HVOF Coating Calender Roll issues. Suggestion needed
02-10-2021, 12:54 PM, (This post was last modified: 07-13-2021, 10:06 AM by tobjung.)
#1
Shy  HVOF Coating Calender Roll issues. Suggestion needed
Greeting from Venture Engineering Thailand.

I would like to ask for some helps on Calender roll-WC17Co HVOF Coating. I have to admit that this was my first time spraying this kind of roll. 

The issue is after the roll was operated for 3 days, as you can see from the picture, there are some marks on the surface distributed all over the roll (like the coating bounce off). 
Moreover, there are cracks appear on the coating surface. (We did PT and it was fine before delivery). 
Now we have to re-coat it but we still have no idea what are these problems are coming from (especially, marks on the surface).

Pictures and Videos

Here are the coating details



  1. HVOF coating (JP-5000)
  2. WC17Co powder (particle size 15-45um and 15-53um)
  3. We did HVOF coating for 400um in thickness
  4. We sprayed 15-45um powder for 200 microns and the rest were 15-53um powders (we ran out of 15-45um powders so we had to use substituted powder)
  5. The operator changed feed rate back and forth throughout the operation
  6. Using slide way instead of handheld (but the gun was vibrated quite hard as you can see from the video)
  7. Temperature control on roll surface was 100 C
  8. Time interval of each ignition was 1-2 hours (as the cooling water was really hot, we had to wait)
  9. Grind to 200 microns with roughness of 0.1 Ra


Here are the working environment (see picture)
  1. This is the Queen Calender roll
  2. In the middle of King and Middle roll
  3. It is working with doctor blade
  4. The roll is in contact with chemical compound
Any suggestion would be helpful
Reply
02-10-2021, 02:03 PM,
#2
RE: HVOF Coating Calender Roll issues. Suggestion needed
Why was the operator changing the feed rate? I would expect that to give less than optimum results. When you resumed spraying did you reheat the roll first? Why spray to 400 microns only to grind half of it off? That is a lot of wasted powder, more time to grind and could leave more stress in the coating.
Reply
04-29-2021, 03:34 PM,
#3
RE: HVOF Coating Calender Roll issues. Suggestion needed
Dear Tobjung,

I know I'm a bit late but I cannot see all the videos and pictures.

Where you able to solve the problem?
Reply
07-13-2021, 10:12 AM,
#4
RE: HVOF Coating Calender Roll issues. Suggestion needed
(04-29-2021, 03:34 PM)JeroenB Wrote: Dear Tobjung,

I know I'm a bit late but I cannot see all the videos and pictures.

Where you able to solve the problem?

Thanks for the reply. Here is the link Pictures. Also, I updated the post with new link already.
Current situation: we cannot identify the problem yet. I discussed with the lab already but they told me they can't do anything if we cannot pull out a small piece of coating from the roll. (Must be from around the defected area). We tried to take the coating out using various tools but not successful as the coating is very dense and adhere very well to the substrate or nearby coating. Unfortunately, we cannot use a chisel to take it off as the customer said it would be too risky to the substrate.
Reply
07-24-2021, 08:53 AM,
#5
RE: HVOF Coating Calender Roll issues. Suggestion needed
Now I suspect that oils or chemical agent embedded in the roll surface was the problem as we didn't degrease the roll prior to HVOF Coating
Reply




Possibly Related Threads…
Thread Author Replies Views Last Post
  Looking suggestion for S2B "Z" notch coating & dove tail ARC spray aluminium coating demionkrishan 0 215 06-14-2021, 02:09 PM
Last Post: demionkrishan
  Masking tape or compounds suggestion texnicar 5 6,367 02-05-2021, 09:07 PM
Last Post: jtonic77
  bridal roll coating rmsengineering 0 1,062 12-15-2019, 02:31 PM
Last Post: rmsengineering
  Hearth roll coating kim jong hun 2 2,668 10-12-2017, 09:11 AM
Last Post: kim jong hun
  Help needed on AlSi coating Brian 1 1,627 12-17-2016, 10:47 PM
Last Post: loriolo
  Coating solution needed for slurry pump application Killswitch 11 9,698 02-19-2015, 02:57 AM
Last Post: Axis Machine
  chrome oxide coating failure - 24" dia. steel roll rconnor 3 6,057 07-10-2012, 02:37 PM
Last Post: loriolo
  Issues in Al coating on photoresist xoobiii 5 4,435 03-13-2012, 10:26 AM
Last Post: loriolo
  Surface prep issues before APS coating msiranni 6 6,104 06-21-2011, 12:56 PM
Last Post: Justin
  sealer for sink roll coating karunanidhi 17 22,389 05-01-2011, 08:32 AM
Last Post: dadasotare
  HVOF on CAST IRON ROLL Guna 1 4,805 10-04-2010, 07:37 AM
Last Post: Gordon
  ROLL CONDUCTOR (HVOF POWDER) ir_minja 1 3,978 10-04-2010, 07:27 AM
Last Post: Gordon
  Erosion-corrosion issues in boiler applications sivakumar 1 5,514 05-04-2010, 08:40 PM
Last Post: MichiganMan
  Conductor Roll -- Copper Coating Stephen Booth 3 8,470 02-27-2010, 04:52 AM
Last Post: Stephen Booth
  Build up and low flame issues! TurbineRepair 4 5,691 09-02-2008, 01:06 PM
Last Post: erick212



Users browsing this thread: 1 Guest(s)





Surface Engineering Forum Sponsor - Alphatek Hyperformance Coatings Ltd