Precision machine shops use a variety of materials, selected according to the specific request to be fulfilled, the purpose of the article, and the machining required to bring it to life.
Usually, metals are preferred because they are the only ones that can guarantee a high level of accuracy and durability in the medium and long term. Such as cast iron G25, which we will discuss in this article.
What is G25 Cast Iron?
Cast iron G25, or GJL-250 EN 16482, is a lamellar alloy characterized by a particular structure: as the name suggests, graphite solidifies in the form of lamellae, generating a discontinuity in the ferrous part of the alloy.
It is a cast iron with an average durability of between 160 and 230 HB, with the figure varying depending on the size of the section.
Compared to other types of cast iron, G25 provides an excellent compromise between wear resistance, strength and machinability, making it one of the most widely used for precision mechanical machining.
The Mechanical Characteristics of G25 Cast Iron
The structure of cast iron G25, composed of graphite sheets in accordance with ASTM A 247, is mainly pearlitic with less than 30 per cent ferrite.
In contrast, the perimeter, on which there is fine interdendritic graphite of types 'D' and 'E', is mainly ferritic with 10-20% perlite and may contain up to 5% fine dispersed carbides. It is not suitable for hardening and its density is 7.2 g/cc.
How is G25 Cast Iron produced?
The most common production method for G25 lamellar cast iron is by continuous casting and extrusion, which yields significantly superior products compared to those obtained by other casting methods.
This practice renders the surface of the bars obtained very fine, free of suction and porosity and, consequently, easy to machine, grind and polish. In fact, the main advantage offered by the continuous casting process is precisely that it produces bars free of non-metallic blowholes or inclusions, characterized by great homogeneity and uniformity in the analytical components.
The products produced can take various shapes: round, square or rectangula
Cast or hydraulic Cast Iron: areas of use
Like the other continuous cast irons, G25 cast iron is also called hydraulic cast iron, with the appellation referring precisely to its extreme compactness and absolute absence of blowholes and microporosity.
There are many areas of application in which this material finds great use. Here are some of them:
- Precision mechanics: dressing plates, test benches, surface plates, clamping squares, clamping cubes and plates, control blocks and cylinders as well as mouting or assembly boxes and support and levelling columns.
- General mechanics: sliding guides, larders, cams, gear wheels, plates and conveyor rollers, bushings, groove pulleys.
- Hydraulic and pneumatic hydraulics: cylinder blocks, hydraulic blocks, motor valves, piston dampers.
- Automotive industry: brake disc, gears, manifold, battery mould, pulleys.
- Glass industry: flow tube, collars.
- Textile industry: roller, gear, cam, bevel gear.
All precision engineering products made of G25 cast iron can be purchased, ready for delivery, by entering Bonanomi's Express Shop: once you have completed the form, we will contact you with a formal offer on the required item. Thanks to the experience gained in over 70 years of activity, a contract machining service is offered by milling, grinding and engraving on any mechanical part.
The Main Advantages of G25 Cast Iron Products
Cast iron G25 makes it possible to achieve high machining standards and to produce precision mechanical engineering products that meet the customer's requirements and pass the strictest quality controls.
Compared to other types of materials, it provides tangible benefits that last in both the short and long term. If we were to make a list, there are 10 advantages of this material:
- Greater compactness of the structure
- High fatigue resistance
- Corrosion resistance
- Low deformability
- High material processability
- Fine, compact and homogeneous material grain
- Low overmolding
- Low inclusions and porosity from gas or sand
- Excellent wear resistance and low coefficient of friction
- Resistance to hydraulic or pneumatic pressure