Flat Form Tool

Straight and flat form tools contain a square or rectangular cross-section along with the form being along the side or end. These tools are identical in appearance to the turning tools. These are generally set centrally so that they will cut their contour which is similar to the desired contoured of the workpiece. A common example of V-notch tool is displayed in Figure. This type of tool is appropriate for making deep straight-sided form grooves. The cutting is restricted type because of the mixed chip flow. Due to the existence of the good surface finish, this type of tool must be operated at extremely low cutting speed.

Figure: V-notching Tool

Figure displays a common flat form tool without rake angle. It is essential to compute x to be machined in the tool in order that the depth BC is correct profile. This distance x is to be planned by a fly cutter or planning tool and is computed normal to the clearance face. The amount of x is less as compared to actual depth of form AB produced on the workpiece due to the clearance angle α. The geometry of the figure

Equation 1

x = AB cos (α) 

Diagram illustrates a flat form tool with rake angle. The wedge angle is given by (90 - ϒ - α). By using geometry of the figure, the depth x to be machined or ground can be ascertained in the following way :

H = r sin (ϒ_s), l_s = r cos (ϒ) and l₁ = √(R² - h²)

Hence,

L₂ = L_s - L₁ = √ (R² - h²) - r cos (ϒ)

= √ {(R² - r² sin² (ϒ_s))} - r cos (ϒ)

Now,    x = L₂ cos (α + ϒ)

Hence,

Introduction of rake angle to make easy cutting action modifies the profile on the tool.

Figure: Flat Form Tool