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making A 671 Blower

30K views 152 replies 37 participants last post by  1970ls8 
#1 ·
Figured id post this on the bullet, dont really post to much, usually just read but i figured some of you might find this really interesting.


I work for an aluminum Foundry and Production CNC shop in Muncie, IN, Phillips Patterns and Castings. We making American made parts, Im an engineer and pattern maker.

I've designed up a 671 blower and am machine the pattern right now which will be used to make casting then the castings will be machined into the final product.

Im machining the pattern right now, should have castings by next week and ill post the video hopefully by beginning of next month if anyone cares to see it.

If anyone has questions, feel free to ask.

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Here is a photo of the CNC machine cutting the pattern, im cutting this in 3" layers of renwood. The layers are just super glued together then i post-process the tool paths and drip-feed it to the machine. This photo is of it doing a Z plan cut and leaving a 0.0500" machine stock.



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This photo is the designed pattern i am cutting.



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This photo is what the finished casting will look like.

 
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#58 ·
Day 22: Casting

Lot of photos today, had a few problems molding but we've sorted it out, have the casting ban sawed and ready to be taken to the cleaning room. You will see this in the photos but we are going to be pouring these cases with X-ray quality metal, we've degassed our metal twice and will be sending one of our cases to X-ray and for lab testing. To give you an idea though, we just got back our lab results of some castings we did last week that where also X-ray quality, there tensile strength was around 33,000-35,000. I will have photos up of the results when we get them and pictures of the x-rays. which will all be in the video too.

Still can't get youtube to upload my rotor video.

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liquid parting line being sprayed on the flask and pattern



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Sand being dropped down into the flask



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Ramming the sand with a air rammer



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Bottom board being placed



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Squeezing, not positive but i believe this machine squeeze above 120psi



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rolling over to mold cope



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Liquid parting on the cope side



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Ramming the sand



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Ramming tools



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squeeze board




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Mold being squeezed, we squeeze once, fill with sand again and squeeze, or just called double squeezing :)



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Compressed over 2", hard as a rock, i punched it and didn't even leave a dent



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Squeeze board off, you can see the risers sticking out



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The second squeeze



 
#59 ·
Day 22.3: Casting

cooling the sample off in our high tech low pressure submersible cooling machine



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Cutting the sample



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Sample one, we where not happen with this so we ran another degas cycle. It is hard to see in the photos but there are minute bubbles in the metal, again, exaggerated from the zero pressure test. They would not be visible by the human eye if cooled normally.







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Sample two is on the left and we are good to pour now, the other sample is from another furnace found a while back, i just wanted to show a bad sample with a good.



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Mold being slide down the line



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2000lb furnace, about 1000lb in it now



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The far ladle is 55lb of metal, the closer one is 35lbs of metal



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Filling up the mold




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Thats all that is left off the 55lb, 35lb was empty



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Mold being dumped into the shakeout trough





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Being hooked up to the crane



 
#60 ·
Day 22.4: Casting

Taken to the scales and weighed with the core still in it. 136lbs





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Sitting outside to cool down before knockout




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We have been testing a new chemical for our airset that is a 50/50 blend, it works so well that we didn't even have to hook up the casting to the knock out, it just feel apart with a few hammer hits. And this core was actually not hollowed out, it is pure solid sand.






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Band sawed and weighed, 47lbs, this will be a little less once it is ground and machined to size





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This machine is the knockout machine, which works by clamping jaws down to the risers and ramming them extremely fast and vibrating the core apart, we just brought it in here though to blow it off with some air to see the casting better.

These photos are of the very first casting off the line. We like to do it right the first time :), this will also be the one X-rayed and tested. It is still a little dirty but once it is ground and ran through the shot blast machine it will look awesome.









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Thats it for now, i will try to get the case ground and shot blast so you can see it cleaned up a bit, but i have a wedding rehearsal to be at in a few hours so we will see. Ill probably go in sat our sun to work on it a bit and get a few more photos and get the video up as fast as i can
 
#67 ·
Day 28:

Sent the casings to heat treat, not sure when we will get them back. Our horizontal is down for right now and all our other mills are running jobs so we can't start on making the fixtures yet. The horizontal should be up by the end of the week and hopefully get started on the fixtures next week. We also had the boring bar salesmen in today to discuss buying 2 roughers for small bore and big bore and 1 finisher.

So for now im working and discussing how we are going to be making the cores and molds for the rotors.

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Cleaning room deburring and grinding the cases before sending out to heat treat.



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Measured the top of the case just to see what the shrink was, my casting model was measured at 15.296, the actually casting is 15.328. So the casting is off by 0.032, not bad considering greensand has a tolerance of �±0.030 and the casting is 15" long. So technically the casting is only off 0.002



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Front plate sitting on the raw Casting

 
#71 ·
Day 29:

back over in the greensand foundry today running some production jobs that were due yesterday :), its the same job that i spoke about earlier that is x-ray quality, took some photos of the castings but i guess my camera didn't want to take a picture of the molds. also saw the adapter plates before they were shipped off.

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adapter plates sitting in the basket, just bandsawed, they still need to be ground, shot blast, and CNC.




