How To Calculate Broaching Machine Tonnage: A Step-by-Step Guide

6 Steps Calculate Broaching Machine Tonnage

Here is a step-by-step guide to calculating broaching machine tonnage:

Step 1: Determine broaching process parameters

  • Measure or obtain the dimensions of the parts being processed, including hole diameter, length, etc., to determine the cutting area.
  • Determine the broach tooth lift, tooth width and other parameters.

Step 2: Calculate cutting area

  • Based on the part shape and broaching dimensions, the cutting area is calculated. For example, for round hole broaching, cutting area = π × (hole diameter + tooth lift) × broaching length.

Step 3: Determine material properties

  • Find or test the tensile strength or yield strength of the material being processed.
  • Obtain the cutting performance parameters of the material, such as cutting coefficient, etc.

Step 4: Estimate broaching forces

  • The broaching force (F) can be estimated by the following formula: F = cutting coefficient × cutting area × material strength
  • Among them, the cutting coefficient needs to be selected based on experience or experimental data.

Step 5: Consider machine transmission efficiency

  • Different types of broaching machines have different transmission efficiencies, usually between 0.7 – 0.9.

Step 6: Calculate broaching machine tonnage

  • Broaching machine tonnage = broaching force / machine tool transmission efficiency

Through the above steps, you can roughly calculate the tonnage of the broaching machine required. However, it should be noted that this is only an estimate. In actual applications, more factors need to be considered, such as broaching speed, tool wear, cooling and lubrication effects, etc., to ensure the accuracy and reliability of the calculation results.

Calculation Equation and Diagram

Expected Broaching Force(Kgf)=Cutting Width(mm) X Cutting Depth Per Tooth(mm) X Cutting resistance Per Unit Area(Kgf.mm2) X Number of Simultaneous Cutting Teeth

Max Allowable Broaching Force(Kgf)=1.8 X Expected Broaching Force(Kgf)

Broaching Force Calculation Diagram

*Cutting Depth Per Tooth(µm)Cutting Depth Per Tooth(µm)Cutting Depth Per Tooth(µm)*
MaterialRound BroachSpline BroachSurface BroachCutting resistance Per Unit Area(Kgf.mm2)
Alloy Steel10~2025~3030~70300`400
Steel10~2025~3530~70300
Cast Iron25~4025~4050·75200
Malleable Cast Iron25~3525~3550·75150~200
Light Alloy Metal25~3530~4060~100100~200

How To Choose A Suitable Broaching Machine Tonnage?

Choosing a suitable broaching machine tonnage requires comprehensive consideration of the following aspects:

1.Requirements for processing parts

  • Part size and shape: Parts of larger size or complex shapes often require larger tonnage broaching machines to provide adequate pulling force.
  • Precision requirements: High-precision machining tasks may require a more stable and larger-tonnage broaching machine to ensure the smoothness and accuracy of the cutting process.

2. Material properties

  • Hardness and strength of the material: Materials with high hardness and strength require greater cutting force during broaching, so a broaching machine with a larger tonnage needs to be selected.
  • Material toughness: Tough materials may increase cutting resistance, requiring a higher tonnage broaching machine.

3.Broaching process parameters

  • Broaching allowance: The larger the allowance, the greater the cutting force and the higher the broaching machine tonnage required.
  • Cutting speed and feed: Higher cutting speed and feed will increase the cutting force and require the support of a larger tonnage broaching machine.

4.Tool design

  • Factors such as the size of the broach, tooth lift, and tooth shape will affect the cutting force, which in turn affects the choice of broaching machine tonnage.

5.Production batch

  • In mass production, in order to ensure production efficiency and equipment stability, broaching machines with larger tonnage and more reliable performance tend to be selected.
  • For small batch production, broaching machines of appropriate tonnage can be selected according to specific circumstances to balance cost and demand.

6.Equipment Costs and Budgets

  • Broaching machines with larger tonnage are usually more expensive, and equipment costs and budget constraints need to be considered while meeting the processing needs.

7.Existing equipment capabilities

  • If you already own a broaching machine of a certain specification, you should first evaluate whether it can meet the new processing tasks, try to make use of existing equipment, and avoid unnecessary investment.

8.Manufacturer recommendations and experience

  • Consult the broaching machine manufacturer or an experienced process engineer for their advice and real-life examples.

By comprehensively considering the above factors, the appropriate broaching machine tonnage can be selected more accurately to ensure the smooth progress of broaching and the processing quality.

What Is The Specific Relationship Between Broaching Process Parameters And Broaching Machine Tonnage?

There is a close relationship between broaching process parameters and broaching machine tonnage. The specific performance is as follows:

  1. broaching allowance
    The larger the broaching allowance, the more material needs to be removed during the broaching process, and the greater the cutting resistance. This results in increased broaching forces, requiring a higher tonnage broaching machine to provide sufficient pulling force to overcome cutting resistance.
  2. Tooth lift
    As the tooth lift increases, the material thickness removed by each tooth increases, the cutting area becomes larger, and the cutting force increases accordingly. Therefore, a larger tooth lift requires a larger tonnage broaching machine to meet the cutting force requirements.
  3. cutting speed
    Normally, increasing the cutting speed may increase the cutting temperature, leading to faster tool wear, thereby increasing cutting resistance. In order to cope with this situation, a broaching machine with a larger tonnage may be needed to ensure the stability and smoothness of the broaching process.
  4. Feed amount
    As the feed rate increases, more material is removed per unit time, and the cutting force will also increase accordingly. This requires broaching machines with higher tonnage to withstand greater cutting forces.

For example, if the broaching allowance increases from 2mm to 4mm, the broaching force may increase by 50% or more, and the original 10-ton broaching machine may not be able to meet the demand, and a 15-ton or higher tonnage broaching machine may be required.

In short, changes in broaching process parameters will directly affect the size of the cutting force, and the tonnage of the broaching machine needs to be selected accordingly according to the changes in cutting force to ensure the quality and efficiency of the broaching process.

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