In this post, we are going to discuss the design considerations of machined parts. The designer should have basic knowledge of various manufacturing processes to decide the shape of machine parts. The design engineer should know the basic principles for shaping machined parts.
Machined components are widely used in all industrial products. They are usually made from ferrous and nonferrous metals. They are as small as a miniature gear in a wristwatch and as large as huge turbine housing.
Machined components are used under the following circumstances:
- Components requiring flatness, roundness, circularity, or parallelism for their proper functioning.
- Components requiring precision and high dimensional accuracy.
- Components of interchangeable assembly.
- Components, which are in relative motion with each other or with some fixed part.
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Design considerations of machined parts are important in order to reduce the time as well as cost required for producing it. The more complicated the design is, the more time is required for its manufacturing and hence, resulting in an increase in its cost.
Subsequentially, this also leads to the wastage of raw material. Hence, in order to avoid all these, a good designer must be aware of the design considerations of machined parts.
Design Considerations of Machined Parts
- Avoid machining
- Specify liberal tolerances
- Use stock dimensions
- Avoid sharp corners
- Avoid shoulders and undercuts
- Design rigid parts
- Avoid hard materials
The general principles for the design of machined parts are as follows:
Machining operations increase the cost of the component. The components made by casting or forming methods are usually cheaper. Therefore, as far as possible the designer should avoid machined surfaces.
Specify liberal tolerances
The secondary machining operations like grinding or reaming are costly. Therefore, depending upon the functional requirement of the component, the designer should specify the most liberal dimensional and geometrical dimensions.
Use stock dimensions
The raw material like bars are available in standard sizes. Using stock dimensions eliminates machining operations. For example, a hexagonal bar can be used for a bolt and only a threaded portion can be machined. This will eliminate the machining of hexagonal surfaces.
Avoid sharp corners
The sharp corners result in stress concentration. Therefore, the designer should avoid shapes that require sharp corners.
Avoid shoulders and undercuts
Shoulders and undercuts usually involve separate operations and separate tools, which increases the cost of machining.
Design Rigid Parts
Any machining operations such as turning or shaping induces cutting forces on the components. The component should be rigid enough to withstand these forces. In this respect, components with thin walls or webs should be avoided.
Avoid hard materials
Hard materials are difficult to machine. They should be avoided unless such properties are essential for the functional requirement of the product.