Do you want to know how the pistons in top-tier engines achieve both lightness and toughness, precision and efficiency? The answer lies in the secrets of CNC piston machining. Whether you’re an automotive enthusiast or a manufacturing expert, understanding this precision process can unlock the key to performance enhancement. Let us take you into the world of piston machining and reveal how Ultirapid uses cutting-edge technology to create perfect components!
What Is Piston Machining?
The piston is the core component of an internal combustion engine, responsible for converting combustion energy into mechanical power. Piston machining, on the other hand, involves shaping raw materials into finished products that meet stringent tolerances using high-precision equipment, particularly CNC machines. CNC (Computer Numerical Control) technology, with its automation and precision, has revolutionized traditional machining methods, setting the standard for modern manufacturing.
High temperatures reduce mechanical strength and create abnormal fits; in addition, localized heating and high-load operation could create such troubles as piston cracking and deformation. Therefore, the material to be used for the piston should possess enough stiffness and strength, good thermal conductivity, and resistance against high temperature, high pressure, and friction. Materials that are lightweight and have low inertial forces should, moreover, be used; therefore, aluminum alloy is the best among all choices. Even today, a very small number of pistons are still made from gray cast iron or heat-resistant steel.
Piston Structure And Functions Of Each Part.
The piston is a very important part of the engine, mainly composed of the piston crown, the piston head, and the piston skirt. Basically, the piston crown is a part of the combustion chamber, which is designed in various shapes to enhance combustion and to dissipate heat effectively. Gasoline engines use flat or concave piston crowns, while diesel ones have different indentations on the piston crowns to help in better combustion of fuel.
Above the piston pin is the piston head, which has grooves where piston rings are installed. These rings prevent high-temperature gases from entering the crankcase and oil from entering the combustion chamber. The number of rings varies depending on the engine type: usually, gasoline engines have fewer rings than diesel engines. A good example is that most gasoline engines have two compression rings and one oil ring, but for diesel engines, more rings could be used for higher pressure and efficiency.
The skirt of the piston guides the piston’s motion inside the cylinder and resists side pressure. Because the pistons are under a high pressure, they expand and deform, so its shape is slightly elliptical, particularly in areas where temperature distribution is not quite even. For that purpose, aluminum alloys are one of the materials which have excellent thermal conductivity, strength, and resistance to high temperatures.
Casting Process Of Aluminum Alloy Piston
Aluminum alloy pistons are one of the most critical parts of automotive engine components, undertaking the function of transferring power to the crankshaft through combustion gas pressure. Working in an extremely hostile environment of high temperature and pressure, the performance of the piston has a direct impact on the efficiency and durability of the entire engine. Consequently, in aluminum alloy pistons, the demands on dimensional control and material strength, or wear resistance, are very high in the casting process.
Modeling Method: The inner surface dimensional accuracy of a metal mold used to cast is 6 to 8 levels. Coating – Mixture of zinc oxide (10%) and sodium silicate (7%) with water.
Melting Equipment: The fuel oil crucible furnace is used for melting the cast iron, whereas the capacity of the furnace is 450 kg per batch of aluminum alloy. At a pouring temperature between 720°C to 750°C, skim the furnace to remove the slag and then pour the aluminum into the ladle.
Melting Process: Remelt ZL101 aluminum alloy by pre-formed aluminum ingot. The proportion of the raw materials is 75% – 85% aluminum alloy ingot and 15% – 25% recycled material. Chemical composition of the aluminum alloy ingot: Si=6.0% – 8.0% Mg=0.2% – 0.4%, trace elements <1%, remainder – Al. Refine the aluminum melt with 0.16% by weight of zinc chloride (dissolve the slag and degas), then treat with a general-purpose modifier at 0.6% by weight of the aluminum melt to improve grain structure.
Classification Of Piston
Due to the very bad conditions of high temperature, high pressure, and load internal combustion engine pistons work in, requirements for pistons are relatively high. Thus, internal combustion engine pistons can be mainly classified as follows.
By fuel type, they may be classified into gasoline engine pistons, diesel engine pistons, and natural gas pistons.
Classified according to material used in the process of making pistons: cast iron piston, steel piston, aluminum alloy piston, and compound piston.
In line with the manufacturing process for piston blanks, they may be divided into three types: gravity cast pistons, extruded cast pistons, and forged pistons. Based on their working conditions, two major categories of pistons are identified: naturally aspirated pistons and turbocharged pistons.
According to the application of the pistons, they can be divided into automobile pistons, truck pistons, motorcycle pistons, marine pistons, tank pistons, tractor pistons, lawnmower pistons, and so on.
Piston Surface Treatment.
According to different requirements, we can also perform different surface treatments on the piston. We can hard anodize the top of the piston to reduce heat absorption and thermal resistance. In addition, to prevent cylinder scuffing due to poor lubrication, and in order to minimize wear on the skirt area, we tin or zinc plate the piston skirt or apply a graphite coating.
Conclusion
Concluding, the performance of an engine highly depends upon precise techniques for pistons, in addition to a careful choice of material. Each step-from casting and forging to surface treatments-all has its own pivotal role to play in withstanding very high temperatures, pressures, and mechanical stresses inside an engine. Advanced machining technologies-such as CNC precision turning, honing, and grinding-are used to achieve the geometrical tolerances and surface quality required for a fully functional piston. Continuously improving piston materials and machining processes-one of several active areas of innovation in both the automotive and industrial sectors-provide incremental gains in engine efficiency and durability.
The Unique Advantages Of Ultirapid
As a professional with 15 years of CNC machining service experience, I understand the complexity and precision required in piston machining. Pistons endure extremely high temperatures, pressures, and loads in engines, making dimensional accuracy, surface finish, and wear resistance critical. For instance, in a recent project at our company, we utilized advanced CNC turning and grinding techniques to ensure precise dimensions and surface roughness for a batch of high-performance engine pistons. We also employed high-quality aluminum alloy material treatments to enhance the pistons’ heat resistance. These precise machining and optimization processes helped Ultirapid’s client improve engine stability and efficiency, showcasing our expertise and technical capability in piston machining.
Our state-of-the-art equipment and rigorous quality control processes ensure that your project is flawless from prototyping to mass production. Curious about how we can help your engine performance soar? Contact us now!
