Applications, Dalton

Extrusion Die Heating

(Article reprinted courtesy of our partners at Dalton Electric Heating Company.)


Extrusion machines can be fitted with a variety of dies. A continuous sheet of plastic employs the use of a sheet die, sometimes called a hanger dies, due to the clothes hanger shape of the plastic channel to the extrusion lip of the die. The die must be heated to keep the plastic viscous and this is accomplished by cartridge heaters.




Heaters are installed from the back of the sheet die, extending toward the lip of the die where the plastic is released as a sheet. The Watt-Flex® cartridge heater has several distinct advantages over conventional cartridges. The hot tip feature of the Dalton heater gets more responsive heat to the end of the bore and the lip of the die for greater production control.


And the sheet die generally has a closed bore, sometimes with a small knock-out hole for stuck heater removal. The Watt-Flex heater will expand in the bore for better heat transfer and contract for ease of removal. Better performance and no seized heaters!



Bore seizures are non existent

A  major aluminum extrusion manufacturer was experiencing a high rate failure rate of electric cartridge heaters used in their process.  The heaters were seizing in the “pusher nose” –  the ram used to push the heated billet through the die.  These “nose heaters” must be kept hot to avoid pulling heat from the billet during the extrusion process.

When the heaters seize, they must be drilled out and the heater holes reamed to smooth out the bore which becomes damaged during the drilling and extraction process. When a new heater is inserted they now had a sloppy fit resulting in poor heat transfer from heater to pusher nose with the heaters sometime falling out.  Needless to say, they were experiencing poor performance and high power usage because the heaters had to run hotter and longer to produce the necessary heat required.

The customer wanted a solution and our salesman suggested using a unique cartridge heater offered by one of our principals Dalton Electric Heating Co., Inc. The “split sheath” cartridges expand up to .020″ over their original diameter – enough to take up the slop created by repeated seizures and drill outs of the old conventional design heaters.  The customer placed a small test order for heaters and we waited for the feedback.  So did we solve the problem for the customer?

Yes,  Bore seizures are non existent since switching to the Dalton heaters resulting in:

1. Reduction in replacement cartridge heater purchases
2. Huge savings in machine shop time drilling out seized heaters
3. Reduced Maintenance time pulling rams for service
4. Reduced power consumption.  How much.  We can’t say for sure because the customer does not measure or keep records of electric power usage by department but we typically see savings of upwards of 20%

This is an example of how we may be able to help you with a production or Maintenance problem in your plant.  Please take a moment to watch the video of the benefits of Dalton Electric Heaters.

Incidentally – we have received several subsequent orders for the Dalton split sheath cartridges from a very happy customer.


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