The technical department of WM, which designs and manufactures complete in-line systems,
is offering a new extruder line, the N.EXT, which promises higher productivity, energy saving
in terms of less cooling and less installed power, wear reduction, very good self-cleaning,
and the highest percentage of regrind possible.
The range of extruders includes screw diameters of 45-75-90 mm, L/D (length/diameter) ratio
of 36 and output capacity range from 450 to 900 Kg/h for Polypropylene material. All the
extruders are single screw operated by water-cooled AC motors for high-energy efficiency and low
noise emissions. All cylinders and screws are made of nitride steel, but special versions made of
bimetal and stellite (tipped hard metal) are available upon request, for the processing of filled materials.
Particular care has been dedicated to the design of the screw profile in order to obtain a better and
optimal homogenization and plasticization values of the material. The temperature control settings
are made through the industrial PC B&R operated by touch-screen.
Special stainless steel covers protect the heating zones and can be easily removed for maintenance.
All extruders are supplied with continuous hydraulic screen changers in order to avoid material
flow interruption. A separate hydraulic power unit for the filter exchange can also be supplied to
be used with other co-extruders.
A gear pump system is supplied as standard on all the main extruders to eliminate the possible
pulsations during the melting process, guaranteeing constant and uniform feeding of the extrusion
flat die head. In case of additional extruders, a co-extrusion feed block is installed before the flat
die head, in order to distribute the material flow in different layers in function of the sheet characteristics
required for the final product. The extrusion flat die head is provided of a flexible lip adjustable
through nuts that works by pulling and pushing to control the sheet thickness, while the deckling bars
adjust the sheet width manually.
The vertical calendars are available in different versions, according to the extruder and the required
output capacity. The standard version is mounted on a rail while a motorized system provides the
correct positioning during the operating cycle.
The main structure of the calendar is made of three chromed mirror-polished cylinders with
the correct hardness degree. The three cylinders are installed on a vertical axis. They are
individually driven by means of a servomotor. The hydraulic pistons, on the other hand, activate
the opening and closing of the upper and lower cylinder. Inside the cylinders, a special multi-principle
spiral cooling circuit guarantees the best temperature uniformity on the surface, which is in contact
with the extruded material.
The calendar is completed by the draft gear made of two rolls located on a vertical axis.
The lower roll consists of a chromed surface and is driven by a motor, while the upper roll is
rubber coated. Opening and closing operations are achieved by pneumatic pistons. All calendars are
supplied with a thermoregulation central unit with three independent circuits.
A separate air-conditioned control cabinet completes the extrusion line with easy access for the
operator. The machine parameters are displayed on the user-friendly touch screen operating
panel by B&R including a USB port that allows all your data storage.