How to effectively control the effect of thermal deformation on accuracy in precision parts machining?

In precision parts machining, thermal deformation is one of the critical factors affecting accuracy. Effectively controlling thermal deformation is essential to ensure machining accuracy. The following aspects can be considered:

I. Optimize Machining Processes

1. Adjust Cutting Parameters

Cutting Speed**: Reasonably control the cutting speed to avoid excessive heat generated by high - speed cutting. Because during high - speed cutting, most of the cutting work is converted into heat, causing the temperature of the part and the tool to rise sharply. For example, when machining precision alloy steel parts, appropriately reducing the cutting speed can reduce the generation of cutting heat and thus the possibility of thermal deformation.

Feed Rate and Depth of Cut**: Reducing the feed rate and depth of cut helps control the cutting force and cutting heat. A smaller cutting force can reduce the heat generated by friction and also reduce the mechanical stress on the part, avoiding thermal deformation caused by stress release.

2. Plan Machining Sequence

Arrange the machining sequence reasonably, separate rough machining and finish machining, and give the part enough time to cool after rough machining. For example, for the machining of a precision mold with a complex shape, first perform rough machining to remove most of the allowance, and then wait for the part to cool to room temperature before performing finish machining. This can effectively reduce the impact of thermal deformation on the final accuracy.

II. Tool Selection and Cooling

1. Tool Material and Geometry

Select tool materials with high thermal conductivity and low coefficient of thermal expansion, such as ceramic tools or cemented carbide tools. These tools can better conduct heat during the cutting process and reduce the heat accumulation in the contact area between the tool and the part. At the same time, optimize the geometry of the tool, such as using appropriate rake and clearance angles to reduce the frictional heat during cutting.

2. Tool Cooling Methods

Adopt an effective tool - cooling system, such as high - pressure cooling and minimum quantity lubrication (MQL) cooling. High - pressure cooling can accurately spray the coolant onto the cutting area to quickly take away the heat; MQL cooling sprays a small amount of a mixture of lubricant and coolant in the cutting area, which not only cools but also reduces friction. For example, when machining precision titanium alloy parts, MQL cooling can significantly reduce the temperature of the tool and the part and control thermal deformation.

III. Control the Thermal Stability of Machine Tools

1. Optimize Machine Tool Structures

Select machine tool materials with good thermal stability, such as granite with a low coefficient of thermal expansion as the basic components of the machine tool. At the same time, optimize the structural design of the machine tool to improve its rigidity and reduce the structural distortion caused by thermal deformation. For example, a symmetrical machine tool structure can make the thermal deformation as uniform as possible in all directions and reduce the impact on machining accuracy.

2. Machine Tool Thermal Error Compensation

Utilize thermal error compensation technology. Install temperature sensors on the machine tool to monitor the temperature changes of key parts of the machine tool in real - time. Then, based on the relationship between temperature changes and thermal deformation, establish a mathematical model and use the CNC system to compensate for thermal deformation. For example, in a high - precision CNC grinding machine, through thermal error compensation technology, the impact of thermal deformation on grinding accuracy can be minimized.

IV. Control the Temperature of the Machining Environment

1. Build a Constant - Temperature Workshop

Establish a constant - temperature machining workshop and control the workshop temperature within a small fluctuation range. For example, for ultra - high - precision precision parts machining, the workshop temperature can be controlled within ±1°C. This can reduce the thermal deformation of the part and the machine tool caused by environmental temperature changes.

2. Insulation Measures

Take insulation measures around the machine tool and in the part - machining area, such as using thermal shields. The thermal shield can reduce the external heat from entering the machine tool and the part and also prevent the heat inside the machine tool from dissipating to the surrounding environment, further stabilizing the temperature of the machining environment.