Threaded-Engagement Diffusion Bonding

Sanjo Machine Works has patented “Threaded-Engagement Diffusion Bonding” as a revolutionary joining method for metal products. This technology breaks the conventional assumption that specialized hot presses are essential for diffusion bonding, enabling the process to be performed using standard vacuum furnaces.

This technology is applicable to all shaft-type products, fundamentally transforming traditional design philosophies (design freedom). Key advantages include: ① achieving extreme lightweighting through hollow structures, ② bonding dissimilar steel grades, and ③ realizing cost-effective production for both long and short products through part standardization. Leveraging these strengths, we are currently developing prototypes for a wide range of shaft products, including high-performance rotor shafts for EVs.

Conventional diffusion bonding (hot press method) and its issues

• Heating components and dies within the press along with the workpiece causes slow temperature rise and poor thermal efficiency
• Limited space inside the hot press is occupied by the dies
• Processing capacity is limited, restricting mass production feasibility (same applies to multi-axis types)
• Hot presses offer little versatility beyond diffusion bonding, making them specialized equipment

Threaded-Engagement Diffusion Bonding(No hot press required)

• ●High Mass Production Capability  
• No dedicated hot press is required (Bonding pressure is precisely managed solely through mechanical screw torque)
• By eliminating the need for complex pre-setup in molds (dies), labor hours are significantly reduced.
• Removing bulky molds allows for the full utilization of the furnace's effective heating zone. (Heating time is drastically shortened as energy is no longer wasted on heating heavy molds, contributing to a reduced carbon footprint).
• ● Low-cost Production 
• Bonding can be performed using general-purpose vacuum furnaces
• No dedicated molds required, keeping running costs low
• ●Simultaneous heat treatments like tempering or carburizing/quenching can be performed as needed
• ●The simplified setup facilitates easy technology transfer to overseas facilities 

• Advantage
  1

  Ultra-thin walls and hollow construction for superior weight reduction at low cost!
  Wall thicknesses can be freely customized.

  
• Advantage
  2

  Simply adjust the length of the center pipe to accommodate multiple vehicle classes at low cost!

  
• Advantage
  3

  Material flexibility for specific applications

  
• Advantage
  4

  High precision screwed diffusion bonding for NVH with exceptional coaxiality after component assembly!

  

  *NVH stands for Noise, Vibration, and Harshness in vehicles, serving as a standard for evaluating automotive comfort.