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ZA12 - a new option for model engineers?

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Stub Mandrel	09/04/2010 21:21:37
4318 forum posts 291 photos 1 articles	I'm really inspired by the article on die casting in the latest ME (4375). I'm not ready to make a 12-part die, but the alloy ZA12 sounds like a godsend - stronger than cast iron and melting at a lower temperature than aluminium with high fluidity and no degassing! (88% Zn + 11% Al + 0.8% Cu) Can it be true? I can't get the Brock Metals website o load but I found this: http://www.eazall.com/diecastalloys.aspx "ZA-12 is the most versatile zinc alloy in terms of combining high performance properties and ease of fabrication using either gravity or pressure die casting. ZA-12 is the best gravity casting alloy for sand, permanent mold and the new graphite mold casting process. It is also a good pressure die casting alloy (cold chamber) which provides a sounder structure than ZA-27, as well as higher die cast elongation and impact properties. For these reasons, die cast ZA-12 often competes with ZA-27 for strength application. An excellent bearing alloy, ZA-12 is also platable, although plating adhesion is reduced compared to the ZAMAK alloys." A quick look at google suggests ZA12 is even better than phosphor bronze for bearings? The big question has to be cost - I bet it costs a lot more than cast iron, but if you can make your own heavy duty castings without even needing to achieve a red heat, you wll save truckloads. Does anyone out there have experience of machining or using this materialfor structural castings? Neil
David Clark 1	10/04/2010 07:35:12
3357 forum posts 112 photos 10 articles	Hi There Try www.brockmetal.com .co.uk works fine but resolves to .com regards David Edited By David Clark 1 on 10/04/2010 07:35:56
Ramon Wilson	10/04/2010 09:54:30
1655 forum posts 617 photos	Hi Neal Having read the article yesterday like you I'm very interested in using this material. I have just been on the site above - lots of info but no costings so will contact them on Monday.. Just a thought but if there is a minimum order and/or if that means having to buy far more than is required for use would you or any others be interested in a shared purchase? It would certainly appear to be good news on the casting front - it might even provide the kick required to resurrect a well dormant project languishing under the bench. Ramon
Terryd	10/04/2010 10:49:21
1946 forum posts 179 photos	Hi Ramon, Having just looked at the website it appears that it is only available in 158kg packs. it would be great if enough people were interested to make such a purchase viable. How about the clubs out there? Terry
David Clark 1	10/04/2010 13:08:27
3357 forum posts 112 photos 10 articles	Hi There I doubt the article writer bought that much. regards David
Ramon Wilson	10/04/2010 13:16:53
1655 forum posts 617 photos	Hi Terry - Well I missed that bit! Thats an awful lot of cylinder heads but I guess it would be possible if enough were interested though it would be a big outlay and would warrant a high degree of commitment. I see that Geoff Ball who wrote the article states that 'an ingot was purchased' - wonder how big that was? I will see what they have to say on Monday. Ramon
Terryd	10/04/2010 13:23:24
1946 forum posts 179 photos	Hi There, I hope that you may be right David but there is a difference between making a donation or selling to an individual for experimental work and selling small quantities to a large number of customers. Many industrial suppliers simply do not have the accounting and administration facilities to be able to handle such custom. I have often been donated small quantities of materials such as silicone rubber mould making materials by large suppliers but they were unable to sell me any in the quantities I need. I look forward to the results of Ramon's enquiries. Regards Terry
Ian S C	10/04/2010 13:39:39
7468 forum posts 230 photos	Our light alloy and copper and alloy supplier here in Christchurch NZ has a good off cuts bin, also the will cut a bit of most things, no cost for small amounts. The chaps that run this firm started up when the large out fit that they worked for changed its policy toward the small buyer. Sounds like you need a few more of this type of supplyer in the UK. Ian S C
Owen	10/04/2010 18:40:43
