What Is The Role Of CNC Machining in Automotive Chassis Components?

1. Technical feature: Double assurance of accuracy and speed
By controlling the movement of machine tools through computer programming, CNC machining may achieve machining accuracy at the micrometre level (± 0.001mm), which is far better than previous mechanical machining methods. The following three things show its main benefits:
Ability to make complicated structures
Chassis parts generally include three-dimensional surfaces, holes that aren't perfectly round, and walls that are very thin (such suspension swing arms and steering knuckles). It is hard for traditional casting or stamping methods to meet their dimensional accuracy needs. With the use of an A/C axis rotating linkage, the CNC five-axis machining centre can do multi-faceted machining in one clamping. For instance, when machining a steering knuckle, it can do the precision machining of the main pin hole, wheel hub installation surface, and brake calliper positioning surface all at the same time, making sure that the coaxiality error of each part is ≤ 0.02mm. This greatly improves the accuracy of the assembly.
Adaptability of materials
Parts of the chassis need to be both light and strong. Aluminium alloy (like 6061-T6), magnesium alloy (like AZ91D), and high-strength steel (like 42CrMo) are all common materials. By adjusting cutting parameters like spindle speed and feed rate, CNC machining can cut diverse materials very accurately. For instance, high-speed milling (speed > 10000rpm) can lower thermal deformation and make sure that the surface roughness Ra ≤ 0.8 μ m while working with aluminium alloy control arms. When cutting high-strength steel steering rods, low-temperature cutting technology (with the cutting fluid temperature kept between -5 and 5 degrees Celsius) can keep the job from hardening and make the tool last longer.
Flexibility in production
By changing the CNC program, CNC machining can swiftly transition between different product types without having to change moulds. This makes it great for making small batches of custom products with a lot of different options. For instance, the suspension geometry characteristics of a new energy vehicle chassis need to be changed since the battery arrangement is different. CNC machining can make new parts in 48 hours, whereas traditional casting procedures need to be remoulded, which takes several months.
2. When to use: Covering the most important parts of the chassis
CNC machining is used to make parts for the chassis in the four subsystems of suspension, steering, brakes, and gearbox. Here are some specific cases:
system of suspension
Control arm: The control arm is an important part that connects the wheels to the body. It needs to be able to handle longitudinal force, lateral force, and braking torque. CNC machining can make sure that the installation hole is accurate to within ±0.05mm, which will stop tires from wearing unevenly due to mistakes made during assembly. For instance, CNC milling is used to make the front lower control arm of the Tesla Model 3. This makes it 15% lighter and 30% longer-lasting than traditional stamping methods.
This part needs a threaded connection between the stabilising rod and the suspension arm. CNC thread milling can get the tooth profile precision to within ± 0.01mm, which makes sure that the connection strength passes 100000 fatigue tests.
the steering system
Steering knuckle: The steering knuckle is the most important part of the steering system. It needs to connect the main pin hole, the wheel hub bearing installation surface, and the brake calliper bracket. CNC five-axis machining may finish the machining of various parts at the same time. For example, the steering knuckle of the BMW X5 uses integral forging and CNC precision machining technology, which makes it 20% lighter and 25% stiffer than split welding construction.
Steering gear with gears and racks: To make sure that the steering feels smooth and there is no strange noise, its gear rack needs to be carved into high-precision tooth profiles (cumulative error of tooth pitch ≤ 0.01mm) using a CNC hobbing machine.
system for stopping
Brake calliper bracket: This part has to be able to handle a lot of heat (≥ 300 °C) and a lot of pressure (≥ 10MPa) while braking. CNC machining can make sure that the bolt hole position is accurate to within ± 0.03mm, which stops the bracket from splitting from the stress of assembly. For instance, the brake calliper bracket on the Mercedes Benz S-Class passed 2 million fatigue tests without cracking after being CNC machined.
Disc for brakes: Even though brake discs are normally cast, their mounting surfaces and ventilation slots need to be CNC precisely cut to make sure they are flat to within 0.02mm. This helps eliminate brake vibration.
System for sending signals
Transmission shaft: To make sure smooth gearbox and noise levels below 65dB, the star-shaped sleeve and bell-shaped housing of the constant velocity universal joint (CVJ) need to be machined with high-precision ball pathways (ball path roundness 0.005mm) using a CNC internal grinding machine. For instance, CNC machining may make the gearbox shaft of Toyota hybrid cars 40% better at NVH.
3. Value to the Industry: Encouraging the Improvement of Chassis Manufacturing Technology
CNC machining is valuable to the industry for making chassis parts in three main ways:
Make products more competitive
High-precision machining helps speed up assembly and debugging. For instance, CNC machining the Audi A8's air suspension control arm cuts the time it takes to put the car together by 30% and lowers the cost of making each car by $120.
Encourage designs that are light
CNC machining can help with topology optimisation design, like hollow structure and reinforcement rib layout. For instance, the rear subframe of the Volvo XC90 is made of CNC machined aluminium alloy hollow structure, which makes it 45% lighter and 10% stiffer than a traditional steel subframe.
CNC machine tools can use sensors and industrial Internet technologies to monitor and collect data on the processing process in real time. This helps make intelligent manufacturing possible. By putting vibration sensors in CNC machining centres, General Motors has made tool wear prediction 95% more accurate and overall equipment efficiency (OEE) 18% better.