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Material Choices for Oval Liner and Screw Element

1. The famous material CPM-9V which is made by the Crucible Particle Metallurgyis one choice, but it is really very expensive, and it usually would take element maker longer time to get. Besides the cost of this material is much higher, and also hard to be machined, so its price is much higher than normal material;


2. For the high-wear resistant screw elements, the material we usually made by is HSS(high speed steel), Chinese name is W6Mo5Cr4V2, American name is AISI: M2. A copy of【Steel name antitheses for Twin or Single screw extruder】is attached for your reference. HSS is one kind of alloy tool steel, its main component is W, Mo,Cr, V, Si, Mn, all the alloy element is up to around 10~25%, after vacuum hardening, its HRC is over 60 even it is working at 500℃. It is used to manufacture wear-resistant tool, die and segment elements, e.g. high grade trimming die, screw die, hob, saw blade and etc.


3. For manufacture ellipse oval liner which inside the segment barrel, We are using PM-HIP technology way.The material of Omega 101A alloy is all according to W&P Company requirement and its hardness is HRC 58~64. PM-HIP technology, that is in order to process high-alloy in powder metallurgy(PM) techniques way into high-density composite materials by hot isostatic pressing(HIP). PM-HIP material is very similar to CPM material, its hardness and main elements as below:

       Alloy

  Base  

  HRC

     Wear

  resistance  

  Corrosion   

  resistance

 Thermal expansion  

   Alloy elements

    (Weight: %)

  Omega 101A  

  Fe

  60~64  

  ★★★★

       ★

           12.6

  Cr:20  

  V:8

  C:2.5  

  Omega 201A

  Co

  52~54

     ★★

  ★★★★

           11.9

  Cr:29

  W:13  

  C:2.2

  Omega 301A

  Co

  58~60

    ★★★

  ★★★★

           10.5

  Cr:33

  W:18

  C:2.5


4. Compare with contact wear ration between two kinds of metal, generally say the elements made by same metal, this contact wear ratio is the worst. Such as if to use CPM segment elements match to our Omega 101A oval liner, then its service life is not longer than in this case that HSS segment elements match to our Omega 101A oval liner. A try will convince you!


5. For corrosion resistant screw element, we could choose the material such as00Cr17Ni14Mo2, also named as 316L in USA. For example, our quotation of OD30 screw element, every mm in length is about Euro 9.20. But the total weight of raw material for making this spec product in one order should be over 200kg;


6. To get more corrosion resistance, there are three corrosion resistant ways to be chosen, one is to get TiN (Titanium Nitride) plating layer, its color is golden brown, hardness is about HV 2000~2300, thickness is 1.2~1.5 uμ and its friction coefficient is about 0.55. Second way is to getZrN (Zirconium Nitride) plating layer, its color is blue-green and all other data is the same as above. But we believe if to getnanometer ceramics compound coating which we are researching now and some samples are trying on customer’s machines, would be the best choice.

 

Chief Engineer Office / Shanghai Omega Machinery Co., Ltd

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