The exhaust manifold refers to a diverging manifold which is connected to the engine cylinder block, and the exhaust gas of each cylinder is collected and introduced into the exhaust manifold. To minimize the exhaust resistance and avoid mutual interference between the cylinders are the main requirements for it. Mutual interference will occur between the cylinders when the exhaust gas is excessively concentrated, that is, when a cylinder is exhausted, it will just hit the exhaust gas from other cylinders. In this way, the resistance of the exhaust gas is increased, thereby reducing the output power of the engine. The solution to this problem is to separate the exhaust of each cylinder as much as possible, one branch per one cylinder, or one branch per two cylinders, and make each branch as long as possible and molding so as to reduce the gas interaction between different manifolds. In order to reduce the exhaust resistance, some racing cars use exhaust manifolds that are produced by stainless steel.
The engine power performance, engine fuel economy, emissions standards, engine cost, matching vehicle front cabin layout and temperature field should be taken into account in producing exhaust manifolds. Presently, in terms of materials and processing techniques, the common used exhaust manifold has two types : cast iron manifolds and stainless steel manifolds .
When it comes to inchoate automobile engines, the power per unit weight was low, the combustion efficiency of the fuel was not high, and the exhaust gas temperature did not exceed 500 °C. With the increasing efficiency of the car engine, the exhaust gas temperature increases to 600-650 °C. In recent years, developed countries have continuously improved vehicle exhaust emission standards. The application of catalytic technology and turbocharger technology has significantly improved the operating temperature of the exhaust manifold to over 750 °C. As the engine performance is further improved, the operating temperature of the exhaust manifold is also increased. At the same time, with the advancement of engine technology, the structure of the exhaust manifold is also becoming complicated. Since the exhaust manifold is operated in the cyclic alternating temperature state, so its material is not only required to have good high temperature performance, but also perfect casting performance. Currently, more and more companies choose stainless steel as the manufacturing material for exhaust manifold, and due to its complex structure, it is produced in stainless steel investment casting process.
Stainless Steel Investment Casting of Exhaust Manifold
Stainless steel casting process used to produce exhaust manifolds is an investment casting process that can have many benefits. The stainless steel investment casting process can help to save costs while getting exhaust manifolds with OEM service. Here are a few of the benefits you can expect to receive when manufacturing cast stainless steel exhaust manifold.
Better Working Performance
Cast iron exhaust manifolds have thick wall thickness, so it is quite heavy, and can not improve the engine performance. While cast stainless steel exhaust manifolds are produced by stainless steel lost wax casting, which can make thinner wall thickness. Besides, the surface quality and dimensional accuracy is much better than that of cast iron exhaust manifolds. These advantages of cast stainless steel exhaust manifolds all help to boost engine performance. Although the prices of stainless steel exhaust manifolds by lost wax casting method are not cheap, it is cost effective in the long term and really worthy for companies to convert cast iron exhaust manifolds into cast stainless steel ones.
One of the biggest benefits that cast stainless steel exhaust manifold over cast stainless iron exhaust manifold is the fact that they are incredibly durable and robust. Cast tainless steel exhaust manifold can be used in any type of temperature and do not have any problems when used in extremely hot or extremely cold temperatures. When a company chooses to purchase high quality cast stainless steel exhaust manifold, they can count on them functioning and remaining in excellent condition for a long time. Considering how durable and long-lasting stainless steel exhaust manifolds are, they are a very good investment that are affordable in the long run.
Free From Corrosion
Cast stainless steel exhaust manifolds are not prone to rust or corrosion. This makes the use of cast stainless steel exhaust manifold the top choice for automotive industry where the conditions may cause metal to rust or corrode quickly. While cast iron exhaust manifolds are also not prone to rust or corrosion, they do not have the strength, durability, or resistance to high pressure that cast stainless steel exhaust manifold have.
At CFS, we have an infinite choice of stainless steel grades, which gives you the flexibility to choose either 304 or 316 stainless steel. This even includes very complex shapes or hollow section parts, helping configure it in a sturdy and repeatable way. This flexibility also comes with the ability to make changes more quickly with a shorter time from the design time to seeing a finished product. Moreover, stainless steel investment casting is a repetitive process, which can produce exhaust manifolds efficiently. This is because a mold is created, making the process more repeatable and efficient when creating multiple casts.
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