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Comment by Jerry2 | Hacker News Reader

From the article:

>they weigh 10 percent less than their forged equivalents and feature an integrated and closed cooling duct in the piston crown that's apparently unable to be reproduced using traditional manufacturing methods. The decrease in weight and temperature results in an extra 30 horsepower on top of the GT2 RS's already mighty 700.

So.. 10% less weight and ~4% increase in performance. But what about the increase in price? 3D printing is magnitudes slower than forging and probably many times more expensive. I guess some Porsche owners would gladly pay for these improvements.

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These are limited edition cars. A relative handful are made. That’s often where a manufacturer goes to more customized tooling and parts. Keep in mind Porsche owners of these types of cars will often easily spend 20-50k usd customizing the most minute details such as stitching color of the seatbelt, etc. Factoring a few thousand extra dollars in engine cost is easy.

I would assume it would be for racing, not consumers. They didn't mention cost, but looking at the process, time and materials involved I'd bet you're looking at tens of thousands of dollars. I don't see consumers going for that, but GT racing clubs? Oh yeah!

I can see some overlap on the extreme consumer end [their 300K 700hp car is probably hundreds produced at most. The profits are already really high on those vehicles so I am curious if/when/how they will release and price this tech, or if it is just some random Porsche team drumming up some marketing for mostly vaporware :)

>Factoring a few thousand extra dollars in engine cost is easy.

Totally get your point from the rest of the comment, but we could be seeing notably more expense from this. 2015-2017 I was working in a university research lab and we had an industry partner with a metal printer. They said a piece 10 inches long and 3 inches in diameter had an all-in cost of 5-8k, depending if it was steel or titanium.

I never saw a detailed breakdown of the costs they accounted for, and hope we see these manufacturing costs continue to drop.

There is a lot of challenge making the powder good for 3d printing. Tons of requirements around the size and shape - not being perfectly spherical, not being too long, etc. My understanding is this leads to much of the high material cost.

> 3D printing is magnitudes slower than forging

Suppose you wanted to mass produce 3D printed parts as cheaply as possible. Would there be opportunities to scale up the speed of printing?

One thought is to steal an idea from traditional (2D, paper) printers. A traditional dot matrix printer has a head which sweeps side to side, but there are much faster printers called line matrix printers (https://en.wikipedia.org/wiki/Line_matrix_printer) which essentially have a head the width of the entire page, so it prints one entire row of pixels in one fell swoop. (One such printer is the IBM 6400. Video here: https://www.youtube.com/watch?v=KnPBWru2Ecg#t=6m57s)

One could imagine a similar approach with 3D printing with a wide print head that prints an entire row at once instead of a point.

Maybe there could be other optimizations or economies of scale as well.

Obviously R&D costs would be high, so you'd probably only do it if you could use for more than just pistons in one low-volume model of car.

You can already see some relatively high-volume components produced with additive processes, but we still need to address part strength/integrity and process reliability.

In my (admittedly limited) experience and leaving aside cost considerations, process reliability is the biggest thing holding us back from widespread adoption of AM in mass production. If you could just leave the machines running lights out with confidence that you’ll get good parts in the end, then individual process speed wouldn’t be a huge issue. We aren’t there yet, though.

I imagine this is where mass CNC machining processes were ~30 years ago.

For some types of 3d printing where the material is laid down in a bead, the path of the nozzle has an effect on the resulting part. So having a wide row of nozzles would give you less flexibility in the design. But this may have less of an effect on certain metal 3d printing technologies. For example, that could work very well for some metal sintering methods.

https://en.wikipedia.org/wiki/Selective_laser_sintering

What I find facinating about 3d printing is how much unexplored area of research there is. Not only is there so much more to explore, a lot of it is very accessable without lots of money or technology. This is especially true on the sofware/gcode/slicing side of things.

>What I find facinating about 3d printing is how much unexplored area of research there is.

I spent about 2 years working on manufacturability analysis software during grad school. We were looking at machining, 3d printing, casting, and die casting, with the intent to give feedback to the design engineer.

There are indeed an incredible number of opportunities when it comes to additive manufacturing. And when you start dealing with integrated CNC/AM machines, you get an order of magnitude more possibilities.

The lab I worked in got one of these machines and I toured the lab last year. They were working on things including:

* Fast 3d printing of big parts. A demo part ~24x12x3 inches was printed in about 2 hours, which would have typically taken a couple days. The nozzle was much larger than most 3d printers, high precision and accuracy weren't required, but the demo part wasn't easy to manufacture with traditional subtractive methods

* Switching materials mid-print, enabling plastic and metal to be integrated in way which are otherwise prohibitively expensive or impossible.

* Integrating machining and 3d printing. Fixturing is traditionally a big challenge with machining, and every time you reset the part in a machine, you add variability to the part. 3d printing features then machining flat surfaces (for later use as datums or functionally) really cleans things up for better assembly, part function, and later fixturing.

Manufacturing capability is growing very fast in neat ways, and I'm excited to see how things will be in 5, 10, and 50 years.

No one is talking about what Forging does to the grain boundaries and consequently increasing the strength of the material.

There is also shot peening which is like case hardening but with little balls of steel. Usually done on piston rods and turbine blades.

I don't think 3D printing can do these things, but I hope to be proven wrong some day.

I don't understand the point of this comment. No one is saying that 3D printing will make forging obsolete. There's always a balance of trade offs. It's up to the designer/engineer to decide how something should be made. Developing more options, and better understanding those options is part of engineering progress. It may be good to temper expectations (no pun intended) to avoid overhype, but at the same time I think it's also good to let people's imaginations run wild because that's where creative developments come from.

For example, I'm sure people will come up with ways to have more control over grain boundary and other material properties of the 3D printed material through the use of heated chambers, annealing, new alloys created for specific processes, etc.

Does it really matter? If it costs say an extra $500 per piston will people really not buy that $290k car?

the real cost is the calculated odds of a thrown rod destroying a $30k engine. I suspect that is why this will be economical in racing applications.

Some people who care about car performance would gladly pay twice the price to get that 4% increase.

It's not only HP necessarily either. Lighter pistons could also improve responsiveness. You're accelerating less mass so that could mean a nicer torque curve if you increase weight savings in the moving parts of the drivetrain.

Yeah, 30hp is a lot, esp considering the weight is reduced.

It’s Porsche not Honda.

Well put. In general, the concerns for "massive scale" manufacturing that manufacturers like Honda and Toyota have are simply not shared by Porsche, who are known over their entire existence to manufacture < 1000 cars for a lot of their models.

Price difference for relatively low run orders probably isn't that bad. I'd estimate 3d printing costs to be on the order of 250-400$/piston in quantity before post print machining for OD and wrist pin tolerance.

Molds are expensive, so you have to spread the cost over many produced units. Probably if not many cars are made, cost isn't very different.

Regarding the extra 30hp, I think they probably come from the ability to slightly increase the RPMs because of the weight reduction.

GT2 RS is already close to $200,000USD (If you can even get one.) Also ask around on Rennlist how many GT2 owners have popped the motor requiring a full replacement in the first 10,000 miles.

True price is waaaaaaaaaay more than that. Nobody pays retail for an RS spec car nowadays. Not to mention once you add options, that's another $100k+.

the GT2 RS has a base price of $294,250. I doubt these pistons cost any increment that anyone that buys a porsche will care.

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