X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from m12.lax.untd.com ([64.136.30.75] verified) by logan.com (CommuniGate Pro SMTP 4.3.4) with SMTP id 985021 for flyrotary@lancaironline.net; Sun, 05 Jun 2005 00:17:19 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.136.30.75; envelope-from=alwick@juno.com Received: from m12.lax.untd.com (localhost [127.0.0.1]) by m12.lax.untd.com with SMTP id AABBLE9DBABY4F3J for (sender ); Sat, 4 Jun 2005 21:15:29 -0700 (PDT) X-UNTD-OriginStamp: L941HVjjYzDhN3itp//mkDfFQ5LSBP+iJ2/Cyt3lCRPBHTqm/7lH0Q== Received: (from alwick@juno.com) by m12.lax.untd.com (jqueuemail) id KUP2EXNF; Sat, 04 Jun 2005 21:15:24 PDT To: flyrotary@lancaironline.net Date: Sat, 4 Jun 2005 21:14:54 -0700 Subject: sand casting porosity Message-ID: <20050604.211513.2820.6.alwick@juno.com> X-Mailer: Juno 5.0.33 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary=--__JNP_000_7ffd.09cd.4f83 X-Juno-Line-Breaks: 8-6,13,16,19-25,27-28,31,34,37,41-42,45-46,48,52-53,55-56,61-63,65-66,70-71,76-77,84-85,90-93,98-99,103-113,115,120,124-125,131,134-138,146-147,151-152,154-155,157-158,161-162,164-165,170,179-191,192-32767 From: al p wick X-ContentStamp: 54:27:837923116 X-MAIL-INFO:17a4fd417911c18504b571fd60054d3d810d01846180443d75a191a031311d65945435b4f4dd1dd1dded29a950c9ddb020e40065b0c950b019b02dd085f94931611d511d756524ed014024359441 X-UNTD-Peer-Info: 127.0.0.1|localhost|m12.lax.untd.com|alwick@juno.com This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. ----__JNP_000_7ffd.09cd.4f83 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Oh, why didn't you say it was sand cast? 90% probability your porosity was shrinkage porosity, nothing to do with hydrogen. You sure want to avoid shrinkage in high stress areas. It's most likely to develop at inside corners near thick sections of casting. A good foundry can take action to minimize risk. Depends on details, but they can add vent, or riser as needed. We also used special sand for optimum qualities. But it would likely be unnecessary for your application. I conducted a number of statistically designed experiments to optimize the process. The goal being to reduce the likelihood of shrinkage defects. Total blast doing that kind of stuff. The nature of shrinkage porosity is that it comes and goes. So most foundries have hard time identifying contributing causes and optimizing. Lot of statistical noise. Good luck in your endeavor! -al wick On Sun, 5 Jun 2005 13:18:44 +1000 "George Lendich" writes: Al, There's reasons for my enquiry, which involves castings for Aviation use. My initial challenge was a multi use bellhousing to accommodate Aussie PSRU and that of Tracy's unit. It doubles as a engine mount and accommodates 5 ( maybe more) starter types and has to be light and strong. This requires strong thin wall castings. Usually thin walled castings require pressure injection technology. This is expensive and not cost effective because of the projected low demand, probably one to 2 hundred (at most), in an initial 2/3 year period. I settled on sand cast technology, but because of the thinness of some of the pattern, the aluminium is heated beyond it's recommended melting temps, to allow for easier running into thinner area before the temps are reduced by the sand casting process. The initial trial did identify obvious porosity, throughout the pattern although later trials, being carried out in the USA have yet to identify any significant reduction in the projected strength requirements. My development partner in the States, Butch as he is affectionally know throughout the Industry - is an Aviation Engineer. This design has been thoroughly tested on Finite Element Analysis, was CAD designed, with myself making the pattern to exacting tolerances, due to design restrictions and as Butch's exacting demands - he's a hard man to please! Although this took some considerable time ( approx 12 months) the pattern was completed and the prototypes done, by a very competent foundry. If I can quote Butch's recent remarks to me " The Bellhousing arrived safe and sound (Excellent Packaging)..... Very Robust to say the least, should be able to handle 800hp at least. It has been Ultrasonically analysed for density and voids, point load tested and torque twisting along both the horizontal and vertical axis. Needless to say it passed with "Flying Colours!! Do you see a pattern developing here? Research design and testing by competent authority!! - even the packaging! To a unenlightened onlooker, on initially first seeing this bellhousing, their response might be this design might not meet what we normally accept as a bell-shaped design i.e. form not meeting design requirements etc. etc. This is the type of development work carried out by many Experimental designers - but not necessarily communicated to everyone to this degree. I won't say this is true in all Rotary installations, but I will say there is much in the way of skilled and talented builders involved in the process of the Rotary development. The point I'm trying to make is, although I believe your risk analysis is valid, I believe it is only valid when the information you base your assessment is correct and complete. Often a valid assessment can be completely turned on it's head when seemingly correct information is found to be incomplete, therefore making the initial assessment completely useless. I believe some assertions, on this discussion group, have pointed to this possibility. BTW I'm on the look out for any good foundries around the East Coast Nth of Washington, who could carry out this Bellhousing work ' Cost Effectively', for the US market, if