The importance of emulsions for Aluminum drawing – Part 2
Technical Support for Aluminum Drawing Oils
The technical service and support for aluminum drawing oils to determine the overall condition and suitability for continued use, are routinely as follows.
The analytical tests carried out are as follows:
- Kinematic Viscosity @ 40 c, cS.
- Specific Gravity @ 15c
- Acid Value mgKOH/g
- Moisture Content p.p.m.
- Ash Content, % expressed as Aluminum and Aluminum Oxide
Each test is important in its own right, but collectively gives an indication of the lubricant system condition and suitability for continued use.
Appearance – This is a primary condition check, often viewing the lubricant colour, contamination of aluminum fines and their particle size. The odour will also be checked.
Kinematic Viscosity – Measured to determine any increase due to aluminum fines contamination and aluminum soap content.
Specific Gravity – This value is required as the viscosity is recorded by a rotary viscometer in units of centipoise. The S.G. converts the value back into centistokes and therefore can be related to the standard value of the lubricant grade.
Acid Value – Indicates the degree of oxidation that is taking place within the drawing oil, in particular the lubrication additives.
Moisture Content – Measured by the „Karl Fischer‟ method, this value is very important, as moisture will have an immediate effect on the lubricants performance. Moisture will vaporise in the die due to the die temperature thereby causing a compressible gaseous area between the wire and the die. Contact between the surfaces is highly probable which will cause heavy die wear and wire scoring; severe cases of which will stop production.
Ash Content – This value records the amounts of aluminum fines and oxides circulating in the system. These can have a dramatic effect in the Kinematic Viscosity and can be abrasive to the dies and capstans.
The analytical tests are carried out as routine when the customer sends a sample for analyses. The frequency of which will bfrom monthly, quarterly to yearly dependant on the customer and the condition of the drawing oil system.
Neat Oil Filtration
Neat aluminum drawing oils can be temperature controlled and also filtered, filtered of oxides, aluminum, debris, soap and moisture. There are many methods and types of equipment available on the market, all have varying cost, effectiveness and maintenance requirements. The best system for the filtration of aluminum drawing oils is by centrifuge. A simple low cost 3 to 5 micron high speed centrifuge can remove soaps, fines and moisture from the drawing oil to extend the drawing oil life and keep the drawing oil in good condition provided the centrifuge is properly maintained.
Neat Oil Summary
The majority of the industry use neat oils for the drawing of aluminum and aluminum alloys from rod to fine wire, the drawing oils with new performance additives can run very well and the drawing machine can have an acceptable productivity.
This is provided that the drawing oil is maintained, temperature controlled and filtered, additionally the testing of a neat oil will take place in a laboratory hence real time data is not available.
The question is how a factory can increase output from the drawing machine; drawing oils can provide good performance with both, for and against arguments as to their suitability. They also can be restrictive in increasing performance in terms of speeds of production or susceptibility to contamination. The wire industry should consider moving forwards and embrace new emulsion technology to improve the production.