRINCIPLE & FUNCTIONS


The twin screw extrusion process developed by CLEXTRAL over the past 50 years enables continuous production, using natural or synthetic raw materials, of homogenous compounds for the agro-industry, paper and plastics and chemical industries.
The active part of the machine consists of 2 identical co-rotating and intermeshing screws, hence the name "twin screw extruder".
The screws are mounted on shafts, supported by bearings and rotate inside a fixed closed housing called "barrel".
To adapt this equipment to different industrial applications, the screws, which perform most of the work of transporting, conveying, mixing, compressing, kneading or shearing of raw materials, have been designed to be totally modular.
Their composition, basically screw segments are stacked one beside another on a splined shaft, can be rapidly modified depending on the products to be processed and the final product desired.
Process department would help you in those compositions; CLEXTRAL technical specialists to choose the best metallurgy according to the raw materials abrasion and corrosion properties.
The twin screw technology has the advantage of creating continuous process, which is both flexible and easy to automatize.
The multifunctionality of this technology improves the compactness of the equipment, reduces the investment costs, often uses far less water and allows the use of greater diversity of raw materials.
This continuous process machine has multiple functions : conveying, melting, shearing, mixing, cooking, cooling, defibering, washing, bleaching, shaping... according to the industrial applications.

The screws and the barrel

Intelligently designed for longevity and ease of use.


A hallmark of CLEXTRAL twin screw extruders is their flexibility; CLEXTRAL engineers have taken the modular concept one step further, with designs that make it simple to change and remove extruder barrels, screws and dies, making it easy to play on production parameters.
Screw elements slide onto the splined shafts to allow numerous configurations of the screw profiles for optimum processing.

The modular barrels are configured using easy to remove clamp fixtures for ease in adding or removing barrel segments for changing process requirements.
Barrel and screw metallurgy options provide solutions for virtually all processing applications; from standard nitrided hardened steel to special industrial alloys that are proven in production to withstand most abrasive and corrosive processing conditions.

According to extruder models, the barrel modules length can vary from 100mm to 700mm.
Same thing for a screw element with a wide range of shapes according to the functionalities required inside the barrel.



CLEXTRAL has introduced many companies to twin screw extrusion and helped them achieve impressive results. Whether you have a new product idea to be turned to reality or wish to optimize the production of an existing product, we can make it for you.


CLEXTRAL has supplied 1,300 extrusion systems to different companies since 1957, from small family-sized companies to huge multinational groups.



For agro-industrial applications, the range of extruders includes 7 BC machines and 5 Evolum machines :

BC RANGE * Figure given for the distance in millimeters between the 2 screw shafts center	EVOLUM RANGE
BC21*- screw diameter 25mm	EVOLUM HT 32* - screw diameter 32 mm
BC45*- screw diameter 56mm	EVOLUM HT 53* - screw diameter 53 mm
BC72*- screw diameter 88mm	EVOLUM HT 68* - screw diameter 68 mm
BC92*- screw diameter 115mm	EVOLUM HT 88* - screw diameter 88 mm
BC 160*- screw diameter 200mm	EVOLUM LT 145* - screw diameter 145 mm

Different motorizations are offered according to the gear ratio and torque requested.



Three versions are offered, and among them the sliding opening barrel being unique within extruder manufacturers:

• H version : available for all range of machines; machine frame equipped with an hydraulically operated sliding barrel system;the module capacity goes from 2 to 9 standard barrel modules.
• OS version : available for BC45/BC72/BC92; machine frame equipped with a mechanically operated sliding barrel system (handwheel); the module capacity ranges from 2 to 6 modules.
• NS version : available for all models; the module capacity goes from 2 to 12 modules; a simple structure without sliding barrel system and no further modification of the barrel length.



For pulp and paper applications, the range includes 2 machines called BIVIS :
KRO 102* EV PAP 240 
KRO 200* EV PAP 240
Those 2 machines are proposed with a long or short barrel according to the process and chemical treatment given to the fibers.
There is a different barrel opening system, clam shell opening system.

CLEXTRAL is your reliable source for extrusion processing systems from a single machine to turn key processing line for the food, feed, chemical, plastic and paper pulp industries.