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Cross head throughput has to match with the attached extruder output to guarantee optimum efficiency of the extrusion line.
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www.microdia.ch Your expert in extrusion needs
March 2013
SWISS MADE
E X T R U D E R O U T P U T / C R O S S H E A D T H R O U G H P U T
N EWSLETTER N O 27 Builder of the largest fixed center
cross head in the world
On an extrusion line, extruder and cross head matching is an important factor to operate with stability and efficiency, therefore extruder output and cross head throughput must be taken into consideration when a line has to be upgraded or the cross head replaced. In other words extruder output and cross-head throughput must be of the same order of magnitude.
Extruder output: Expressed in kilogram/hour or dm3 (liters) per hour. Depends on: 1.- Barrel diameter. 2.- Barrel length. 3.- Screw type. 4.– Extruder speed. 4.- Compound type & properties. 5.- Compound density * *if expressed in kg/hour.
Cross head Throughput: Usually expressed in kg/hour.
Depends on: 1.- Cross head size. 2.- Distributor channel depth. 3.-Compound type & properties. 4.- Compound density.
www.microdia.ch Your expert in extrusion needs
March 2013
SWISS MADE
Well matched extruder and cross
head example:
Extruder 60 - 24D
Extruder speed max: 180 rpm
Compound: PVC
Output at 180 rpm: 275 kg/hour
Cross head Microdia Avantis 20 Standard distributor
Throughput PVC 350 kg/hour
Advantages of a good match: 1.- Good extruder speed level. 2.– Good compound mixing in barrel
Page 2 Newsle t ter No 27
There are two wqys to measure the extruder output.
1.– Line OFF. Output is measured extruding compound through by-pass or cross-head.
The result in kg/hours is calculated from the weight of the samples extruded during 36 seconds (see procedure description on the right)
2.– Line in production.
Extruder output is calculated from line speed and insulation cross section, result is expressed in dm3 ( liters ) per minute..
converts dm3/min into kg/hour.
M A T C H I N G E X T R U D E R O U T P U T A N D C R O S S H E A D T H R O U G H P U T
speed [m/min] x cross section [mm2] x 10^-3
dm3/min x 60 x density = kg/hour
3.– Correct residence time in the barrel.
4.– Correct residence time in the cross head.
5.– No head shear overheating.
6.– Normal barrel pressure.
Extruder output calculation
www.microdia.ch Your expert in extrusion needs
March 2013
SWISS MADE
Page 3 Newsle t ter No 27
New technological compounds can be extruded at
higher speed with Microdia distributors and
tooling.
To solve the problem of speed limitation when ex-truding low MFI and shear sensitive compounds,
Microdia’s engineering developed a range of
special components which can be adapted on any cross head of the 9000 and Avantis series.
The graphic on the right shows the difference be-tween standard and high viscosity configuration of an Avantis 20 in terms of pressure and production
speed
Good matching
T O B E A V O I D E D
Extruder / cross head configuration
Large extruder attached to a sme-
dium size extruder.
Extruder output.: PVC 1300 kg/hour
Cross head throughput:: 350 kg/hour
Configuration shortcomings:
• Low extruder speed.
• Poor mixing in the barrel.
• Excessive residence time in barrel.
• High barrel pressure.
• Stagnation zone in the flange.
• Sharp acceleration between flange
and head entry.
• Heat over-heating by shear.
Not recommended either:
Small extruder attached to a medium
size cross head.
• High extruder speed.
• Short residence time in barrel.
• Excessive residence time in the head..
• Limited line speed.
LSZH, PE + MgOH and other heavy compounds extrusion
www.microdia.ch Your expert in extrusion needs
March 2013
SWISS MADE
News le t ter No 27 Page 4
Head Of f ice Microdia SA Prés du Lac 69bis 1400 Yverdon les Bains Switzerland
Tel: +41 24 447 3500 Fax: +41 24 445 1228
[email protected] www.microdia.ch
USA Microdia USA
P.O.Box 1419
Pawcatuck CT 06379
Alban Adams Director 1-860-495-5788 (phone)
1-401-688-6731 (mobile)
Stephanie Chasseloup
Sales assistant
Microdia Head Office
+ 41 24 4473510
Japan
T.Fukase & Co., Ltd.
Sole agent of Microdia in
Japan
2-10-10 Makuhari Hongo Hanamigawa-Ku,
Chiba, Japan 262-0033
Tel: +81-43-276-0630 Fax: +81-43-276-0463 [email protected]
http://www.fukase.co.jp
LSZH extrusion case study
With the standard configuration designed to run PVC, PP, PE with enough back pressure to guarantee a good compound mixing in the barrel, the barrel pressure limit was making impossible the extrusion of this special formulation
of LSZH and limiting the speed at 10 m/min. The Avantis 20 high viscosity configuration multiplied by almost 10 the production speed, now limited by the extruder’s capacity.
Atlanta Interwire April 23d to 25th
Microdia USA
PO Box 1419 Pawcatuck
CT 06379.
www.microdia.ch
Booth 1824
Personal:
Alban Adams Director North.American sales (English, French)
Jose Noriega Sales Manager Latin America (English,Spanish,French)
Jean Daniel Steiner Extrusion specialist (English, German, French)
