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CNC'ing housings

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Old 04-12-15, 09:22 PM
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Originally Posted by j9fd3s
China already makes iron rotor housings. turns out that iron is unusable as a rotor housing material.
I've scoured the internet for these supposed housings but come up empty handed as I wanted to try them myself. Not only can they not be found, there's certainly no hard data shown so far that anyone has actually seen or tested them.

Until someone can post up some hard data on these, I'm calling these magical imaginary unicorn housings.

Last edited by 88 SE; 04-12-15 at 09:25 PM.
Old 04-12-15, 10:33 PM
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Originally Posted by 88 SE
I've scoured the internet for these supposed housings but come up empty handed as I wanted to try them myself. Not only can they not be found, there's certainly no hard data shown so far that anyone has actually seen or tested them.

Until someone can post up some hard data on these, I'm calling these magical imaginary unicorn housings.
actually you should just read the rotary engine book, by kenichi yamamoto, he has a section about the materials for the rotor housings.
Old 04-12-15, 10:40 PM
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pic/scan that page in? is that a no-no?
Old 04-12-15, 11:57 PM
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Originally Posted by j9fd3s
actually you should just read the rotary engine book, by kenichi yamamoto, he has a section about the materials for the rotor housings.
I'm not doubting the section on heat transfer efficiency of Iron vs Aluminum originally filed by the NSU then subsequently published in other publications, and the fact that aluminum is superior as tested in center sections during the NSU research.

I'm doubting that the chinese made Iron copies exist, and that there is any data proving either way that they are acceptable or not.
Old 04-13-15, 12:04 PM
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Originally Posted by lastphaseofthis
pic/scan that page in? is that a no-no?
why? just read the whole book
Old 04-13-15, 12:42 PM
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Originally Posted by lastphaseofthis
pic/scan that page in? is that a no-no?
I'll just save you the effort...

http://foxed.ca/rx7manual/manuals/RE...amoto-1981.pdf
Old 04-13-15, 05:50 PM
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It should be noted that in the long distant past when these papers were written, technology was pretty inferior.

I think the clear "economical" method to create new housings is to use CNC machines to remove the steel inner lining of used housings and replace them with new ones.

The cost of chrome plating sheet steel then forming it to the inner surface should be fairly reasonable. The real challenge comes in creating a mechanical lock between the new liner and the existing housing. Of course given that CNC routing routines can be programmed, it should be possible to use a program that can etch mechanical locking surfaces into both pieces. There's also the possibility of industrial adhesives, which have come a long way since way back when.
Old 04-13-15, 06:02 PM
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Originally Posted by lastphaseofthis
there is a video on the mazda website of them making rotor housings. maybe you could review it and tell us if the sand is fired? I can't tell either way... but its' definitely sand.
I could not find the video.
Old 04-13-15, 06:13 PM
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Old 04-13-15, 08:48 PM
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The housings are made by High Pressure Die-Casting (says so in the video). The say "Special" in which I have to agree. It is a bit different than I'm used to seeing because of the large runners (you can see the remnants at the bottom of the housings you have at home, they just saw the runner off). Honda lower engine blocks are made this way. The pressures are many times over normal die-casting and result in less porosity, greater density, and a stronger part.

The rotors are made by the precision sand casting method using the fired sand, as I suspected.

Oh yeah, thanks for the video.
Old 04-13-15, 11:39 PM
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Forgive me if this is obvious, but why hasn't Mazda tried hypereutectic aluminum for the rotor housings?
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