Moly spraying and casting

Published - 29th Apr 2019

Moly spraying is a process used to increase the wear resistance of our aluminium castings. ‘Moly’ is the shortened name for molybdenum – a silvery-grey metal that has the sixth highest melting point of any element (2623°C). It is not found naturally as a metal but rather in various compound forms. When added to various alloys, it increases the strength and wear/corrosion resistance of the resultant materials.

The applications for moly spraying

Molybdenum’s ability to withstand extreme temperatures makes it ideal for use in aerospace and defence parts. In fact, molybdenum was used extensively in armour plating and tanks during the First World War. The Germans used molybdenum-doped steel for heavy artillery instead of traditional steel, which melted from the heat produced by the gunpowder.

In the Second World War, molybdenum was also used as an alternative to tungsten in steel alloys due to its lower density. However, the popularity of molybdenum waned in the postwar years due to its relative scarcity and difficulties in extracting the raw metal.

Advances in metallurgical techniques have overcome these issues and molybdenum is now used extensively in industrial applications – often replacing chromium plating and other techniques. More than 43,000 tonnes of molybdenum are used as alloy agents in stainless steels, cast irons and high-resistance super alloys every year.

At Haworth Castings, we use moly spraying for castings that are destined for high-end aerospace applications – where the parts often need to withstand adverse weather conditions and temperatures.

The process of moly spraying

Molybdenum is sprayed into a pre-formed aperture that is machined into the surface of the casting. The spraying can be carried out in a number of ways but typically molybdenum wire is fed into a spray gun and melted onto the surface. The liquid droplets form a layer on the casting, which then solidifies to form a hardened surface. The casting is usually machined again to ensure a smooth finish.

What are the benefits?

The benefits of this process include:

• Reduced friction and wear (thus providing longer life parts)
• Lower abrasion on any mating parts
• Ease of penetration and bonding to metal surfaces
• Excellent corrosion and chemical resistance

At Haworth Castings, we offer moly spraying and a range of other specialist services to meet all your casting needs. For further information, contact us today at: sales@haworthcastings.co.uk or call +44 (0)1794 512685 to find out more.