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  1. dchu129

    Helicoil jam on screw

    You mean the helicoil itself or the insert thread for helicoil? Screw is of 15-5 stainless steel The helicoil is also coated with dry film lube, could the build up from the dry film cause the problem too?
  2. dchu129

    Helicoil jam on screw

    It gets tight immediately, but as I turn deeper, it will eventually be stuck halfway through the screw
  3. dchu129

    Helicoil jam on screw

    Having problem with screw jam when installing into helicoil and cannot be turn anymore. When I force the jammed screw out, the helicoil will be remove from its insert thread. Here are the spec Screw: .190-32 UNJF-3A Perfect Thread Helicoil: .190-32 Fine Thread Helicoil Insert Thread: .190-32...
  4. dchu129

    Can extrusion be good on one end and pitted in the middle section?

    Have here Aluminum extrused parts that are pitted. Seems like material problem, but the same lot of material ran fine a month ago.
  5. dchu129

    Holes oversized, heat treat will help?

    Thought its an untold trick; because flattening the part to get more material in the hole does make sense. Just gotta see if I can use as is.
  6. dchu129

    Holes oversized, heat treat will help?

    But the holes are only .133"; how do you place .5~.75" diameter ball bearing in the hole; unless you placing on top and hammer it on the surface to peen/flatten surface Thanks
  7. dchu129

    Holes oversized, heat treat will help?

    These parts came with oversized hole during deburring of the hole .128-.1305" holes; currently at .133" These parts do go to Heat Treat, wondering if the heat treat will help close up that gap of .003" Material is 17-7 Stainless Steel Thanks
  8. dchu129

    Recommended passivation method for 303 SS

    What would be the best method to passivate 303 Stainless Steel? In order to get a good clean on the material, it is placed in 1) electro chem (with current) to remove oil 2) phosphoric acid 3) passivate solution however, the phosphoric acid will react with 303 leaveing a stain on 303; without...
  9. dchu129

    17-7/304 cracking when curl?

    Would like everyone's input on this 17-7 material or 304 material is notch and curl. However during the curl, there will be crack on one side of the curl. Tool guy is claiming it happens during notching (possible dull die and not enough clearance, because one side of the notch has more break...
  10. dchu129

    Best Passivation Method?

    Lately, we changed replaced electro polish soap solution and passivation solution and the process run fine again. However we are never sure what happen when things started failing again. Generally we test right away in salt spray chamber. What is the reason behind testing after a night? Thanks
  11. dchu129

    Heat Treat Atmosphere

    The furnace is going to be a batch furnace. Intention is austenite and aging (heat treating to bring hardness up)
  12. dchu129

    Best Passivation Method?

    The electro polish has a metal belt that gets the oil out of the tank and the phosphoric acid has a filter. Thanks for the input and I will try to clean it before it enters the tank
  13. dchu129

    Heat Treat Atmosphere

    Hi everyone, Came across a question regarding nitrogen atmosphere Here is general guideline of current heat treat 1) Furnace ram up to 1400F 2) Parts austenite for 1 hour (nitrogen atmosphere) 3) Within 1 hour cool below 60F with freezer 4) Age part to TH1050 or TH1100 (nitrogen atmosphere)...
  14. dchu129

    Best Passivation Method?

    Working with stainless steel, mainly 17-7, 17-4, and 15-5 The only cleaning processes are Electro polish with current through part to remove excess oil; and soak in phosphoric acid to let it react and clean the rest of the part. However problem we have is the process could be running well...
  15. dchu129

    Does Volumetric flow rate remain constant?

    It is actually for a nitrogen generator Supplier claims in order to have a nitrogen output of 25 SCFM, 75 SCFM of compressed air is needed into the generator. I have the PSI of the compressed air, but the diameter of the pipe went from a 2" OD (By the compressor) to "1 OD inside the facility.
  16. dchu129

    Best Passivation Method

    Here I have at my work place the passivation process. It would work for most of the time with new solution but only last for a month or so and parts would start failing and the phosphoric acid would need to be change. For more complicated parts (bigger and more edges/holes made from NC), it...
  17. dchu129

    Best Passivation Method?

    Here I have at my work place the passivation process. It would work for most of the time with new solution but only last for a month or so and parts would start failing and the phosphoric acid would need to be change. For more complicated parts (bigger and more edges/holes made from NC), it...
  18. dchu129

    Does Volumetric flow rate remain constant?

    Need to determine volumetric flow rate for compressed air Any easier way to determine the volumetric flow rate? So far I found this website http://www.rapidairproducts.com/flowrate.asp I can probably estimate the length, but the cross section area decreased from the air compressor to the...

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