26 forum posts	I have started to get into ZA-12 casting. I acquired some alloy from a supplier in the U.S. but later found out that it is available much closer here in Canada(Vancouver). I have yet to cast anything but I'm gradually gearing up. I'm exploring trying to make semi-permanent molds to cast multiple parts like axle box covers with my logo in raised lettering on them(1 1/2 inch scale). the alloy itself is widely used in industry so should be readily available. Just open the hood or bonnet of your car, all that greyish stuff is one of these alloys. or the mounting bracket in that burned out household appliance you just took apart. Now before you run out to the scrap yard there are a number of these alloys with specific properties and I can't find out how to single out ZA-12, the one most suited to our use. anyway lets hear the ideas. Edited By Owen Hanam on 10/04/2010 18:42:07
Jeff Dayman	10/04/2010 20:25:17
2356 forum posts 47 photos	For manufactured goods the ZA family of metals are used because they have good properties for this class of work but the main reason is they are relatively cheap compared to steel, aluminum alloys or copper alloys. They are better in strength and bearing properties than even high grade engineering plastics, but can be moulded (die cast) so are cheap to make per part, and often no machining or little machining is needed after casting. This is why you see them in cars and consumer goods. I have designed and had made many parts in these alloys over 25 years professionally. For consumer products with a limited life they perform well. Personally I would not use any zinc or ZA alloy on any heirloom ME project because they all corrode to some extent, some rapidly in wet or salty / soapy enviroments, and rapidly lose their properties as they do so. Also they creep far more than any other class of metal. They are not suitable for use near high heat (like near a boiler). Getting paint to stick to them can be difficult. In short I wouldn't go near the stuff unless it is a quickie throwaway project. If you're planning to eventually have your project sit on your great grandkids' mantel use cast iron, steel, bronzes and copper. Edited By Jeff Dayman on 10/04/2010 20:26:54
John Stevenson	10/04/2010 20:52:07
5068 forum posts 3 photos	Posted by Ian S C on 10/04/2010 13:39:39: Our light alloy and copper and alloy supplier here in Christchurch NZ has a good off cuts bin, also the will cut a bit of most things, no cost for small amounts. The chaps that run this firm started up when the large out fit that they worked for changed its policy toward the small buyer. Sounds like you need a few more of this type of supplyer in the UK. Ian S C Ian different ball game the Zn12 is a specialist material and is only handled by a very small number of people as opposed to a non ferrous supplier. The non ferrous supplier I use, ASC Metals at Lincoln will supply any quantity you need, no matter how big or small. A while ago I needed a pulley 10" diameter and 1" wide, because I couldn't afford 3 metres or 10" alloy, or even lift it come to that I asked them for 1" 1" was duly cut off presumably a long bar, and delivered to the door. I also do a regular job out of 8mm thick alloy plate, these finish up at 100mm x 150mm so I order 10 pieces cut to 105 x 155 to allow for finishing. Next day delivery and no messing having to manage a large plate and attempt to cut it. John S. Edited By John Stevenson on 10/04/2010 20:52:28
Terryd	10/04/2010 22:52:08
1946 forum posts 179 photos	Hi Ramon, See here: Terry http://www.brockmetal.com/page.asp?node=145&sec=Ingot___Pack_Sizes
Ramon Wilson	11/04/2010 10:01:37
1655 forum posts 617 photos	Hi Terry See what you mean - that's a big investment for a few inlet manifolds and cylinder heads I think your point on the small order will have some bearing here but undaunted I will still try and see what they have to say - obviously they are selling this material on so it may be available from someone else a bit further down the chain. Jeff, could you comment further on your ref to these alloys 'not suitable for use near high heat' - my specific interest in it is to use it as in the original article in ME - cylinder heads on I/C engines and similar parts - are you saying this will not be suitable and if so what is the likely outcome if it were used. Ramon
Jeff Dayman	11/04/2010 14:06:02
2356 forum posts 47 photos	Hi Ramon, ZA-12 ahould not be used where the temp is higher than 100 deg C, because it has a low melting point, and its properties degrade rapidly above room temperature. It has low creep resistance as well, so if you use it for a cylinder head the bolts holding it will seem to loosen over time. This is actually not the bolts loosening, it is the alloy relaxing and squeezing out under the bolts! ZA-8 has better creep performance but is also not a high temp material. I would not recommend any ZA or zinc alloy for cylinder heads or other model IC engine parts. High silicon aluminum would be far more suitable, as used in mower engines and trimmer engines.
