IH Heat Treatment IH Solutions

Here are some recent cases where we've applied our expertise in IH Heat Treatment to solve our customer's technical challenges.

case4 Minimizing Warpage

Fig.1 Stress Concentration

Stress Concentration
[The Many Causes of Warpage]

In today’s manufacturing industry, high demand for precise parts leads to tolerances often less than 0.01mm.
Such small tolerance is a concern when hardening parts because of unavoidable warpage.
Major causes of warpage are:

・release of residual stress
・change of structural composition

Parts undergo various processes before hardening.
The raw material undergoes stretching, forging, tapping, molding and cutting, all which create stress.
This stress, pulling and pushing on the part from the inside, is released when heated, causing warpage.

Fig.2 BCC, FCC Structure

BCC, FCC Structure

Hardening also alters the structural composition of the part.
When steel is heated above 911℃, the nuclear structure changes from body-centered cubic (BCC) to face-centered cubic (FCC).
This affects the amount of space taken up by and distance between atoms, causing the steel to expand and deform in unpredictable ways.
※ Amount of expansion depends on carbon content.

Adding a grinding margin to achieve desired dimensions is an extra process and is difficult for knurling and angled surfaces.
Altering the part dimensions before hardening to account for warpage is also difficult to reproduce constantly.
Straightening with too much force can cause cracking and reduce the part’s hardness.

At Fuji Denshi, we have developed original IH technology that solves these problems and minimizes warpage for various parts.
For customers using atmosphere processing, we highly recommend switching to our IH hardening.