Cylinder head

When it comes to cars, the cylinder head is cast from aluminium alloys. The configuration and features for machining vary according to the engine fuel. The cylinder head is fitted on the cylinder crankcase and is responsible for the fuel and fresh air supply. Due to its stringent requirements for quality and tolerance, it is the most demanding component for machining in engine manufacture. Through precise valve control and minimal friction losses in the camshaft bearings, fuel consumption and emissions are already reduced before the combustion process.
„Cylinder head with valve train, injector bores and camshaft bearing bores structure

Key features

  1. Valve Train
  2. Injector bore
  3. Camshaft bearing bore
  4. Core plug bore

  • The tool carries out the pre-machining of the base bore in the internal combustion engine.

    1. Pre-machining – blind bore

    High feeds and large chip quantities require sturdy, PCD-tipped boring tools with efficient chip removal. Machining forms the foundation for all subsequent process steps in the valve train.

  • The tool carries out the finishing of the blind bore in the internal combustion engine

    2. Finishing – blind bore

    Multi-blade, PCD-tipped boring tools ensure dimensional accuracy and surface quality. In this machining step, precision is crucial so that the valve seat rings and valve guides can be pressed in later.

  • “The tool carries out the pre-machining of the valve seat in the internal combustion engine.”

    3. Pre-machining – valve seat and valve guide

    Once the valve seat ring and valve guide are pressed in, machining of the hard workpiece materials takes place. Extremely tight tolerances and wear-resistant cutting materials are required.

  • The tool carries out the finishing of the valve seat in the internal combustion engine.

    4. Finishing – valve seat and valve guide

    Fine boring or reaming tools are used for precise sealing surfaces. These ensure high process reliability and long tool lives.

1. 配气机构

工艺条件
  • High-precision requirements for form and position tolerance
  • Cylindricity 10 μm 
  • Diameter tolerance 15 μm
  • Coaxiality from valve seat to valve guide
  • Circularities < 8 μm
  • Angle tolerances on the valve seat ring in the μm range
  • Materials with high resistance to wear on valve seat ring
  • Maximum process reliability and accuracy of repetition
PCD fine‑boring tools for machining the valve train pilot bore in the cylinder head

基础孔

1.粗加工
聚晶金刚石镗刀
  • 短结构、高稳定性的刀具设计, 可实现最高的定位精度。

2.精加工
聚晶金刚石镗刀

  • 多刃刀具方案，可大幅缩短 加工时间。

Werkzeuge zur Bearbeitung vom Zylinderkopf: Ventilsitz und Ventilführung

气门座圈和气门导管

3.粗加工
导向-刀具
  • 短结构、高稳定性的刀具设计，可确保后续 精加工刀具能够实现最高的定位精度。

4.精加工。
精加工-刀具

  • 采用带EA-简易微调系统的可调式精密镗刀和 快换式气门导管铰刀，实现高精度精加工。

2. 喷油器内孔

PROCESS CONDITIONS
  • Very large step changes > 10 mm
  • Critical chip removal due to component contour
  • Fluctuating casting situations
  • Surface requirements of up to Rz 4
  • Diameter tolerances in H7 range
  • Wide range of contour designs with multiple tight-tolerance
  • radii and chamfers (± 0.1 mm)
Three tools for machining the cylinder head via the injector bore using a three‑stage process

3-step process for maximum process reliability

1. Pre-machining
PCD multi-stage solid drill
 
  • Multi-blade solid drill and boring tool with brazed PCD inserts and special chip flutes for optimal chip removal.


2. Semi-finishing
Solid carbide step drill

  • Special cutting-edge geometry and spiralisation for the best chip breaking and chip removal.


3. Finishing
PCD step reamer

  • Multi-blade step reamer with brazed PCD inserts, special cutting-edge geometry and expanded chip flutes for optimal chip removal.

Two tools for machining the cylinder head via the injector bore using a two‑stage process

Two-step process for maximum productivity

1. Pre-machining
PCD boring tool with solid carbide drill

  • Maximum usable tool life of PCD inserts due to Drilling from solid stage that can be changed separately.

2. Finishing
PCD step reamer

  • Multi-blade step reamer with brazed PCD inserts and expanded, polished chip flutes for optimal chip removal.

3. Camshaft bearing bore

PROCESS CONDITIONS
  • Cylindricity (15 μm over 100 mm)
  • Circularity < 5 μm
  • Diameter tolerances of 15 – 20 μm
  • Surface qualities of < Rz 5 μm
  • Repeated cutting due to the interrupted cut
  • Tools with very high length–diameter ratio
Large tool, also known as a line boring bar

通过一站式 解决方案， 实现了 最高生产率

1.预加工和精加工
线镗杆
  • 通过带有滚动轴承或者滑动轴承的附加 导条机构，完成一站式加工，达到极佳的 孔直线度。

Two fine boring tools for machining the internal combustion engine

通过两步 工艺流程， 确保最高 工艺流程安全性

1.粗加工
精镗刀具
  • 带导条的精密镗刀，配置易于调节的 HX-可转位刀片。

2.精加工
精镗刀具

  • 采用带导条的可转位刀片精密镗刀—— 通过方便调整的切削刃和附加预切削步骤，极大满足了极高质量要求。

3. 水堵孔

工艺条件
  • Surface quality Ra < 16 μm
  • Circularity 0.05 mm
  • Diameter tolerance H7
  • Positional accuracy
Tool for machining the core plug bore on an internal combustion engine

4. 水堵孔

1. Semi-finishing
PCD step boring tool

  • Short, compact tool design for maximum tool stability.