Electrolytic hard chrome coatings are irregular due to the use of an electric current during their deposition. However, specific techniques (auxiliary anodes, etc.) can be used to make the deposited coating more uniform, although this markedly increases the costs of the process. These additional costs can be minimised if the specific characteristics of hard chrome plating are taken into account during the design or manufacture of the part.
CHROME COATINGS OBTAINED AS A RESULT OF AN INCORRECT PART DESIGN
POINT 1. EDGE DEFECT
Excess thickness and configuration of chrome coating.
Solution: Expect rounding at the edges or unchromed edges.
POINT 2. ANGLES
Lack of chrome plating.
Solution: Avoid sharp angles by using minimal radii or perform a bed on the chrome for subsequent rectification.
POINT 3. GAPS AND GROOVES
Result in a lack of chrome at the base of the grooves, with the external edges approaching each other, and incorrect measurements.
Solution: Decrease the depth of the groove by rounding its internal angles and opening it in a lateral trapezoidal form.
POINT 4. SCRATCHES AND FISSURES
The chrome coating copies the defects of the underlying material, amplifying them.
Solution: Attenuate the scratched region by rectifying with a grinder and rectify again after plating.
POINT 5. TEETH AND THREADS
The profile becomes modified.
Solution: Wear down the profile of the regions to be chrome plated by either electroerosion or electrolytically and rectify to the dimensions after plating.
POINT 6. BORED INTERNAL ANGLES
The chrome applied to the internal angle formed and the wall perpendicular to the boring axis is not correct.
Solution: Expect a groove in the internal angle.
To avoid misunderstandings, a series of basic guidelines which must be followed when sending a part for hard chrome plating are provided below:
1) Mark the surface to be chrome plated on a sketch or drawing or on the part itself.
2) Indicate unimportant surfaces that can be partially or fully chrome plated.
3) Indicate any surfaces that must be completely protected during chrome plating.
4) Provide information regarding the material from which the part is made.
5) Provide relevant information concerning the quality of the hard chrome coating, especially with regard to the part's manufacture (indicate the type of heat treatment applied, if any, and its hardness).
6) List the intended applications of the hard chrome plated part.
7) The desired coating thickness, noting the current measurements of the part and those after chrome plating.
We recommend that you consult our technical staff in the event of any special requirements. We are always available to help and resolve any doubts you may have.
