Wich spray gun for a beginning?
12-29-2009, 03:57 PM,
#1
Wich spray gun for a beginning?
Hello everyone!

My name is Fran�ois, I'm studying engineering in Belgium (I'm belgian), engine tuning and restoring are my hobbies as well as general metal working.

This summer I'd like to upgrade my workshop with some metallizing equipments, so I have many newbie's questions. I tried to find answers in the previous threads and on the internet but some "basic" questions still unanswered...

I'd like to have your opinion about the type of equipment I should get for the following requirements:

-Anti-corrosion of metal, principally steel. (motorcycle parts, frames,...) prior to painting
-Thermal insulation (Turbo housing, exhaust pipes) I've heard it is a ceramic coating.

I don't plan to coat large surface area, but maybe complicated forms. Time and price/sqft are not really important, I want an affordable equipment which permit to change of coating easily.

From what I've read, I thought about something like a Metco 5P, is it a good choice or is it obsolete? They seem to be easy to find at a good price on ebay, what about the parts which need to be replaced in order to operate safely and correctly?
I understood that the auxiliary units were oxyfuel bottle, air compressor and gas control, I have a few questions about them:

-Air compressor: how much air flow? I have a 800l/min (28cfm) at 10 bars dry air (3� dew point) unit, is it enough?
-I don't have oxyfuel bottles, what is a good start for my small parts, low volume activity?
-Gas control unit: I don't really understand what it is, why aren't simple pressure regulators enough, like in oxyfuel welding torch?
-Powder: Is it possible to buy in small quantities, I mean to cover a few square meter, is it expensive?

I'm sorry to post so many questions, this coating technique is totally new for me, I don't see where are the limits of the flame spray systems and what is needed to have a functional setup.

Thank you for your help!

Fran�ois
Reply
01-02-2010, 04:02 PM,
#2
RE: Wich spray gun for a beginning?
Hello forum's member!

First of all I'd like to wish you an happy new year, full of great things!

Since my last post I did some (long) research on the internet, and K09 sent me some nice informations about flame spray coating. I also bought a Metco 5p on ebay, I know it might be a premature investment but I wanted to try, here is what I bought:

Metco 5p

It appears to be in good condition and the vendor said it is working, I'll see when I'll receive it.
What kind of things should be checked on the gun before using it? I guess that changing the seals would be more safe? are the spares available somewhere?

Could somebody help me about the covering efficiency that I should expect with this equipment, for example how long would it take to spray an anti-corrosion coating on a motorbike steel frame (or a bicycle frame if it is more universal) ?
Actually I try to know which kind of oxygen/acetylene bottles I should go for, in order to have bottles large enough (autonomy and refill price) but not too large either (bottle price). I guess that I'll need more than one bottle of each type if I want to stay under the maximum flow per bottle, I couldn't find much informations on gas supplier's websites, is the rule "1/4 of the bottle capacity per hour" true?

About the gas control unit, are they "simply" a pressure regulator and a gas rotameter? I still don't understand why flowmeters are used in flame spray coating, is it because flows are more "representative" of what's happening than pressures?

Again, thank you for your help!

Fran�ois
Reply
01-04-2010, 03:05 PM, (This post was last modified: 01-04-2010, 03:17 PM by djewell.)
#3
RE: Wich spray gun for a beginning?
I would have suggested a twin wire arc system instead of the Metco 5P. You would have only needed air and electricity to run it. The wire is readily available from many sources, and the process is inherently safer since you do not have combustible gases. Also, spare parts consumption is lower. However, the twin wire arc system would not allow you to spray pure ceramics. As your hobby grows, you may consider an addition to your workshop.
Reply
01-04-2010, 04:02 PM,
#4
RE: Wich spray gun for a beginning?
Thank you for helping djewell!

I would also have preferred something which only use air and electricity, but I guess that twin arc spraying equipment is more expensive than flame spray, even second hand... So it would justify if I had medium-large needs, which is not the case for the moment, but I will consider that option in the future!

I did some progresses in my project, my 5p gun is now crossing the atlantic and I'm planning my gas system, I think that I'll buy the bottles in Germany and also go there for the refills, they're much more friendly to the "privately owned bottle concept" than Belgium and France which almost only use rented bottles.

I will use two 50 litters acetylene bottles and two 50 litters oxygen bottles, piped in tandem, my maximum acetylene need is 1,9 cumt/h, that stays under the 1cumt/h/bottle recommended. I would have a 21 cumt of oxygen and and 18 cumt of acetylene capacity, I guess that means something like 10 hours of anti-corrosion coating autonomy?

I'd like to ask some questions about the powders that I should use and where I could find them, I don't know if small quantities orders can be sent from suppliers? I have no ideas of the minimum quantities, nor about prices, is it a matter of 10, 100 or 1000 euros/kg? I suppose it depends of the powder.

