Compared to casting and forging, skew rolling has significantly higher productivity in steel ball production. Some reasons are:
1. Faster forming speed. In skew rolling, the steel bar is pressed by two high-speed rotating rollers to form balls. The whole process only takes a few seconds. This enables a forming speed of 30-50 balls per minute. Casting and forging methods are much slower, with a speed of only a few balls per minute.
2. Simpler procedures. Skew rolling only involves feeding, heating, rolling, quenching and finishing. It requires fewer equipment and shorter processing time. Casting needs to make moulds and cores, melting, pouring, shaking out, heat treatment, etc. Forging also needs pre-forming, reheating, multi-stroke forging and trimming. These additional procedures reduce productivity.
3. Less human intervention. Skew rolling is a continuous automated process that requires little human operation. Casting and forging are more manually operated, needing workers to make moulds, pour melted steel, forge the balls with hammers, trim excess materials, etc. This significantly lowers their productivity.
4. Better material utilization. In skew rolling, there is almost no waste of steel since the balls are formed directly from bars. But in casting, extra steel is needed to make runners and risers. And in forging, large amounts of excess steel remain as flashes and need to be trimmed. This results in additional wastage of steel and reduced productivity.
5. Lower cost. Thanks to its higher efficiency, fewer procedures and better material utilization, skew rolling is more cost-effective than casting and forging. It helps cut both labor cost and material cost per ball. This also contributes to its higher productivity.
In summary, skew rolling has the advantages of faster forming speed, simpler procedures, less human intervention, better material usage and lower cost. All these factors enable skew rolling to achieve a much higher productivity, usually several times that of casting and forging methods. That is why skew rolling is the most economical technique for mass production of steel balls.