you know of any I would love to hear about it. One of the problems on supply to the USA, is the 'Tyranny of Distance'. George ( down under) I only did hydrogen experiments with permanent mold castings(thick wall parts), so unsure if it applies to other types. But the experiments were conclusive. Hydrogen was absolutely trivial. It was shrinkage porosity which dominates the mechanical properties. Hydrogen porosity develops round voids, shrinkage voids tear. I suspect the myth continues regarding hydrogen. I did those experiments over 10 years ago. It gave us huge advantage over competition. We focused on methods to reduce shrinkage defects. Ended up out performing our competition. That was a blast. I miss those challenges. -al wick Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5 N9032U 200+ hours on engine/airframe from Portland, Oregon Prop construct, Subaru install, Risk assessment, Glass panel design info: http://www.maddyhome.com/canardpages/pages/alwick/index.html On Sat, 4 Jun 2005 08:32:19 +1000 "George Lendich" writes: I've had a look at Al Wicks approach and for me it leaves a lot of unanswered questions. I have the benefit of being a ( now retired) Government Logistics manager, trained in Quality Assurance, Occupational Health and Safety, Risk management and of course procurement. I had a good deal of experience within the medical logistics field. This basic approach gives a basic guide provided you get your facts straight and work on with the right information - I can't see this being done with the Rotary. Perhaps he has done quite well with the Subaru - who would know. Al if your on here would you please elaborate on the statement on Aluminium - the information to me is that Hydrogen is indeed the major problem with non- injection cast aluminium. Especially if it involves elevated thin pour castings - the elevated temperature draws hydrogen from the air and releases it as bubbles in the aluminium, the higher the humidity the greater the chace of Hydrogen porosity. As we all know porosity is the primary cause of strength reduction in a cast aluminium piece. I understand there are other causes of porosity, but am unsure of what they all are. George ( down under) Ernest Christley wrote: Jim, Al is not following his own process (I think I alluded to this previously). First, you have to ask, "How many failures have accurred due to a faulty CAS?" That's a fair question. Do you know? Does anyone? If so, Who? Seems there was a thread around that just a month or two ago. Intuitively, I would say that CAS would be a single point of failure, important enough to be remediated. The text below is copy and pasted from http://www.maddyhome.com/canardpages/pages/alwick/risk.html The key phrase is the last sentence. We are going to do an FMEA. What is the goal we are trying to achieve with this process? It’s to make sure we place our efforts on the facets which need it. Put another way, it’s making sure we don’t waste time and effort on insignificant items, while ignoring the truly important items. There are only three pieces to the puzzle. In the case of CAS (just my guess) 1) If the component failed, how serious would that effect the airplane? catastrophic 2) What is the probability of the component failing? Undetermined. Start with doing some research at NAPA et al and repair shops around how many they sell. 3) What is the likelihood that you would notice the problem before failure? I'd guess very VERY remote. You may have heard statements like “You have to replace component x on your engine before installing into an airplane because it represents a single point failure”. Meaning that if x fails, there is no backup component. That statement is not meaningful until you assess all three questions above. Exactly. Al's question is "... to what extent are "we" using his methodology. My own guess would be "not much ...". Single point(s) of failure in Tracy's ignition (and fuel control) systems - if there are any - would be a case in point. As would redundant fuel pumps powered by a single source, and charging systems that are not sufficiently redundant and with appropriate indicators. If one DOES have a single point of failure (and there are inevitably many) we must be sure that that component is sufficiently robust to give us all confidence that it will NOT fail. >> Homepage: http://www.flyrotary.com/ >> Archive: http://lancaironline.net/lists/flyrotary/List.html -al wick Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5 N9032U 200+ hours on engine/airframe from Portland, Oregon Prop construct, Subaru install, Risk assessment, Glass panel design info: http://www.maddyhome.com/canardpages/pages/alwick/index.html ----__JNP_000_7ffd.09cd.4f83 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Oh, why didn't you say it was sand cast? 90% probability your porosity= was=20 shrinkage porosity, nothing to do with hydrogen. You sure want to avoid=20 shrinkage in high stress areas. It's most likely to develop at inside = corners=20 near thick sections of casting. A good foundry can take action to minimize = risk.=20 Depends on details, but they can add vent, or riser as needed. We also used= =20 special sand for optimum qualities. But it would likely be unnecessary for = your=20 application.
I conducted a number of statistically designed experiments to optimize= the=20 process. The goal being to reduce the likelihood of shrinkage defects. = Total=20 blast doing that kind of stuff.
The nature of shrinkage porosity is that it comes and goes. So most=20 foundries have hard time identifying contributing causes and optimizing. = Lot of=20 statistical noise.
 
