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topic 10817

Dents coming from sink roll in hot dip galvanized strip

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I would like to mention a problem in our line, which is dents coming from sink roll. It badly effect the quality of our strip. We tried to solve the problem by cleaning the sink roll after taking it out from bath. When we place the roll again and start the line, similar problem appears again. It is very surprising for us that when we examine the roll for dent cleaning no such big lumps are found over the roll which may cause such a big dents over the strip.

I will be very grateful to you if I get some solution to this problem.

Regards,

Subhashis Chowdhury
steel - Jamshedpur, Jharkhand, India

Faults in Hot-Dip Galvanizing

Hot Dip Galvanizing

 

Concerning dents from a sink roll - We have a sink roll scraper, which is a tool we made in-house. I believe and it has a long handle and a blade at the end to scrape the sink roll while it is rolling in the pot. When there is an accumulation on the roll you can feel vibrations in the handle of the scraper. We use it once or twice during the day. Other thing I can think of is a problem with your coating or bath temperature too low or grooves on the surface are plugged so that there is now flow of zinc.

I hope this helps!

Luc Leblanc
- Windsor, Ontario, Canada
 

Several suggestions to your problem:

1. After removing your sink roll, you need to re-machine the surface.
2. If you are using a grooved roll, make sure the edges of the grooves are bevelled (or chamfered) with a "soft" edge.
3. Our experiences with a scraper isn't that great. It works if you catch the build-up soon after it's formed, but they're difficult to remove if it's had time.
4. Also, drill "drain holes" in the trough of the grooves at some periodic distance.

Karl Hermann
- Fort Wayne, Indiana, USA
(2006)

Sink roll grooving is important and chamfering is recommended. you have not mentioned size of roll.
In one case we coated sink roll with HVOF carbide and the reported life is 2 1/2 months.

P T Bindagi
spray metallurgy - Bangalore, India

(2007)

I want to know the material and manufacturing process of sink roll & support rolls in detail.

Adarsh Naidu shift Engineer - Nagpur, India

June 1, 2009

Hi, Adarsh. This public forum is well suited to quick tips and general guidance. But seeking a manufacturing process "in detail" really isn't compatible with short and free comments :-)

Please consider retaining a galvanizing consultant for this assignment, or contact a manufacturer of galvanizing equipment for their advice. Best of luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


August 9, 2011

We are facing rotation problem of sink roll at galvanizing line. Further, what action is to be taken?

Vibhay Taywade
engineer - Mumbai, India



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