Improving the air knife process in Hot Dip Galvanising

Key Information

How Air knives perform in Hot Dip Galvanising affect coating weight (cost) and the appearance of modern cars.

Air knives are essential equipment in the process of car body manufacturing, since present steel car bodies are manufactured from galvanised material, e.g from Tata Steel Llanwern ZODIAC line. In the process of galvanising a steel strip is pulled through a bath of molten zinc and the zinc coating would be 200 µm without any measures; much higher than the required 10 µm coating thickness. Therefore, the thickness of the liquid film on the metal sheet needs to be reduced by 90%.

For this task in a galvanising line air knives are used. These ‘knives’ blow a high velocity gas jet on the strip through a slot, and the shear force induced on the strip reduces the coating to the desired level; the gas flow of this gas jet is of turbulent nature and therefore inherently unstable. Only recently, the effect of this instability on the surface has been investigated, and in this research it has been found that the interaction between the jet and the liquid metal is a source for irregularities on the final coating. These surface irregularities very well can be responsible for an unwanted surface appearance known as ‘orange peel’.

More knowledge on this process will improve the surface appearance thus more premium product can be produced. Furthermore, the air-knife process is limiting line speed. It is anticipated that increased knowledge could extend production capacity. Finally, improved layer homogeneity reduces zinc consumption, resulting in huge potential savings.

Project Aims

·       Build an air knife CFD model

·       Use this model to identify the influence of air knife design and geometrical parameters

·       As follows, optimise air knife design

·       Design validation by a 150 mm wide air knife model on Tata Steel IJmuiden compressed air fed test stand

·       Validate optimised design in full scale on Tata Steel IJmuiden galvanising water model.

Suitable candidate 

Background in physics/aerospace preferably with knowledge on fluid dynamics


Sponsoring Company Tata Steel

Candidates should hold an Engineering or Physical Sciences degree with a minimum classification level of 2:1 or equivalent relevant experience. 

 Our funders require applicants to also meet the following eligibility criteria:

  • You must be a UK or EU citizen (i.e. eligible for ‘home’ tuition fees at the University) and have the right to work in Wales at the end of your studies.
  • You must be resident in West Wales and the Valleys at the point of enrolment and throughout the duration of your studies.
  • You must not be financially able to participate without the award of grant funding.

Further information regarding eligibility criteria can be found at: http://www.materials-academy.co.uk/eligibility

The Athena SWAN Charter recognises work undertaken by institutions to advance gender equality. The College of Engineering is an Athena SWAN bronze award holder and is committed to addressing unequal gender representation.


The studentship covers the full cost of UK/EU tuition fees, plus a tax free stipend of £20,000 p.a.

Closing Date 28 February 2018

Start Date October 2018

Apply Now

Informal enquiries about this studentship are welcome and may be directed by email to: M2A@swansea.ac.uk