Posts by bill doherty
Posts by bill doherty [ 9 ]
Re: etching alumunum [ Started by hammerhead in Pre-Treatment : 3 replies ]
We in Australia have a standard AS3715 for powdercoating Architectural Aluminium components.
It is very good though sometimes lubricants used in Al fabrication like Beeswax for example cause difficulty.
Essentially we have a caustic wash/ rinse/ hydrofluoric acid etch/ rinse/ Chromate conversion/ rinse/ overflow rinse/ de-i rinse.
the conductivity of rinse run off from the finish part is to be less than 25 micro siemens. I have preceded this process with an MEK wipe when fabrication lubricants are present.
Re: Recurring Powder Defect [ Started by jfieker in Powder Coating : 12 replies ]
Check the cleaning.
especially if any beeswax derived lubes are used anywhere.
Preclean the parts with MEK then process as normal.
Regards,
Bill
Re: Powder coat anything anywhere [ Started by danjaddak in Powder Coating : 4 replies ]
There are a lot of questions to be answered before this system can be regarded as a credible alternative to a well applied powdercoat system.
It has taken a very long time to overcome the damage done by ill informed applicators from the early days.
That said, let us be receptive to new technologies when they are supported by adequate testing.
Re: Cleaning and passivating stainless steel [ Started by apurdey in General Discussion : 4 replies ]
Hi Al,
Just a few words of caution:
304 is subject to "tea staining" if subject to corrosive elements.
Might be a good idea to observe the entire weld prep/process and cleanup.
This might avert your problem altogether.
Chemical cleaning and passivating can use some pretty nasty chemicals.
If you are not well trained in chemistry get some one who is to experiment.
That said I would suggest a 5 percent 1 n hydrofluoric acid / 5 percent 1 n nitric acid solution as an immersion cleaner/passivation solution.
Try some prepared test pieces first.
It is easy to up concentration / temperature later to achieve desired speed.
Make sure test pieces are thoroughly rinsed.
Make sure spent solutions are disposed of appropriately.
Hope this helps,
Regards,
Bill Doherty
Re: Cleaning and passivating stainless steel [ Started by apurdey in General Discussion : 4 replies ]
Hi,
I have a bit of experience here.
Please advise stainless grade and end finish required.
Regards,
Bill Doherty
Re: Graphitic Carbon Coating [ Started by Mark Smith in Other : 1 replies ]
I am not sure if this is the same process but I have used a colloidal graphite wet spray to coat items which are not conductive as a primer to allow subsequent decorative powdercoat. It works a treat on kiln dried pottery for example.
I can not vouch for it's protective functionality though.
Hope this is of some help.
Regards,
Bill
Re: Make 'em say "Wow!" [ Started by Southern Metal Finishing in Metal Finishing Associations : 17 replies ]
Someone has sent me a message **************************
I don't understand in oz, this is reserved for expletives.
Have I offended somebody?
Hope not.
Regards,
Bill
Re: Make 'em say "Wow!" [ Started by Southern Metal Finishing in Metal Finishing Associations : 17 replies ]
The course has been "contextualised" for powdercoating from pre-existing Production Engineering Trade courses. It has been recognised and accredited nationally. I contextualised it. There are now two of us accredited to teach it. We both have training and assessment qualifications/ engineering qualifications and thirty years experience in the industry. The training is competency based. We have both demo conveyorised and batch coating plants on a small scale. The course is being delivered one evening per week (4 hrs) and supplemented with trainer visits to the students workplaces. For regional students who can not readily access the training base we deliver at the workplace. The regional students tend to be with smaller organisations and so the delivery is more intense more often one on one. This we achieve by taking the trainer to the workplace 1 full (8 hr) day per month. I set up a route which generally takes me around a circuit 1 week per month. The course is very new and this wil …
Re: Make 'em say "Wow!" [ Started by Southern Metal Finishing in Metal Finishing Associations : 17 replies ]
Here in Australia we have recognised this and recently developed an apprenticeship trade training course in Powdercoating.
If only we could develop this further using E-learning techniques the industry world wide would benefit enormously. I think what we need as an industry is to form a multi-national & multi-skilled group to advance this cause. Any thoughts would be appreciated.
Bill Doherty
