Cartridge Heaters versus Oil Heaters
Cartridge Heaters versus Oil Heaters
(OP)
I am looking for data on the pro's and con's of both. Thermal imagery of a cartridge heater compared to oil heated tools? I am not a fan of cartridge heaters and i am trying to convey a message that oil heaters offer a more uniform controlled heat across the the tool compared to cartridge heaters. Any help is appreciated..






RE: Cartridge Heaters versus Oil Heaters
Oil does have associated costs, mess and OH&S issues.
Regards
Pat
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RE: Cartridge Heaters versus Oil Heaters
Know of at least one rubber molding shop that junked all their cartride-heated mold tooling, and converted to steam heat, for a net savings (mainly due to faster cycle times, but also no more repair of broken heaters, and lower scrap rates due to inconsistent heat). Dunno if that can be applied to a plastic molding machine?
RE: Cartridge Heaters versus Oil Heaters
Not so. It depends where and how many oil channels/cartridge heaters there are and their positioning relative to the cavity surfaces, along with the thermal mass of the tool.
We use both, and the real problem with cartridges is keeping the tool cool - especially if fast cycling or substantial mass of the the parts.
btrueblood: The problem with oil is if a pipe bursts - hot oil @ 150°C or so spraying everywhere is a bit of a problem. It's always a very high flash point oil. It's also messy to clean up.
Cheers
H
www.tynevalleyplastics.co.uk
It seems to me you have confused a safe drinking limit with what I like to call "lunch"
RE: Cartridge Heaters versus Oil Heaters
I really dislike cartridge and strip heaters for the fact that one can rarely place them optimally. Hot spots can be more than a nuisance, they can ruin the processing parameters of an otherwise good tool.
Do you have mainly heat input, or do you need to regulate both a heat and cool cycle?
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.
RE: Cartridge Heaters versus Oil Heaters
Both types of heating can be poorly designed or well designed. A poorly designed oil system will result in cold spots. A poorly designed cartridge system will result in hot spots and, perhaps, cold spots.
One important point that many overlook is that it is not possible to have high heat fluxes and very uniform temperature. Where there is heat flow there must be temperature gradients.
RE: Cartridge Heaters versus Oil Heaters
Hot oil under pressure does not evaporate when released so it travels further and soaks through clothing and retains heat to transfer to the body more than steam does.
Small leaks and spillage when changing moulds also causes a slip hazard.
I have seen both cartridge and oil used successfully and unsuccessfully on thermoplastic GF PET where a mould surface temperature on ejection should be at least 130 deg C (I think from memory) to obtain optimum crystallization and properties and consistent and predictable shrinkage/warpage is dependent on that level of crystallization at all points within the moulding.
Temperature gradients always exist and change continually throughout the cycle. Keeping the material cooling rate optimum is the art or skill in placing mould cooling/heating media.
For thermoplastics, so called mould heating is actually controlled mould cooling so it does not cool to fast. If ambient air cools the mould to fast, cartridge heaters reduce the cooling rate by offsetting air cooling. Thermoplastic in it's molten or mouldable state is always hotter than when ejected, so heat is always removed while in the mould. Controlled rate of heat removal from exactly where you want it removed is the secret to success.
Oil generally gives you more scope for better control, but it still has to be done right.
Regards
Pat
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RE: Cartridge Heaters versus Oil Heaters
Hmmm...perhaps plutonium molds?
RE: Cartridge Heaters versus Oil Heaters
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.