Why are corner relief notches mandatory on a 4-flange sheet metal box?

Where two perpendicular 90-degree bend lines meet at a corner, the metal inside the bend radius would overlap and pinch if cut straight to the intersection. A relief notch of at least 1.5x sheet thickness gives both flanges clean clearance to fold up without tearing or deforming the corner.

What K-Factor does this sheet metal generator use?

Our calculator uses the industry standard K = 0.42 for 90-degree air bending on a V-die with an inside bend radius equal to material thickness (R = T), compliant with DIN 6935.

Are the bend lines on a separate layer in the exported DXF file?

Yes! The outer cut profile with corner reliefs is placed on the 'CUT' layer (ACI Color 1 Red), while the 4 press-brake bend lines are isolated on the 'CREASE' layer (ACI Color 5 Blue) so your laser cutter does not cut through the bend lines.

Can I use this flat pattern for a CNC press brake setup sheet?

Yes. Export the 1:1 .PDF with Dimensions enabled to give your press-brake operator the exact bend allowance (BA) and bend deduction (BD) reference.

TEMPLATE ID: PRE-SHT-001 220 × 140 × 40 mm (T=1.5mm) Pre-Verified 1:1 Static Files Ready

16-Gauge (1.5mm) Sheet Metal Electronics Chassis Tray Flat Pattern (220 x 140 x 40 mm)

Interactive Parametric 2D & 3D Studio

Live 2D Dieline, Interactive 3D Fold Preview & Custom Size Generator

Pre-loaded with 1.5mm Sheet Metal Chassis Tray (220×140×40 mm, T=1.5mm)

1:1 CAD ENGINE READY

16-Gauge (1.5mm) Sheet Metal Electronics Chassis Tray Flat Pattern (220 x 140 x 40 mm)

1CAD Style & Material SetupSheet

Select CAD Style / Model (36)Search & Filter

Material Stock Preset (Auto-Sets Caliper T & Kerf K)

Display Units

Reference Mode

2Dimensions (ID Mode)Millimeters (mm)

Internal Length (L)220 mm

Internal Width (W)140 mm

Internal Height / Flange (H)40 mm

Inside ID: 220×140×40mmOutside OD: 223×143×43mm

Thickness (T mm)

Laser Kerf (K mm)

3Brand Logo & 1:1 ExportZero Login

2D & 3D Brand Logo Mockup:

📤 Upload Logo

Print Artwork Bleed Guide:

Embed Spec Sheet & 50mm / 1" Scale Bars (Added on separate DIMENSIONS layer)

Pre-Flight Geometry Audit8/8 PASSED

PASS
Closed Outer Contours: 1 closed LWPOLYLINE cut loop(s) verified
PASS
Zero Duplicate Cut Paths: 20 unique segments (0 laser double-burns)
PASS
Flute & Kerf Tolerance Guard: T=1.50mm, K=0.150mm within structural limits
PASS
ISO Layer Color Separation: CUT (Red), CREASE (Blue), SCORE (Emerald), DIMENSIONS isolated
PASS
1:1 Physical Unit Header: Explicit mm/in SVG viewBox + DXF $INSUNITS=4 + 50mm PDF bar
PASS
Exact 2D Cut Bounding Parity: Cut Bounds 297.35×217.35mm === Blank Size
PASS
2D ↔ 3D Kinematic Model Sync: Archetype 'sheet_metal_pan' synced (2 3D component(s))
PASS
True Vector Sheet Nesting Sync: 1:1 vector paths mapped to multi-up sheet grid

100%

CUT (1.01m) CREASE/SCORE (0.72m)● 1 Loops · Est. Cut: ~33s

1:1 Synced · Blank: 297.35 × 217.35 mm

2D 1:1 Unfolded Vector BlueprintBlank: 297.35 × 217.35 mm (11.71" × 8.56")

3D Interactive Fold & Orbit (Kraft Board)

80%

0%100%

Camera:

Yaw: -28°Pitch: 24°

⟳ Drag Anywhere to Rotate 3DL=220 × W=140 × H=40mm

BASE (220×140mm)4 Corner Reliefs (K=0.42)

FRONT (H=40)

REAR WALL

Flat Pattern Size

297.3 × 217.3 mm

90° Bend Allowance

3.35 mm

Bend Deduction (BD)

2.65 mm

K-Factor Standard

K = 0.42 (DIN 6935)

Direct Pre-Generated 1:1 CAD Files

Download Static Ready-to-Cut Files (220×140×40 mm)

These static files are pre-calculated for 1.5mm material thickness and 0.15mm laser kerf. Click any format below to download the pre-built static file, or export custom dimensions directly from the interactive Studio above.

↓ Download .DXF AutoCAD / LightBurn ($INSUNITS=4) ↓ Download .SVG Illustrator / Corel (1:1 mm) ↓ Download .PDF 1:1 Print + 50mm Scale Bar

Product Manufacturing Specification Sheet

Calibrated Physical Clearances & Material Stock for 1.5mm Sheet Metal Chassis Tray

Parent Parametric Engine: Sheet Metal 4-Flange Pan →

Target Physical Product Size

220 mm x 140 mm Base with 40 mm Vertical 90-Degree Press-Brake Flanges

Engineered Internal Cavity & Clearance

DIN 6935 Bend Deduction (K=0.40, Inside Radius R=1.5mm) + 3.0mm Corner Relief Notches

Recommended Board / Sheet Stock

1.5mm (16 Gauge) 5052-H32 Aluminum or Cold-Rolled Mild Steel Sheet

Grain / Flute Orientation Rule

Bend lines oriented at 45° or perpendicular to sheet rolling grain to prevent outer flange micro-cracking

Production Engineering Note: Designed for standard 12mm V-die air bending on CNC press brakes. Adjust Thickness (T) in the studio if cutting 1.2mm (18-gauge) or 2.0mm (14-gauge) sheet stock.

Structural Geometry & Material Reference (DIN 6935 Sheet Metal Bend Allowance & K-Factor Standard)

When bending a 4-flange sheet metal pan or electronics chassis on a CNC press brake, the outer fibers stretch while the inner fibers compress along a neutral axis governed by the material's K-Factor (typically K = 0.42 for mild steel and aluminum in air bending). If you do not subtract the Bend Deduction (BD) from each flange or omit corner bend relief notches, the metal tears at the corners and finishes oversized. Our parametric unfolder calculates exact DIN 6935 90-degree bend allowances and places square corner relief cutouts for fiber laser, plasma, or waterjet cutting.

90-Degree Bend Allowance (BA)

BA = (pi / 2) * (R_inside + K_factor * T)

Computes the arc length of the neutral sheet metal axis across a 90-degree press-brake bend.

Bend Deduction (BD)

BD = 2 * (R_inside + T) - BA

Total amount subtracted from the sum of outer flange lengths to determine the true flat pattern blank size.

Corner Bend Relief Notch (R_relief)

R_relief = max(2.0 mm, 1.5 * T)

Prevents adjacent 90-degree flanges from colliding and tearing at the bend intersection.

Internal CAD Silo & Related Ready-to-Cut Templates