Analysis of Advantages and Disadvantages of Hot Forging and Cold Forging

Analysis of Advantages and Disadvantages of Hot Forging and Cold Forging

As two core processes in the forging industry, hot forging and cold forging each form unique advantages based on their high-temperature and room-temperature forming characteristics, while also having their own limitations. The core logic for comparing the advantages and disadvantages of the two lies in "material adaptability" and "performance priority". Clarifying their differences is a key prerequisite for selecting processes on demand, which is of great significance for improving forging quality and production efficiency.

The significant advantages of hot forging are concentrated in material adaptability and forming capacity. By heating materials to a high temperature of 800-1200℃, it greatly improves material plasticity, enabling easy processing of hard and brittle materials such as high-carbon steel and alloy steel, and realizing one-time forming of complex structures like large crankshafts and gear blanks. Additionally, high temperature can eliminate internal defects such as material porosity and refine grain structure, increasing the impact toughness of forgings by more than 30% compared to castings. Moreover, hot forging has lower requirements on blank precision, which can reduce the cost of preliminary material preparation. However, hot forging also has obvious shortcomings: high-temperature heating increases energy consumption and working hours; size shrinkage is prone to occur after cooling, with precision only reaching IT12-IT14 grade; oxide scale is easily formed on the surface, requiring additional treatment and increasing subsequent processing costs.

The core advantages of cold forging are reflected in precision and surface quality. Room-temperature forming eliminates the need for heating, with energy consumption only 30% of that of hot forging. It avoids the problem of oxide scale, achieving a surface roughness of Ra1.6μm and dimensional tolerance controlled within ±0.02mm. After realizing near-net forming, it can reduce machining volume by more than 60%. Meanwhile, the work hardening effect can increase the surface hardness of forgings by 20%-40%, making it suitable for manufacturing high-precision fasteners. However, its limitations are also prominent: it can only process low-hardness and high-plasticity materials such as aluminum alloy and low-carbon steel, and cannot handle hard and brittle materials; high-pressure equipment is required for forming, which has high requirements on the surface finish of blanks, leading to high preliminary material preparation costs; work hardening is prone to cause material embrittlement, requiring intermediate annealing treatment and affecting production efficiency.

From the perspective of comprehensive cost and scenario adaptability, hot forging is more suitable for the production of heavy-load and complex structural parts. Although it has high energy consumption and subsequent processing costs, it can solve the forming problem of hard and brittle materials. Cold forging is suitable for manufacturing high-precision and lightweight parts, with high initial equipment investment but low subsequent processing costs. In actual production, the combined process of "hot forging for rough forming + cold forging for finishing" is often adopted, which not only exerts the forming advantage of hot forging but also improves precision with cold forging, achieving complementary advantages.

In summary, hot forging takes "strong forming and wide adaptability" as its core advantages, with "low precision and high energy consumption" as its main limitations; cold forging features "high precision and low loss" as its highlights, with "material limitations and high material preparation requirements" as its shortcomings. There is no absolute superiority between the two. Scientific selection based on material characteristics, precision requirements and cost budget is necessary, and together they form a forging process system covering diverse needs.