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Example of New-type Six Valve Grinding
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From:https://mp.weixin.qq.com/s/iqqqyUkkf1bKk6QWVJk6gw
Types of valve materials

According to the use occasion of the valve, the valve materials can be divided into the following three categories.

1) The applications in automotive gasoline engines are roughly divided into 4 types:
① For light passenger cars and trucks, 40Cr is used for intake valve and 4Cr9Si2、4Cr10Si2Mo steel is used for exhaust valve;
②Medium-sized passenger and truck, 5Cr8Si2、4Cr9Si2 is used for intake valve, 21-4N steel is used for exhaust valve;
③4Cr10Si2 Mo is used for the intake valve of low and mid-range cars, and 21-4N is used for the exhaust valve;
④ 4Cr10Si2Mo、21-4N is used for the intake valve of medium and high-end cars, and 21-4NWNb、Inconel751、Nimonic80A is used for the exhaust valve.
2) For vehicle diesel engines, 4Cr9Si2、4Cr10Si2Mo is used for the intake valve of medium-sized vehicles, XB、MF811、X85CrMoV182、21-12N,23-8N for exhaust valve; 4Cr9Si2、4Cr10Si2Mo、MF811、X85CrMoV182、MF811、X85CrMoV182、 XB, the exhaust valve uses 21-12N, 23-8N, 21-4Nb, ResisTEL.
3) 4Cr9Si2、4Cr10Si2Mo is used in the intake valve of high-speed diesel engines for locomotives and ships; exhaust valves: 4Cr14Ni14W2Mo、21-12N、LF2、LF4 for domestic locomotive diesel engines, 21-4NWNb、ResisTEL、Inconel751、Nimonic80A .
Type Material grade
Heat treatment state at the time of delivery
Hardness
HB
Tensile strength
Constructional
steel
40Cr Anneal ≤269 --
45Mn2 Anneal ≤269 --
Martensitic steel 4Cr9Si3 Anneal ≤269 --
5Cr9Si3 Anneal ≤300 --
5Cr8Si2 Anneal ≤300 --
  4Cr10Si2Mo Anneal ≤269 --
8Cr20Si2Ni Anneal ≤300 --
9Cr18Mo2V Anneal ≤300 --
Austenite steel 4Cr14Ni14W2Mo Solution ≤255 --
2Cr21Ni12N Solution ≤209 --
5Cr20Mr8Ni2N Controlled cooling ≈385 ≈1300
1000-1100℃ solution ≤385 ≤1300
5Cr21Mr9Ni4N Controlled cooling ≈385 ≈1300
1000-1100℃ solution ≤385 ≤1300
5Cr21Mn9Ni4Nb2WN Controlled cooling ≈385 ≈1300
1000-1100℃ solution ≤385 ≤1300
6Cr21Mn10MoVNbN Controlled cooling ≈385 ≈1300
1000-1100℃ solution ≤385 ≤1300
3Cr23Ni8Mn3N Controlled cooling ≈360 ≈1250
1000-1100℃ solution ≤360 ≤1200
High-nickel alloy GH145 930-1030℃ solution ≤325 ≤1100

 Common failure modes in valve material processing


The grinding characteristics of valve material in grinding. The abrasive debris is easy to adhere to the surface of the grinding wheel, filling the pores between the abrasive grains, and the grinding wheel loses its grinding ability. This phenomenon is most obvious in high nickel materials, followed by austenitic stainless steel, and martensitic stainless steel is lighter. Because of its high toughness, the grinding debris is not easy to be cut away, and the abrasive grains of the grinding wheel are easy to become dull, which worsens the grinding and causes the grinding wheel to be repaired frequently. The grinding force per unit area is large, up to 68600MPa, the grinding temperature can reach 1000~1500℃, and burns are easy to occur; the surface hardening is serious, which is 1.4~2.2 times the hardness of the substrate, and the hardening depth is 0.1~0.2mm; due to stainless steel The coefficient of linear expansion is 50% larger than that of ordinary steel, causing the workpiece to be easily deformed; austenitic stainless steel is non-magnetic, and it is difficult to grind and clamp.


More Super Hard Valve Case Sharing

More Super Hard After years of research on valve materials and the accumulation of actual grinding application performance, let's share some actual cases of processing national Emission six emission standard valves.

1. Grinding of valve head: (valve material: high nickel material)
 
Product name Rough grinding head (external circle + cone) 60° grinding wheel
Specifications 510D-30T-203.2H-60°
Binding agent Electroplated
Weight 20-25Kg
Dynamic balance ≤0.5g
Installation requirements Radial runout&end runout  ≤0.003mm
 
Workpiece
Margin φ0.5-1mm
Material Nickel 30(High-nickel)
Working accuracy Rz≤10μm
Other requirement No scratches, burns, vibration marks and other defects on the surface

According to the use occasion of the valve,
 
Machining effect
Processing life 100-120 thousand Pcs
Roughness Rz≈5μm
Processing time 10s
Stability Batch processing size is stable, no need to debug

2.Grinding of valve lock groove: (valve material: martensite/austenite)

According to the use occasion of the valve
 
Products name
Locking groove grinding wheel
Specifications 400D*24T*160H
Binding agent Electroplated
Weight 16-20kg
Dynamic balance ≤0.5g
Installation requirements Radial runout&end runout  ≤0.003mm


 
Workpiece
Margin φ1.2mm
Material Martensitic heat resistant steel
Working accuracy Ra≤0.8μm
Other requirement The grinding surface has the same texture, no chatter marks, burns, and no burrs.


 
Machining effect
Processing life 120-150 thousand Pcs
Roughness Ra≤0.8μm
Processing time 7~8s
Stability Batch processing size is stable, no need to debug

https://www.mogrinding.com/products/electroplated-diamond-cbn-wheel/

 
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