Shearing Force & Energy Module – Twisted Sheet Metal Part Length Calculation Tools (Excel – Design – Sheet Development)

Sheet Metal Plates and Processing
Sheet metal plates are widely used flat metal sheets with relatively low thickness in industrial and manufacturing processes. They are typically made from metals such as steel, aluminum, stainless steel, copper, and brass. With thicknesses often less than a few millimeters, these sheets are employed across numerous sectors—from automotive and home appliances to defense and construction—thanks to their high formability and machinability.

Sheet Metal Cutting, Shearing Force, Cutting Energy, and Cutting Processes
The sheet metal cutting process is one of the fundamental steps to shape a sheet into the desired form. This operation is generally performed using methods such as shearing, punching, laser cutting, plasma cutting, or water jet cutting.
In mechanical cutting processes, one of the most critical parameters is the shearing force. The shearing force depends on factors such as the material’s yield strength, thickness, and the length to be cut. The approximate shearing force can be calculated as follows:

Shearing Force = Cutting Length × Sheet Thickness × Material Shear Stress

Shear stress is typically estimated as 70% to 80% of the material’s yield strength.
During the cutting process, cutting energy must also be considered. Cutting energy is calculated as the product of the applied force and the cutting distance. This value is particularly important for energy consumption and machine sizing in mass production lines.
Undesirable conditions such as burrs, crushing, or deformation can occur on the cut surface during cutting operations. Therefore, correct blade clearance, cutting speed, and appropriate tooling selection are critical.

Sheet Metal Bending, Grain Direction and Bending Effect, Flat Length Calculation of Bent Sheet, and Bending Processes
The sheet bending process is a forming method in which the sheet is bent at a specific angle to achieve the desired shape. Bending is generally performed using press brake machines. The dimensions of the punch and die used during bending are selected based on the material thickness and the required bend radius.
Grain direction refers to the alignment of metal grains formed during the sheet’s manufacturing process. Bending operations should take this direction into account. Sheets bent parallel to the grain direction are at higher risk of cracking. Whenever possible, the bend line should be planned perpendicular to the grain direction.
To calculate the flat length of a bent sheet, factors such as bend allowance and bend deduction are considered. The basic formula is as follows:

Flat Length = Flange 1 + Flange 2 + Bend Allowance

Bend allowance is determined based on the material thickness, the internal bend radius, and the bend angle. These values are typically calculated using tables or with the assistance of CAD software.

Various problems can occur during cutting and bending operations. Common issues during cutting include burr formation, deformation on the cut surface, sheet warping, and dimensional deviations. These problems are usually caused by:

• Incorrect blade clearance
• Worn cutting tools
• Poor material quality
• Insufficient tool rigidity

To prevent such issues, regular tool maintenance should be performed, correct clearance values should be applied, and high-quality materials should be used.

The main problems encountered during bending include cracking, springback, corner deformation, and inaccurate dimensions. Cracking typically occurs when the bend line is parallel to the grain direction or when the internal radius is chosen too small. Springback is especially common in materials with high yield strength and manifests as a partial reopening of the bend angle after forming.

To address these issues:
The bend direction should be perpendicular to the grain direction

Appropriate internal radius and tooling should be selected
The bend angle should be over-applied in advance to compensate for springback
CAD/CAM-supported bending simulations should be conducted

By using correct material data, proper tool selection, and controlling process parameters, such manufacturing defects can be minimized. Attention and precision in these processes not only improve product quality but also reduce time and cost losses.

Sheet Development Examples:

SHEARING FORCE AND ENERGY MODULE TOOL

Project Objective
This project has been developed to calculate the shearing force and cutting energy that occur during the cutting of sheet metal parts. In industrial press cutting operations, reliables are required to make informed decisions regarding material selection, tooling design, and machine capacity. The primary goal of the project is to provide a user-friendly, automated system in Excel that performs these calculations both technically and practically.

Project Structure and Page Layout
The workbook consists of four main sheets:

Input
This sheet serves as an interface where the user manually enters data into only three cells (calculation type, data source, and material selection), while all other values are loaded automatically. Users can perform calculations using either shear stress or tensile stress. Material selection references the list in the Database sheet, from which sheet thickness and cutting length are also determined.

Calculation 

On the calculation sheet, the appropriate formulas run automatically based on user inputs.

If calculations are based on shear stress, the formula used is:

• Pk = τ × Lt × T

If tensile stress is used, the formulas are:

• Pk = C₁ × σt × T × Lt
• or alternatively: σt = K × (n / e)ⁿ

For cutting energy, the formula implemented is:

• Ek = C₂ × Pk × T

Both the cutting force (Pk) and cutting energy (Ek) are calculated separately in this section.

