The process of using the product

I. Full-Cycle Precision Manufacturing System for Sunroof Bracket Injection Molds

Driven by the dual demands for lightweight and high strength in automotive components, the manufacturing of injection molds for sunroof brackets has evolved from traditional processing to a composite process integrating "digitalization + experience". Taking the molding of PAG+GF30 (30% glass fiber-reinforced nylon) materials as an example, the mold manufacturing needs to overcome three core links:

1. Pre-Design: Dual Verification from DFM to CAE

• DFM (Design for Manufacturability) Analysis: For the long-strip structure (common size: 200-350mm) and multi-snap design of sunroof brackets, potential stress concentration risks are avoided in advance by simulating draft angles (preset 3°-5°), wall thickness uniformity (controlling a tolerance of ±0.1mm for 1.8-2.5mm thickness), and gate positions. In a case of a German-style vehicle bracket, we identified a 1.2mm wall thickness difference in the original design through DFM; after optimization, the molding defect rate dropped from 18% to 3%.

• In-Depth Application of Moldflow Analysis: To address the fiber orientation issue of GF materials, a "three-point gating + spiral runner" design is adopted. Combined with CAE simulation of filling pressure (120-150MPa) and cooling rate (mold temperature: 80-100℃), the weld line strength is increased by 40%, meeting the ISO 16750 vibration test standards.

2. Precision Machining: Collaborative Control of Micron-Level Process Chain

• Core Machining Processes:

◦ High-Speed CNC Milling: Five-axis linkage equipment is used to machine mold cores. For the curved guide rail surface of the bracket, a surface finish of Ra0.8μm and a contour tolerance of ±0.02mm are achieved.

◦ Wire Electrical Discharge Machining (WEDM): It is applied to process the mating surfaces of sliders and lifters, with the gap controlled between 0.01-0.02mm to ensure no jamming during millions of mold opening and closing cycles.

◦ Precision Electrical Discharge Machining (EDM): For complex structures such as snap undercuts, copper-tungsten alloy electrodes are used for electrical discharge, achieving a surface roughness of Ra0.4μm and preventing flash residue after molding.

• Material and Surface Treatment: Mold cores are made of 2344 hot-work mold steel (hardness: HRC48-52). Key wear-resistant parts (e.g., sprue bushings, ejector pins) undergo TD coating treatment, extending the wear life from 500,000 cycles to 1.2 million cycles.

3. Intelligent Mold Testing and Data-Driven Debugging

Mold testing data (injection speed: 80-120mm/s, holding pressure: 80-100MPa, cooling time: 25-35s) is collected via the MES system, and warpage (target: ≤0.15mm/100mm) is analyzed using AI algorithms. During the debugging of a U.S.-style vehicle bracket, through "conformal cooling channels + reverse deformation compensation" (pre-deformation: 0.2mm), the flatness of the product was reduced from 0.3mm to 0.08mm, meeting the sealing requirements of the sunroof assembly.

II. Typical Industry Technical Challenges and Breakthrough Solutions

❶ Overcoming the Contradiction Between Material Properties and Mold Life

• Challenge: GF30 materials have high flow resistance (melt viscosity is 3 times that of pure nylon), and glass fibers erode the mold, causing wear to the sprue bushing. Traditional H13 steel molds can only produce 300,000 parts before requiring maintenance.

• Solution:

◦ A "stepped gate + wear-resistant bushing" design is adopted. The sprue bushing is made of ASP60 powder high-speed steel (hardness: HRC64-66), combined with PVD TiAlN coating (thickness: 3-5μm), reducing the wear rate from 0.05mm/100,000 cycles to 0.01mm/100,000 cycles.

◦ Screw speed (120-150rpm) and back pressure (8-12bar) are optimized to reduce mold corrosion caused by heat generation from material shearing.

❷ Controlling Dimensional Stability of Complex Structural Parts

• Challenge: Brackets with guide grooves (length: 300mm) tend to have "S-shaped" warpage after molding. Traditional rectangular cooling channels cause uneven cooling, resulting in a temperature difference of over 20℃.

• Solution:

◦ "Bionic conformal cooling channels" (spiral channels distributed according to the bracket contour) are designed, controlling the mold temperature difference within 5℃ and reducing internal stress by 60%.

◦ "In-mold compensation technology" is applied: Initial warpage data (maximum 0.4mm) is obtained through 3D scanning, and a 0.3mm compensation amount is engraved in the reverse direction on the mold cavity surface, resulting in a final product warpage of ≤0.1mm.

❸ Optimizing the Operational Reliability of Multi-Slider Mechanisms

• Challenge: Sunroof brackets usually integrate 4-6 sets of sliders (e.g., for guide groove and snap hole core-pulling). Traditional angle pin designs are prone to phase deviation (error ≥0.05mm) during high-speed mold opening and closing.

• Solution:

◦ "Servo motor-driven sliders" are used instead of angle pins, achieving a positioning accuracy of ±0.01mm, with sensors real-time monitoring the slider position.

◦ The slider guide surface adopts a "T-slot + wear plate (material: SKD11, hardness: HRC58-60)" structure, with annual wear of <0.01mm.

III. Extended Technical Value: Cost Optimization from Mold to Vehicle

Through the above process upgrades, the comprehensive performance of a single set of molds has been significantly improved:

• Production Efficiency: The cycle time is shortened from 45s to 38s, increasing the daily output per mold from 240 pieces to 280 pieces.

• Cost Control: Mold maintenance costs are reduced by 60%, and the mold cost allocated to a single product is decreased by 25%.

• Quality Improvement: The product defect rate is <0.5%, meeting the host factory's PPAP Level 3 certification requirements and helping customers increase the assembly efficiency of sunroof assemblies by 15%.