microdia newletter no 45 square vs round
DESCRIPTION
Wire & cable extrusion cross heads, advantages of square shaped cross heads. Rigidity, stability, long life span.TRANSCRIPT
www.microdia.ch Your expert in extrusion
SWISS MADE
°microdia
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N EWSLETTER N O 45 April 2015
Square vs round.
The square shape is a characteristic of most of microdia’s crossheads since the company
founding more than 30 years ago, and its no accident that this shape is preferred by many satisfied customers.
Basically, the square shaped head is much more rigid compared to the other types of heads, it is
also particularly suitable for rod heating without mechanical strength loss .
The flat top surface of the crosshead, perfectly
parallel with the tooling center line makes levelling of the head easier, absolutely necessary to achieve a good concentricity and limit the wear of the wire guide..
RIGIDITY
Solid prismatic sections in each of the four corner act as reinforcement beams which guarantee the cross head geometric stability during its long life span, even when working at high temperature with
frequent shut down.
STABILITY
LEVELLING
The same hot top surface is ideal to pre-heat the tools to be used for the next product as well as to keep them warm for easy cleaning; it can even be use to heat up a coffee mug !
PREHEATING
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SWISS MADE
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Newsletter No 45 Pa ge 2
Multi extruders cross flow cross head.
Nowadays, most of crossheads are attached to several extruders, at least two and often four. Being the connecting point between those machines it is submitted to extremely high mechanical stress due to the thermal expansion or shrinkage of the extruder’s barrel during the heating and cooling phases. This is particularly critical when the extruder’s frames are not equipped with devices designed to absorb the length variations caused by changes of temperature of the barrel.
If the head is not strong enough to bear the stress, its deformation will result in loss of centring, leaks or even destruction of the crosshead.
STRENGTH
microdia quick color change cross flow
three layers plus stripe.
microdia quick color change main + stripe cross flow
attached to four extruders.
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SWISS MADE
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Newsletter No 45 Pa ge 3
Heating elements.
With the increasing number of attachments to extruders (entries), the shapes of heating collars become more complex with numerous voids arranged to fit the extruder’s connections,
thermocouple and pressure gauge.
The heat distribution cannot be uniform all around the head surface. The heating rods become the only solution for an efficient
and perfectly distributed heating.
Band and plates heaters short commings:
Heat distribution.
The heating collar is exposed to mechanical damages during the head handling, whereas the rod heaters located inside of the block
are fully protected.
Mechanical shocks exposure
Hot spots
Chemical agents exposure
Heat losses
The heating collar is never 100% in contact with the head’s surface, there are many hot spots and the heat distribution is uneven particularly when holes in the collar have been arranged for the passage of pressure gauge,
thermocouples, head holder and connecting flanges.
The Heating collar is exposed to the corrosive fumes and vapors which may be released by the compound at the exit of the head causing the heater’s corrosion and shorter life
time.
50% of the band heater’s surface only is in contact with the head block, the other 50% is exposed to the air, causing an important
heat loss by thermal radiation and convection.
It is obvious that there is an important thermal dissipation at the surface of the head heated by rod heaters too; however, the losses
are up to 20% lower compared to the head with band heater
resulting in more efficient operation and energy savings.
www.microdia.ch Your expert in extrusion
SWISS MADE
°microdia
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Newsletter No 45 Pa ge 4
Thermocouples.
In the round heads, the thermocouples are located between the heaters and the flow
path.
Location
Square crosshead rod heaters are close to the
thermocouple’s tip:
The temperature measurement is much more accurate and a large part of the over-shot occurring during heat heating up is
eliminated.
Heating element failure.
Multiple rods heating
Band heating
Band heater failure means no more heating.
Line must be stopped. All extruders fittings (flanges) have to be
disconnected. Thermocouple nipples, centring screws, a.s.o.
removed. In order to replace the band heater.
With parallel heater connexion, failure of one
heating cartridge only reduce the heating power by 12.5% to 16.6% for respectively 8 and 6 cartridges
heating configuration.
Production is not interrupted.
Cartridge replacement can be carried later on. N.B. Perodical heating cartridges condition is easily
performed measuring the resistance of the
heating cartridges set. [ Ω ]
www.microdia.ch Your expert in extrusion
SWISS MADE
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Newsletter No 45 Pa ge 5
http://www.fukase.co.jp
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
Switzerland USA
JAPAN
microdia USA
P.O.Box 1419
Pawcatuck CT 06379
Alban Adams Director 1-860-495-5788 (office)
1-401-688-6731 (mobile)
skype: alban.adams
P.R China 上海
microdia asia pacific Room A201, Building 3, No. 526,
Swiss Center
3rd East Fute Road,
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200131 Shanghai, China
中国（上海）自由贸易区富特东三路526号3号楼A201室，
陈曙欣 +86-13917923939
祖照亮 +86-18616387577
Germany
Head Off ice & works :
microdia S.A. Prés du Lac 69bis 1400 Yverdon les Bains Switzerland Tel: +41 24 447 3500 Fax: +41 24 445 1228 [email protected] www.microdia.ch
Phi l ippe Chasse loup Sales Manager Deutschland & Austr ia Tel.: +49 171 8654289
Fax: +41 24 445 12 28 E-mail: [email protected]
Skype: microdia deutschland
For USA & Germany
Contact in Switzerland:
Stephanie Chasseloup
Sales assistant
Microdia Head Office
+ 41 24 447 3510
microdia S.A.