The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Client wants hot-dipping but part won't take the heat

2006

Hi,

I have a question and sincerely hope you will help me with appropriate answers.

zinc plated (electro-galvanized) Lipped channels are used as Ceiling sub-framings and brackets of width 75 mm suspended with rods.

The edges of the bracket are cut from standard lengths procured.

How do I treat these edges?

I have used brand "CROWN" galvanizing spray paint over the cut edges but was rejected as Client insist that it should be hot-dipped galvanized.

The thickness of the channels would have melted if dipped in a hot bath (hot dipped galvz).

Please advise.

Regards,

Daniel Cheong
- Singapore

---

First of two simultaneous responses -- 2006

Daniel, I don't understand what you mean by the channels will have melted if hot dipped. I presume the frames are made from a material that melts below about 450C. If it does,then the rods cannot be hot dip galvanised - there is no way around this since zinc melts at 420C. You could always rejig the rods and recoat the ends with electrogalvanize, or better still, cut them up before they are galvanised.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK

---

Second of two simultaneous responses --

There's something you're not telling here 0 insufficient info.

Only steel can be galvanized. It melts at about 1600C, yet you say your material to be galvanized would melt in hot dip galvanizing which is only 450C (occasionally to 550C for specialist applications).
This is more than a thousand degrees C below melting point of steel.

If client insists on Hot Dip Galvanize and its not steel you're talking about, then your client needs educating!

Geoff Crowley
Crithwood Ltd.
Westfield, Scotland, UK

2006