Aluminium casting

zefarelly · 24 Feb 2006, 11:38 (Ref:1530613)

Ally castings . . . . . anyone got any recommendations for making this.

I 've drawn it up, can possibly get the model made . . . . . machinings not a problem, but casting I know little if anything about.

http://img161.imageshack.us/img161/7...ercover3jm.jpg

Dave Brand · 24 Feb 2006, 12:34 (Ref:1530652)

It's a simple enough casting, although thin sections are not easy in aluminium unless you can afford pressure die-casting - the cost of that would be prohibitive for a one-off! What sort of casting are you considering? Sand casting will be the cheapest, but investment (lost wax) casting will produce a better product. In either case pattern-making is likely to be the biggest expense - you need to get it done by somebody who knows what he's doing!

The only comments I would make ae that you won't be able to cast the screw holes (you probably knew that!) & it would be advisable to blend the bosses at the top of the picture into the ribs, otherwise you'll have a very fine, sharp edge on your mould which won't make for a good casting.

PS: Seen this month's 'Octane'? Julius seems impressed with your performance!

zefarelly · 28 Feb 2006, 11:30 (Ref:1533157)

initial feed back says 4mm thick minimum ( i started at 8mm ) I'd already removed holes and added 2 degrees draught for mould release . . . next project is a head !

Dave Brand · 28 Feb 2006, 12:47 (Ref:1533207)

Quote:

Originally Posted by zefarelly

initial feed back says 4mm thick minimum ( i started at 8mm ) I'd already removed holes and added 2 degrees draught for mould release . . . next project is a head !

A few more pointers on sand casting, some of which you may already be aware of.

The pattern must be made oversize to allow for shrinkage on cooling, otherwise you'll have an undersize casting. Patternmakers use a contraction rule to make the job easier - saves a lot of calculation.

For this job you'll almost certainly need a pattern for the outer profile & a core for the inner profile. Core location is important, as a badly located core can shift when the metal is poured, resulting in a poor or scrap casting.

Aluminium gasses a lot when poured. If sufficient vents (risers) aren't provided for the gases to escape you'll get blowholes or porosity in the casting.

You'll need to add a machining allowance (typically 3-5mm) to all surfaces which you want to machine.

Casting is a simple process, but it requires a lot of skill & experience to do the job properly - talk to your foundry sooner rather than later to avoid the pitfalls!

Marshal · 28 Feb 2006, 15:28 (Ref:1533301)

Though you could get it cast either by a sand casting or better still investment (lost wax as mentioned - and you coud probably do that direct from a rapid prototype). But as I'm assuming you have no closed angles etc, for a limited bacth size (not more than half a dozen I'd guess?) you'd probably be cheaper and get a stronger component just milling it out of some decent high strength extruded bar.

Tanky · 28 Feb 2006, 18:04 (Ref:1533386)

Quote:

Originally Posted by zefarelly

Ally castings . . . . . anyone got any recommendations for making this.

I 've drawn it up, can possibly get the model made . . . . . machinings not a problem, but casting I know little if anything about.

http://img161.imageshack.us/img161/7...ercover3jm.jpg

That cam cover looks good. Must have taken a while to sketch those letters out.

How did you do the writing on the cover? I take it you are using solidworks? I have solid works pro 2005 and wondering if there is an easy way I can tart up a wing mount post im desiging with some fancy writing ( dont tell the aero guys they will have a fit!).

thebear · 28 Feb 2006, 20:52 (Ref:1533469)

Quote:

Originally Posted by Marshal

Though you could get it cast either by a sand casting or better still investment (lost wax as mentioned - and you coud probably do that direct from a rapid prototype). But as I'm assuming you have no closed angles etc, for a limited bacth size (not more than half a dozen I'd guess?) you'd probably be cheaper and get a stronger component just milling it out of some decent high strength extruded bar.

That would result in a very large waste of material aside fom an extended machining time.

More thoughts on the casting:

Dont forget fillets on the bottom of all the ribs in the debossed areas. Just specify `fillet' and let the patternmaker choose a suitable radius. You will probably wind up with a 2 or 3mm radius.

If the radius is too large you might get sinkmarks in the ribs on the farside but that is out of normal view and cosmetic rather than functional.

If you are interrested in saving weight/material you could also enlarge the ribs and core them.

