Refurbishment and coating of mould plates with nickel and nickel alloys

AMT offers comprehensive reconditioning of mould copper plates including high quality nickel and nickel alloy coatings.

The nickel & nickel alloy coatings can be also applied to narrow face plates. A narrow face mould plate coated with HN20, HN40 or HNK2 offers much better wear resistance than a plate without coating.

The HN 40 nickel alloy has twice the hardness of HN 20, which leads to considerable improvement in mould life. Both types of coating can be applied in greater thickness so that they can be re machined.

The rate of wear can be reduced considerably by way of coating the edges of the adjustable narrow-face plates, which slide on the inside (hot face) of the wide-face coppers, with a material that has greater hardness.

It can be seen that very complex inter relationships have to be taken into account when selecting a suitable coating and layer thickness. Recommendations can be made in relation to specific system and casting parameters. Close consultation between the system operator and the mould supplier is necessary to ensure that the appropriate coating systems are selected.

Properties

HN 20

HN 40

HN K2

Chemical Composition

Ni

Ni – Co

Co – Ni

Process

Galvanic

Galvanic

Galvanic

Hardness (Min) in HV

220

400

250

Thermal Conductivity in W/(m·K)

90

80

90

Thickness in mm

< 7

<3

<3

Calculation based on constant coefficients of heat transfer heat flux approx. 1.8MW/m²

Material CuAg (DPS-Cu)

Ni & Alloy coatings (mm)

∆ T Wall(°C)

∆ Heat Transfer %

Hardness (Min Wall thickness 35mmn)

0.7

+11

-0.9

1

+15

-1.3

2

+30

-2.6

3

+45

-3.8

 

Excessive wear of the moulds is accelerated by an incorrectly adjusted strand guidance system and casting parameters. Common causes are, the taper of the mould is not consistent with the shrinkage behavior of the steel, poor alignment of the casting machine (oscillation / strand guidance) or a casting speed that is not adapted to the mould geometry. These are all possible causes of a high degree of wear which ultimately leads to a change in the mould geometry.

Coating Types

Type of coating can be adapted to the specific requirements of individual casting plants based on the casting process.

most-common-coating-ni-copy1
Anti-wear coatings

Ni & Ni Alloy coating is done for

  • Metallurgical protection to improve the surface quality of the cast strand (e.g. prevention of star cracks)
  • Anti-wear coatings to improve resistance to abrasion