You asked: What is ‘Throwing’ in Metal Finishing?

If you have ever worked with or been quoted any sort of metal finishing process then you may have come across the term ‘throwing’ but what exactly does this term mean?

Throwing is short for throwing power. It is defined as the measure of a metal finishing solution’s ability to plate a uniform thickness, on the surface of an irregular shape.

This is normally categorised into poor, medium or good, with good throwing power being represented by an entire surface plated/coated with a uniform thickness and poor throwing power being where an item has built up in some areas but not in others. There are a number of different factors that might affect the throwing power of any particular process and this includes…

Component Condition – As we have often said, Pre-Treatment cleaning is often the most critical stage in ensuring effective metal finishing. It is important that all traces of oils, dust, dirt etc are removed. Depending on the material used and process specified, parts may also need to undergo a process called ‘Activation’ this is defined as the “elimination of a passive condition on a surface” and usually refers to the removal of a naturally occurring oxide layer.

Material/Production Method- Similarly the material and the process in which the component is created can have an impact on throwing power. As an example Cast Components may be heavily oiled and often contain sand residue on the surface and a high carbon content, making them challenging to plate.

Bath Chemistry- There are a number of different factors within the metal finishing environment itself which can affect Throwing Power. This includes an imbalance in the bath chemistry itself, the temperature within the bath being too high or low, poor electrical contacts, passive anodes, current density being too low.

As you can see above, ensuring that any given process has the best possible throwing power is not necessarily straight forward. This is the reason Silchrome employ a skilled team of technicians and operatives. Silchrome provide a very wide range of metal finishing processes including: electro-plating, conversion coatings, specialist coatings as well as paint and powder coating. We are fully ISO 9001 and 14001 certified and based in Leeds, West Yorkshire.