# The first bead starts cold: thermal history of a bead sequence

Source: https://www.therness.com/videos/first-bead-starts-cold/
Language: en

Same robot, same program, same bead sequence. The first bead is the coldest one.

![The first bead starts cold: thermal history of a bead sequence](https://i.ytimg.com/vi/g5BczltjzXc/maxresdefault.jpg)

Thermal footage of bead 1 and bead 2 of the same sequence, side by side, with the apparent peak temperature frame by frame. One bead later the metal around the weld is already warm.

## What you see

- HeatCam thermal footage at 25 fps of bead 1 and bead 2 of the same sequence, with the apparent peak temperature frame by frame.
- Bead 1 median apparent peak 737 °C, bead 2 882 °C: one bead later, +145 °C, because the metal around it is already warm.
- All 10 beads of that sequence: bead 1 is the coldest.
- In 7 of 8 bead sequences the first bead runs 64–169 °C below the median of the beads that follow.

## How to read it

- Values are apparent temperatures (emissivity 0.8).
- They come from 97 robot welds in 8 sequences, ER70S-6 0.8 mm wire, recorded in our R&D cell.
- It is a thermal-history observation, not a weld-quality verdict.

## Who it is for

Welding and quality engineers in multi-pass and robotic welding who need to see the thermal history of every bead, not only the parameters that were set.

## Where the recording comes from

The thermal footage comes from a [HeatCam IR-C](https://www.therness.com/products/heatcam-ir-c/) thermal camera, the sensor behind [HeatCore AI](https://www.therness.com/products/therness-heatcore-ai/). To see the thermal history on your own welds, ask for a HeatCore AI demo.

## Related videos & products

- [Weld pool, thermal image and welding current, recorded during the same bead](https://www.therness.com/videos/three-sensors-same-weld-bead/)
- [HeatCore AI](https://www.therness.com/products/therness-heatcore-ai/)
- [HeatCam IR-C](https://www.therness.com/products/heatcam-ir-c/)
- [Welding monitoring system](https://www.therness.com/welding-monitoring-system/)

[Ask for a HeatCore AI demo](https://www.therness.com/contact/?product=HeatCore) [Back to video library](https://www.therness.com/videos/)