Final answer:
Forging is considered superior to casting for professional shears, as it results in stronger and more durable products that are easier to adjust and repair. Casting can lead to a less durable product with increased brittleness. Forged high carbon steel shears are particularly known for their optimal performance.
Step-by-step explanation:
When comparing the durability, ease of adjustment or repair, and overall quality of professional shears, forging is typically considered the better process over casting. Forging involves the manipulation of metal through hammering, pressing, or rolling. This technique aligns the grain of the metal, which generally enhances the strength and durability of the final product. Forged shears can be adjusted and sharpened more easily than those made through casting, since the material is less brittle and holds an edge better.
Casting, on the other hand, involves pouring molten metal into molds where it solidifies. The process is more prone to creating air pockets and doesn't align the metal grain, which can result in a product that is weaker and less durable. Cast shears might be more susceptible to breaking and can be more difficult to repair or adjust because of their inherent material properties.
Additionally, different types of steel have different properties. Mild steel, with up to about 0.25% of carbon, is not as hard but is widely used for manufacturing. High carbon steel, containing up to about 1.5% of carbon, is harder but also more brittle. This type of steel is often used for cutting tools like shears, and when forged, can provide optimal performance.