The problem of the Mazda RX7 motor is that creators made it uncompromising. It means that it is difficult to make any changes to it; it is already on its limit. One of the limit point is the engine manifold. That is why I decided to modify it.
Denis's project Idea: to scan the engine manifold; improve it using fluid and gas dynamics analysis and topology optimization; and after that, to produce a new engine manifold of metal using investment casting.
Although fluid and gas dynamics and 3D scanning are very entertaining processes, 3D printing does not relate to them. If you find it interesting, you can listen to Denis talking about these processes.
He is the Head of Technical Department of "Phoenix 24". Now he is working on improvement of an inlet manifold for Mazda RX7.
Denis holding the manifold
After the improved collector has been calculated, it is possible to proceed to casting. At this point, we find main difficulty in investment casting, which is the producing of master model. Master model is required to make casting form, which is to be filled with metal.
There are several classical technologies in casting like milling, sand-mold casting or manual cutting of a master model of foam. They are not suitable for complex geometric shapes like the engine manifold. Solution: to 3D-print the master model of special material. Look how Denis describes this:
Special materials created for burning-out, which have low ash level, should be used for 3D printing of master model.
It is needed to avoid penetration of plastic remains after burning-out into metal while casting. One of material we can use for it is "Cast" by company Rec
for 3D printing of investment pattern
In addition, this method can provide smooth surface, without roughness. You just should set the layer thickness on minimum value – 20 micron
Going forward the master model is put into gypsum solution, and after gypsum hardened, the material of the master model is burned out. After that empty space in the gypsum form remains and is to be filled with metal.
I do not think that nowadays-alternative method of producing such complex form exists.
Denis has an opportunity to make a master model quickly, with high precision, and without defects. Expenses for producing of parts using this method is much lower than machining or making a chill mould for casting.
Burning plastic out in a furnace
Filling the form with metal
Putting the master model into gypsum solution