The main thing I'd like to do is anti-corrosion on steel, prior to polyester powdercoating. The second thing, would be to spray a TBC on steel pipes (exhaust) and turbo housing, if it's possible with a metco 5p? I've heard it is ceramic and very expensive, but what exactly means "very expensive"?

Fran�ois
Reply
01-04-2010, 04:36 PM,
#5
RE: Wich spray gun for a beginning?
I am happy to help you with your project. Make sure you get the Metco instruction manual before lighting the gun. If the flows are not correct, you can burn it up very quickly.

You can buy powders from many different manufacturers, and they will usually sell as little as 5 kg at a time. To find them, search around this forum, do an internet search for the powder you want, or look in some industrial directories. SulzerMetco provides a lot of information for operating their equipment, so hit them up as well.
Reply
01-07-2010, 10:22 AM,
#6
RE: Wich spray gun for a beginning?
The powder pistol route that you have chosen may well be OK for your requirements but I just wanted add a bit more information that may help you out.

Firstly, anti-corrosion spraying with powder pistols is now almost an obsolete process. You would be considering using either zinc powder or aluminium powder. Both of these are becoming increasingly difficult to source and particularly in the case of aluminium powder, difficult to ship because of the explosive nature of the product. Much more common is either wire flame or twin wire arc spraying as previously mentioned using zinc, aluminium or zinc/aluminium alloy wire. It may be worth you looking for a wire flame system for your anti-corrosion requirements.

Regarding ceramic coatings on exhausts, this is most commonly done by plasma spraying but is also done with powder pistols. Typical materials used are Magnesium Zirconate. Powder spraying will produce a less dense coating than plasma but OK for the DIY workshop application.

Take your time learning about the correct setup and parameters for powder spraying. With wire spraying, if you don't have the correct parameters, the wire doesn't melt and hence it is easy to know if something is not correct. With powder spraying, you may not have sufficient heat in the flame to soften or melt the powders but it will still produce a coating - just not the quality of coating that you expect or need.

One last thing is that you have not mentioned blasting above. Are you aware that you will need to blast clean the surfaces well before applying metal sprayed coatings? Contact Straaltechneik in Belgium if you need assistance with this.

Good luck.
Stuart Milton
Metallisation Ltd
https://www.metallisation.com
Reply
01-07-2010, 02:38 PM,
#7
RE: Wich spray gun for a beginning?
Thank you Stuart for your help.

When my setup will be ready, I'll try to find a second hand wire spray gun, for my anti-corrosion applications. I'll also look for some books about thermal coating because my knowledges of the process only come from the web, there are some gaps which need to be filled.

About the blasting part, I have a blasting cabinet and several blasting media, I usually use glass beads and alumina before powder coating (polyester) my parts. I've been interested in flame spraying because I wanted to have an anti-corrosion coat under the powder coat. I don't know what kind of media should be used before flame spraying, I guess something hard and angular? I already have a good supplier of abrasive in Belgium (it's called "The abrasives center"), they have many different kinds of media. I planned to buy a pressure blaster for large and difficult jobs, it might be useful to prepare the parts before flame spraying them no? I've seen some posts about blasting on the forum, I'll read them again to see if I can find some informations.

Regarding Magnesium Zirconate, I only found in the Metco material guide, zirconia powders for plasma spray process (210, 204,..), but nothing for flame spray gun. I might be asking a very stupid question but, can powders developed for a particular spray technology be used with another spray equipment?

Thank you for your answers!

Fran�ois
Reply
01-07-2010, 03:00 PM, (This post was last modified: 01-13-2010, 04:06 PM by djewell.)
#8
RE: Wich spray gun for a beginning?
Stuart makes a good point about blasting the parts before spraying. Not only will the coating quality be poor if you do not blast your parts well, the bond strength will be very low, so the coating will peel off. An angular grit is necessary to get a good surface roughness profile and to clean rust from the surface. Grit blasting does not remove oil from the part, so parts should be solvent cleaned as well. It is good practice to not touch the blasted surfaces with your bare hands, as the oil in your skin will contaminate the surface.

The chemistry of the powders for different application methods is the same. The difference is the particle size. If the particles are too small, they will clog your spray nozzle (speaking in general, not necessarily about your 5P). If they are too large, they will not melt in your flame, so they will simply bounce off of your part. It is best to get the right particle size distribution for your type of spray gun in order to get good results.
Reply
01-07-2010, 03:43 PM,
#9
RE: Wich spray gun for a beginning?
djewell has summed up the blasting well. You need an angular profile on the blasted surface so glass beads are no use. Typically for carbon steel substrates, people will use chilled iron grit, around G17-G24 grade. Equivalent grades of garnet, copper slag or Alumina are also used depending on your requirements, budget etc.

