Laser cutting of the car roofs

Preface

In the field of automotive manufacturing, the cutting process of car roofs has a profound impact on the overall quality of the vehicle and production efficiency.

This article focuses on the recently delivered project of laser cutting car roofs with carbon dioxide, covering the entire process from customer requirements, plan formulation, plan verification, equipment installation, to equipment delivery. It comprehensively analyzes the project implementation path to help industry colleagues accurately grasp the key points of the process.

Customer Requirements: Pain Points of the car roof Cutting

The core demands of customers for ceiling cutting are concentrated in three dimensions: precision, efficiency, and compatibility.

• Precision requirements: Details such as ventilation openings and installation holes on the car roof must be controlled within a tolerance of ±0.1mm to ensure compatibility with the overall interior of the vehicle.
• Complex texture cutting requires smooth edges without burrs to avoid abnormal noises due to friction during later assembly.
• Efficiency requirements: It is necessary to match the high-speed rhythm of the automotive production line. A single device should be capable of cutting 15 to 20 pieces of ceilings per hour to support large-scale mass production demands.
• Compatibility requirements: Compatible with various ceiling materials such as leather, fabric, and plastic composites, and capable of quickly switching cutting programs for vehicle models (such as sedans and SUVs), responding to the trend of customized production.
• In addition, the client emphasized the stability of the equipment (7×24-hour continuous operation without failure) and cost control (reducing maintenance costs and commissioning costs), providing a clear direction for the formulation of the solution.

Plan Formulation: Prototype of Professional Cutting System

Based on the requirements, it is necessary to integrate six core components to build a “laser + motion control + process assistance” system:

• Selection of core components

80-watt carbon dioxide radio frequency laser.

Due to the high absorption rate of non-metals to carbon dioxide lasers, CO2 radio frequency lasers are selected as the laser source. Its output power is stable (fluctuation < 1%), and the pulse frequency (1-50kHz) and pulse width are adjustable. At the same time, in view of the material characteristics of the car roof (such as leather being prone to carbonization and fabric being afraid of burning), by controlling the laser energy density, a “precise cutting” effect is achieved – no charring at the edge and the heat-affected zone being less than 0.2mm.

Estun’s 50-kilogram load robot.

On the one hand, considering the curvature of the car roof surface, and on the other hand, taking into account the load of the robot and its processing accuracy, an Estun robot with a repeat positioning accuracy of ±0.05mm was selected. It has a maximum load of 50kg and is equipped with a laser and an optical path system to perform cutting. Through the external PLC main control system, the program number of the robot is called to make the laser output synchronously, ensuring the continuity of cutting.

Light guide arm & carbon dioxide laser head.

Considering that carbon dioxide lasers cannot perform flexible transmission like fiber lasers, a light guide arm is needed to achieve flexible three-dimensional processing. The laser head at the end integrates a focusing module and a coaxial air-blowing system (compressed air), which can reduce the focused spot diameter to 0.1mm, effectively improving the smoothness of the cutting surface.

Small graphic motion mechanism.

As the highest processing accuracy of the robot is ±0.15mm, the smaller the processed graphics are, the lower its efficiency will be. To ensure its processing accuracy, it is necessary to pair it with a small graphic motion mechanism to achieve precise cutting and make up for the shortcomings of the robot.

1500-watt water-cooled machine.

Provide constant temperature cooling for the laser (temperature control accuracy ±0.5℃) to ensure stable performance of the equipment during continuous operation. Through intelligent flow regulation, power attenuation caused by overheating is avoided, and the service life of the equipment is prolonged.

Automobile roof fixture.

It adopts a quick clamping design (pneumatic gripper + magnetic positioning), completing the ceiling fixation within 30 seconds, with a repeat positioning accuracy of ±0.1mm.

System Collaboration Plan

Integrate each component through the PLC control system:

The robot’s movement trajectory is in real-time linkage with the laser output (for example, when cutting curves, the robot slows down → the laser reduces power to ensure the cutting quality at corners).

The small graphic cutting mechanism is connected to the robot path (the robot is positioned in the processing area → triggers the high-precision operation of the small mechanism → returns to the main trajectory).

The intelligent response of process auxiliary modules, such as water cooling machines and pneumatic systems (laser start/stop synchronous switch for water cooling and air blowing), enables integrated control.

Meanwhile, a process database is developed, and cutting parameters (power, speed, gas pressure) for different materials and vehicle models are preset. Operators only need to select “vehicle model + material”, and the system will automatically call up the parameters, reducing the threshold for manual debugging.

Solution Verification: Multi-dimensional testing ensures delivery

Build a simulated production line test platform and ensure the feasibility of the solution through two-step verification of “functional verification → stability verification”.

