Carbon & Tool Steel FeCl₃+HCl

Chemical Etching Formula
50CrV4 Spring Steel with FeCl₃+HCl

The FeCl₃+HCl chemistry is a proven formula for 50CrV4 Spring Steel. This reference sheet lists the concentration (44 °Bé), specific gravity (1.410), bath temperature (50°C), and the full range of conveyor speeds and feature tolerances that result. Use it to size your process before committing to a production trial.

Formula Summary

The table below summarizes every parameter that defines this etching formula. Values listed as ranges scale with sheet thickness across the supported band.

FeCl₃+HCl Etchant System
44 °Bé Concentration
1.410 Specific Gravity
50 °C Bath Temperature
Through etch (double-sided) Etch Depth Type
0.1-0.3 mm Thickness Range
0.20 mm Typical Thickness
0.2-1.05 m/min Conveyor Speed Range
0.37 m/min Typical Speed
120-360 μm Min Hole Ø Range
100-300 μm Min Line Width Range
19-56 μm Undercut Range
2.68 Etch Factor (EF)
96.5% Typical Yield (96.2-96.8%)

Why FeCl₃+HCl for 50CrV4 Spring Steel?

On 50CrV4 Spring Steel, the ferric chloride system attacks the alloy's oxide layer continuously while ferric ions drive dissolution. It is regenerable, compatible with standard photolithography, and produces clean burr-free edges — which is why nearly every 50CrV4 Spring Steel etch line runs a variant of this formula.

Process Window & Bath Control

Hold the bath at 50°C with concentration 44 °Bé (specific gravity 1.410). Across the 0.1-0.3 mm thickness range, conveyor speed runs from 0.2-1.05 m/min — thinner sheets move faster, thicker sheets slower, in roughly inverse proportion to thickness. A typical mid-range setpoint is 0.37 m/min for 0.20 mm stock. Use redundant PID temperature control to hold the bath within ±1.5°C, and titrate at least once per shift.

Design Rules & Tolerances

Design rules for this recipe: hole diameter 120-360 μm, line width 100-300 μm, single-side undercut 19-56 μm — all as a function of thickness across 0.1-0.3 mm. The higher the etch factor (this formula holds about 2.68), the tighter the achievable tolerance. Below the minimum feature sizes, yield falls off steeply, so treat those numbers as hard floors rather than targets.

Design Rule Summary
• Minimum hole diameter range: 120-360 μm
• Minimum line width range: 100-300 μm
• Single-side undercut range: 19-56 μm
• Typical etch factor (EF): 2.68

Yield & Production Economics

Expect a yield in the 96.2-96.8% range for 50CrV4 Spring Steel with FeCl₃+HCl, with 96.5% typical on a well-controlled line. Most rejects trace back to upstream coating and exposure rather than to the etch bath itself, so tightening photolithography control is usually the fastest path to a higher number.

Typical Applications

50CrV4 Spring Steel etched with this recipe typically ends up in spring elements, blades, shim stock, and stamped-replacement flat parts. Because chemical etching applies no mechanical or thermal load, the finished features are free of work-hardening and heat-affected zones — a decisive advantage over stamping or laser cutting for these uses.

More Carbon & Tool Steel Formulas

Other formulas in the same material family.

65Mn Spring Steel FeCl₃+HCl Through etch (double-sided) 65Mn Spring Steel FeCl₃+HCl Half etch (single-sided) DT4 pure iron FeCl₃+HCl Through etch (double-sided) SK2 Tool Steel FeCl₃+HCl Through etch (double-sided) SK3 Tool Steel FeCl₃+HCl Through etch (double-sided) SK5 Tool Steel FeCl₃+HCl Through etch (double-sided)

Frequently Asked Questions

Minimum producible hole diameter ranges 120-360 μm across the 0.1-0.3 mm thickness band, following the 1.2× material-thickness design rule. The smallest holes are only available on the thinnest stock; attempting holes below the floor for a given thickness causes yield to drop sharply.

Need a Quote for This Process?

WET Etched runs production wet chemical etching lines using the FeCl₃+HCl chemistry. Send us your part drawing and quantity for a full process quote.

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