Bend radius and bend allowance in Solidworks - Dashboard Guide

Dashboard Mode - Bend radius and bend allowance

Goal

Understand how bend radius and bend allowance affect sheet metal part dimensions in manufacturing.

Sample Data

Part ID	Material Thickness (mm)	Bend Radius (mm)	Bend Angle (degrees)	Flat Length (mm)	Bend Allowance (mm)
101	2	5	90	100	12.57
102	3	6	90	150	15.71
103	2	4	45	120	6.28
104	1.5	3	135	130	18.85
105	2.5	5	180	140	31.42

Dashboard Components

• KPI Card: Average Bend Radius
  Formula: AVERAGE([Bend Radius (mm)]) = (5+6+4+3+5)/5 = 4.6 mm
• KPI Card: Average Bend Allowance
  Formula: AVERAGE([Bend Allowance (mm)]) = (12.57+15.71+6.28+18.85+31.42)/5 = 16.966 mm
• Bar Chart: Bend Radius by Part ID
  Shows bend radius values for each part (5,6,4,3,5 mm)
• Bar Chart: Bend Allowance by Part ID
  Shows bend allowance values for each part (12.57,15.71,6.28,18.85,31.42 mm)
• Table: Detailed Part Data
  Shows all columns from sample data for reference

Dashboard Layout

+----------------------+-----------------------+
|  Avg Bend Radius KPI  |  Avg Bend Allowance KPI |
+----------------------+-----------------------+
|    Bend Radius Chart                      |
|                                          |
+------------------------------------------+
|    Bend Allowance Chart                   |
|                                          |
+------------------------------------------+
|    Detailed Part Data Table               |
+------------------------------------------+

Interactivity

Filter by Material Thickness:
- Selecting a thickness (e.g., 2 mm) updates all components to show only parts with that thickness.
- KPI cards recalculate averages.
- Charts update to show filtered parts.
- Table shows filtered rows.

Filter by Bend Angle:
- Selecting an angle (e.g., 90 degrees) filters parts accordingly.
- All visuals update to reflect selection.

Self Check

If you add a filter for Material Thickness = 2 mm, which parts remain?

Answer: Parts 101 and 103 remain.

Which components update?

• Average Bend Radius KPI updates to average of 5 and 4 = 4.5 mm.
• Average Bend Allowance KPI updates to average of 12.57 and 6.28 = 9.425 mm.
• Bend Radius and Bend Allowance charts show only parts 101 and 103.
• Table shows only rows for parts 101 and 103.

Key Result

Dashboard shows how bend radius and bend allowance vary by part and material thickness.

Practice

1. What does the bend radius represent in sheet metal design?

easy

A. The inside curve size of the bend

B. The thickness of the sheet metal

C. The total length of the flat pattern

D. The angle of the bend

Solution

1. Step 1: Understand bend radius definition

   Bend radius is the radius of the inside curve where the metal bends.

2. Step 2: Differentiate from other terms

   Thickness is metal thickness, length is flat pattern size, angle is bend angle, so they are incorrect.

3. Final Answer:

   The inside curve size of the bend -> Option A

4. Quick Check:

   Bend radius = inside curve size [OK]

Hint: Bend radius is always the inside curve size [OK]

Common Mistakes:

• Confusing bend radius with metal thickness
• Thinking bend radius is the bend angle
• Mixing bend radius with flat pattern length

2. Which of the following formulas correctly represents bend allowance (BA) for a bend with angle θ (in degrees), bend radius R, and thickness T?

easy

A. BA = (π/180) x θ x (R + T/2)

B. BA = (π/180) x θ x (R - T/2)

C. BA = (π/180) x θ x (R + T)

D. BA = (π/180) x θ x R

Solution

1. Step 1: Recall bend allowance formula

   Bend allowance = angle in radians x (bend radius + half thickness).

2. Step 2: Convert angle to radians and apply formula

   Angle θ in degrees converted by (π/180), then multiplied by (R + T/2).

3. Final Answer:

   BA = (π/180) x θ x (R + T/2) -> Option A

4. Quick Check:

   Bend allowance = angle x (radius + half thickness) [OK]

Hint: Add half thickness to radius in bend allowance formula [OK]

Common Mistakes:

• Using full thickness instead of half thickness
• Omitting thickness in the formula
• Using radius minus half thickness

3. Given a sheet metal bend with bend radius 7 mm, thickness 2 mm, and bend angle 90°, what is the bend allowance using the formula BA = (π/180) x θ x (R + T/2)? (Use π ≈ 3.14)

medium

A. 10.5 mm

B. 12.56 mm

C. 15.7 mm

D. 13.23 mm

Solution

1. Step 1: Calculate (R + T/2)

   R = 7 mm, T = 2 mm, T/2 = 1 mm, so R + T/2 = 8 mm.

2. Step 2: Convert 90° to radians

   (3.14 / 180) x 90 ≈ 0.01744 x 90 ≈ 1.57 radians.

3. Step 3: Compute bend allowance

   BA = 1.57 x 8 = 12.56 mm.

4. Final Answer:

   12.56 mm -> Option B

5. Quick Check:

   (π/180) x 90 x 8 ≈ 12.56 mm [OK]

Hint: Multiply angle in radians by (radius + half thickness) [OK]

Common Mistakes:

• Forgetting to convert angle to radians
• Using full thickness instead of half thickness
• Incorrect π value or rounding errors

4. Identify the error in this bend allowance calculation code snippet:

angle = 90
radius = 5
thickness = 2
bend_allowance = (3.14 / 180) * angle * (radius - thickness / 2)

medium

A. Thickness should be doubled, not halved

B. Angle should be in radians, not degrees

C. Using radius minus half thickness instead of adding

D. π value is incorrect

Solution

1. Step 1: Review bend allowance formula

   Correct formula uses (radius + half thickness), not minus.

2. Step 2: Check code snippet

   Code uses (radius - thickness / 2), which is incorrect and will underestimate bend allowance.

3. Final Answer:

   Using radius minus half thickness instead of adding -> Option C

4. Quick Check:

   Bend allowance uses radius + half thickness [OK]

Hint: Always add half thickness to radius in formula [OK]

Common Mistakes:

• Subtracting half thickness instead of adding
• Not converting angle to radians
• Using wrong π value

5. You need to create a flat pattern for a sheet metal part with a 120° bend, bend radius 4 mm, and thickness 1 mm. Which bend allowance should you use to ensure accurate flat length?

hard

A. BA = (π/180) x 90 x (4 + 1/2) = 7.07 mm

B. BA = (π/180) x 120 x (4 - 1/2) = 7.54 mm

C. BA = (π/180) x 180 x (4 + 1) = 15.7 mm

D. BA = (π/180) x 120 x (4 + 1/2) = 9.42 mm

Solution

1. Step 1: Identify correct formula and values

   Use BA = (π/180) x angle x (radius + half thickness). Angle = 120°, radius = 4 mm, thickness = 1 mm.

2. Step 2: Calculate bend allowance

   Half thickness = 0.5 mm, so radius + half thickness = 4.5 mm.
   BA = (3.14/180) x 120 x 4.5 ≈ 2.09 x 4.5 = 9.42 mm.

3. Final Answer:

   BA = (π/180) x 120 x (4 + 1/2) = 9.42 mm -> Option D

4. Quick Check:

   Bend allowance uses angle 120° and radius + half thickness [OK]

Hint: Use angle x (radius + half thickness) for bend allowance [OK]

Common Mistakes:

• Using wrong bend angle
• Subtracting half thickness
• Doubling thickness instead of halving