Mold Tech

Effective Strategies to Shorten Mold Manufacturing Cycle

• 2024-09-19

In the rapidly evolving automotive industry, the pace of car model updates has accelerated, leading to shorter development cycles. The mold development department needs to conduct a comprehensive analysis of each stage of mold development to shorten the development cycle and improve mold development efficiency.

The development of automotive body panel molds can be divided into two stages: design and manufacturing. The design phase includes stamping die (SE) design, stamping process DL diagram design, CAE analysis and die surface compensation design, CAM die surface design, die structure design, FMC, structure and die surface programming. The manufacturing phase includes FMC production, preparation of cast and forged blanks, primary assembly, secondary processing, assembly, grinding and fitting, debugging, quality improvement, and delivery processes. In the mold development cycle, the mold design phase for the entire vehicle usually takes about 4 to 5 months, while the mold manufacturing phase lasts for 12 months. Debugging and quality improvement take up 5 to 6.5 months. Therefore, improving mold manufacturing efficiency is of great significance in shortening the development cycle.

Current Status of Body Panel Mold Design and Manufacturing

In recent years, significant technological progress has been made in the development of body panel molds. Most have already implemented 3D DL diagram design, comprehensive process CAE analysis, started die surface compensation design, and designed non-uniform clearances on mold surfaces. Three-dimensional solid design has been applied to mold structure design, including dynamic interference simulation, scrap sliding simulation, and stamping automatic line simulation.

In mold manufacturing, three-dimensional processing (FMC) has been implemented, primary processing has been fully programmed, secondary processing has been automated, and mold quenching (medium frequency quenching and flame quenching) has been promoted. Some companies have also introduced laser quenching and post-fire surface finishing. Mold manufacturing has adopted a "one-flow" manufacturing mode.

The main reasons for the long mold manufacturing cycle include difficult clamping of some parts, inappropriate clearances between male and female molds, extensive grinding and fitting work, cracking, wrinkling, and springback of some parts requiring repeated debugging and rectification, improper planning and design errors.

Issues in Process and Die Surface Design

1. Unreasonable product processability that is difficult to resolve in stamping process leads to parts not meeting quality requirements, resulting in significant debugging difficulties and multiple revisions to the mold.

2. Unreasonable CAE analysis parameter settings or use of material properties superior to those used in actual production can lead to significant deviations between process design data and manufacturing debugging results, resulting in repeated debugging.

3. Defects in process data or part product data lead to issues that need to be resolved during debugging.

4. Unreasonable die surface clearance design leads to extensive grinding and fitting work later on. The design does not consider material thickness variations during part forming, machine bed deflection compensation, and part expansion treatment. For example, the clearance design for the top cover deep drawing die is based on material thickness, resulting in more than 30 hours wasted in complete grinding and fitting due to excess allowance in colored areas.

5. Unreasonable trimming edge angles or burrs at the junction of straightening and trimming often lead to repeated debugging. Lack of precision in edge unfolding or inaccurate trial material verification leads to edge adjustment and welding work. In some cases, the reworked edge is not vertical or sharp and has uneven clearances, resulting in burrs requiring multiple debugging sessions.

6. Die surface design does not consider the need for root cleaning or extensive pressure areas, leading to significant grinding and fitting work.

7. Inadequate transmission of process information such as lack of understanding of grinding and fitting requirements for various parts of the mold by fitters or inadequate knowledge of quenching areas by surface treatment personnel leads to rework or prolonged information confirmation time.

Optimizing Mold Design and Manufacturing Processes

1. Designing mold exhaust holes and screw holes reduces the need for fitters to manually create them, reducing drilling time and improving accuracy.

2. Establishing a standard clamping support system for non-standard punch dies, wedges, sliders, etc., ensures the use of process clamping heads in design to achieve unified programming and processing, thereby improving processing efficiency and accuracy.

3. Implementing standardized mold identification on mold bases and blocks facilitates part identification and installation while also aiding in maintenance.

4. Researching processing parameters for numerical milling of critical surfaces to improve efficiency and accuracy.

5. Adjusting the processing route for trimming and straightening blocks to save time and improve efficiency.

Conclusion

With the continuous improvement of body panel mold databases and the deepening application of analysis software in combination with the improved machining accuracy of machine tools, a detailed approach to technical design work is essential. By addressing various issues from the outset in the product, process, and mold design stages through virtual validation and early preventive measures, along with efficient information transmission, assembly time can be reduced while manufacturing accuracy is improved. This will inevitably lead to a significant reduction in grinding and fitting time, fewer debugging sessions, meeting quality requirements for stamped parts, ultimately achieving the goal of shortening the mold manufacturing cycle.

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