You need stainless steel sheets cut to specific sizes. You order from a supplier, but when the sheets arrive, the cuts are not square. The edges are rough. Now your parts do not fit.

Custom cut stainless steel sheets require attention to cutting method (laser, plasma, shearing), tolerance, edge quality, and material grade. Laser cutting offers the best precision (±0.1mm) for thin sheets (up to 6mm). Plasma cutting is for thicker plates (over 6mm). Always specify the tolerance and edge finish you need.

I have supplied custom cut stainless steel sheets¹ to many customers. A machine shop needed laser-cut blanks with ±0.1mm tolerance. A fabricator needed sheared plates with ±1mm tolerance. Let me walk you through what to look for.

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What to look for when buying stainless steel plates?

When buying stainless steel plates, look for grade verification (304 vs 316), dimensional accuracy (thickness, width, length), flatness, surface finish (No.1, 2B), edge condition (sheared, laser cut, plasma cut), mill test reports (MTRs), and corrosion resistance for your environment.

Also check for rust or pitting, especially on 201 or lower grades. For critical applications, request PMI testing to verify grade. For large orders, inspect a sample before full shipment.

Buying Checklist

Let me provide a checklist for buying stainless steel plates.

Grade Verification¹

Check	Method
Grade matches order	MTR, PMI gun
304 vs 316	Molybdenum test or PMI
201 vs 304	Magnet test (201 is magnetic)

Dimensional Accuracy

Dimension	Tolerance	Tool
Thickness	±0.05-0.10mm	Micrometer
Width	±3-5mm	Tape measure
Length	±5-10mm	Tape measure
Flatness	<3mm per meter	Straightedge

Surface and Edge Quality

Check	What to Look For
Surface finish	No scratches, pits, roll marks
Edge condition	Clean cut, minimal burr
No rust or pitting	Especially on 201 or 430

Documentation

Document	Required?
Mill test report (MTR)	Yes
EN 10204 Type 3.1	For traceability
Certificate of origin	For import

My Experience
A customer received 201 plate instead of 304. The magnet test (201 is magnetic, 304 is not) revealed the problem immediately.

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What is the 4T rule¹ in sheet metal?

The 4T rule¹ in sheet metal is a guideline for bend radius: the inside bend radius should be at least 4 times the material thickness (4×T). For stainless steel, the minimum bend radius is often 2-4×T depending on the grade and direction of grain.

For 304 stainless steel, a minimum bend radius of 2×T is acceptable for cold bending. For harder grades (301, cold worked), a larger radius (3-4×T) is needed. Bending across the grain requires a larger radius than bending with the grain. Always test before production.

Bend Radius Guidelines

Let me provide bend radius guidelines² for stainless steel.

Minimum Bend Radius by Grade

Grade	Condition	Minimum Bend Radius
304 (annealed)	With grain	1-2×T
304 (annealed)	Across grain	2-3×T
316 (annealed)	With grain	1-2×T
301 (1/2 hard)	With grain	3-4×T
430	With grain	1-2×T

Example: 2mm thick 304 plate

Bend Radius	Multiplier	Result (mm)
Minimum (with grain)	2×T	4 mm
Recommended	3×T	6 mm
Safe	4×T	8 mm

Why the 4T Rule is Often Used

• Safe for most grades and conditions
• Allows for grain direction variation
• Prevents cracking
• Conservative for production

My Experience
A customer cracked 304 sheet during bending because they used a 1×T radius. I recommended 2×T for with-grain bending, and the parts formed successfully.

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What are common sheet metal cutting mistakes?

Common sheet metal cutting mistakes include using the wrong cutting method for the thickness, incorrect tolerances¹, rough edges that require secondary finishing, heat-affected zone (HAZ) distortion², and cutting parts too small without accounting for kerf³ (material removed by the cut).

Other mistakes: not specifying edge finish (sheared vs laser vs plasma), using dull tools⁴, cutting at the wrong speed, not clamping material properly, and cutting before verifying material flatness.

Cutting Mistakes and Solutions

Let me list common cutting mistakes and how to avoid them.

Mistake 1: Wrong Cutting Method

Thickness	Wrong Method	Right Method
<3mm	Plasma (rough edge)	Laser or shearing
3-6mm	Shearing (difficult)	Laser or plasma
>6mm	Laser (not possible)	Plasma or waterjet

Mistake 2: Not Accounting for Kerf

Cutting Method	Kerf (mm)	Impact
Laser	0.1-0.3	Small
Plasma	1-3	Significant
Shearing	0	No kerf
Waterjet	0.5-1	Moderate

Mistake 3: No Edge Finish Specification

Requirement	Specify
Deburred edges	"Deburr all cut edges"
No heat tint (laser)	"Remove heat tint"
Smooth finish	"Grind edges smooth"

Mistake 4: Incorrect Tolerances

Cutting Method	Typical Tolerance
Laser cut	±0.1-0.2mm
Shearing	±0.5-1mm
Plasma	±1-2mm
Waterjet	±0.2-0.5mm

Mistake 5: Heat-Affected Zone (HAZ)

Issue	Solution
Discoloration (laser/plasma)	Specify "remove heat tint"
Hardened edge	Specify "grind edge"
Warping (thin sheet)	Use laser with low heat input

My Experience
A customer ordered plasma-cut parts expecting laser-cut tolerances. The parts were 1-2mm oversized. We had to re-cut on a laser.

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What is better, 304 or 316 stainless steel?

Neither is universally better. 304 is better for general use and cost-sensitive projects. 316 is better for marine, coastal, and high-chloride environments.

304 is the standard grade for most applications. It offers excellent corrosion resistance¹, good formability, and lower cost. 316 contains molybdenum, which provides superior resistance to chlorides (salt). For indoor, freshwater, and most outdoor inland applications, 304 is sufficient. For coastal, marine, or high-salt environments, 316 is recommended.

304 vs 316 Comparison

Let me compare 304 and 316 for custom cut sheets.

304 Stainless Steel

Property	Value
Corrosion resistance	Excellent (general)
Chloride resistance	Moderate
Formability	Excellent
Weldability	Excellent
Cost	Lower
Best for	Indoor, freshwater, inland

316 Stainless Steel

Property	Value
Corrosion resistance	Excellent (marine)
Chloride resistance	High
Formability	Excellent
Weldability	Excellent
Cost	Higher (30-50%)
Best for	Coastal, marine, chemical

Selection Guide

Application	Recommended Grade
Kitchen equipment (inland)	304
Outdoor sign (inland)	304
Coastal handrail	316
Seawater exposure	316
Food processing	304
Pharmaceutical	304 or 316
Chemical (chlorides)	316

My Experience
For a customer near the ocean, we recommended 316 for outdoor use. For an inland factory, we used 304 to save cost.

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Conclusion

When buying custom cut stainless steel sheets¹, verify grade, dimensions, and edge quality. Laser cutting offers the best precision (±0.1mm). The 4T rule recommends a bend radius of 4× thickness for safe bending. 304 is for general use; 316 is for marine environments.

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