• Function Verification (Single-piece testing)

Precision testing: Cut standard samples (including complex curves and small graphics), and inspect them with a three-coordinate measuring instrument.

The path cutting error of the robot is less than ±0.1mm, meeting the assembly requirements of the entire vehicle.

The error of the small graphic cutting mechanism in the 30×30mm area is less than ±0.05mm.

Material compatibility test: Five types of ceiling materials, such as leather and fabric, were switched. After adjusting the laser parameters, the roughness of the cutting surface Ra was ≤1.6μm, and the edge quality compliance rate was 100%.

• Stability Verification (72-hour continuous test)

The simulated production line has been running continuously for 3 days, and the key monitoring indicators are:

The power fluctuation of the laser is less than 1.5%, and the deviation of the robot’s repeat positioning accuracy is less than ±0.05mm.

The temperature control of the water-cooled machine is stable, and the equipment has not shut down due to overheating.

A total of 200 sample pieces were cut, with a yield rate of 99.5% (only 1 piece was scrapped due to minor deformation of the fixture).

Equipment Installation: Professional commissioning ensures the integration of the production line

• On-site survey and planning

Conduct advanced surveys of the customer’s production line environment (space dimensions, power load, gas source pressure), and plan the equipment layout.

The distance between the robot and the production line conveyor belt should be no less than 1.5m, and a maintenance passage should be reserved.

Water-cooled machines should be placed independently, away from heat sources, to ensure heat dissipation efficiency.

The routing of the light guide arm should avoid narrow areas to prevent path interference.

• Integration and Debugging

Hardware integration: Install the robot, laser, fixture, etc. As planned, calibrate the levelness of the robot base (error < 0.1mm/m), and ensure the accuracy of movement.

Connect power cables and signal buses, and carry out insulation and anti-interference treatment.

Software integration debugging: Load the process database and test the synergy of each device.

Verify the motion synchronization between the robot and the laser head (such as no trajectory offset during high-speed cutting).

Test the visual positioning trigger logic of the small graphic cutting mechanism (recognition accuracy < ±0.05mm).

Analog production line signal interaction (such as robot arrival signal → equipment automatically starts cutting).

• Production line adaptation and optimization

Connect with the customer’s existing production line, adjust the equipment trigger logic and data interaction protocol to ensure:

The cutting completion signal is automatically transmitted back to the MES system to synchronize the production data.

Defective product marking (such as cutting deviation) triggers the production line rejection mechanism without the need for manual intervention.

• Mass production Verification (Small-scale trial production)

After the equipment was installed and debugged at the customer’s site, 1,000 pieces of real ceiling cutting were completed.

Production cycle: A single machine can complete 18 pieces of cutting per hour (including clamping time), meeting the production line requirements.

Model change efficiency: It only takes 5 minutes to switch the vehicle model program (by calling the process database + robot path optimization).

Cost comparison: Compared with traditional die cutting, the cost of tool wear is reduced by 80%, and the manual adjustment time is decreased by 60%.

Equipment Delivery: Training + after-sales service to form a professional service loop

• Delivery and acceptance

When the customer conducts on-site acceptance, complete the “document delivery + function re-inspection” :

Deliver the “Operation Manual”, “Maintenance Manual”, “Process Parameter Library”, and “Equipment Calibration Report”.

Randomly re-inspect 10 pieces of ceiling cutting. After ensuring that the accuracy and yield rate meet the standards, sign the acceptance document.

• Operation and Maintenance training

Conduct stratified training for the client team.

Operator training: Practical equipment clamping, program invocation, and simple troubleshooting (such as handling alarms for insufficient fixture air pressure), ensuring independent operation.

Operation and maintenance training: Explain laser cleaning, replacement of light guide arm lenses, lubrication and maintenance of robots, etc., and formulate preventive maintenance plans (such as calibrating fixtures monthly and testing laser power quarterly).

• After-sales guarantee

Establish a 7×24-hour response mechanism.

Remote support: Assist in troubleshooting remotely via phone or WhatsApp.

On-site service: Arrive at the customer’s site within 48 hours (covering major automotive manufacturing areas) to solve complex faults.

Regular follow-up visits: Conduct on-site inspections every quarter, update the process database (to adapt to new materials and vehicle models), and ensure the long-term stable operation of the equipment.

Processing video display

From customer demand to delivery and implementation, the project of cutting car roofs with a carbon dioxide laser has built an efficient, precise, and stable processing system through the integration of core components, scheme verification, installation, and commissioning.

It not only provides professional practical references for industry peers but also helps promote the popularization and upgrading of automotive manufacturing technology.