Internal Combustion Engine

Focus components from the internal combustion engine sector

Cylinder head

Cylinder head

In the passenger car sector, the cylinder head is usually cast from aluminum alloys, whereby the structure and the features to be machined differ slightly depending on the engine fuel. It is mounted on the cylinder crankcase and is primarily responsible for the fuel and fresh air supply. Due to its extremely high quality and tolerance requirements, the cylinder head is the most demanding component to be machined in engine production. Precise valve control in the valve train and minimal friction losses in the camshaft bearings reduce fuel consumption and thus emissions even before the combustion process begins.

Machining highlights:

• Valve train
• Injector bore
• Camshaft bearing bore
• Face milling
• Spark plug bore

Cylinder crankcase

Cylinder crankcase

The cylinder crankcase, also known as the engine block, is the central element of every combustion engine. Depending on the vehicle model and engine size, there are a variety of different designs and sizes, from 2-cylinder in-line engines to 12-cylinder V-arrangements. Due to the weight advantage, aluminum alloys are predominantly used in the automotive sector today. However, this forces car manufacturers to use cast liners or wear-resistant coatings, especially for cylinder bores, in order to guarantee a high mileage. During machining, tool manufacturers are increasingly encountering mixed machining (cast aluminum) or extremely abrasive coatings. The increased combustion pressures of modern engines also increase the mechanical and thermal load requirements, which, among other things, leads to increasing quality requirements for the features to be machined.

Highlight machining:

• Cylinder bore
• Crankshaft bearing bore
• Honing pass

Connecting rod

Connecting rod

High-strength steel materials such as 70MnVS4 or C70 are generally used for the connecting rods, which are subject to alternating heavy loads, in order to convert the linear movement of the pistons into a rotational movement of the crankshaft. In order to reduce the moving mass during engine operation, the components are reduced to a minimum weight. Over the years, this has resulted in an enormous number of variants with, for example, parallel, trapezoidal or stepped shapes, which entail a wide variety of tapping situations, especially when machining the small connecting rod eye. Due to the enormous production quantities, manufacturers are particularly focused on cost-effectiveness in series production.

Highlight machining:

• Large eye
• Small eye
• Screw hole drilling

Turbocharger

Turbocharger

To increase the efficiency and performance of modern combustion engines, exhaust gas turbochargers are increasingly being used today. The compressed air supply via the turbocharger increases the efficiency of engines and at the same time reduces emissions. At speeds of up to 300,0001 rpm, it is imperative that quality requirements are met, especially with regard to coaxiality and roundness. Extremely abrasive high-alloy materials, especially on the exhaust gas side (turbine side), demand maximum wear resistance from the cutting tools. If the tool life quantities for the various machining operations are increased by even just a few components, this has an enormous cost benefit for the manufacturer.

Highlight machining:

• Turbocharger housing connection surface
• Turbine housing
• Control pin bore
• Turbine inner contour & V-band
• Connection machining

Rocker/toggle lever

Rocker/toggle lever

The high-precision control of the valves for intake and exhaust is a decisive factor for the performance and efficiency of combustion engines. 4 valves per cylinder are usually controlled in the automotive sector, with 2 valves controlling the intake for fresh air or air/fuel mixture and 2 valves controlling the exhaust gas outlet. Depending on the engine design, various rocker arms or (roller) finger followers are used for OHV and SOHC valve actuation in order to minimize friction and the associated wear on the moving parts. In addition, the valve clearance can be set and readjusted via the integrated adjusting disks in order to maintain an optimum combustion process and prevent possible engine damage. 

Highlight machining:

• Bearing bore
• Fitting bore

Rail

Rail

As in diesel engines known as common rail, fuel is now also injected into the combustion chamber of every second new petrol car via efficient direct injection systems, in which the air-fuel mixture is first formed in the combustion chamber. This enables more powerful petrol engines with reduced fuel consumption and lower exhaust emissions. The increasing pressure requirements of up to 2,500 bar are decisive for the use of moderately to difficult-to-machine materials such as cast steel or stainless steel.

Machining highlights:

• Central rail bore
• Injector bore / Injector transfer
• High pressure connection
• End machining

Crankshaft

Crankshaft

The basic design of the crankshaft is largely determined by the number of cylinders and the engine layout. However, the steel shafts, which are generally forged, have to be made lighter and lighter to reduce emissions. This means that additional machining operations are required in the manufacture of the already complex components. Furthermore, due to the increasing combustion pressures of modern engines, the crankshaft is constantly exposed to increased bending and torsional stresses, which results in higher quality requirements. 

Highlight machining:

• Central relief bore
• Oil channel bore
• End machining