JasonB	11/04/2010 14:19:59
25215 forum posts 3105 photos 1 articles	Model Engine Builder Magazine ran a two part article about casting with ZA12 in issues 16 and 19 if you want a bit more reading on the subject for our uses Jason
Ramon Wilson	11/04/2010 23:00:54
1655 forum posts 617 photos	Thanks Jeff, Following your update I found this http://www.mrt-castings.co.uk/zinc-diecasting-za12.html which confirms what you are saying. The article in ME is, as Neil said initially, quite inspiring but it would appear that to use this material for my intended application would lead to later disappointment so not much point in pursuing it further I'm afraid. Back to milling it from solid then. I will still contact them tomorrow just to see what the outcome is on purchasing a small amount. Thanks for the links Jason I have been on the site before but have prevaricated - previously took SIC and MEW - but I think perhaps a years subscription is in order Regards - Ramon
Ramon Wilson	12/04/2010 11:50:47
1655 forum posts 617 photos	Hi Just an update following contacting Brock Metals - Spoke to a very helpful guy in sales but this doesn't appear to be very viable. Normally they deal in tons - minimum one ton however if they would cast an extra ingot (7kgs) for around £150 - (pity there isn't a smiley for 'gulp'!) The price fluctuates due to the market price of Zinc so no 'fixed price'. That price included no delivery either which would be extra. Having explained the low need and the origination of the request - ME article - he felt that this is how this had been previously done though he had no knowledge of the sale. He was quite happy to help though in providing one ingot if required. He gave me a name of a 'local' user in Suffolk and thought that he might be able to help with a small amount on a one off basis - just as you said Terry After Jeffs advice and reading up on it however I don't feel I want to use this material for the hoped for application. Geoff Ball in his article seemed to be confident enough in recommending it however so perhaps David can get him to do a follow up on it's 'survivability' in his engine. Now, after a weekend of gardening it's back to the Racer con-rods Regards - Ramon PS Subscription to MEB dealt with. Thanks for the jolt Jason. Edited By Ramon Wilson on 12/04/2010 11:54:30
Terryd	13/04/2010 12:32:41
1946 forum posts 179 photos	Hi Ramon, Brock's response was much as I expected unfortunately, a lot of industries that used to be helpful (a good example being Foseco foundry supplies) are no longer bothered to help the individual due in part to the more 'corporate' approach these days.. However as we have found out through the marvel of this forum the material seems inappropriate for stressed components in relatively high temperatiure environment. such as cylinder heads. I noticed on re-reading the original article that the author did point out that he was not sure of the other characteristics of the material except the few that he noted in his table. Perhaps a bit more research such as we have all contributed to here would have been appropriate for someone writing such an article. The problems of creep and corrosion seem to be the worst problems although there are others. I just hope that anyone reading the article sees these postings before investing a lot of time or money on producing such components in the material. Terry
Ramon Wilson	13/04/2010 23:02:18
1655 forum posts 617 photos	Hi Terry, Yes this is a bit disappointing all round. Like Neil I found the article on initial reading to be very encouraging but it's potential for failing to meet the longer (?) term requirement of a cylinder head makes its use for that application rather suspect. So for the time being the long dormant project remains under the bench and it's back to the milling then! Regards - Ramon
Stub Mandrel	18/04/2010 19:45:32
4318 forum posts 291 photos 1 articles	Sorry for starting a hare running, then disappearing - it turns out the reason I couldn't access the Brock Metals website was that my wife's computer had caught a cold - a nasty virus, despite multiple layers of protection! Aeinstall of windows later and it's all working much faster now. The temperature issue does suggest it isn't the best thing for cylinder heads of reven steam cylinders I wonder if it would do for the gear bellhousing for my backburner Fordson Tractor project? Ill have some thinking, maybe 5 of us could share a #150 ingot ? Thanks Neil P.S. can anyone remind me where in XP you set the keyboard to UK? I can't get a pound sign!

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