Form honing
- Form honing result
- Cylinder bore - free form
At present, the most important objective when developing internal combustion engines for vehicles is the reduction of fuel consumption and pollutant emissions. The focus is currently on the CO2 value (g/km). The reduction of internal engine friction is considered a contribution to the targeted limits.
The earlier production of internal combustion engines required cylinder bores with high cylindric form and surface qualities. During operating conditions there are complex distortion mechanisms which deform the cylinder bore.
We have therefore developed a process which does not have the cylindrical bore shape as a target but which reproduces the deformation in the manufacturing process.
Principle of Form honing
The ideal cylindrical bore distorts during operating conditions. By means of form honing, this deformation is reproduced during manufacturing which results in an almost cylindrical shape during operation.
Objective of form honing
By honing non-cylindrical free forms, the component deformation in operating mode is taken into consideration. The deformation in the operating condition depends on:
- Static assembly distortions
- Dynamic distortion
- Thermal cylinder distortions
The cylindrical free form is determined either by FEM calculation or simulations using torque plates and tempering.
- Form honing
- Cross section of a cylinder block
Form Honing Components
In order to implement form honing from a manufacturing point of view, a number of innovations to control the work surfaces of the diamond honing stones are required. For this reason, a tooling concept was developed featuring four expandable honing stones which are independent of each other.
The form data of the negative cylinder form are converted into hone tool feeding parameters for each cylinder of a block using the form hone control. These parameters and the form honing tool dynamically use this feed profile on the form honing stones during honing. In the next step, a pneumatic shape measurement system determines the free form geometry achieved.
Your benefits
The major advantages of form honing are:
- Reduced blow-by
- Reduced piston ring tension
- Reduced friction
This has a positive effect on the overall engine performance such as quality of emissions, oil and fuel consumption as well as power output and wear.
