What are the properties of cast iron?

The heavy-duty machine tools are designed to machine hard materials. That is why they need to be extremely rigid to transfer the high torque and continuously work with the installed high power. To achieve that rigidity the main bodies of our DTI machine tools are casted .

Advantage of castings

Here you can compare the characteristic of grey iron, ductile iron and steel. All three of these materials are used to manufacture different components of the heavy-duty machine tools.
Grey iron Ductile iron Steel
Machinability +++ ++ +
Vibration damping +++ ++ +
Thermal Conductivity +++ + ++
Impact strength + ++ +++
Compressive strength +++ ++ +
Tensile strength + ++ +++
Elongation + ++ +++
Hardness + +++ +++
Application machine tool bodies milling head body slide ways

Gray cast iron

Gray cast iron offers stiffness and  has extremely high damping capacity. That makes it the preferred material for machine tool beds, tables, columns and cross rails as in our horizontal machining center with swiveling spindle unit.

Another advantage is the flexibility. It is easy to form in the most complicated shapes. Also cast iron compared to steel offers improved corrosion resistance. This is also an important advantage when we take under consideration that the lifetime of the heavy-duty machine tools can be few decades.

 And last but not least the thermal expansion of the gray cast iron is significantly lower than the steel one. This clearly influences the machine tool alignment, accuracy and repeatability as you can see in our  FB series milling machine tools.

zdjęcie nr 3

Adapting the type of cast iron

The main bodies of our heavy-duty vertical machine tools and heavy-duty horizontal machine tools  we cast from gray iron type GG20 and GG30. Our tables are always a casted monolith not a welded one. When it comes to bodies directly transferring the big loads (headstocks, milling heads etc) we always use ductile iron type GGG30. This way we ensure higher strength and resistance.

All castings are manufactured and machined in Poland. They are all heat treated for stress relief.

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