Thermal spray welding and cladding welding are both technologies used to strengthen and repair the surface of materials. Thermal spray welding is a technology that uses a high-temperature heat source to spray molten or semi-molten material onto the surface of the workpiece to form a coating. Common heat sources include flame, arc, plasma, etc., while cladding welding is a technology that uses a welding method to melt the filler material onto the surface of the substrate to form a cladding layer. Common cladding methods include arc welding, plasma arc welding, laser welding, etc. Common application scopes of thermal spray welding/cladding welding include large ball valves, laser cladding molds, rollers, heavy cylinder pistons, etc.

The surface hardness of the workpiece after thermal spraying/surfacing is high, and the surface of the workpiece after surfacing is not very regular, which places high requirements on the high temperature red hardness and impact toughness of the inserts. In this regard, Halnn  Superhard can provide three types of inserts materials: carbide inserts, ceramic inserts and CBN inserts for processing different materials.

Based on years of practical experience,Halnn Superhard has concluded that more suitable inserts materials can be selected through the following three aspects.

1. The hardness of the inserts itself and the hardness of the material being processed: The hardness of the inserts must be greater than the hardness of the material being processed. In terms of their own hardness, carbide inserts, ceramic inserts and CBN inserts are: carbide inserts < ceramic inserts < CBN inserts.

2. High temperature resistance of inserts and cutting temperature of processed materials: The high temperature resistance of inserts must be greater than the cutting temperature of processed materials. In terms of their own high temperature resistance, the three types of inserts are: carbide inserts< ceramic inserts < CBN inserts.

3. Impact toughness of inserts and working conditions and processing surface morphology: For example, the surface of the workpiece repaired by surfacing materials is irregular, uneven, and has high hardness, forming intermittent cutting, which has high requirements for the impact toughness of inserts. In terms of their own impact toughness, the three types of inserts are: ceramic inserts < CBN inserts < carbide inserts.

The following is a successful case study of Halnn  Superhard inserts processing thermal spray welding/surfacing materials for reference.

(1) Case parameters of Halnn Superhard inserts processing spray welding ball valve

Technical difficulties:

1. The hardness of the surface after spray welding is HRC55-60, and the spray welding surface is irregular, so the inserts needs to have not only high hardness, but also a certain impact toughness.

2. Conventional CBN blades with negative chamfers cannot be used during cutting, otherwise the surface spray welding layer will be peeled off.

Machine inserts: CNC vertical lathe

Processing object: Surface spray welding of ni55, Ni60 nickel-based alloy

Hardness: HRC55; HRC60

Processing content: Spray welding layer thickness: 1.6mm, retain 0.6mm thickness, and remove 1mm thickness during processing.

Based on this working condition, Halnn  provided an original solution: BN-H10 material chip breaker insert, which not only solved the customer's processing difficulties, but also improved work efficiency and was well received by customers.

Conclusion: The selection of suitable inserts materials needs to be based on the specific processing hardness and material toughness, and the high temperature resistance and impact resistance of the inserts should be comprehensively considered in order to better achieve the best processing effect and inserts life.