Are there going to be any secondary finishing operations other than machining the ribbed & gasket surfaces, boring the holes and preparing the tube to receive the filler cap?

zefarelly · 1 Mar 2006, 10:05 (Ref:1533800)

Tanky, send me a PM and email me the file, text is easy, my logo is imported as a DXF ( I drew it in Autocad years ago ) probably took me about 4 hours to draw the whole thing

I can use the mould commands in solidworks to create the 2 halves of the mould and scale up 1.75% for shrinkage. I'll probably get the master model machined from Ciba board by the people who do our work stuff. The Idea is to start with about 10 or so to use and sell with any engines/headds I do, also to go with the rocker posts I've also drawn up and am investing in

http://img202.imageshack.us/my.php?i...erblock2ea.jpg

Marshal · 3 Mar 2006, 21:17 (Ref:1535708)

Quote:

Originally Posted by thebear

That would result in a very large waste of material aside fom an extended machining time.

True, but unless you'regoing to make more than say 25 off, it'd still be cheaper - besides that's the way we'd do it in Aerospace

ger80 · 4 Mar 2006, 19:16 (Ref:1536268)

Hey, are you from Airbus UK? Yes, i would mill it too. Maximum one hour milling. Or if you want to cast, i would ask someone to make a rapid prototyp part, use the casting with ceramic tool

zefarelly · 7 Mar 2006, 11:18 (Ref:1539472)

I'm hoping to machine or 3d print the model, then cast some

billet rocker covers are a little excessive I think !

Dave Brand · 7 Mar 2006, 12:11 (Ref:1539503)

Quote:

Originally Posted by zefarelly

billet rocker covers are a little excessive I think !

.....and not very '1960s'!

icemachine · 8 Mar 2006, 00:07 (Ref:1539925)

For a lot of our low volume prototypes we use a company that does graphite casting

zefarelly · 8 Mar 2006, 15:08 (Ref:1540356)

graphite ? how does that work ?

it'll cost me £800 to have it 3d printed . . . bit pricey, still waiting for a machining price

Dave Brand · 8 Mar 2006, 16:47 (Ref:1540543)

Quote:

Originally Posted by zefarelly

it'll cost me £800 to have it 3d printed .

Have you priced up conventional (i.e. old-fashioned) wooden patterns.....if there are any patternmakers left!

icemachine · 8 Mar 2006, 18:24 (Ref:1540638)

zefarelly, not sure exactly how, but I understand they machine the block of graphite for the negative, and then pour like you would for any gravity cast piece.

zefarelly · 13 Mar 2006, 10:20 (Ref:1546976)

I'm working on traditional methods and costs now !

graphite sounds pricey !

StephenRae · 13 Mar 2006, 11:47 (Ref:1547031)

I have one of these surplus to requirements...I've changed my engine builder, it would be easy to machine the name off and just cast your logo and stick it on....or use it as a pattern.

zefarelly · 14 Mar 2006, 11:23 (Ref:1547862)

a scaled model Stephen ? pm me the details maybe ?

***Chris Y*** · 14 Mar 2006, 19:35 (Ref:1548295)

Zef, I believe I may be able to get hold of a comprehensive set of pattern-maker's tools. I'm told this set has been handed down from master to apprentice over many generations and is therefore of very good traditional quality. Let me know if you're interested.

Marshal · 14 Mar 2006, 20:31 (Ref:1548895)

Quote:

Originally Posted by ger80

Hey, are you from Airbus UK? Yes, i would mill it too. Maximum one hour milling. Or if you want to cast, i would ask someone to make a rapid prototyp part, use the casting with ceramic tool

Yes

I agree milling isn't very period, but probably is cheaper - still, if you need good tolerance, I'd go for an SLA (quickcast) Investment casting, as previously mentioned by ger80

zefarelly · 15 Mar 2006, 11:24 (Ref:1549362)

Quote:

Originally Posted by Chris Y

Zef, I believe I may be able to get hold of a comprehensive set of pattern-maker's tools. I'm told this set has been handed down from master to apprentice over many generations and is therefore of very good traditional quality. Let me know if you're interested.

wow, in all honesty I know very little about casting and am trying to learn a little as I go. I don't even know what the tools would be like. would love to kmnow though

Andy Law · 3 Sep 2009, 16:58 (Ref:2533904)

I dug up this old thread to see if anyone can recommend a company to do a one of or small run of Alloy inlet manifolds.

XKRacer · 3 Sep 2009, 17:58 (Ref:2533947)

You can try a company called SureCast used to be based at Devizes

http://www.surecast.co.uk/wsa/

I use to use them a lot for all my ali castings!

SZRacer · 4 Sep 2009, 20:21 (Ref:2534647)

Also used these people a long time ago, for some magnesium racing wheels.

Only downside is they are in the Isle of Sheppey!

http://www.uk-racing-castings.co.uk/

James

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