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WKTaylor, I would think .001-.004" clearance would be perfectly acceptable. Should the bolt to hole clearance be eliminated? A core drill being is used for match drilling after the wing assembly is fit up?

Investment casting in my experience have a fair amount of subsurface defects (small voids, slag inclusions). If the part is highly loaded and in a critical application (aircraft, vehicle) forging is the better choice.

Thanks for all the replies........ The part is partially splined and about 3/4" diameter. The splines transmit some rotary motion but sometimes they are loaded longitudinally. Its the longitudional loading that is causing problems as the splines are not very long and they are fairly tall...

Thanks for the suggestion Terry. The problem with this part is that it is overloaded and needs a redesign. But because of how long this part has been in the field (mid 1960s) the geometry can't be changed because it has to still fit with the rest of the machines still in use. It's a bit of a...

We have legacy part traditionally made from 9310 AQ steel, vacuum carburized and shotpeened. It is highly loaded in a semi-shock mode and under low cycle fatigue (75k cycle expected lifespan). Failure (cracking) of the component has always been a problem way before 75 k is reached. Changing...

Yes, We do spot MP before heat treatment and 100% after heat treatment.

I have a pawl looking type of part that is made from either 8620 or 9310 steel. It is carburized to an RC50 of .015" and then cryo treated and tempered back to a hardness of about 90 R15N. After heat treat certain critical sections are shotpeened . The part is failing in fatigue. After about...

We are in need of a good hardness tester. It will need to do about 300 Rockwell C hits a day + the occasional R15N. We are looking at the NewAge Indentron. Cost is about $17k. Does anyone have any experience with this one or others? TIA

Thanks everyone for your replies

Any other suggestions?

We are in Pennsylvania.

I am in need of a good testing laboratory. The ones near us just do not have the experience or equipment necessary. The lab should be able to perform complete failure analysis with in house *SEM *Grain Size determination *Retained Austinite determination *experience with failures of...

I had a go at this last week. Ionic Technologies in SC did the nitriding and PVD coating. A very professional outfit. In testing the PVD/nitriding wore thru at one critical location after 20,000 cycles of the part. I think it was due to the lower hardness of the core 4130 not being able to...

Thanks TVP, I getting some samples that are Ion Nitrided .010" thk with an Aluminum Chromium Nitride coating. I will report back with how it goes.

We are having a problem with wear on a 1/8' thk 4130 sheet metal lever. Currently the lever is Q&T to 50 HRC. We are thinking about taking the existing levers and having them Ion Nitrided about 0.010" deep and then possibly PVD coating. I am aware that the 50 HRC lever would decrease in...

arunmrao, Could you make an exception in this case and discuss the business aspects? This is actually very important to my company. Understanding the underlying reason behind this request from the foundry, does....in some way....relate to the technical aspect of the forum. many thanks.........

Redpicker, I have discussed this with the foundry and actually people on a message board know more then them. They do not want to help with these problems and are basically blowing me off. We are currently looking for another foundry. Thanks all for the comments.....................

I know they do not use ignot but create their melt from low carbon scrap sheet metal punchings, pellets of chromium, nickel, moly etc. I think this is how they can offer us 4370. Its really a non-standard alloy. We may have to switch foundries and use S7 but I don't think S7 can be hardened...

They are macro inclusions.....you can see them by eye with no magnification. They are showing up in a WEDM step. The wire deflects around the inclusions. I am not getting very good help from the foundry........they have been doing these castings for 5 years without trouble. Now there is an...

We use some small 4370 investment castings that have been having problems with non-metallic inclusions. The foundry wants to raise the silicon content from 0.3% to 1.0% in an effort to help with the inclusions. What would be the effect in raising the silicon content? The castings are heat...