How to improve the uniformity of the heat treatment furnace by optimizing the design of the Heat Treatment Tray?

In the field of industrial heat treatment, the temperature uniformity in the furnace is one of the core indicators that determine product quality. According to statistics, the economic losses caused by the unqualified performance of metal parts due to the temperature deviation of the heat treatment furnace exceed 2 billion US dollars each year. As a key carrier for carrying workpieces, the design optimization of the Heat Treatment Tray has become an important breakthrough in solving this problem.
1. Analysis of the pain points of existing tray design
Traditional trays are mostly made of heat-resistant steel or cast alloys, but the following problems are common:
Low heat conduction efficiency: Insufficient thermal conductivity of the material leads to uneven temperature distribution of the tray itself. For example, the thermal conductivity of ordinary heat-resistant steel is only 25 W/(m·K), which makes it difficult to achieve rapid temperature uniformity;
Rough structural design: The proportion of the solid bottom plate is too high (usually more than 70%), which seriously hinders the airflow circulation in the furnace;
Uncontrollable thermal deformation: The tray is prone to warping at high temperatures. The measured data shows that the deformation of the traditional tray can reach 3-5mm under 800℃ working conditions, which directly changes the heating position of the workpiece.
2. Four strategies for optimizing design
Material revolution: Gradient application of composite materials
The composite structure of silicon carbide ceramics and nickel-based alloys is adopted. The surface of the tray uses a silicon carbide ceramic coating with a thermal conductivity of up to 120 W/(m·K), and the bottom layer uses a nickel-based alloy with high specific heat capacity. Experiments have shown that this design can reduce the temperature difference of the tray itself from ±25℃ to ±8℃.
Structural reconstruction: bionic honeycomb topology design
Based on the topology optimization algorithm, a honeycomb structure is generated to increase the tray opening rate to 45%-55%, and the structural strength is verified by finite element analysis. The measured data of an aviation parts company showed that the standard deviation of the airflow velocity distribution in the furnace was reduced by 32% after the improvement.
Airflow reconstruction: guide fin integration technology
Adding a 15° inclination guide fin to the side wall of the tray, the fin arrangement angle is optimized through CFD simulation, and the dead zone area in the furnace is successfully compressed from 12% to less than 4%. The case of the American Heat Treatment Association (AHT) shows that this design narrows the fluctuation range of the carburized layer depth to ±0.05mm.
Intelligent embedding: thermal deformation compensation mechanism
Shape memory alloy (SMA) is introduced as a supporting structure to automatically compensate for the thermal expansion of 0.8-1.2mm in the range of 600-900℃. After a German automotive parts supplier applied this technology, the hardness deviation of three consecutive batches of gear parts decreased from HRC 3.5 to HRC 1.2.
III. Quantitative verification of economic benefits
Comparative data before and after the transformation of a bearing manufacturing company showed:
The service life of the tray increased from 200 times to 500 cycles
Unit energy consumption decreased by 18% (thanks to the shortened temperature averaging time)
The qualified rate of product quenching hardness jumped from 82% to 97%
The return on investment period was shortened to 8 months, proving that the optimized design has significant economic value.