Result

This sheet summarizes the calculated values and provides technical comments accordingly. For example, if the cutting force is very high, the system advises the user on appropriate press selection; if energy is high, cutting angles are suggested; and if the material hardness is high, warnings regarding tool material are issued. All comments are automatically updated based on the calculation results. This sheet allows engineers to gain a qualified perspective not only on the numerical results but also on how to interpret them.

Database
This sheet contains mechanical properties of different materials, such as shear and tensile stresses. Constants used in calculations, including strain-hardening exponent, strength coefficient, and the C1 and C2 coefficients, are also provided. The material list has been expanded from common steel types in sheet metal processing to non-ferrous metals. Average values for each material are provided, offering reliable data suitable for engineering calculations. Users can also input their own values in this sheet if necessary.

Calculation Methods and Technical Basis
Two calculation types are supported in the project:

1. If shear stress is provided, the force is calculated directly.
2. If tensile stress is provided, it is first converted to shear stress and then the force is calculated.

The calculation formulas are based on established theoretical principles in plastic deformation, material strength, and manufacturing engineering. All formulas in Excel are written using Turkish function names, and only basic Excel knowledge is required from the user.

Applications
This tool is suitable for all engineering levels involved in sheet metal production. It is particularly effective in the following areas:

• Tool and die design
• Press capacity determination
• Pre-simulation of sheet cutting processes
• Production line planning
• Educational and academic case studies

Advantages

• All data is consolidated in a single Excel file; no additional software is required.
• Automated calculation and comment generation reduce the technical analysis burden on the user.
• The wide material range covers different industry segments.
• The input interface is simplified, requiring only three cells for operation.
• Engineering evaluations are provided alongside the calculated results, supporting direct decision-making.
• The database can be updated over time, allowing system expansion.

Project Contribution
This work ensures that engineering decisions related to sheet metal cutting are made quickly, consistently, and in a standardized manner. Pre-design calculations provide advantages in terms of time and cost. Additionally, the project serves as a strong educational resource for young engineers in understanding cutting processes and force analysis.

SHEARING FORCE AND ENERGY MODULE CALCULATION TOOL

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BENT SHEET METAL PART LENGTH CALCULATION TOOL

This project is an Excel-based engineering tool designed to reliably and user-friendly calculate the total flat length of sheet metal parts that are formed by bending. One of the most frequently required calculations in sheet metal manufacturing, determining the flat length, is often done through experience-based estimates or left to CAD programs. However, this approach is prone to errors. Therefore, a solution has been developed in Excel that automates all calculations, provides user guidance, and is based on theoretical principles.

Project Objective
The primary goal of this tool is to accurately calculate the total flat length of sheet metal parts with multiple bends, taking into account each bend’s angle, radius, and material thickness. This ensures the correct cutting length is obtained before production and minimizes errors.

Target Users

• Mechanical design engineers working on sheet metal design
• Production planners and sheet metal manufacturers
• Engineers who want to perform calculations before CAD modeling
• Users working with CAD programs who want to verify flat length results

Tool Structure and Sheet Layout
The project consists of three main Excel sheets:

1. Technical Calculations Sheet
This sheet requires only three basic inputs from the user:

• Material thickness
• Measurement type (inside-to-inside or outside-to-outside)
• Number of bends

After entering these, a table displaying straight and bent sections becomes active. The user is only required to input the lengths of straight sections, bend angles, and bend radii. All other calculations are performed automatically using formulas.

The sheet also guides the user based on the selected measurement method. For example, if the user selects "outside-to-outside," the system issues a warning and recommends "inside-to-inside" measurement.

2. Calculation Table
For each bend, the following information is displayed:

• Straight section length (manual entry)
• Bend angle (manual entry)
• Bend radius (manual entry)
• R/T ratio (calculated automatically)
• Distance between neutral axis and inner surface, C (calculated automatically)
• Bend arc length, LA (calculated automatically)
• K factor (calculated automatically)

The C distance is assigned based on the R/T ratio according to three ranges:

• R < 2T → C = 0.33T
• 2T ≤ R ≤ 4T → C = 0.4T
• R > 4T → C = 0.5T

The user only provides measurement inputs; all technical calculations are automated. Unused rows are visually highlighted for guidance.

Usage Advantages

• Operates entirely within Excel without requiring CAD programs.
• Minimal user input; all other calculations are automatic.
• Neutral axis is modeled accurately according to the R/T ratio.
• System warns the user if the wrong measurement type is selected.
• Visual guidance (color coding and explanation rows) ensures ease of use.
• Can be used as a verification tool before production.
• Allows easy comparison with CAD results.

Applications

• Dimensioning the flat sheet of multi-step bent parts, such as L, Z, U, and box shapes
• Preliminary cost estimation and cutting planning
• Pre-CAD modeling verification
• Supporting the creation of bend tables in engineering processes
• Manual verification of sheet metal module outputs

BENT SHEET METAL PART FLAT LENGTH CALCULATION TOOL

For the video, click here ▷