Manufacturing of Coated Production Tooling
Authors: Smolentsev V.P. , Levin A.V. , Gribentchikov A.V. 
Published: March 2009

It is difficult to select the materials combining in modern industry, this paper analyzed
the drawbacks of different materials (the stainless, the copper alloys, aluminum and its alloys) on
selecting materials for tooling and selection of coatings that help to eliminate drawbacks, analyzed
the micro-arc oxidation (MAO) and its application of different materials. It is ascertained that
aluminum alloys may be practical to use for electrodes for electroerosive machining only in
exceptional cases when the wear of the tool is not determinative.
Selection of materials combining required physical and mechanical properties may be a difficult
task in tooling designing and manufacturing in modern industry. This problem is especially evident
when current-conducting elements of tooling used for electrophysical and electrochemical
processing methods are manufactured. The main distinctive feature of these methods is maintenance
of values under the influence of electrical current and corrosive medium and during electrochemical
reactions. The article addresses comparative analysis of properties of different materials used for
tooling manufacture, advantages and drawbacks of these materials and selection of coatings that
help to eliminate drawbacks.
When selecting materials for tooling, the alloy in use shall have the following properties [4]: high
electrical conductivity, high corrosion resistance, high resistance to local fracture, high adhesion to
dielectric coatings, sufficient mechanical strength, high machinability and low cost.
The following materials are considered to meet operating requirements to the fullest extend [4.5]:
stainless steels and copper alloys that have high machinability, electrical conductivity, weldability
and mechanical strength; titanium- and chromium-base alloys that have high mechanical strength,
corrosion resistance and resistance to local fracture and enables to make oxide insulating layer
protecting surface from anodic dissolution.
However, these materials have a number of drawbacks, the most important of which is high cost
that impedes their usage especially in serial production. Furthermore, stainless steels and titaniumand
chromium-base alloys have the following drawbacks that affect product cost:
- complexity of machinability that results in high labor-intensiveness of manufacturing
process of tooling;
- heavy losses in electric voltage provided that these materials are used as current-carrying
elements that makes current supply calculation difficult and requires application of more powerful
sources;
- cracking and fracture of oxide surface coating even when mechanical effect is insignificant
that results in loss of isolating and protective properties [1,2]. Furthermore, oxide coating
application process cannot be controlled completely and as a result, coating uniformity in thickness,
composition and properties cannot be achieved. Application of coatings to the areas with varied
sections and to the surfaces with projections and sharp edges is a difficult problem. Layers applied
to these surfaces have little adhesion to parent material and their thickness is limited due to high
stress concentration and etching.
The revealed drawbacks require development and usage of surface layer improvement process to
receive required physical and mechanical properties of composite material.