Good luck in your endeavor!
 
-al wick
 
 
On Sun, 5 Jun 2005 13:18:44 +1000 "George Lendich" <lendich@optusnet.com.au>=20 writes:
Al,
There's reasons for my enquiry, which involves = castings for=20 Aviation use. My initial challenge was a multi use bellhousing to=20 accommodate Aussie PSRU and that of Tracy's unit.
It doubles as a engine mount and accommodates 5 = ( maybe=20 more) starter types and has to be light and strong. This requires strong = thin=20 wall castings.
Usually thin walled castings require pressure = injection=20 technology. This is expensive and not cost effective because = of the projected low demand, probably one to 2 hundred (at most)= , in an=20 initial 2/3 year period.
I settled on sand cast technology, but because = of the=20 thinness of some of the pattern, the aluminium is heated beyond it's=20 recommended melting temps, to allow for easier running into thinner area= =20 before the temps are reduced by the sand casting process. 
 
The initial trial did identify obvious porosity, = throughout=20 the pattern although later trials, being carried out in the USA have yet = to=20 identify any significant reduction in the projected strength=20 requirements.
 
My development partner in the States, Butch as he is= =20 affectionally know throughout the Industry - is an Aviation=20 Engineer.
This design has been thoroughly tested on Finite = Element=20 Analysis, was CAD designed, with myself making the pattern to exacting=20 tolerances, due to design restrictions and as Butch's exacting demands - = he's=20 a hard man to please!
 
Although this took some considerable time ( approx 12= =20 months) the pattern was completed and the prototypes done, by a very = competent=20 foundry.
 
If I can quote Butch's recent remarks to me "= The=20 Bellhousing arrived safe and sound (Excellent Packaging)..... Very Robust= to=20 say the least, should be able to handle 800hp at least. It has been=20 Ultrasonically analysed for density and voids, point load tested and=20 torque twisting along both the horizontal and vertical=20 axis.
Needless to say it passed with "Flying=20 Colours!! 
 
Do you see a pattern developing here? Research design= and=20 testing by competent authority!! - even the packaging!
 
To a unenlightened onlooker, on initially first = seeing this=20 bellhousing, their response might be this design might not meet what= we=20 normally accept as a bell-shaped design i.e. form not meeting design=20 requirements etc. etc.
 
This is the type of development work carried out by = many=20 Experimental designers - but not necessarily communicated to = everyone to=20 this degree. I won't say this is true in all Rotary installations, but I = will=20 say there is much in the way of skilled and talented builders involved in= the=20 process of the Rotary development.
 
The point I'm trying to make is, although I believe = your=20 risk analysis is valid, I believe it is only valid when the information = you=20 base your assessment is correct and complete. Often a valid assessment = can be=20 completely turned on it's head when seemingly correct information is = found to=20 be incomplete, therefore making the initial assessment completely useless= . I=20 believe some assertions, on this discussion group, have pointed to this=20 possibility.
 
BTW I'm on the look out for any good foundries=20 around  the East Coast Nth of Washington, who could carry out this=20 Bellhousing work ' Cost Effectively',  for the US market, if = you=20 know of any I would love to hear about it. One of the problems on = supply=20 to the USA, is the 'Tyranny of Distance'.
George ( down under)
 
 
I only did hydrogen experiments with permanent = mold=20 castings(thick wall parts), so unsure if it applies to other types. But= the=20 experiments were conclusive. Hydrogen was absolutely trivial. It was=20 shrinkage porosity which dominates the mechanical properties. Hydrogen= =20 porosity develops round voids, shrinkage voids tear.  
 
