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What is the functions of chamfers in mechanical part

Mechanical design should achieve "everything under control", which includes two layers of meaning: first, all structural details should be carefully considered and fully expressed, and cannot rely on guessing design intentions during the manufacturing process, allowing manufacturing personnel to redesign or "freely express"; The second is that all designs are based on evidence and cannot rely on "brainstorming" to make arbitrary decisions. Many people do not think it is possible to achieve it. In fact, they have not mastered the methods of design and developed good habits. The chamfers/fillets that are easily overlooked in design also have design principles. Do you know where to turn corners, where to round corners, and how many large corners to turn?

1、 Definition

Chamfering and rounding refer to cutting the edges and corners of a workpiece into a certain inclined/circular surface. The core function of chamfering in mechanical components is to remove burrs to ensure safety and provide guidance for assembly, while also reducing stress concentration and optimizing machining performance.

2、 Purpose

1) Remove burrs generated by machining on parts to make the product less sharp and avoid cutting the user; 2) Easy to assemble parts; 3) When the material is hot, it is conducive to stress release, and chamfering is less likely to cause cracks, which can reduce deformation and solve the problem of stress concentration.

3、 Five design principles

1. Principle of inner circle and outer circle (machined parts)

1) Machining with rotating cutting tools for machined parts, processing rounded corners inside the workpiece and square corners outside the workpiece;

2) Try to make the outer and inner corners of a certain feature in the same workpiece as consistent as possible to reduce the number of tool changes. reduce costs

3) When designing chamfers, the machining process should be considered. For example, using a 45 degree chamfer for some irregular surfaces may be easier to machine than an R-angle, otherwise it will unnecessarily increase the cost of the machining center.

2. Principle of inner and outer circles (sheet metal parts)

1) Sheet metal parts are processed by laser, which is different from traditional cutting processing;

2) Uniform rounded corners inside and outside the workpiece;

3) The rounded corner range is R=2-5.

3. Adhere to the principle of neat and beautiful appearance

1) Chamfering ensures that the assembled parts are neat and aesthetically pleasing;

2) No obvious sharp edges to prevent bodily injury during handling, assembly, and use;

3) Unmarked chamfer defaults to C0.5.

As shown in the figure below, the hook indicates a neat assembly.

Note: Sometimes, whether a part needs to be chamfered or not depends not only on the part itself, but also on its assembly relationship with other parts.

4. Principle of reducing internal stress and increasing strength

1) There is internal stress concentration in material heat treatment, and increasing transition fillets can eliminate deformation and fracture caused by internal stress; 2) For cantilever components, adding rounded corners can increase strength. Prevent stress concentration at the tip from causing component failure. Proper chamfering can eliminate stress concentration points caused by sharp right angles and improve the fatigue life of parts under alternating loads.

5. Guiding principles

1) Place the product at the acupoint, and for ease of insertion, tilt the angle to increase guidance; Guidance for easy assembly: inclined guidance is formed at the fitting parts such as the shaft end and hole opening, so that the parts can be automatically aligned during installation, reducing assembly difficulty and avoiding collision and damage to edges and corners

2) For the convenience of assembly, the fitting of parts needs to be angled backwards.

Although chamfering is not the most important feature in parts, if designed in conjunction with manufacturing processes and usage scenarios, it will make our products more cost-effective. More professional.