Solid Aluminium Engine Blocks

[culver]

CULVER Modern casting is much better than it was 10-15 years ago.
Using CAD a modern casting is easily made up for low volumes using epoxy/sand multiple comopnents assembled and then botom injected.

With castng it is MUCH easier to include internal fillets and webs to make the cast block much stronger that could be achieved with machining.

As you noted, the advantage of machining is very low volume flexibility.
I'll bet when the 100/week Mellings are being assembled in teh US ( that's the plan ) they won't be using a CNC block

I am aware of that. You are correct about the fillets and the like. However, the material quality (strength of material) in casting is still not as strong as the other methods. However, as you pointed out, you are able to create fine features with casting that are prohibited difficult in the other methods.

[revetec]

It's an ideal prototypying tool but is VERY expensive for mass production and can't match casting for complex galleries and stress-reducing xurves. CNC'ing inside a box is very difficult and limited.

I have been talking to a manufacturer for our engine. Under 1,000 units it is cheaper to billet them as the tooling costs are cheaper for machined billet as opposed to casting then machining. Over 1,000 units it becomes viable to cast.

If it is a limited production engine then billet is the choice. Tooling costs for all a typical engine's parts is about US$1 million. Then about US$6k to US$8k for each unit. In production of a cast engine, the highest profitable volume is 300,000 units. If production is over this, then the production line is usually doubled which is quite an expense.

[Matra et Alpine]

Interesting, R.
Are you machining the same head 4 times and is the core of the X a single billet or joined anywhere ?
I think your engine block is significantly simpler internally than say a V8 or V10. Especially wrt side stresses on crank journals and chamber walls.

[revetec]

There are 2 base heads and 2 mirrored heads, so two programs to machine.

Pictures below before valve guides and seats were installed. They started out as solid 6061 billet aluminium and CNC machined. Pots are machined from two angles to meet up.





Our engine block is incredibly simple (note: our barrels are separate from the block as it has to be serviceable for aircraft applications.)

[Matra et Alpine]

hmmm, my views on complex CNC for machined blocks has re-educated

In the past, the best a CNC could do was 4 degees of freedom. This meant thatcomplex machining was difficult as it had to be doe in multiple stages/machiens and hence costly and prone to tolerance errors.

See the V8 and W16 blocks being machined at http://www.youtube.com/watch?v=QsmiI...elated&search= and http://www.youtube.com/watch?v=GU32Q6QXtWQ


This has 5 degrees of freedom, so can rotate the billet whilst moving the cutting tool. Amazing they're maintaining tolerances and handling forces !!

So it will be cheaper to machine on equipment like that than before. Liekly reducing the task down to a 3 or 4 stage machining process. Well impressed Knew all the other nerdies here woudl appreciate it too !!!!

[Cyco]

Brilliant videos.

I still suspect that for the difficulty of cleaning up the chips that if the quantity is reasonable that casting will still be a better proposition for reducing waste cost of material.

[revetec]

For setting up the casting for one engine, it will cost about US$1 million. You still have to machine it. So limited runs under 5,000 units it is still cheaper to billet machine. High speed machines operate at incredible speeds, and the spindles go up to 25,000rpm.

[Pando]

See the V8 and W16 blocks being machined at http://www.youtube.com/watch?v=QsmiI...elated&search= and http://www.youtube.com/watch?v=GU32Q6QXtWQ

Interesting clips, really a showcase of technology. But it got me wondering, I'm a newbie when it comes to engines and engineering but I thought a W engine is basically two V engines side by side with the cylinders angles forming a W shape. In my books this engine would've been a V16 as the cylinders only were angled in two directions, similar to mounting two V8 on top of each other. Am I totally off?

edit: Never mind, I was way off. Learn something new every day, huh.

[hightower99]

Wow but those machines are obsurdly expensive...


Does anyone have any ideas how much it would cost to get a machining company with one of those machines to do a one off or maybe a short run of something?

