TANK
A welded steel tank with an overflow partition and a drain cock at one end and an arrangement for heating is recommended for efficient operation. Lead-lined, galvanized or tinned tanks are unsuitable.
HEATING
Steel or Iron sheathed electric immersion heaters are most suitable. The solution can also be heated by applying heat externally from the bottom. By electric heaters, gas burners or any other source of heat. If steam is available a steam coil of black steel (not galvanized) can be used.
CONCENTRATION
| ‘Usex’ Metal Cleaner | 45gms.-60gms. | Water to | 1 litre |
|---|---|---|---|
| For ABS Usex Metal Cleaner |
90°C (119°F) | Water to | 1 litre |
PREPARATION
The tank should be filled with clean soft water to over half its working capacity and heated to about 70°C, 80°C (160°F). The necessary quantity of cleaner is added in small lots, stirred and fully dissolved after which the level of the solution is built up with clean hot-or cold water.WORKING TEMPERATURE
Ronuk Metaprep HSC solutions are alkaline. Neutralize pH 6 to 8 with an acid and discharge to sewer. The acid must be added slowly and with caution. Avoid eye or skin contact and wear protective clothing and safety goggles.
- For Iron and Steel Articles. Near boiling 90-95°C (200°F) Never below 85°C (185°F).
- For Copper and its alloys such as brass and for tin lead alloys such as pewter and britannia metal: 70°C (160°F)
- For ABS at 50°C to 60°C
OPERATION
The Period of immersion will depend upon the degree of soil and grease and type of metal. The nonferrous metal will require shorter immersion than the ferrous ones. When the article is withdrawn after a few minutes and swilled in clean water there should be an unbroken film of water. Formation of beads or globules of water indicate presence of grease and the articles should be re-immersed for a few more minutes. Persistent film of grease can be removed by swabbing the surface with a cotton hand mop or soft brush.
HANDLING OF ARTICLES
Articles that are to be subsequently plated may be wired or held in racks or jigs. Small articles can be held in baskets made of perforated steel or steel wire. Rolls of strips and bundles of wire can be handled in cradles and large articles suspended by steel hooks.
FLOATING FILM OF OIL AND GREASE
It is very important that the film of unsafonifiable grease or oil that may appear on the surface is skimmed off or floated over the partition weir periodically and drawn off through the drain cock.
MAINTENANCE
The density gives a fair picture of the strength of the solution. It should be maintained at about 4°Baume (6°Twaddel) when cold. Depending upon the quantum of work, regular additions of cleaner at the rate of 7 gms to 14 gms per litre (1 to 2 ounces per gallon) should be made to make up the strength and losses by drage- out. The solution that has become dirty on prolonged use should be discarded and a fresh one made.
ELECTROLYTIC CLEANING WITH USEX METAL CLEANER
GENERAL
A direct current supply at 6 volts is required and the article is made a cathode, when current passes through the cleaning solution, the water in the solution gets electrolyzed and hydrogen at the cathode and the oxygen at the anode are liberated. As these gases rise to the top of the solution they agitate the suspended colloidal matter in the cleaning solution. The vigour of the gas and the moving colloidal matter removes the soil and grease quickly and more effectively. This agitation further removes the solution in the immediate vicinity of the soiled metal surface together with the layer of soil it has wetted and replaces it with a film of fresh solution which is ready for action on the next layer of soil. Cleaning takes place chemically as well as mechanically. High Tensile or hardened spring steels can not be cleaned in this way for the fear of their occluding hydrogen and getting brittle Aluminium and tin-lead alloys electrolytically.
EQUIPMENT
The tank can be made of welded mild steel with a drain cock and a partition at one end and should be fitted with arrangement for heating. A source of direct current supply at 6 to 12 volts should be available. The tank is fitted with wooden capping, insulators and cathode and anode bats. The positive lead may be connected to the tank. But it is advisable to have separate steel anodes hung with hooks of the same metal. For suspending the article in the cleaning solution hooks made of clean iron or steel. preferably heavily coated with nickel, should be used.
A knife switch is fitted near the tank for making and breaking the circuit. A current density of about 2.16 amps. per sq. dm. or 20 amps. per sq. ft. is applied,and the capacity of the generator should be adequate for the total load.
CONCENTRATION AND OPERATION
| ‘Usex’ Metal Cleaner | – | 60gms. |
| Water |
– | 1 litre |
| Temperature | – | 90°C |
| Voltage | – | 6 Volts |
| Current | – | 20 amps. per sq. ft. |
| Period of immersion | – | 2 to 3 minutes |
| Maintenance As described for immersion cleaning | ||