Microdia newsletter No 34 head heating
3
www.microdia.ch Your expert in extrusion SWISS MADE °microdia °microdia N EWSLETTER N O 34 Cross head heating systems: Band heater Pros: Available everywhere. Easy to connect (cord plug). Cons: Exposed to impacts, easily damaged. 50% of the surface not in contact with the head. Numerous passage holes reduce heating surface and weaken the heater. Uneven heat transfer between heater and head body, hot spots. Short life span. Thermocouple sensing point between heater and flow path, risk of temperature overshot during heat up. In case of failure, line has to be stopped to replace the heater. >> heat only << Rod or cartridge heater Cons: Spares not available everywhere. Rods to be connected by maintenance crew. Pro: Long life span. Protected against shocks. Protected against corrosive gas (fluoropolymers). 100% in contact with the head body. No hot spots, even heat transfer between heater and head body. Thermocouple sensing point close to the heating elements, no risk of temperature overshot during heat up. If one element fails, more than 85% heating power remains available. High heating power, working temperature is reached much faster. April 7—11 Wire Düsseldorf Germany Hall 11 Booth D27
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Comparizon between band heater and heating cartridges.
Transcript of Microdia newsletter No 34 head heating
www.microdia.ch Your expert in extrusion
SWISS MADE
°microdia
°microdia
N EWSLETTER N O 34
Cross head heating systems:
Band heater
Pros:
Available everywhere.
Easy to connect (cord plug).
Cons:
Exposed to impacts, easily damaged.
50% of the surface not in contact with the head.
Numerous passage holes reduce heating surface and weaken the heater.
Uneven heat transfer between heater and head body, hot spots.
Short life span.
Thermocouple sensing point between heater and flow path, risk of temperature overshot during heat up.
In case of failure, line has to be stopped to replace the heater.
>> heat only <<
Rod or cartridge heater
Cons:
Spares not available everywhere.
Rods to be connected by maintenance crew.
Pro:
Long life span.
Protected against shocks.
Protected against corrosive gas (fluoropolymers).
100% in contact with the head body.
No hot spots, even heat transfer between heater and head body.
Thermocouple sensing point close to the heating elements, no risk of temperature overshot during heat up.
If one element fails, more than 85% heating power remains available.
High heating power, working temperature is reached much faster.
April 7—11 Wire Düsseldorf Germany
Hall 11 Booth D27
www.microdia.ch Your expert in extrusion
SWISS MADE
°microdia
°microdia
Newsletter No 34 Pa ge 2
>> heat / cool <<
Thermostatic with fluid circulation
PUR Thermostatic control is the future of the head’s
temperature regulation.
Prior to the line start, the fluid circulation brings the head to production temperature, it will cool it down during the run, when the heat generated by the mechanical friction of the compound
needs to be dissipated.
Compared to electrically heated cross heads, high-
er production speeds can be achieved.
Most of microdia cross heads can be supplied with
thermostatic heat/cool system.
TPR
XLPE
ecomex TH with steam tube fitting
and bleed out quick color change
Water. Thanks to its good heat conducting properties the water is the most frequently used heat
transfer medium in the industry.
Water is easier to use, cheap, and non con-taminating, but the pressure may become a safety hazard at high working temperatures,
not acceptable in many cases.
Corrosion and scaling can be serious issues if the quality of the water is not periodically checked and modified when its composition,
dissolved minerals, oxygen content etc. .
Oil. Oil is also a good heat transfer medium and has a wide range of operating temperatures. It is
corrosion free and has a long life span, but it is also a contaminating agent and care must be taken in case of leaks when the heat exchanger is cleaned or repaired, oil must be disposed of
according to local regulations.
Open circuit systems operate up to 150°C, pres-surized equipment with cold oil cooling are de-
signed for operating temperatures up to 350 °C.
Thermostatic fluids.
Pro:
More accurate temperature control.
No overshot at heat up.
Superior thermal stability.
Compound mass temperature better control.
Cross head longer life span, no thermal shocks.
Extremely reliable.
Cons:
Needs thermostatic fluid circulation unit. but nowaday such devices are not expansive.
Cross head: thermostatic heat/cool option.
To be avoided absolutely !
Electrical heating and Cold water cooling
Cross head temperature constantly oscil-lates and never stabilize.
Thermal shocks inside of the hardened steel head when cold water is injected in the hot head, will result in early structure alteration and premature head failure.
www.microdia.ch Your expert in extrusion
SWISS MADE
°microdia
°microdia
Newsletter No 34 Pa ge 3
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Pawcatuck CT 06379
Alban Adams Director 1-860-495-5788 (phone)
1-401-688-6731 (mobile)
skype: alban.adams
http://www.fukase.co.jp
T.Fukase & Co., Ltd.
Sole agent of microdia in Japan
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Chiba, Japan 262-0033
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