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Here are the castings that we make that are x-ray quality, they are some kind of hydraulic housing for aeronautical company. The mold, which i didn't get to take a picture of cause my camera decided not to, weighs over 500lb of airset sand. Im gonna be molding them for the next few days with another guy, and they are all hand lifted :/

 
#73 · (Edited)
these are cast rotors and there is a plug in each lobe closing a hollow core and i was realy asking if this is a commin practice?sorry to interupt your post as it is ment to be a tech question.

i really couldn't tell you without seeing the tooling and how they made the core and mold.

one guess would be that they used that hole as a way to get the core out, pretty small for core knock out and if it was designed from the tooling you would see them down the length of the rotor equally spaced(so probably not). Which i would say is bad tooling, something as crucial as blower rotor that holds thousands tolerances could cause a lot of escaped air in the compression resulting in less boost.

The other reason it could be there and is a lot more practical than the first, is that it was something used to keep the core in place(usually a chaplet) so the hydraulic pressure of the metal didn't shift the core and cause it to be unbalanced. Chapels are usually a mild steel placed in the mold when there isn't adequate core print to keep the core from shifting. Usually a result of bad tooling and the foundry having to compensate in order to have good castings. What is even more surprising is that if it was a chaplet, they should have welded the hole before they where machined so you would have never noticed it, another lack of quality and or the manufacturer didn't want to pay for the extra work.
 
#74 ·
day 29.2:

Got the photos of the molds for those x-ray castings, they don't look big but these are over 500lbs a piece



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Some people have been asking me why greensand is called green if it isn't green at all. There is some debate between foundrymen and why greensand is called greensand, some say its because of the color, others say its merely the state its in(new, unused). Most everyone i've asked doesn't really have a definite answer, While this sand does look green, there is also many different kinds of sand; silica base, graphite, olivine that don't look too green. foundry work and molding dates back to before 3000BC so to really know why its called greensand, i couldn't tell ya.

 
#76 ·
Kudos to you for posting this as it is very interesting to myself and obviously the others following the thread too. Question, What are the castings in the bin that the blower housings are sitting on, looks like something with pistol grips. Sorry if I missed it somewhere in the thread. Thanks again for the informative posts here.
 
#83 ·
here is a short article i wrote back in May on our website discussing the difference in supercharger, most of you probably know this but i figured i'd share it anyways.

http://www.diamondp.com/kb_results.asp?ID=8

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"Types of Superchargers and their Efficiency

There are three main types of superchargers in today's automotive market, Root style, Lysholm twin screw and centrifugal, each one suited for a different application. While there are more types of superchargers i am only going to use the three most common types in this article.

First we need to know what exactly a supercharger is designed to do, while most of you many know what one does or how it works i would still like to state that a superchargers job is to force a larger mass of air into the same amount of volume into a engine, i will explain later the emphasis on mass and volume.

The Lysholm supercharger is the newest in design of a positive displacement supercharger and is more efficient that the roots style. the reason they are more efficient is because of the way they compress the air into the intake. Speaking in terms of physics, When ever u move, smash, compress anything, whether it be a solid, gas or liquid it causes the molecules of the substance to heat up, which causes the volume to expand but u still have the same amount of mass. For superchargers, the hotter the air gets the less you will have density wise going into each cylinder. So while a roots spin outwards towards the casing wall smashing the air as it spins and is then forced and compressed within the intake manifold, the newer twin screws has a male(blue) and female(pink) rotor that spins the air in between its rotors and much more fluidly, moving the air from the front to the back, compressing the air while it is still in the blower, reducing the friction and resistance caused by the air, reducing the heat as it enters the cylinders.



A centrifugal supercharger is nothing more than a turbocharger that is driven by the engine instead of the exhaust system, centrifugals work by spinning multiple blades and very high RPMs(much higher than roots or twin screw) to force air into the intake, they are much more efficient at high rpms compared to roots or twin screw but they lack low rpm boost and create much more heat.

A simple example of boost loss would be if you where to install a boost gauge in you manifold and block off the intakes, then heat the manifold from 70°F to 150°F the gauge would actually register an increase in boost, although obviously its not running any boost and you still have the same amount of air in the engine.

The faster you spin a supercharger the more it will heat up the air and the more the volumetric efficiency will drop but the boost will still show an increase. If you can build an engine to actually withstand it, you could theoretically spin a supercharger so fast and heat the air so much it would actually become parasitic to the engine. (I don't recommend that)

On the reverse side of intake modification, take an engine that runs NOS. NOS is used in high performance engine for short duration to temporarily increase hp, it works by being injected into the intake system and does two things, one it super-cools the air and two, when the nos enters the combustion chamber and reaches 296°C the nitrogen and oxygen atoms split releasing more oxygen so the air becomes more dense thus you are able to pack a larger mass of air into the same amount of volume.

You might be thinking though if u take a large 1471 blower and throw it on a engine you can spin it slower than a smaller 671 and still get the same amount of compression and since it is spinning slower it wont produce as much heat, and your right but you have to factor in the extra weight and resistance that the engine has to push, the heavier your components are, the more hp it will take to drive the supercharger."
 
#87 ·
:) haha, sry been working on my engine a bit and the castings are still at heat treat, our mazak 500 is still down right now and we are having a maintenance guy come in this week to look at it.

I've been working on the corebox and pattern for the rotors with one of my fathers friends that owns a machine shop across town, he also is installing anodizing right now so we will be getting some samples of our parts anodized when he has it up.
 
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