Is there any paste available which can be used to fill in pits and cavities in iron castings before powder coating which can withstand the baking temperature of around 140deg C?
Nadi
Thank you all for the replies. I infer that we can use chills forever provided they are kept clean and the cost economics of cleaning to using new is viable.
I had posted a thread years ago of serration in chills used in Aluminum industry.
But I do not find serrated chills in the ferrous...
How many times can a chill be re-used in moulds in ferrous foundry practices?
Is there any logic to restricting life of chills to four or five times?
Nadimuthu.
Swall,
356 castings in green sand can be cast to have shrinkage defect free castings(sponginess ) as mentioned by arunmrao.
In moulding have sufficeint vents and ensure a sand to metal ratio of at least 4:1.
In Melting use min 1.5 to 2% Sodium modification.
You can see detailed notes on my...
Dear Waross,
The unit is fed from the nearest distribution substation with a 22kV supplyAt the outdoor - both at the distributor point and at our receiving point we have horn gap fuses of 60 and 30 amps respectively.This is received by us at the outdoor and though underground cable taken to...
Dear All,
THanks for the quick replies. The secondary voltage is 440V.
The furnace transformers have been checked and we also changed to a different furnace to operate but the problem persists.
The first suspicion was on the Group Control transformer whose rating is 1000kVA to which the supply...
We are being fed from a 22Kv feeder and the sanctioned demand is 1750kVA. The fuse from the distribution side is 60A and on our side is 30 A. These are horn gap fuses.
When we raise our furnace load the fuse on both sides gets blown. This is in spite of the fact that all the OCBs in our side and...
We are using TC(Tungsten carbide)burrs for finishing work(fettling)on our castings using pneumatic grinders.
We find that there is loading(sticking onto the tools)of Aluminium which results in tool wear, excessive force used on grinder and therefore premature failure of the pneumatic tools.
We...
Galvanic potential in millivolts or so is enough to cause corrosion.
If you are unable to get a chemist to solve the problem which will be long term, you are remove the impurities by cleaning as you suggest.
Good luck.
Dear Metengr,
Thanks for the suggestions.I will conduct a microstructure study to rule out inclusions first.This is a more serious problem for the foundry and then get along with your suggestion of going in for low feed and speed with carbide tooling.
The answer to this will come very clearly from an industrial chemist.If there are iron oxide or carbon deposits on the aluminium that is being heat treated, and there is a difference in potential, a galvanic cell will be formed and this will lead to the corrosion phenomenon.
Contact your firms...
Dear Metengr.
Thank you for the immediate response and suggestion.Yes.It is a sand casting and we have already done microstructure study for the casting of this product which is a housing into which gears are assembled and we have also conducted a microstructure study for another part of the...
We are supplying a lot of A356 alloy castings in T6 condition.Our machining partner complains of shrinkage and blowhole and rejects the castings on many occasions.
Whereas when we do a rough machining of these bores and conduct a Dye Penetrant test, it does not reveal any porosity.
With joint...
We are trying out castings in ALMAG 35.But the trials are posing difficulties in 1.Metal flow getting choked up and 2.Heavy drossing.
The gating design has been changed to 1.1:1:1.2 with the runner as a choke and we have used Ceramic filter 75x75x13 on two sides of the runner.We have already...
You must first rule out anything to do with water.Conduct experiments with different water samples.
Also do a macro etch of the component to find out the grain structure.
319 contains 6% Silicon and 4% Copper and segregation can cause this phenomenon.
Dear all,
We are using AlZn10Si8Mg alloy as per previous DIN1725 standard for our customers.
This alloy is not prescribed in the new EN1706 1998 standard but our customers still want it.
The problem is the yield of castings for this particular alloy is very low.
Also in the case of AlSi12(LM6)...
I would suggest that you look into the reasons for the cold lap first.This can cause discontinuity in the casting thicknes and load will not be carried in this area(Static as well as dynamic) and could be the reason for the failure.As the material yielded at this area, it could have fouled with...
We have an order for supplying sand castings in Aluminium 319 alloy.Our customer wants to know what is the maximum stress to failure for a 20 million cycle loading?
Data available in the ASM Handbook "Specialty"Aluminium has information only for 5 million cycles/
Request help from some...
Dear TVP,
Thank you for your excellent and precise info (that I am always happy to read).
I shall look into customer approval for trials with 201 and keep you informed of the developments.
Nadimuthu.
Dear Friends,
We have an order for sand casting in 771 alloy in T71 condition(.Aluminium).But the mechanical properties could not be attained.
WE have been asked by our customer to suggest an alloy that will have the same mechanical properties.
THe castings will undergo cyclic loading .WE...
