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Uncontrolled heat treatment gives Hyundai and Kia a headache!

Two Far Eastern automobile giants started a recall process covering a total of 330,000 vehicles due to the same heat treatment problem in the last month.

heat treatment recall

Which models are Kia and Hyundai recalling?

Last month, Kia recalled more than 147,000 2020 and 2021 production Soul and Seltos SUVs due to a piston ring heat treatment issue. The automaker said there were four reports of potentially related fires.

This month (05 May 2021), Hyundai announced that it would recall 187,000 2019 and 2020 model Elantra and 2019-2021 production Kona and Veloster models with 2-liter engines.

Hyundai and Kia will inform vehicle owners to take their vehicles to local services for inspection in late June 2021. All vehicles will be installed with "Piston Ring Noise Detection System" (PNSS) control software to monitor for signs of the relevant problem. This software will warn the user about possible damage in the future. If damage is detected during the inspection, the engine will be replaced free of charge.


What is a piston ring?

Piston rings are ring-shaped parts made of gray cast iron or steel alloys that work inside ring channels opened on the piston or pistons moving in the cylinder block in internal combustion, 2-stroke and 4-stroke engines . Rings ensure compression by preventing the air taken into the cylinder from leaking into the crankcase during compression stroke. It prevents the oil and air in the crankcase from leaking into the cylinder cavity. Generally, there are 2 types and 3 rings in engines: compression ring and oil ring. If the rings wear or are destroyed after a certain period of time after the car has been used, the engine oil leaking into the cylinder block mixes with gasoline and burns, causing engine oil loss and environmental pollution. Rings that cannot fully seal during the compression stroke cause the engine's performance to decrease.

Let's try to take a look at the problem after a brief wiki information. When piston rings are not properly heat treated, this can lead to oil leaks, piston seizing, and possible fires.

Although the two manufacturers do not provide full details, Hyundai says that the rings can be very hard and wear down the engine cylinder and break apart.

Since piston rings are exposed to serious friction and wear, their heat treatment is very important. While PVD coatings come to the fore in high-end engines, nitriding is used as classical core hardening heat processes austempering , martempering or surface hardening in mass production vehicle engines.

I will try to learn the type of heat treatment that causes this problem in the coming days. I will even examine the possibility of supplying these piston rings from our country.

Design or heat treatment error?

The error may be a lack of heat treatment design (completely wrong hardness and specification selection) or it may be a heat treatment that does not comply with properly selected heat treatment details. In both cases, it would not be unfair to say that the CQI-9 process was not well managed.

From the story...

When this problem experienced by Hyundai and Kia is examined in depth, the fact that the heat processor and the subsequent chain are not well managed and under control will come to light.

This is an important, experienced event that shows how careful a purchasing engineer, a manager or a company owner should be when choosing a heat treater.

How is your heat treater? Does it have process management like CQI-9? Does the bakery do SAT and TUS? Are laboratory equipment sufficient and staff competent? Finding answers to many questions like this is very important for the future of the product.

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