In the manufacturing process of laser-cut ultra-thin metal gaskets, controlling flatness error is crucial to ensuring product sealing performance and assembly accuracy. Due to the thinness and low rigidity of ultra-thin metal gaskets, laser cutting is prone to flatness deviations caused by thermal stress, mechanical vibration, or material deformation. Therefore, a comprehensive approach is needed, addressing issues from multiple dimensions including equipment precision, process parameters, material condition, and environmental control.
The mechanical and electronic precision of the laser cutting equipment directly impacts flatness control. Regarding mechanical precision, the parallelism, straightness, and levelness of the guide rails need regular calibration to prevent guide rail deformation from causing deviations in the cutting head's trajectory. The transmission precision of gears or steel belts also requires attention, as transmission errors can be transmitted to the cutting head, causing periodic flatness fluctuations. Regarding electronic precision, the pulse equivalent of the CNC system needs precise calibration. Improper pulse equivalent settings may result in incomplete or non-circular cuts when cutting arcs, and the contour accuracy of large parts will also be affected. Furthermore, the stability of the servo drive system is critical. Loss of servo response signals or fluctuations in the drive circuit can cause irregular shaking of the cutting head, leading to localized flatness errors.
Optimizing process parameters is crucial for controlling flatness errors. Laser power needs precise adjustment based on material thickness and type: when cutting ultra-thin metal gaskets, excessive power can lead to over-melting, resulting in wavy deformation upon cooling; insufficient power may cause incomplete cutting and localized stress concentration. Cutting speed must match the power; excessive speed leaves uncut areas, while excessive speed causes thermal expansion due to excessive heat input. The selection and pressure control of the auxiliary gas are equally important. Oxygen is suitable for cutting carbon steel but easily forms oxide slag at the cut; nitrogen is more suitable for stainless steel cutting, reducing oxidation, but insufficient pressure may prevent slag removal, while excessive pressure may bend the ultra-thin gasket. The focal point must be calibrated in real-time using an automatic focusing system to ensure laser energy is concentrated on the material surface, preventing tilted cut surfaces due to focal point deviation.
The influence of material condition on flatness is often overlooked. The raw material for ultra-thin metal gaskets must have a uniform thickness distribution and low internal stress characteristics. If the material itself has thickness deviations or residual stress, deformation can easily occur during cutting due to stress release. Before cutting, the material needs pretreatment, such as annealing to eliminate internal stress or using a leveling machine to correct the flatness of the sheet metal. Furthermore, the cleanliness of the material surface is crucial; oil, scale, or dust can cause uneven laser absorption, leading to localized overheating and deformation.
Cutting path planning and process design must balance efficiency and precision. When cutting along common edges, the compensation amount and kerf width must be set appropriately to avoid workpiece dimensional deviations due to improper spacing at the common edges. For complex contours, the cutting sequence needs to be optimized to reduce the impact of heat accumulation on flatness. For example, cutting the inner hole first and then the outer contour can reduce the risk of deformation due to thermal stress. Additionally, using wire cutting technology with transition sections at the start and end points can reduce flatness errors caused by sudden energy changes during cutting.
Environmental control is an implicit condition for ensuring cutting accuracy. Laser cutting machines are sensitive to ambient temperature, humidity, and vibration. Temperature fluctuations can cause thermal deformation of the equipment, excessive humidity may cause short circuits in electrical components, and vibration will affect the stability of the cutting head's movement. Therefore, the equipment must be installed in a temperature- and humidity-controlled workshop, and vibration reduction measures must be taken, such as laying anti-vibration pads or installing an independent foundation, to isolate external vibration interference.
Detection and feedback are essential means of closed-loop control of flatness errors. During the cutting process, non-contact measuring equipment, such as laser displacement sensors or machine vision systems, must be used to monitor flatness in real time to avoid workpiece deformation caused by pressure from traditional contact probes. For the final product, a full-dimensional inspection must be performed using an optical projector or a coordinate measuring machine, focusing on verifying whether the flatness of critical areas meets design requirements. If the inspection results are out of tolerance, the cause must be analyzed and process parameters adjusted to form a closed loop of continuous improvement.
