FREQUENTLY ASKED QUESTIONS

 

Does the component suffer from distortion from the heat used in the process?

Answer : No, a wide variety of surfaces and substrates can be coated with no distortion. This includes thin wall components and fabrications. Ancillary cooling (compressed air or CO2) can also be employed if required.

 

Is it possible to coat flat surfaces?

Answer : Yes, a wide variety of geometries can be coated. Large flat surfaces can be processed. Precise manipulation methods can ensure that a uniform and controlled coating thickness can be maintained if required.

 

Can you coat non-metallic substrates?

Answer : Yes, materials such as plastics, wood and even paper can be coated depending on the coating choice.

 

How strong is the bond, will it come off?

Answer : The processes employed in the thermal spray industry normally utilise a mechanical bond between the coating and the component. Depending on the energy of the spray gun employed, bond strengths as high as 80MPa can be produced. If post treatment is carried out, reactions with the substrate will create a bond of an even higher value.

 

Can you deposit ceramics as well as metalics?

Answer : Almost any metallic or ceramic material (as well as plastics) can be made into a powder. Once this powder has been produced to the correct size (and so far its melting and vaporisation temperatures are not too close) it can normally be sprayed by one of the thermal spray processes in order to build up a functional coating. Coating compositions can be tailored to exact customer requirements.

 

Can you coat high volumes?

Answer : Yes, the thermal spray process is ideally suited to high volume applications. Specific manipulation devices can be designed in order to cope with many varieties of parts. Typical high volume applications include for example piston rings, lamda sensors and kitchen irons...

 

Can you coat complex shapes?

Answer : Many complex geometries can be coated. With the use of multiple axis robotic systems difficult shapes can be uniformly processed. Special guns have also been developed in order to coat internal diameters down to diameters as small as 40 mm.

 

Is your process environmentally friendly?

Answer : The thermal spray process utilises closed loop systems for the collection of waste products such as over-spray material. These materials can then be bagged and re-processed if required. As these products are dry they can be easily handled.

 

Can you turn or grind the coatings after spraying?

Answer : Yes post machining of most coatings is a standard requirement. Depending on the hardness of the deposit the coating can either be turned, ground or indeed diamond ground.

 

Can you get a high finish?

Answer : Depending on the choice of coating, very high finishes can be achieved. Less than 2 micro-inches can be achieved with the denser coatings.

 

How hard are the coatings?

Answer : Because of the almost infinite choice of material compositions which can be sprayed, the hardness of the material can be defined exactly as per the application requirements. Typically, however, the hardness range will be at a minimum of 100Hv for metals up to a maximum of 1500 Hv for carbide coatings.

 

How does the process work?

Answer : The process uses a heat source to soften and accelerate a consumable material (powder or wire) onto a substrate to be coated. Relative motions part /gun allows a coating to be built up via a series of passes.

 

How long does the process take?

Answer : The time taken in order to produce a coating is directly related to variables such as part size, coating thickness and consumable feed rate. However, compared to processes such as electroplating, process times can be as low as 10% of those needed to build up the same thickness.

 

Will the coating operate in high temperatures?

Answer : Various coatings have been designed to run at temperatures greater than 1000 °C. The two main deposits employed are Thermal Barriers (TBC's) and MCrAlYs (where M is Co, Ni, or Fe). Thermal barriers are designed to create a temperature gradient across the coating. They allow parts with a coating to work at high temperatures where they would otherwise soften or melt. The MCrAlY deposits are designed to improve oxidation and sulphidation resistance or part running in fuel rich high temperature environment.

 

How many coatings are there?

Answer : There are over 200 standard deposits available 'off the shelf'. In addition to this, many "special" composition are available. Powders and wires can also be tailor made to customer and application requirements.