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ISO 18203 Calculator: Steel-Determination of the thickness of surface-hardened layers
Inspiration
I built the ISO 18203 Calculator because surface hardening is a small-but-critical step in many steel parts' lives. Designers and shop-floor engineers needed a quick, reliable way to estimate the required hardened-layer thickness for common steels (and the effect of process choices) without digging through long standards or running full simulations. The goal was a clean, practical tool that produces usable numbers engineers can trust during design reviews, quoting, and production checks.
What it does
Lets users enter steel type, hardening process parameters, and target case properties and returns the recommended hardened-layer thickness (and simple checks against ISO 18203 guidance).
Shows both numerical results and a clear, copyable summary suitable for inclusion in inspection reports or work orders.
Provides helpful hints and units alongside inputs (e.g., mm for thickness, °C for quench/tempering, time in seconds/minutes).
Validates inputs and warns when a parameter is out of the typical range for the chosen steel/process.
How I built it
Front-end-first web app using a lightweight responsive layout so the calculator works on desktop and mobile.
Clear input controls and inline help so less-technical users can still get correct results.
Calculation core implemented as deterministic functions that follow the ISO 18203 logic (material properties → heat-treatment parameters → estimated case depth).
Outputs formatted for copy/paste into technical emails or inspection reports and for easy export later (CSV/print-ready).
Challenges I ran into
Translating ISO language into plain, actionable inputs - standards read like legal text; engineering teams want quick numbers.
Handling incomplete inputs: users sometimes know only temperature or only target hardness, so the tool must make sensible assumptions or provide safe ranges.
UI/UX trade-offs for clarity vs. compactness on small screens - showing enough help without cluttering the page.
Ensuring the calculator warns (not hides) when a requested value is outside typical practice so users don't get false confidence.
Accomplishments that I'm proud of
A compact UI that delivers standard-aligned outputs in seconds - engineers can use it during meetings or quoting.
Thoughtful input validation and human-friendly help text that reduces misuse.
Built with an exportable summary so results are traceable in quality documents and inspection reports.
The app is modular: the calculation core is separated from the UI so it can be reused later in other Modulus Metal apps or an Android port.
What I learned
Engineers value clarity more than clever visuals - clear labels, units, and example values reduce support questions.
It's better to surface conservative assumptions explicitly than to hide them - users appreciate knowing when the calculator filled a missing value.
Small differences in terminology (case depth vs. hardened-layer thickness) cause confusion; consistent wording matters.
Designing the logic as pure functions (inputs → outputs) pays off when adding new materials or connecting to other calculators later.
What's next for ISO 18203 Calculator
Mobile app version (standalone Android) and offline mode so field inspectors can use it without internet.
Add support for more steels and process presets (e.g., induction hardening, gas carburizing) with published example profiles.
PDF/CSV export of calculation summaries and a small API so other Modulus Metal tools and customer systems can request calculations programmatically.
Improve visualization: optional small diagram of the part cross-section showing the calculated case depth (SVG or canvas), and a printable "result card" for QC files.
Add a short "recommended inspection" checklist based on the result (hardness sampling intervals, microsection suggestions) to help inspectors follow up.
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