We've got some P275 24%Mag Oxide/Zirconoxide which will should spray OK through a 5P. Either email us directly of contact via Straaltechniek in Belgium if you are interested. They may also know of second hand or do a deal on new wire flame kit when the time is right for you.

You could also consider spraying white alumina as an alternative material that is OK for flame spraying and using in your specific application.
Stuart Milton
Metallisation Ltd
https://www.metallisation.com
Reply
01-07-2010, 05:09 PM,
#10
RE: Wich spray gun for a beginning?
Good afternoon Francois,

As the manufacturer of your system I would be happy to email you a .pdf copy of the manual for your gun along with settings for any of the powders you intend to spray. No charge.

We can of course also supply you with a very wide range of materials designed specifically for spraying with your gun - although I would agree with some of the other posts in that it is not ideal for spraying the anticorrosion coatings, intended more for engineering coatings.

You may wish to consider the 16E wire spray gun for that anticorrosion application? with the addition of an air line / control unit it will utilise all the same hoses, connectors, gases and flow meters etc that you require for the 5P. You could then simply change the gun whenever you needed to change between powder and wire spray.

I hope the above is of help, if you need anything else please don't hesitate to ask.
Simon Hiiemae
Sulzer Metco (UK) Ltd
01633 488 091
emailaddressisSimon.Hiiemae@Sulzer.com
Reply
01-11-2010, 12:57 PM,
#11
RE: Wich spray gun for a beginning?
Hi Francois,

Technical information emailed to you as requested.
Simon Hiiemae
Sulzer Metco (UK) Ltd
01633 488 091
emailaddressisSimon.Hiiemae@Sulzer.com
Reply
04-08-2010, 11:45 PM,
#12
RE: Wich spray gun for a beginning?
Hi everyone.

Sorry for answering that late, I've had exams and let my "flame spray project" alone for a while.

I've just bought an acetylene gas station and a Metco 3GF flowmeter, now I have some question about the rest of the equipment that I should buy.

Which size of hoses should I buy? 6,3 mm? larger? same size for both gases?
what kind of gas threads are on the gun, are they standard?
About the flashback arrestors, where should I position them? One just after the regulator and one just before the gun?

I think that I'll also buy a wire spray gun in the future for my anti-corrosion jobs, is it interesting to have quick couplers in the gas lines or should I run the wire gun with propane (I'll only spray zinc and aluminum with it)

Thank you all for your help in my project!

Fran�ois
Reply
05-28-2010, 10:21 PM,
#13
RE: Wich spray gun for a beginning?
Hello,

First I would like to thank Simon, who once again, kindly sent me informations about my new purchases.
As a complement to my 5P gun, I was interested in buying a wire gun, I think that I will spend more time spraying anti-corrosion coating than engineering, at least at the beginning.
A small factory was selling their wire guns as they stopped producing the part which needed zinc coatings, so it was a good opportunity, now I have a 11E, 12E and 14E, they also gave me a lot of new spares.
These guns (and the spares they gave me) are set to use propane, it's quite a good thing as it will be easier for me to buy the fuel gas.

Which wires can exactly be used with propane, I guess at least zinc and aluminum, anything else?
As my first flame spray project I would like to spray an anti-corrosion coating on motorbike parts I'm restoring, which wires should I go for?
In general, in which cases aluminum is used instead of zinc for anti-corrosion protection? what are the advantages/disadvantages of aluminum ?

Thank you!

François
Reply
08-17-2015, 09:13 AM,
#14
RE: Wich spray gun for a beginning?
Hi
I have this older metco 5p gun. I was wondering if for a starter this is something that can be useful today, or if it's more of a museum part? Second is this something that could be useful for (and used by) a hobbyist (Im working on old vw cars). What would I need to get it running? If not ideal for anticorrosion coating, but can it be used for it or for example flame spraying exhausts? The nozzle on the Gun is labled P7-F, and there are two extra P7-B and two P7-G.


Reply
08-17-2015, 11:55 AM,
#15
RE: Wich spray gun for a beginning?
Hi Frederik
This is a good gun, as well as Metco is not more a good choice, this kind of gun has the possibility to use Oxigen or acetylen as carrier gas, you can use it in order to coat with the following powders: Al oxide, or Al/Ti oxide, both 3%Ti or 13% Ti, for the spares you can contact FST, MEC, GTV and many others, all of them have the spares you need.
Best regards
Luigi
Reply
08-20-2015, 07:03 AM,
#16
RE: Wich spray gun for a beginning?
Thank's Luigi!

Does anyone have the manual or know where to find it?

Kind regards
Frederik
Reply




Users browsing this thread: 1 Guest(s)





Surface Engineering Forum Sponsor - Alphatek Hyperformance Coatings Ltd