What is the difference between 3D printing, casting and machining?

3D printing, casting and machining are three different manufacturing technologies, which have some obvious differences in working principles, applicable scenarios, advantages and disadvantages:

3D printing (Additive Manufacturing):

Working principle: Create three-dimensional objects by stacking materials layer by layer, and directly manufacture physical products from digital models.
Advantages: Ability to manufacture parts with complex geometric shapes, reduce material waste, and quickly manufacture prototypes or small batches of products.
Disadvantages: Slow speed, high surface roughness, limited material selection, and strength and heat resistance may not be as good as traditional manufacturing methods.

Casting:

Working principle: By forming a delicate model on the surface of the prototype model, and then covering the surface of the model with a layer of silicone or other materials, the required parts are finally obtained by casting.
Advantages: High-precision and smooth-surface parts can be manufactured, suitable for products that need to be mass-produced.
Disadvantages: It takes a long time to make molds, suitable for small and medium-sized batch production.

Machining (CNC Machining):