Steel Clutch Lever Reclamation Using Flame Spray
Reason for use: Repair of worn pressed steel clutch levers.
The wire flame spray reclamation of clutch and many other automotive components has now become common practice. By using the flame spray process, considerable savings may be made over replacement costs.
Savings of up to 50% are common, where on large components savings of up to 90% may be achieved. The requirement for metal spray may be to repair an obsolete part, correct manufacturing errors or apply hard-facings onto areas prone to excessive wear in use.
Equipment: Metallisation MK 61 Flame Spray System
Materials: Molybdenum Wire
Cleaning
- Steam clean if equipment available.
- Degrease by solvent vapour if equipment available.
Preliminary Inspection
Check for cracks or faults taking lever below the manufacturers recommended operating tolerances.
Note: Metal Sprayed deposits do not import any strength to the base material.
Preparation
- Preliminary Machining - Grinding or linishing may be used to remove any major scoring on level tips, blending in to form a uniform and concentric base.
- Masking surfaces adjacent to area requiring treatment with a heavy duty masking tape. Thoroughly inspect for contamination prior to blasting.
Blasting
Thoroughly blast area to be metal sprayed with clean n° 30-36 Grade Aluminium Oxide Grit.
Application of Sprayed Coating
Masking
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Apply No Bond masking fluid using a small brush to all areas adjacent to the area being sprayed. Ensure fluid is not applied to area being metal sprayed. (Small amounts of masking fluid on area to be sprayed can be removed with emery cloth).
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Check thoroughly that area to be sprayed is free from contamination.
IMPORTANT: Areas to be sprayed should not come into contact with oil, grease, hands or any other form of contamination.
Note: Masking is not always required when spraying clutch release lever tips.
Spraying
Spraying should be as soon as possible after preparation and before any visible sign of deterioration occurs. A multiple of levers should be set in a fixture or laid in line ready for treatment.
- Bond Coating
A deposit of Molybdenum Wire is applied to a deposit thickness of 0.05mm-0.15mm (0.002”-0.006”) at a range of 75mm (3”). The spray stream should be at 90° to the surface being coated and traversed by hand at a surface speed of not less than 18 metres/minute (60 feet per minute). - Main Deposit
Continue to spray the main deposit of molybdenum using the same spraying parameters as the bond coat but increase spray range to 100mm-150mm (4”-6”). Complete the spraying of the main deposit traversing the spray head to give a uniform coating over the lever tips. The final deposit thickness will depend upon the condition of lever tips prior to spraying and should be adjusted accordingly.
Note: If a hard final deposit is required, oxygen pressure should be increased after bond coat is completed.
Spraying Parameters of Metallisation MK61 for Molybdenum Wire
- Acetylene Pressure: 1.03 bar (15 psi)
- Oxygen Pressure: 1.9 bar (30 psi)
- Air Pressure: 4.5 bar (65 psi)
- Flowmeter Pointer Settings: Gas 5.5, Oxygen 2.25
Finishing
Under normal circumstances, it is possible to use the component in the as sprayed condition without any problems but for cosmetic purposes, a light polish may be required.
