Increasing cylinder head manufacturing productivity
The cylinder heads of today’s car engines are usually made of aluminium alloys. The moulds used to cast the cylinders are repeatedly filled with molten aluminium heated to over 600°C. This exposes the moulds to enormous stress, the flow of the liquid metal wearing out the mould surface and frequent temperature changes causing fatigue and cracking. Corrosion and oxidation also combine to shorten the mould’s service life, creating poor surface quality on the castings and increasing scrap.
Heat treated steels are commonly used for aluminium moulds because of their mechanical, thermal and chemical properties. But these materials still have significant weaknesses in terms of oxidation and thermal expansion and conductivity.
Breakthrough results
TLM Laser’s product partner, InssTek, was asked by a global carmaker to participate in a project to increase productivity in cylinder head manufacturing. The strategy was to increase the service life of the moulds and improve the surface quality of the castings, so reducing scrap.
InssTek set about finding a suitable metal to work with its versatile DMT technology. After an extensive search, the nickel-molybdenum alloy, Hastelloy, was chosen because of its excellent thermal expansion characteristics and corrosion and oxidation resistance.
A 570x380x126mm mould made of heat-treated steel was prepared. The mould’s dimensions were processed and a thermal model calculated and printed by the InssTek 5-axis 3D metal printer, MX-1000. The nickel-molybdenum layer was applied in thicknesses varying from 2 to 30mm depending on how intense the need for heat conductivity.
The result has been an impressive increase in productivity. With the alloy’s higher heat dissipation, pores and unnecessary heat stress in the cylinder casing are eliminated. The castings have a better surface and there is a much shorter production cycle time.
For more information on the MX-1000 and the complete range of InssTek’s DMT 3D metal printers, please contact sales@tlm-laser.com