I suspect the myth continues regarding hydrogen. I did those=20 experiments over 10 years ago. It gave us huge advantage over = competition.=20 We focused on methods to reduce shrinkage defects. Ended up out = performing=20 our competition. That was a blast. I miss those challenges.
 

-al wick
Artificial intelligence in cockpit, Cozy IV = powered by=20 stock Subaru 2.5
N9032U 200+ hours on engine/airframe from Portland,= =20 Oregon
Prop construct, Subaru install, Risk assessment, Glass panel= =20 design=20 info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html<= BR>
 
 
On Sat, 4 Jun 2005 08:32:19 +1000 "George Lendich" <lendich@optusnet.com.au>= =20 writes:
I've had a look at Al Wicks approach and for me = it=20 leaves a lot of unanswered questions. I have the benefit of being a (= now=20 retired) Government Logistics manager, trained in Quality=20 Assurance,  Occupational Health and Safety, Risk management and = of=20 course procurement. I had a good deal of experience within the = medical=20 logistics field.
This basic approach gives a basic guide = provided=20 you get your facts straight and work on with the right information - = I=20 can't see this being done with the Rotary. Perhaps he has done quite = well=20 with the Subaru - who would know.
 
Al if your on here would you please elaborate on = the=20 statement on Aluminium - the information to me is that Hydrogen is = indeed=20 the major problem with non- injection cast aluminium. Especially= if=20 it involves elevated thin pour castings - the elevated temperature = draws=20 hydrogen from the air and releases it as bubbles in the aluminium, = the=20 higher the humidity the greater the chace of Hydrogen=20 porosity.
As we all know porosity is the primary cause of = strength=20 reduction in a cast aluminium piece. I understand there are other = causes=20 of porosity, but am unsure of what they all are.
 
George ( down under)
Ernest=20 Christley wrote:
Jim, Al = is not=20 following his own process (I think I alluded to this previously).= =20 First, you have to ask, "How many failures have accurred due to a= =20 faulty CAS?"  That's a fair question.&= nbsp;=20 Do you know?  Does anyone?  If so, Who?  Seems = there=20 was a thread around that just a month or two ago.   = Intuitively,=20 I would say that CAS would be a single point of failure, = important=20 enough to be remediated.  The text below is copy and= =20 pasted from  http://www.maddyhome.com/canardpages/pages/alwick/risk.html=20 The key phrase is the last sentence.

We are going to do = an=20 FMEA. What is the goal we are trying to achieve with this process= ?=20 It=92s to make sure we place our efforts on the facets which need= it.=20 Put another way, it=92s making sure we don=92t waste time and = effort on=20 insignificant items, while ignoring the truly important items.=20

There are only three pieces to the puzzle.   <= FONT=20 color=3D#333399>In the case of CAS (just my guess)

= 1) If=20 the component failed, how serious would that effect the=20 airplane?  catastrophic

= 2) What=20 is the probability of the component failing? Undetermined.  Start with doing some = research at=20 NAPA et al and repair shops around how many they=20 sell.

3) What is the likelihood that you would = notice=20 the problem before failure?  I'd guess= very=20 VERY remote.

You may have heard statements like =93= You=20 have to replace component x on your engine before installing into= an=20 airplane because it represents a single point failure=94. Meaning= that=20 if x fails, there is no backup component. That statement is not=20 meaningful until you assess all three questions above.
Exactly.  Al's question is "... to what = extent are=20 "we" using his methodology.  My own guess would be "not much= =20 ...".  Single point(s) of failure in Tracy's ignition (and = fuel=20 control) systems - if there are any - would be a case in point.&= nbsp;=20 As would redundant fuel pumps powered by a single source, and = charging=20 systems that are not sufficiently redundant and with appropriate= =20 indicators.  If one DOES have a single point of failure (and= =20 there are inevitably many) we must be sure that that component is= =20 sufficiently robust to give us all confidence that it will NOT=20 fail.

>>  Homepage:  http://www.flyrotary.com/

>>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
 
 

-al wick
Artificial intelligence in= =20 cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on=20 engine/airframe from Portland, Oregon
Prop construct, Subaru install, = Risk=20 assessment, Glass panel design=20 info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
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