Having finished in December 2022 the pCommissioning of our new industrial plant, we continue with our plans continuous improvement. With this objective, we are implementing a change in the construction material of our centrifugal pump bodies. sayings bodies which until now had been built in gray cast iron according to ASTM A48 CLASS 30, become of nodular gray cast iron according to ASTM A395 CLASS 60-40-18, which has many advantages.
In gray cast iron, carbon precipitates in the form of graphite. Its shape and size have a great influence on the mechanical properties of the casting.
The graphite appears in the form of sheets, this generates discontinuities in the metallic matrix acting as strong stress concentrators, resulting in a brittle material. for his part ductile iron precipitates graphite in a spheroidal form and is concentrated in volumes, which favors the elimination of discontinuities in the metallic matrix. This difference in the way graphite is precipitated between both materials, gives as a result that NODULAR cast iron is a material with greater ductility, high resistance to fatigue and better behavior at high operating temperatures.
Likewise, the nodular gray cast iron provides better machining conditions so the presence of graphite nodules act as a self-lubricant. This material presents a good behavior under vibratory stress since it allows them to be attenuated and presents a better performance in terms of fluid tightness, these motifs are of great interest to the application of this material in our centrifugal pump bodies.
Nodular iron allows to obtain mechanical properties similar to those of cast steel and superior to gray cast iron:
| Mechanical properties | tensile strength MPa | Elastic modulus MPa |
| Cast Iron ASTM A48 | 214 | 90-113 |
| Nodular Gray Cast Iron ASTM A395 | 414 | 120-132 |
Our centrifugal pump casings made of nodular gray cast iron are machined in our new HAAS VF4 machining center, which allows us to perform operations quickly, safely, accurately and with less cutting tool wear.
This change allows us increase the reliability of our centrifugal pumps, providing our customers with higher quality equipment without increasing their cost.
