Bloc moteur sans chemise-Nemak

Nemak, un des leaders mondiaux de la culasse et du bloc aluminium vient de breveter un alliage d'aluminium permettant de réaliser des blocs moteurs sans chemise inséré.


Bloc moteur 8 cylindres Nemak (aluminium)

Tenedora Nemak vient de breveter un alliage d'Al dont la composition est :
13% - 14% Si;
2,3% - 2,7% Cu;
0,1% - 0,4% Fe;
0,1% - 0,45% Mn;
0,1% - 0,30% Mg;
0,1% - 0,6% Zn;
0,05% - 0,11% Ti;
0,4% - 0,8% Ni;
0,01% - 0,09% Sr

Cet alliage qui permettrait de couler des blocs moteur qui n'auraient pas besoin de chemise.
La microstructure présente évidemment des carbures de silicium primaire qui seraient bien répartis. Le cuivre ne ségrégerait pas durant la solidification. Cette solution sans chemise permettrait de réduire les coûts de 40 % par rapport à une solution plus conventionnelle avec chemise.
[Brevet mondial n° WO2008053363,08/05/07] - Info CTIF

La société Nemak
Nemak is a full service supplier of high technology aluminum cylinder blocks and cylinder heads to the worldwide automotive original equipment manufacturers. To support the standards expected in today’s competitive markets, Nemak offers several state-of-the-art manufacturing processes.

The technologies utilized for manufacturing cylinder blocks are either precision sand casting or high-pressure die-casting. In the precision sand process, a cylinder block is cast by introducing molten aluminum into a mold composed of sand cores.

Nemak uses several different precision sand processes depending on the customer’s exact needs and product design requirements. High strength materials properties are possible by utilizing a chill that induces efficient metal solidification. In high-pressure die-casting, molten aluminum is injected at high speed into a metal die where it rapidly solidifies under pressure.

For cylinder heads, Nemak once again has the option to choose the best process to meet the customer’s design requirements. The two main technologies utilized for heads are based on the semi-permanent molding process. In this process, sand cores are placed into a steel mold and molten aluminum is introduced to the mold. This is accomplished in either a gravity system in which metal is poured into the mold or a low-pressure system in which metal is pumped into the mold and held under pressure until the casting solidifies. Nemak also uses rollover and dynamic tilt casting for specific cylinder head applications.

For both blocks and heads, the process selected is matched to the customer’s needs, driven by part design and materials properties requirements. To support the varied customer base demands, Nemak has five strategically located Technical Development Centers. With complete center in Monterrey, Mexico, Linz, Austria, Dilligen, Germany, and Bielsko Biala, Poland, and support centers in Windsor, Canada, and Wernigerode, Germany, Nemak has the ability to quickly support any of its customers with know-how and technical expertise.

     Site Nemak

---

Octobre 2008