How do you calculate oval and square for tmt bars rolling?

Answer 1

This is a bit more technical (rolling mill side), but I’ll explain it in a simple way based on how it’s usually handled in practice.

In TMT bar rolling, square → oval → round is the typical pass sequence. The calculations are mainly based on area reduction and shape transformation, not just dimensions.

🔹 1. Basic Principle

The key rule followed in rolling is:

👉 Volume remains constant (before and after each pass)

So,

Area × Length = Constant

Since length increases during rolling, cross-sectional area reduces.

🔹 2. Square Section Calculation

For a square:

Area = side × side

Example:

If square side = 20 mm

→ Area = 20 × 20 = 400 mm²

🔹 3. Oval Section Calculation

Oval is treated like an ellipse.

Area of oval = (π / 4) × Major Diameter × Minor Diameter

Example:

Major dia = 22 mm

Minor dia = 18 mm

Area ≈ 0.785 × 22 × 18 ≈ 311 mm²

🔹 4. How Rolling Pass is Designed

When converting square → oval, you aim for:

Controlled reduction (usually 15–25% per pass)

Proper filling of grooves

No overfill or underfill

Reduction % formula:

Reduction = (Initial Area – Final Area) / Initial Area × 100

🔹 5. Practical Flow (Simple View)

A typical sequence looks like:

Square (roughing pass)

Diamond

Oval

Round (finishing)

Each step:

Reduces area gradually

Improves shape

Controls metal flow

🔹 6. Important Practical Points (from experience)

Oval dimensions are not random — they are designed to spread metal evenly

Too much reduction → cracks or defects

Too little reduction → improper shape filling

Groove design (roll pass design) matters more than just formulas

🔹 7. Simple Way to Think About It

Instead of memorizing formulas, most rolling mill engineers:

Start with final bar size (say 12 mm)

Work backward calculating areas

Distribute reduction pass by pass

Adjust oval & square dimensions accordingly

Answer 2

TMT bar oval weight

Stand oval size in mm

like 12mm size bar oval size-12*.8=9.6kg/m