Best material for aluminum die cast tool core pins?
whrl...@webtv.net
I am looking for something that is 'solder' resistant, and will break
before it bends, and is long lasting and resilliant.
I know titanium alloys are very heat resistant, but there are many to
choose from, I am not a metallurgist, I am a quality man. And bent core
pins are a bane to me! Production men hate me, If a pin is out on our
CMM, then pull the die and replace the pin(s). We have alot of downtime
for this. There must be a better material than 'anvalloy' for core pins.
They bend, they break, they solder up and drag, get burnt. Anyone know
of some material better?
PS I know the main purpose of Die-lube is to cool the dies, not
neccessarily for release value, but does anyone have any good ideas for
increasng release properties? Burnt animal fat and silicone kind of
stinks!
BobK207
Rc 50-55
Maybe you have die design issues.
This would seem to be a topic for sci.engr.manufacturing
cheers
Bob
whrl...@webtv.net
LOL...our dies are supplied by our customers. We got a 2 cavity
die one time where the runners were two different lengths. We had a
porosity problem with one side for 'months'! Our engineer finally
figured it out..."geez, the runners are two different lengths"...we had
to recut the die and reshape the gates. We had to sort thru 20,000 parts
for porosity in an M10 threaded hole! This took awhile to do, and cost a
few bucks in overtime. I tried not to laugh while writing the 5P for
this one.
I am a quality man, and I can't help but wonder why this technology,
aluminum die casting, seems to have stopped in the 1960's? Whatever
happened to R & D? New materials, new die lubes? Whatever happened to
innovation?
If anyone ever came up with a lubeless die they could retire! Animal
fat and silicone kinda stinks!
BobK207
Sorry about that, using other folk's (unless you know & trust them)
tooling can be a real pain.
my limited experience w/ DC is that the die & the part need to be
designed with each other in mind.
Lubeless die, not likely. New lubes more likely.
R&D is probably a tough sell; DC industry is driven by cost.
can you increase the diameter of the pins? what are they now?
cheers
Bob
whrl...@webtv.net
would like to see a die life of at least 125,000 shots...when we get
dies cracking after 250 shots! Crack in half kinda cracking! Big
dies...$250,000 dies! ...(Production men will still run with a cracked
die...lol...GOD love 'em...water leaking into the cavity...black
parts...porosity...flowlines and all..."If the quality guy didn't see
it, we didn't do it!")... And the average core pin lasting about 1000 to
5000 shots...these costs add up. And they add up fast! Not to mention
sorting parts that the quality guy didn't see!...lol.
I mentioned innovation...I recall a few articles in an old magazine
about "memory metal"... "nitanol" I think it was called...a
titanium/nickel alloy that had some bizarre properties...they primarily
made wire out of this stuff and one could bend it any shape they wanted,
then 'program' the shape with an acid solution...then bend it
again...and when an electric charge went thru it, the original
'programmed' shape was restored. Now 'what if..."
What if a core pin was made of this stuff, then soaked in the acid
solution and 'programmed' to hold that shape...set into a die...then
when a shot is made and the alluminum is still molten an elecric pulse
is shot into the pin making it hold it's shape on a molecular level!
I am not a metallurgist, nor am I a chemist, I don't know the
'physicals' of 'nitanol' and I don't know if 'nitanol' could withstand
the punishment of what I propose...but somebody knows...
anyone? anyone?
BobK207
sci.engr.manufacturing ?
Forgive me, but, I think your company's operation has bigger issues
than tooling problems.
There must be an underlying reason that the production people will run
a die into the ground.
I understand your situation but the QC guy can't do his job w/o real
help & participation by the rest of the team.
Do you have die makers on board? are the experienced, knowledgeable
"old hands"? If asked would they offer useful suggestions? I'll take
tooling advice of a good tool maker over an average engineer any day!
IMO you solution lies not in material's "silver bullet" but process.
Your org needs a major dose of "Edward Deming", in these competative
times, the kinds of production problems your describe lead to loss of
business & eventual bankruptcy.
cheers
Bob
BobK207
whrl...@webtv.net
The way it works in my company is this...dies cost money to make, the
customer supplies these dies to us. We test the dies...ie. pin
location...fit / function...machinability.
Anyway, when a die is approved, the customer desires we run at least
120,000 shots out of it before we retire it, so they get their money's
worth out of it. We get a 'monetary benefit' for dies run beyond thier
expectancy. Production men run dies into the ground because we
have no backup dies of the same part! Example: our die cavity A is shot
out, we are running cavity B at present, and cavity C hasn't been
approved yet...by our customer.
