INTERNAL HIGH PRESSURE FORMING
HFA-fluids used for IHF (Internal High pressure forming) in water hydraulic systems
HFA-fluids used for IHF (Internal High pressure orming) in isostatic presses
Outer lubrication at IHF
HFA-fluids in entire application –
Experiences and suggestions at application of lubricants for inner and outer lubrication at IHF
Due to experiences with HFA-fluids used in water hydraulic systems, particularly at application in isostatic presses, it is known, that coarse-particle mineral oil emulsions are almost unsuitable, because of instability at high pressures, some above 2 000 bar, and even on isostatic presses about 6 000 and 8 000 bar. They are only applicable with a large amount of costs, because they show separation occurrencies even at low pressures (strokes). Meanwhile these experiences are well known at all IHF plant manufacturers. But there are still manufacturers of IHF plants who did not adapt market experiences.
For pressures between 2 000 and 6 000 bar synthetic fluids fit best, because they form solutions and not emulsions. Synthetic based HFA-fluids are highly aging-resistant and can be enriched with high pressure additives like mineral oil based fluids, according to the needs of the lubricating value.
MKU has many years of experience with the series Pressol® Spezial MF in water hydraulic systems, particularly with the application of HFA-fluids in isostatic presses with high pressures.
Outer lubrication, if necessary anyway, can be adapted to synthetic HFA-fluids by two options.
- Concentrate of synthetic HFA-fluid (Pressol® Spezial MF 326-3) is in pure condition usable for outer lubrication and mixes afterwards with the circulating HFA-fluid. High performance lubricity values are sufficient in majority of cases.
If this is not required, there is a second alternative
- Products on basis of high performance drawing oils with demulsifying effect may be valuable for outer lubrication, as they can be skimmed or separated effortless from circulating synthetic HFA-fluids, due to this demulsifying effect.
As a result of this effect, HFA-fluid for internal high pressure forming is not loaded, allowing longer service life (durability of solution) in comparison to emulsions.
Special, specialised external lubricants would be the series Putrol® NW V 1442 and the series Putrol® NW V 1679.
Experiences made over years show, that with former mentioned combinations also such systems can be made reliable which had negative results with mineral based emulsions.
In addition to this there are some more options, to make outer lubrication more reliable for production. These options are the use of:
- Bonded coatings, partly with molybdenum disulfide (MOS2)
- MOS2-containing substances like greases or as spray medium etc.
At the latter, relevant tool pretreatments may lead to the wanted results, as diffusing of MOS2-particles into the tool is not desired in many cases.