1. Design: creating a blueprint or a 3D model of the radiator, which includes its dimensions, shape, and material specifications.

2. Material selection: select the appropriate materials for the radiator. Radiators are typically made of aluminum, copper, or brass, as these materials have good thermal conductivity and are resistant to corrosion.

3. Cutting and shaping: cut and shape the material according to the design specifications. 

4. Assembly: The individual components of the radiator, such as the fins, tubes, and tanks, are then assembled together. 

5. Testing: tests to ensure that it meets the required performance standards. These tests include pressure testing, leak testing, and thermal performance testing.

6. Finishing: finish the radiator. This involves cleaning, polishing, and painting the radiator to give it a smooth and attractive finish.