How do they make the non-circular holes in an engine block?

Maintenance/Repairs
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I’m thinking that using a CNC machining p[rocess would ultimately be less expensive than a sand casting process - and the smaller the number of parts made, the more advantage CNC has. My thought process on this:

In the days where paper and pencil was used to design molds, you needed a carver to make the master. Then copies were made of the master. Then the sand is formed around the copies, then the part was cast.

In a CNC process, the design is done in the computer and you can take that directly to a CNC machine. (Yes, yes. I’ve simplified the explanation, but I did that with the sand casting process, too!) The net effect is that a lot of middle steps are eliminated.

I honestly didn’t imagine we would see 3D printers and while that doesn’t seem to be a viable way to make engine blocks, maybe in the future that would change.

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Going up as fast as other businesses like consumer goods, finance, medical care?

Consumer goods in general is a lower paying job across this country. Finance can pay a decent amount…but that market is almost flooded with finance majors. Medical care at the high-end (Doctors) usually pays well. But nursing in many parts of this country is just slightly higher then teachers.

Here in the Boston area…a starting salary for a software engineer is about $60k. If the candidate is really good from a higher end university then maybe $75k. Starting salary for a person with a finance degree is about $35k. Consumer Goods - here in NE…you’re lucking to make much over minimum wage.

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@keith-

“TwinTurbo, I worked in a foundry that made cylinder heads for all three US manufacturers and one Asian manufacturer. The molds were made by hand. A million dollar CNC machine will pay for a lot of manhours. You don’t invest in that kind of machinery that will only be used a couple days a year, and you still have to pay a machinist to operate it.
”

You are using a lot of past tense here. Things have changed DRAMATICALLY in the last decade even. CNC machines are no longer costing even a fraction of $1M. We recently bought one that could easily do your cylinder heads for around $150k.

Secondly, you do not need to have a machinist babysit the machine anymore. They are machine OPERATORS and far less skilled than a machinist. Essentially, they load and unload the raw materials and finished parts and make sure nothing dramatic happens in between.

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“I’m thinking that using a CNC machining p[rocess would ultimately be less expensive than a sand casting process - and the smaller the number of parts made, the more advantage CNC has. My thought process on this:”

Depends on the end product. A block of material (billet) can be costly compared to casting almost to the finished dimensions. Efficiency is sought every day. If you start with a billet and have to whittle away every bit you don’t need, that costs time. If it is pre-cast and then only finished with the machine, throughput goes way up. Some alloys are not easily recycled. In that case, you’d prefer not to create great volumes of shavings to be recovered and recycled. You can bet the cost-benefit calculation has been well vetted assuming the technical issues are a wash…

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And it isn’t easy to CNC the complex internals of a head or block, right?

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@GeorgeSanJose, the wages for Civil Engineers right now is decent, and keeping up with inflation.

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Good on you BK for having a job that at least keeps up w/inflation. I guess in your field there isn’t much lack of qualified job seekers, otherwise wages would be going up more than inflation. And what with the hiring freeze you mention, I can see why many US students might be somewhat shy about investing a lot of time and money on an engineering degree. My expectation – given that college students are pretty street-smart savy these days – is that the number of US citizens being granted advanced engineering degrees isn’t advancing much. Hiring freezes don’t breed much in the way of confidence. Thanks for the interesting info.

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TwinTurbo,

Secondly, you do not need to have a machinist babysit the machine anymore. They are machine OPERATORS and far less skilled than a machinist

That is not necessarily true. At the foundry, I ran the finishing department. We had a transfer line consisting of several CNC machines, one line had 27 stations with 12 CNC machines. These were operated by machine operators, but mistakes turned out to be costly when you are running a cylinder head every 18 seconds. All the operators were eventually sent to a local technical college to get an AA degree in machining. All paid for by the company and they even got paid for their time at the school.

Another company that I worked for tried that and eventually had to lay off all the “operators” and hire machinists, although a few operators kept their jobs because they took night school in machining on their own time.

Sometimes things just don’t work as well as planned.

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Just curious here. What would the machine do to the cylinder head in just 18 seconds? Seems like that would barely be enough time to drill one hole.

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It doesn’t drill any holes. A transfer line is an automated line that picks up a part and moves it from one station to another. In the machines at the foundry where I worked, the transfer rail was a mild steel 2x10 with saddles that the heads sit in when moved. The bar would come up and lift the heads, move about 3.5’, then set the head down in the next station and return to zero position, all in about 2 seconds.

Some stations didn’t do anything, but at some of the stations, there were high speed CNC mills. The head would be pushed against a set of locator points, then it would be clamped in place. A mill would follow its path to machine a surface on the head. Some of the mills cut as fast as 100,000 surface mm per second. Depending on the line in operation, there would be 16 to 27 heads in the line at any given time. The line moved the heads every 18 to 24 seconds so one pre-finished head would exit the machine every time the transfer line cycled, and one raw casting entered.