What I am looking for is some material, that can withstand the heat
better, and has a stronger resistance to stresses and strains than what
we are using at present. The molten aluminum alloy we cast has a temp of
1230 degrees C average. Our molds develop heatchecks after only 20,000
shots or so, these have to be deburred by machine operators...extra
steps.
We have a die, only has about 50,000 shots on it...it has 18
breakouts the machine operator (one man!) has to deburr...there is an 84
second cycle time between castings...Our die maintainance crew has
rewelded each of these breakouts at least 2 times each, and when it
breaks out again...it is always bigger than before it was welded!
What is the odds of any single breakout being missed on any single
part during the coarse of an 8 hour shift? Rework...rework...and rework
again! Overtime for rework, and downtime for burnt or bent or broken
core pins.
I can't help but think there must be a better material than hardened
steel for core pins, and I can't help but think of some sort of titanium
alloy...something with better heat resistance and flexural strength.
There are alot of known titanium alloys, which one is best for this
appication?
I once talked with one of our die maintainance men about this very
subject...he said,"Get me the material, I can machine anything"...he
kinda liked the idea. WHICH ONE IS BEST FOR THIS APPLICATION?
I know titanium alloys ain't cheap, but if I can get a long life out
of a core pin, it is worth it!
PS I looked up nitanol after my last post, and must correct myself. I
had it confused with another material I read from the same magazine.
Robot muscles made with PVA. Sorry about that. Nitanol shape is
'programmed'
with heat, not acid. And heat, again, is what makes it resume it's
original shape...I doubt it would work with my application. ie...1230
degrees C is quite extreme.
BobK207
cheers
Bob
whrl...@webtv.net
"Your solution lies in process / procedure , not material selection."
I disagree...case in point:
We're running a part...flatness spec is .50mm max...at the start of the
shift it is running about .18mm...half-way thru the shift it gradually
increases up to .40mm...the machine has never gone down.
Investigation shows the core pins have 'soldered' slightly and some
'drags' have appeared (from 'soldering' also) on the inside of the part.
These in turn cause 'bending' issues upon extraction of the part. The
technician polishes the soldered areas and makes an adjustment to the
die lube sprayers...flatness comes back down. But after awhile the
flatness will go back up, and the soldering will return.
'Washout' of the die is also a major contributor to the flatness going
out of spec! Usually near the gates, the metal of the die will literally
get removed over time (imagine Chinese water torture). Where the die
should be flat, it has a 'sink' in it, and when the part gets ejected,
it causes it to 'resist' on one side of the part .
What is the 'root cause' here for flatness going out of spec? Is it
innadequate spray pattern, or innadequate die lube altogether? Or
perhaps operating temperature is getting too high, causing a higher
incidence of 'soldering'? Or could it be 'washout' of poorly constructed
dies?
If the die lube spray time is increased too much then 'flowlines'
start to appear (too cool), and 'dark parts' happen (too wet). But the
soldering goes away!
How long do you expect the average die to last Bob? What is your
experience? We have had dies last over 1 million shots before, but they
were well designed, and simple...small, flat part, no moving cores...no
washouts... straight- in gates...few core pins.
I still think a more 'durable' material is a plus.
BobK207
Your latest post (IMO) points to process.
I have over 30 years experience as an ME.
What is your experience??
Sounds to me like you are trying to do the manufacutring engineering
for your operation without the training of experience.
BTW I was only guy to reply to your post
did you ever post to manufacturing engineering?
IMO a simple material change is NOT going to fix your problem.
But if I'm wrong you can have your money back,
Your in-house die people (if they have the smarts, experience &
desire) are your best source of useful info.
cheers
Bob
whrl...@webtv.net
'Inconal' and 'hasteloy'. I am still doing some websearching on these.
Hey, I never meant it to be a challenge to you personally...I was
actually curious as to your real experience with this. Seriously, My
company has no R&D department! The customer spoon feeds us our dies, how
they are designed, and how they are to be 'processed.' The dies wear out
long before they are 'payed for.' And my company pays for all the
rework! ALOT of rework!
How can SPC extend the lifespan of a die? Must I, a humble Quality
man, set up a DOE, and spend thousands of manhours, experimenting with
conditions on obsolete equipment...and at the same time, maybe set up
some control charts to plot the mayhem a 'cycle-time' mentality causes?
On top of that, I can try and do my job...which is watch over 24
machines, and make sure all the 'pins' are straight, not soldered, the
flowlines are 'within limit', The machine shop doesn't get 'flashed'
parts, or the pins are still straight after they get done with them!
Yes, Bob, I want...no... I need a silver bullet...BAD! LOL!!!!! A
Titanium alloy bullet!!!!
BobK207
you've got a very good handle on the situation. You need someone
closer to the work to bounce ideas off.& the freedom to pursue your
ideas.
