East Coast Parts billet rotors weigh 7lbs each, believe they have a lighter design in the works.

I'd be more impressed with these if they didn't have the whole 'aircraft quality aluminum' bit on their website, T6061 is the most commonly used billet aluminum out there, just about anything you buy made out of machined aluminum is made from T6061 billet, I'd be more impressed if the rotors were made for T7075 aluminum and then Type III hard anodized.

But they do see to be making progress where no one else has, which is good to see.

 

is it possible to bore out the rotors and irons and use larger bearings with a larger diameter eshaft. lighter rotors and a bigger (theoretically tougher) e-shaft.

 

I think its more like actually trying to make a rotor than progress. As a former machinist, a solid billet rotor wouldn't be very hard to make, especially once the cnc program has been proofed and jigs were made. The side seals are the only part I see as troublesome, but I don't know how wide or deep those slots need to be.

Yeah 6061 t6 aluminum is more or less the universal industry standard for aluminum. Its the jack of aluminum alloys, good weldability, good corrosion resistance, good strength, good machinability, but not exceptional at any of them.

Personally, I'd like a to see a 50/50 aluminum/silicon rotor, but I'd don't see anyone getting involved with powdered metallurgy, except maybe mazda. (fingers crossed)

 

7075 isn't near as stable as 6061T6. As far as aluminum goes, its either crazy cost for slight benefits, or 6061T6.

About the PM, I don't believe you can make complex interior shapes. PM is more/less for mass production of small complex exterior shapes. You also have to remember that you lose like 30% strength when going with PM aswell.

I believe that the solution isn't in the material, but in the design. There is always performance vs part life vs cost.

 

Right, my mistake. I still had solid rotors on the brain when I typed that. If my math is right a solid 50/50 alusil rotor would weigh 6.52lbs.

Actually mazda could keep their current casting techniques but switch to a high-aluminum heat resistant cast iron. Its already a good thermal insulator and could drop the oem rotor weight by as much as 25%.

 

sounds like a certain machinist should try it and let us know how it works
sounds promising

 

I can't resist replying.

As a machinist, I've often though about making the rotor out of a lighter material and three-piece.

Imagine the faces, webbing, and hub in the perspective of an extrusion. Secondary machining to except the side plates. Either press or shrunk fit. The side seal groove could also be automatically incorporated into this design with no use of an extremely small end mill.

The "extrusion" could be most likely machined from billet. Or wired for those of us with access to such machines.

 

I think I read somewhere that the 787 had rotors much like described here.

 

Heh, trust me, I wish I could be that certain machinist. Unfortunately I don't have any machines of my own, and with companies like Deere and Caterpillar laying off people, I may be going back to college AGAIN.

I hadn't considered an actual extrusion before. That would be extremely simple once the design is proven durable enough (since aluminum isn't as strong as iron). Even the side plates could be their extrusion to cut down on scrap and machining time.

 

0.7mm wide x 4mm deep

Mazda made a few million rotors in a high-volume production setting, so it's not that complicated. That being said, I have a feeling that Mazda used/uses a special slotting machine. You or I could probably use a CNC mill with a high spindle speed and a simple end-mill.

 

I thought they were a little deeper then that.

Is the bottom of the slots curved or flat?

 

I would think that a lighter rotor like that would reduce torque, or maybe I'm wrong? I thought there was a disadvantage for lightened rotors.

I'm personally looking into e-shaft production.
Currently it looks like I'll have to forge the base shaft and mill down the remainder.
Going to get some quotes from a local forge on 4130 and 4330 soonish.

 

Lightened rotors will mean less rotational inertia but not less torque, you will notice the reduction in rotaty weight off the line as the lighter rotating mass will store less energy, so as you dump the clutch there will be less stored energy to help accerate the rest of the drive train, this could be mistaken for a loss of torque but it's not really. (This is the same effect fitting a light weight fly wheel has.)

In return you will get much lower forces acting of all the bearings and eccentric shaft, and the lighter rotating mass will mean the engine will rev quicker as you accelerate, and you will gain a few HP.

You could overcome the loss rotational inertia by running a heavier fly wheel, because the weight of the fly wheel is evenly distributed about its center, a heavier fly wheel will put no additional stress of the eccentric shaft or bearings. A lighter drive shaft, wheels and break rotors will all help hide the lowering of rotational mass in the engine itself.

 

Nice, thanks for the info.