Typical machining would be: saw off the riser, cut the combustion chamber face, cut the intake manifold face, cut the exhaust manifold face cut the front end face, cut the rear end face, cut the cover rail, then some pre-machining that was unique for the head.

Then the castings would be sent to the assembly factory where final machining was done and then assembly. Pre-machining or pre-finishing is called “cubing” in the auto industry.

Watching these transfer lines work is like watching a ballet. It is something to see. But if a head gets out of position, it is a gut wrenching sound. I saw one bend that steel 2x10 into a pretzel shape.

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One of the problems with discussions such as this is thinking outside the box. That is, technology changes over time and things that used to be impossible become possible.

We’ve now agreed that it is possible to CNC machine an engine block - something that in the past wasn’t feasible. So it might not be economical today, but maybe in the future.

Remember, air cooled motorcycle engines have cylinders separate from the crankcase. That presents a possibility that a CNC engine block or a CNC head might be economically possible.

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Wow! 20 seconds per station. Thanks for taking time to post the info Keith, interesting.

One time it took me 2 hours laying on my back in the dirt just to free up a stuck brake wheel-cylinder bleeder screw. In that same time 600 cylinder heads could have had all their surface machining done. 600 cylinder heads vs 1 bleeder screw? hmmm … I guess I have to face the facts, no doubt about it, I’m a slow worker!!.

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@Texases … I just got the DVD set of “How It’s Made-Automobile” last night. I watched several of the segments already. Thanks for the suggestion, it is a great vdo for the auto-enthusiast, especially if interested in how the stuff is actually made.

One thing I noticed straight-away is those robot welders are scary!! In the “making a car” segment, there were what looked like a dozen of these robots, sparks a-blazing, bending over and welding the cross support members of a car, the structure the floor pan is later attached too. It looked like a scene from one of those 1950’s outer space movies! Those robots, they almost look like real people, how they sort of bend over to reach what they are welding, and each one is doing something different. Me, I’m staying away from the robot welding areas … they might get loose … and robot zombies on the prowl would be harder to kill than actual zombies I’m thinking … lol …

I also watched the “making an automobile engine” segment and I finally saw how the sand-mold technique works. The trick to getting all those contorted paths inside the engine is they make the mold in sections, sort of like making a layer cake. Layer by layer, then they glue all the sections together and fill it with metal ( aluminum in this vdo) . The actual sand mold section is made exactly as you’d think, mixing sand with glue to it holds together. They don’t use any old sand, like beach sand, they said they use zirconium-based sand, I guess they figure if zirconium is good enough for nuclear reactor control rods, it is good enough for automobile engine molds too. Not sure if they use just powdered elemental zirconium or a zirconium oxide. You’d think titanium oxide would work too, it must have a pretty high melting point.

The part where they showed how they machined the crankshaft was crazy! I envisioned an elderly grandfather type working away on a lathe, hand machining each one. No way. It’s this crazy robot gadget that machines 6 or 8 surfaces at the same time! Gadgets rotating carbide steel cutting surfaces every which way. I think I’ll stay away from that section of the factory too!

The “making a motorcycle engine” was fun to watch too. As was the final segment I watched, which was making a big truck. Its the kind of truck that could be later made into a flatbed truck or a panel truck. Like a 16-20 foot moving truck, that kind of truck. What impressed me about making the truck was how everything heavy was lifted by mechanisms, all the workers had to do is overcome the inertial forces to position the part into place. Like installing the wheel, it is held up by this crane-like thing, and the worker just positions it to the hub. Then this other gadget comes on and torq’s the lug nuts down, not one at a time, but all of them at once. I guess that’s the only way they can make these trucks for the prices they do, automate anything they can.

Anyway, thanks for the good suggestion. Anybody else care to watch it, here is the info.

How it’s made – Automobile (2 DVD set)

Summary: Collection of episodes about the manufacturing of various personal transportation vehicles and their parts.

Gaiam Americas, Inc
Discovery Communications, Inc
ISBN: 9780766253056 0766253058

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@GeorgeSanJose -Glad you liked them, one of my favorite shows. Yes, those robots are amazing. There was one show like that about a BMW plant, I think. Almost NO PEOPLE involved for many of the assembly steps - a robot-powered factory.

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Wait until 3D printers get there. More amazing stuff to come.

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Yeah, good point @CapriRacer, a 3D printer that could print sand molds, maybe more likely it would print a reverse mold from which a sand mold could then be made from it, yes, I can see that could be useful to the engine block makers.

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I was thinking more along the lines of a finished part.

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Are we to expect 3-D printing of iron and steel, @CarpriRacer? I have seen the plastic zip gun that was produced on a 3-D printer and it wasn’t very impressive. Plastic engine blocks and crankshafts leave a lot to be desired.

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Are we to expect 3-D printing of iron and steel, @CarpriRacer?
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Great link, Mike. If you’d have told me 30 years ago that this would be coming I would have asked you what you were smokin’!