To make an excellent automobile control arm, the following conditions must be met:

1. Strength and durability: The automobile control arm needs to have sufficient strength and durability to withstand various forces and vibrations during the running of the vehicle, so as to ensure that the control arm will not be deformed or broken during long-term use.

2. Lightweight design: In order to reduce the overall weight of the vehicle, the control arm needs to adopt lightweight design and choose high-quality materials and structural design, which can not only ensure the strength and durability, but also reduce the overall weight and improve the fuel economy and handling performance of the vehicle.

3. Accurate size and geometry: The size and geometry of the control arm need to be designed and machined accurately, so as to ensure the precise cooperation with other parts and components, which can stably connect the suspension system and steering system of the vehicle and ensure the stability and maneuverability of the vehicle.

4. Excellent suspension and steering performance: As an important part of the suspension system, the control arm needs to have good suspension and steering performance, which can maintain the stability and comfort of the vehicle and provide good handling performance to ensure the safety and stability of the vehicle.

5. Corrosion and rust resistance: Because the automobile control arm is located in the chassis of the vehicle, it is easily eroded by water, mud and chemicals splashed on the road surface, so the control arm needs to have good corrosion and rust resistance to prolong its service life.

6. Cost-effectiveness: Cost-effectiveness should be considered in manufacturing the automobile control arm, and appropriate materials and manufacturing processes should be selected to ensure that the production cost is reduced and the production efficiency and competitiveness are improved on the premise of meeting the performance requirements.

To sum up, in order to make an excellent automobile control arm, it is necessary to comprehensively consider the requirements of strength and durability, lightweight design, accurate size and geometry, suspension and steering performance, corrosion resistance and rust prevention performance, and cost-effectiveness, so as to ensure that the control arm can be stably and reliably connected with the suspension system and steering system of the vehicle and improve the performance and safety of the vehicle.