Nikhil Devisetty

Induction Heating Device for Automated Soldering — EOSPACE

09/12/24

Overview

I designed and manufactured a compact induction-heating system for EOSPACE to automate the process of soldering stainless-steel tubes. Their previous workflow relied on a handheld soldering iron, which was slow, inconsistent, and required continuous operator attention. The goal of this project was to create a reliable, repeatable, and efficient heating solution tailored to their production needs.

System Design

Heating Method

To heat the stainless-steel tube, I used induction heating, targeting a resonant frequency of 100 kHz, calculated to be optimal for efficient coupling with stainless steel. The coil, custom ferrite geometry, and capacitor bank were tuned to ensure stable resonance at this frequency.

Power Electronics

  • Off-the-shelf DC oscillator used as the primary power stage
  • Custom capacitor bank designed to match the inductance of the heating coil
  • Custom-cut ferrite to focus magnetic flux and increase heating efficiency
  • System optimized to handle high currents and power density despite the compact form factor

Temperature Control

To achieve consistent solder melt profiles without operator intervention:

  • Used an RTD sensor for accurate temperature feedback
  • Implemented a bang-bang (on–off) control loop on an Arduino
  • Designed the controller to follow a temperature-vs-time curve required for the solder ring to melt cleanly and uniformly

This allowed the system to operate autonomously with minimal user input.

Engineering Challenges

  • High Current Management:
    Designing busbars, traces, and thermal paths capable of safely carrying the required current in a compact layout.

  • Thermal and Magnetic Optimization:
    Tuning resonance and ferrite geometry to achieve stable heating at 100 kHz.

  • System Miniaturization:
    Fitting the power electronics, capacitor network, coil, sensor, and control circuitry into a small enclosure.

Impact

The final device:

  • Reduced soldering time per part
  • Increased consistency across production
  • Required far less operator intervention
  • Improved overall throughput for EOSPACE’s manufacturing line

Key Takeaways

This project strengthened my experience in:

  • Power electronics and inductive heating design
  • Embedded control for thermal systems
  • Practical resonance tuning and ferrite selection
  • Designing with the end user and production workflow in mind
  • Improving documentation practices for manufacturability and serviceability