[Matra et Alpine]

Wow but those machines are obsurdly expensive...

all depends on what you consider "expensive".
As an investment for an engineering company it makes a lot of sense as they get paid per job.

Does anyone have any ideas how much it would cost to get a machining company with one of those machines to do a one off or maybe a short run of something?

Yes.
All down to the time to develop the CNC instructions and the time in the machine and the time for each of the cutting tools. All depends on the material, size and complexity.

[revetec]

Interesting clips, really a showcase of technology. But it got me wondering, I'm a newbie when it comes to engines and engineering but I thought a W engine is basically two V engines side by side with the cylinders angles forming a W shape. In my books this engine would've been a V16 as the cylinders only were angled in two directions, similar to mounting two V8 on top of each other. Am I totally off?

A Staggered bore V Type engine is classed as a "W" engine.



Note the 8 spark plugs inline on a common head. This is a staggered bore W16.

The VW VR6 engine is a staggered bore 6. One cylinder head. In the trade we said VR6 stood for Virtual Reality 6.

[mikelzapi3]

See the V8 and W16 blocks being machined

that's CNC porn, even to do the CNC program you need very expensive software. We use CATIA to do the programs for high speed machining because normal software like GibbsCAM isn't good enough

[Kitdy]

Why is silicon alloyed with Aluminum for car engines and what else if any is added? Why are these things added?

Also, why silicon in cast iron?

I had two materials science classes coming up on 3 years ago and have forgotten pretty much all of it.

[Cyco]

All sorts of other elements are added to various alloys to give better properties than the raw element posses.

Depending on the finished parts requirements then you chose the properties you want and the alloy to give them to you.

MatWeb has one one the best databases I know of (that is publicly accessible) of all the material properties, and compositions.

[Knuto]

Why is silicon alloyed with Aluminum for car engines and what else if any is added? Why are these things added?

The manufacturing process applied to engine blocks is casting. The Al-Silicon alloys provide the best casting properties of all Al-alloys. Because Alu contracts when solidified, but Si expands, the result is little change in volume during solidification when Si is added. This leads to less strains on the fused casting, less pores, hot cracks.

Si is also less dense (2.33 g/cm3) than Alu (2.7 g/cm3) which reduce the density of the alloy.

Usually the alloy content is lower than eutectic point (12 wt% Silicon), but still high (> 5%), to give a short solidification interval, i.e excellent fluidity and casting properties.

For cylinder liners the alloy is hypereutectic, i.e the content is higher the eutectic point. This gives hard silicon crystalls before the Aluminium phase forms. These faceted crystals give excellent wear properties against the iron lined aluminium piston and the piston rings. This alloy is used if the liner is made of Al instead of steel, Ni plating, cermet...

In addition to Si there are other elements. Cu (~3.5 %) is added to increase strength and hold its strength at elevated temperatures. It also increase casting properties. Mn, Mg and Ni also give higher strength. Typical alloy,Typical alloy2


If the block is machined from billett, that kind of alloy is not used. There is no need of the high Si content and there's overall lower alloying content. There are much stronger alloys out there. I imagine they use an alloy similar to piston alloys:
Alloys containing Mg (<2 %), Cu (~2%) and some Ni, Si and Zn gives highest possible strength at elevated temperatures after heat treatment by precipitating different particles (Al2Cu,MgCu2,MgZn2).Typical alloy

Maybe Al-Mg-Si can also be used, but now the role of Si is different. These are alloys contain ~1% Mg and ~1.5% Si. Together with Mg it forms Mg2Si particles during heat treatment which increase strength.
Typical alloy
However the strength of these alloys drops off more with increasing temperature.

Also, why silicon in cast iron?

I had two materials science classes coming up on 3 years ago and have forgotten pretty much all of it.

This is a different story. Here it's mainly for desoxidation during solidification to form oxide particles instead of pores. These particles also give an increase in strength and limit the grain growth during casting. With high numbers and low size, these particles can produce acicular ferrite at higher cooling rates. This is an extremely finegrained microstructure with high strength and good ductility.