newsletter no - microdiayour expert in extrusion swiss made microdia microdia newsletter no 60 page...
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www.microdia.ch Your expert in extrusion
SWISS MADE
°microdia
°microdia
N EWSLETTER N O 60
Die drool .
“Die drool” or “die build-up” is a problem faced by all engineers involved in extrusion process in the wire &
cable industry as well as in precision tubes domain.
During extrusion, some very small resin particles start to stick at the die exit and a kind of ring or part of ring
begins to grow. Under the effect of the heat the ring get progressively scorched, and after a while is dragged
by the extrudate., then a new ring starts to grow again
and again.
Caught along the cooling trough or in the dryer the die
build-up ring can cause a wire break, if not it will remain
on the product and make it unacceptable by the quality
control.
While the line is running, a skilled operator can try to
remove periodically the die build up, but the risk of
damaging the insulation layer is high.
The undesirable accumulation of material around the exit of an extrusion die is observed in many extrusion processes, wire insulation, fiber buffering, tube extrusion, etc. with a wide variety of polymer .
Tooling shape, angles, land, etc. Tooling size. Tooling surface. Die exit shape, sharp, rounded, chamfered.
Compound filling. Mass temperature. Die temperature. Materbatch. And more...
Numerous causes are suspected but die drool seems to depend on a combination of them, reason why it is so difficult to control.
The next page describes the different ways existing to eliminate or at least reduce the die build-up, headache of many wire & cable makers.¨ microdia , on its side has always been active looking for solutions to this problem in cooperation with its customers and is constantly testing new tooling shape and high tech coating proposed by the specialists in this field.
Origins of die drool.
www.microdia.ch Your expert in extrusion
SWISS MADE
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Newsletter No 60 Pa ge 2
A simple way, widely used to destroy the die build-up, but not to stop its generation, is the use of a flame directed straight to the die exit.
As long the wire is moving the flame will not affect the insulation but it will carbonize the die drool as soon as it starts to grow. The flame of course has to be automatically switched off when the line is stopped.
Open flames are not welcome on extrusion lines, particularly when a marking unit working with flammable solvent is installed nearby.
Hot air guns are giving good results without the risks of the flame.
A) Burning the die drool !! a brutal way !!
B) Changing the die shape.
C) Polymer processing aid PPA.
Numerous die shapes have been tested with only some relative improvement. (See next page).
The standard shape designed by Maillefer many decades ago remains the best and the most economical but die drool might appear with some compounds.
C) Internal die coating.
Internal die coating has been tested too and have helped in some cases but they are difficult to apply to small size dies and their life span is usually limited. However, new coating types are coming up regularly, with better performances in terms of efficiency and longevity.
PPA seems to have help reducing and even supressing the unwanted die build-up.
Pellets based on fluoro-polymers added in a proportion of 0.2 to 1 % are said to improve the surface and reduce the extrusion pressure either.
Some wire & cable makers found an optimal formulation, kept secret of course but ready made PPA pellets are proposed by several companies specialized in the field of extrusion additives.
www.microdia.ch Your expert in extrusion
SWISS MADE
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Newsletter No 60 Pa ge 3
Fluoropolymer washer. FEP, PTFE
Holding pin
Sharp edge die exit Chamfered die exit Rounded die exit
Changing the die shape.
First of all we made trials just changing the form of the die exit; sharp, chamfered, rounded without major improvement. In term of machining cost , the sharp edge remaining the best option.
Die exit shape.
Trials have been made with a conical die front. Die build-up seems to have a relation with the polymer type and the angle α, however, the necessity of
adapting the angle to each product makes this solution unpractical for the industry as it multiplies excessively the number of dies required to cover the whole range of cable production program.
Placing a calibrated FEP or PTFE washer in front of the die gave good results but with several shortcomings:
Die construction more expensive. Short life span of the washers. Time consuming cleaning.
α Conical die front.
Ingenious idea.
www.microdia.ch Your expert in extrusion
SWISS MADE
°microdia
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Newsletter No 60 Pa ge 4
microdia anti die drool achievements
Standard extrusion lines.
Based an its long experience in the field of wire & cable extrusion, microdia R&D designed a type of die which is giving good results particularly with LSZH and flame retardant compounds. microdia is interested in a cooperation with customers to continue the development of this new die.
technology. An exclusivity agreement can be considered in order to protect the cooperating customer knowhow. microdia secrecy is legendary, we have never published a customer’s list.
Your knowhow is safe in microdia hands
In this kind of lines, the die is hidden inside of the steam tube fitting, it is not possible to see and remove the die build-up
Unwanted degraded particle of polymer going into the tube will clog filters and pipes. Die build up can also damage the surface of the cable insulation and make the cable rejected by quality control.
Continuous vulcanisation lines (CV lines).
ECOMEX 20
Thermostatic cross
This thermostatic cross head extrudes cross linking polyolefin on a CV line.
Features:
One main layer Colored skin. Bleed out type quick color change. Adjustable gum space. Special die fitting to avoid premature X-linking Special no drool die.
Cooperation
The constant development of new compound is a challenge to the wire & cable industry and to cross head maker like microdia .
Or R&D and field extrusion specialist engineers are constantly seeking innovative solutions in order to overcome the problems encountered by the wire, cable and tube industry and always looking for close and trustful cooperation with the customers for the benefit of both parties.
www.microdia.ch Your expert in extrusion
SWISS MADE
°microdia
°microdia
Newsletter No 60 Pa ge 5 Newsletter No 60
Switzerland USA
Japan
Roger King
Sales Engineer Tube division
13533 Camino Carmel
Del Mar CA 92014 1-858-792 6962 (office) 1-858-442 4587 (mobile)
microdia USA
Alban Adams American sales Director
P.O.Box 1419
Pawcatuck CT 06379
1-860-495-5788 (office) 1-401-688-6731 (mobile)
P.R China 上海
microdia Asia Pacific Room A201, Building 3, No. 526,
3rd East Fute Road
Pilot Free Trade Zone
200131 Shanghai, P.R.China
中国（上海）自由贸易区富特东三
路526号3号楼A201室，
邮编: 200131
Yuca Chen
陈曙欣 +86-13917923939
Brian Zu
祖照亮 +86-18616387577
Germany
microdia S wi s s H e a d O f f i c e & w o r k s : Prés du Lac 69bis 1400 Yverdon les Bains Switzerland Tel: +41 24 447 3500 Fax: +41 24 445 1228 [email protected]
P h i l i p p e C h a s s e l o u p S a l e s M a n a g e r D e u t s c h l a n d & A u s t r i a Tel.: +49 171 8654289 Fax: +41 24 445 12 28 [email protected]
Skype: microdia deutschland
For USA & Germany Contact in Switzerland:
Stephanie Chasseloup
American sales coordinator Microdia Head Office
+ 41 24 447 3510
microdia Germany 深瀬商事株式会社
業務センター
〒262-0033
千葉市花見川区幕張本郷2-10-10
TEL：043-276-0630
FAX：043-276-0463
E-Mail：[email protected]
T. FUKASE AND 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 : [email protected]
http://www.fukase.co.jp
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