Aerospace & Automotive Full Slotting of AISI-4140 Alloy Steel

📈 Quality - surface roughness (Ra) improved 2.5x | ⚙️ Tool Life - 300% longer (from failing to cut, to cutting 3 full slots per tool)
  • Difficulties in Machining
  • HIT Achievements
  • Industry Application
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What makes AISI-4140 Alloy Steel difficult to machine?


AISI-4140 alloy steel is rated approximately 62HRC for its hardness.  Its high strength and toughness allow it to be widely used in high toughness alloy structural steel.  The material has great machining performance under high temperature and nice appearance after machining.  It also has excellent performace in impact absorption that the hammer may bounce back and has hardly any damage caused on impact.

However, due to its high hardness and toughness, it is hard to increase the machining efficiency while maintaining acceptable workpiece quality.  Let alone the stability in tool life.


 
 

☑️ AISI-4140 Alloy Steel Full Slotting: Machining Information

 
    AISI-4140 Alloy Steel Full Slotting: Machining Information          
  Material   AISI-4140 Alloy steel
  *material hardness around HRC28~32
  Feature   Slot width 0.726mm_length 126mm_depth 3.7mm
  *aspect ratio 6.2x
  Ultrasonic Machining Process & Parameters   [Rough: full slotting + Ae 0.11mm side milling]
  S 15,000rpm_F 245mm/min_Ap 0.03mm

  [Fine: Ae 0.03mm side milling]
  S 15,000rpm_F 375mm/min_Ap 0.03mm
  Ultrasonic Tool Holder        HBT40-R02-06
  Tool Selection   Union Φ0.6x4.2mm_2-flute corner radius end mill
  *use the same kind of tool, one for roughing and one for finishing


 
HIT HBT-40 ultrasonic machining module was used on AISI-4140 alloy steel full slotting
(Figure 1. HIT HBT-40 ultrasonic machining module was used on AISI-4140 alloy steel full slotting)




 

HIT's Goal in AISI-4140 Alloy Steel Full Slotting


The goal is to enhance the surface quality of slot wall while maintaining high efficiency, and prolong the tool life.




 

Ultrasonic-Assisted AISI-4140 Alloy Steel Full Slotting: Machining Results



the comparison of machining results between HIT ultrasonic-assisted full slotting AISI-4140 alloy steel and without ultrasonic
(Figure 2. the comparison of machining results between HIT ultrasonic-assisted full slotting AISI-4140 alloy steel and without ultrasonic)


 
【AISI-4140 Alloy Steel Full Slotting: Rough Milling Process】
  • In conventional machining (without ultrasonic) of such high aspect ratio (6.2x) full slotting, high cutting force caused the tool bent and broken once it started cutting.
  • With HIT ultrasonic, the high frequency micro-vibration allowed for easier inflow of cutting fluid.  This helped bring better cooling effect and better evacuation of cutting chips.  It managed to complete 3 full slots with one tool owing to great reduction in cutting force.


 
【AISI-4140 Alloy Steel Full Slotting: Fine Milling Process】
  • In conventional machining (without ultrasonic), the poor results from rough milling also imapcted the fine milling process.  Awful surface roughness of slot wall (Ra 0.7µm) and "cone-shaped" slot failed to meet up with customer's requirement.
  • With HIT ultrasonic, the fine milling process only took one tool to complete.  The great reduction in cutting force helped improve 2.5x of surface roughness (Ra 0.28µm) with perfect shape of slots (width of the 3 full slots were all 0.73mm).



 

AISI-4140 Alloy Steel Full Slotting: Workpiece Quality

​​​HIT ultrasonic-assisted full slotting AISI-4140 alloy steel achieved 2.5x better surface quality
(Figure 3. HIT ultrasonic-assisted full slotting AISI-4140 alloy steel achieved 2.5x better surface quality)


 

AISI-4140 Alloy Steel Full Slotting: Tool Life

HIT ultrasonic-assisted full slotting AISI-4140 alloy steel achieved 300% longer tool life, from failing to cut, to cutting 3 full slots per tool
(Figure 4. HIT ultrasonic-assisted full slotting AISI-4140 alloy steel achieved 300% longer tool life, from failing to cut, to cutting 3 full slots per tool)




 

HIT Ultrasonic Machining Technology Achievements



📈 Quality - surface roughness (Ra) improved 2.5x
⚙️ Tool Life - 300% longer (from failing to cut, to cutting 3 full slots per tool)


 

AISI-4140 Alloy Steel Full Slotting: Industry Application



Full slotting AISI-4140 Alloy Steel is often applied in the Aerospace & Automotive industry, especially for the key components in airplanes and drones (unmanned flying vehicles).


AISI-4140 alloy steel is rated approximately 62HRC for its hardness.  Its high strength and toughness allow it to be widely used in high toughness alloy structural steel.  The material has great machining performance under high temperature and nice appearance after machining.  It also has excellent performace in impact absorption that the hammer may bounce back and has hardly any damage caused on impact.

However, due to its high hardness and toughness, it is hard to increase the machining efficiency while maintaining acceptable workpiece quality.  Let alone the stability in tool life.


HIT's Ultrasonic Machining Module offers a comprehensive solution in machining these difficult-to-cut materials.  With the assistance of HIT's Ultrasonic Machining Technology, clients stopped worrying about poor surface quality and tool life.  Not only the surface quality can be improved, but the tool life can also be greatly enhanced.  HIT assures its clients of matching up with their requirements and achieving even better outcomes!




💡 Learn more about HIT ultrasonic-assisted machining of other metal, heat-resistant alloy, and hardened steel case studies

💡 Introduction on HIT ultrasonic-assisted machining of other metal, heat-resistant alloy, and hardened steel