Below is an overview of what to consider when performing high‑quality weld toe treatment using the Weld‑Hit HFMI kit.

Before starting, make sure to read the Safety and Operations Instructions included with the machine.     

The content of Weld-Hits - standard HFMI kit- Which can be bought here

Choosing the Right Tool

Weld‑Hit offers wear pins with radii of 1.5 mm, 1.75 mm, 2.0 mm, and 4.0 mm, as well as an edge‑peening tool included in the standard package.

  • For most weld toe applications, the R1.5 mm pin is recommended.
  • The R2.0 mm pin is used when maximum fatigue improvement is required. Keep in mind that a larger radius means a larger cross‑section must be plastically deformed, which may require higher pressure and/or lower travel speed.
  • On sharp weld transitions, the tool may not fully reach the toe in one pass, and multiple treatments may be necessary.

To change wear pins, remove the spring cap, take out the tool and O‑ring, insert the desired pin, replace the O‑ring, and tighten the spring cap.

Setting Up the Equipment

Ensure that:

  • All safety equipment is in place
  • The workpiece is securely fastened
  • The air pressure is set between 2–6 bar

The correct working pressure depends on several factors: operator experience, working position, tool radius, steel grade, and weld geometry. Good results can be achieved with many different settings, but we recommend starting at 3–3.5 bar and adjusting from there.

Control is always the priority.
If the tool begins to bounce or lose contact with the weld toe, apply slightly more force or reduce the air pressure. The tool tip must remain in contact with the weld toe at all times.

In the first video below, we demonstrate slow upward vertical treatment at 2 bar for maximum control.
In the second video, we show a more optimal position where 6 bar allows for a very high treatment speed.

Treatment Angles and Technique

Follow the recommended treatment angles shown in the illustration. These angles depend on the weld shape.

Aim primarily at the plate, not the weld. The plate surface is where treatment depth is controlled. A slightly convex weld with a smooth transition is often easier to treat, as the weld helps guide the tool along the toe.

Use a pushing angle during treatment.
When everything is set correctly, the tool will naturally move forward with each impact.

Quality Control

After treatment, the surface should be shiny and free from visible defects. Use a strong light source for inspection. If defects are seen addtional treatment is needed.

Use the HFMI gauge:

  • The groove depth must be greater than 0.2 mm.
  • Place the No‑gap side against the plate with the tip in the groove
  • Shine a flashlight from behind
  • If no light passes through (the gauge sits tight), the depth is sufficient

If you see a gap, the treatment is too shallow. Re‑treat the area and reduce travel speed to achieve the correct depth in one pass.

If the 0.4 mm “small gap” side also shows no gap, the treatment is deeper than necessary — increase speed, as additional depth does not improve the result.

Summary

Most welders can achieve high‑quality HFMI weld toe treatment with Weld‑Hit equipment. It requires some practice to understand the tool and control the process, but it is not complicated. Quality control is straightforward and can be mastered quickly.