You seem like a guy who wants to do a good & struggling to do it in an
insane environment. The WHOLE process (eps your customer) is out of
control. Do they have an R&D dept? Are their die designers any good?
Can you partner with them to improve the process? Are they aware of
the problems with their dies? Is there any feedback from mfg to them?
Do they ever visit your shop floor & see their tools in action?
Demning is much more than SPC; it's a point of view, a way of looking
at things. You cannot do this by yourself, you need support from above
& below.
In my experience looking for & using exotic alloys usually means the
basic design or process is marginal.
Your job sounds more like mfg engineering or production manager rather
than QA/QC; is there anyone else in the organization that is somewhat
like minded & who you could enlist as a "partner" for change?
If management cannot see the problems associated with the current way
of doing things and has no desire to fix them; bluntly put you're
screwed. Maybe it's time to look elsewhere.
I assume you're young, which is a good thing, don't use up all your
personal energy on an impossible task. Pushing a sled uphill gets
old.
cheers
Bob
madz
are you sure about the casting temperature of molten aluminum alloy
(>1230 degrees C)? Usually the melting point of aluminum is slightly
beyond 600 degrees.
If the temperature is really that high you cant use neither hardened
steel, nor some titanium alloy (maximum service temperature below 600
degrees C).
Maybe ceramics is the material you need (for example zirconia, titanium
dioxide, silicon carbide, sialon, boron nitride etc).
Regards
m
whrl...@webtv.net
demand has grown into a monster as of late. Orders have gone up, new
business has also come into play. Weekend work is becoming more common
place. Three of our machines are getting 'refitted', which puts more
production burden on the other machines.
Our dies are getting abused! This is the process problem in a
nutshell. We are in a non-stop frenzy to get orders ran and out the
door. Too many corners are cut to get things going, i.e. Warm up of
dies...dies should be preheated for a certain amount of time before any
shots are made...Then 'warmup' shots, a certain amount of these are
neccessary to insure a good 'seal' of the cavity. Drop an ice-cube in
warm water, what happens?
We also have continuous adjustment, not so much for quality issues,
but for the reduction of 'cycle time'...usually die lube spray is the
first to be reduced! Our 'bell-shaped curve' is all over the place.
Motorola designed it's cell phones so a 2-year old could play with
them...drop them, throw them...they still work. I'm looking for over
kill, even a 2-year old can't break it! LOL.
Michael Armata
International) had continuous problems (60% scrap rate due to porosity )
with aluminum pressure die casting at least between 1995-2002 and I
suspect continues to this day so it is not an easy problem. When the
Chrysler Intrepids first started rolling off the lines many years ago,
many of them had oil slicks under them a few days later - oil leaking
thru the engine block due to porosity again. Don't know about die
problems though ...
whrl...@webtv.net
that expensive taboot! As a quality man, that would drive me absolutely
nuts...lol...especially if it lasted as long as you say....it is
inexcusable. (unless the company is a tax write-off or something)
Porosity comes in several basic forms...gas porosity and shrink
porosity and non-fill. You must first determine what form of porosity
you are dealing with before a solution can be found.
Step 1 - do some mapping of the leak sites on the blocks...where do they
leak at?
Step 2 - Do some cut tests at different angles at the leak sites...Try
to get a good cut section of the porosity.
Step 3 - Examine the porosity in the cut samples...the shape of the
porosity.
*Round, spherical shaped porosity is indicative of gas porosity. usually
small in size relatively.
*Long, disk shaped porosity indicates shrink, usually found in the gates
but associated with indentations at the surface (dents) along with
visible cracks.
*Non-fill porosity looks like a slow shot under magnification, no
discernable shape.
Solutions to all these porosities are different. If you don't know
which porosity you got, then it's anybodies guess as to fixing it.
Re: Best material for aluminum die cast tool core pins?
Group: sci.engr.analysis Date: Wed, Jun 29, 2005, 11:23pm (EST+1) From:
arm...@rogers.com (Michael Armata)
Michael Armata
(x-ray) and they were going about automating the process with a vision
system. The 60% was on and off for only one part though (I was exposed
to only the one part - if it was continous at 60% for the whole plant, I
agree that they would be out of business pretty quick). I know that
porosity was still a horrible problem throughout though. Has anyone
published a book on aluminum die casting?
whrl...@webtv.net
the search engines on the web and came up with this one:
http://www.campusi.com/bookFind/asp/bookFindPriceLst.asp?prodId=0471201316
I tried to get my company to order it, but alas it is around $135 U.S.
Also, X-ray is not a very good tool for 'thick' parts such as engine
blocks. Until you actually cut into porosity and determine what type it
is, an answer can't be found. An x-ray will only reveal that porosity is
indeed present.