Düsseldorf, 19-11-07 

Cast Cylinder Heads and Crankcases Offer Versatile Solutions for the Cars of Today and Tomorrow

In the last ten years, the stresses to which reciprocating engines and, consequently, their cylinder heads and crankcases are exposed have been increasing steadily. This is mainly because the power output per litre as well as the pressure and temperature of combustion have been increasing continuously, while power-to-weight ratios have been declining. This being so, a variety of crankcases were developed in the past that match the requirements of their respective applications as closely as possible in terms of design, manufacture, and material selection.

Today, the materials used in the manufacture of crankcases are highly diverse, and their selection largely follows the principles of lightweight construction. While the classic crankcase is still made of cast iron with lamellar graphite, there are also highly innovative components made of Al-Mg composites and magnesium crankcases featuring Al-Si cylinder liners. While the piston bearing surfaces in cast-iron components require no further effort because of the good friction characteristics provided by the enclosed carbon, light-metal components call for dedicated bearing-surface technologies.

Cylinder heads are geometrically complex heavy-duty castings which are mostly made of aluminium alloys by gravity die-casting. To ensure that they withstand the great stresses to which they are exposed in an engine, many tests are applied in developing a cylinder head. The material used in its production is stress-dependent. While aluminium alloys still dominate, more sophisticated aluminium alloys as well as cast-iron materials will certainly be used as the power output of the engines grows further.

Comprehensive studies in which materials and casting methods have been evaluated together indicate that casting is the dominant process in the production of these motor-vehicle components.

The subject 'cast cylinder heads and crankcases offer versatile solutions for the cars of today and tomorrow' was covered in No. 4/2005 and 4/2006 of 'konstruieren + giessen '. Copies are available free of charge at zgv@bdguss.de.

Photo: Pattern cluster for casting two cylinder heads by the lost-foam process

 

The subjects dealt with in previous ZGV information brochures include

• High-alloy Casting Materials for Special Applications in the Pump Industry World
• Steel Castings for Buildings all over the World
• What to know about Cast iron with spheroidal graphite
• Versatile Non-destructive Tests for Castings
• Black Malleable Cast Iron – Strong and Tough
• Visual Determination of the Surface Quality of Castings by Reference Samples Graphite
• New Studies of the Bending-fatigue Behaviour of Cast Iron with Spheroidal Graphite
• Continuous Castings – Versatile Quality Semis
• Thin-walled complex components made of white malleable cast iron
• Heat-treated cast-iron materials conquer market shares
• Cast Iron – a Versatile Material for Motor-vehicle Design
• ADI – A Cast-iron Material for Lightweight Components Exposed to Extreme Stress