product-cabinet-NBValve seats are one of the most important components in a cylinder head. They are often referred to as the heart of the engine since the valve must create the perfect seal on the valve seat face, to ensure maximum efficiency of the engine and the deliverance of rated power and fuel efficiency. They also act as a heat sink for the thin valve seating face, to prevent the valve from burning and ultimately, valve destruction.

The raw material properties in the valve seat insert play a vital part in the function and longevity of a valve seat. The valve seat is also subjected to a sophisticated heat treatment cycle to ensure hardness and the correct microstructure. This material must be able to withstand temperature ranges from cold to hot operating temperatures without losing their interference fit (the co-efficient of expansion) to ensure that they do not become dislocated during operation, which would have catastrophic results in the engine itself.

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The dimensional machining to OE specifications is also critical, as this ensures the fit to the cylinder head for maximum heat dissipation as well as squareness to the valve itself. Again, we are able to produce the various raw materials required to comply with OE specifications for both heavy diesel and petrol applications.

Microfinish also produces a range of valve seat inserts suitable for alternative fuels, such as natural gas (LPG) and compressed natural gas (CNG), methane etc. These valve seats are made from a very specific material that will endure the high temperatures and extremely aggressive combustion environment that this alternative fuel creates.

Valve Seats Typical Chemistry (%) Hi Chrome Iron Mechanical Properties Dimensions
C Si Mn Cr Mo Hardness Outside Diameter Inside Diameter Width
Min 1.80 0.80 10.0 2.0 40 HRc 18mm 10mm 5mm
Max 2.30 1.30 1.0 18.0 2.5 50 HRc 200mm 120mm 20mm
Tolerance ±0.01mm ±0.1mm ±0.05mm