Extending the life of die casting molds is not just about using strong materials. It requires a comprehensive approach that covers everything from design to daily operation. By carefully selecting the right mold steel, optimizing mold structure, controlling every step of the die casting process, and maintaining molds regularly, manufacturers can significantly reduce mold wear and failure.
This article will introduce mold material selection, structural design, surface treatment, lubrication strategy, die casting process control, maintenance monitoring, handling, and storage methods. Read on to learn how these key factors affect the life of die casting molds.
Correct Selection of Mold Materials
Use High-Quality Tool Steel
The mold is subjected to high temperatures and pressure for a prolonged period. If low-quality steel is used, it is easy to crack or break during operation.
It is recommended to use high-performance tool steels such as H13 and H11, which are widely used in aluminium alloy die casting molds.
They have good thermal stability and wear resistance, and are suitable for most medium and high-strength die casting applications.
Proper Heat Treatment
Heat treatment is related to the strength and crack resistance of the mold.
Taking H13 as an example, it is recommended to first quench to 1020-1050℃, then double temper at 550-620℃, and finally stress relieve at 500-550℃.
The whole process requires precise temperature control to ensure that the mold does not easily crack during use and has a stable life.
Mold Design Optimization
Avoid Stress Concentration
The mold should avoid sharp corners, sudden changes in cross-section, and asymmetric structure to prevent stress concentration from causing cracks.
Optimization methods include increasing fillets (≥3mm), controlling wall thickness changes (≤30%), setting transition zones, and symmetrical parting to disperse loads and improve durability.
Optimize Runner Layout
The runner design should maintain balanced length and reasonable cross-section (such as circular or trapezoidal) to avoid local scouring and unstable filling.
Combined with mold flow simulation, optimize the gate position and angle to make the metal flow smoothly and reduce wear.
Strengthen Cooling Design
The cooling focus should be on the hot zone, and the channel should be close to the hot spot and maintain a suitable spacing (such as 20-30mm).
Bubble tubes, baffles, or 3D cooling structures can be used for complex parts. Ensure that the cooling water circuit is closed evenly to reduce the risk of thermal fatigue.
Reasonable Exhaust Arrangement
The exhaust groove should be set at the end of the flow, thin wall, or intersection, with common dimensions of 0.02-0.05mm deep and 2-5mm wide.
Exhaust pins can be used in inconvenient areas to groove. The structure should be easy to clean to prevent residue clogging.
Optimize with Software Simulation
Moldflow analysis (Moldflow or ProCAST) should be used in the design phase to perform heat flow, filling, and stress simulation to identify hot nodes and stress concentration areas.
Optimize the gate, cooling, and exhaust layout based on the results to reduce trial-and-error costs and improve mold molding efficiency and life.
CEX In-House Mold Development
Surface Treatment and Protective Coating
Nitriding Treatment
Nitriding treatment can form a high-hardness compound layer on the mold surface to enhance its wear resistance and thermal cracking resistance.
It is recommended to perform gas nitriding or ion nitriding after the mold processing is completed, and the treatment temperature should be controlled at 500-550℃.
PVD or TD Coating
PVD coating (such as CrN, TiAlN) is suitable for improving the surface hardness, corrosion resistance, and anti-aluminum adhesion of the mold, and is often used in the gate, core, and ejector positions.
TD coating is suitable for areas with severe heat and high wear, such as gate sleeves or nozzles.
Polishing the Cavity Surface
Polishing can reduce the surface roughness of the cavity, reduce the adhesion of aluminum liquid, and improve the demolding stability.
Fine polishing can also remove machining residual traces and tiny stress concentration points to avoid crack propagation.
At the same time, it helps to improve the surface finish of the casting and reduce the burden of subsequent processing.
Lubrication and Release Agent Strategy
Choose a Suitable Lubricant
Ordinary lubricants are easy to burn and carbonize at high temperatures, affecting the surface quality of the mold and the demolding effect.
A water-based high-temperature release agent developed specifically for aluminium die casting components should be selected, which has good lubricity and clean separation performance, and can effectively reduce wear and aluminum liquid adhesion.
Optimize Spraying
Excessive spraying of release agent will cause pores, while insufficient spraying will easily stick to the mold or even scratch the surface.
The automatic spraying system should be used to accurately control the spraying amount, angle, and interval time to ensure uniform lubrication in each cycle.
Regularly Remove Residues
Even if a suitable release agent is used, carbides or chemical residues will still form on the mold surface after long-term use.
Cleaning work should be arranged in each shift or a certain period to remove carbon deposits and dirt in time to avoid affecting the mold life and casting quality.
Die Casting Process Control
Preheat Molds Properly
Cold molds in contact with high-temperature aluminum liquid are prone to cracks and filling defects.
It is recommended to use a mold temperature controller or heating rod to evenly heat the mold to 180-220℃, and equip key areas with thermocouples for real-time monitoring to ensure uniform heat distribution and avoid local cold spots.
Stabilize Injection Parameters
Pressure or speed fluctuations will impact the mold and cause filling defects.
A multi-stage injection program (low-speed start, high-speed filling, stable pressure holding) should be set up with a servo or closed-loop control system to achieve a smooth process and reduce wear.
Control Cycle Time
A cycle that is too short will overheat, and a cycle that is too long will affect efficiency.
Through mold temperature monitoring, reasonable injection, cooling, and demolding times can be set, cooling efficiency can be optimized first, mold heat accumulation can be controlled, and production capacity and mold life can be taken into account.
Unified Demolding Spraying
Uneven spraying of the release agent can cause mold sticking or carbon deposition.
The spraying distance (15–20cm), angle (about 45°), and time should be controlled, and an automatic spray gun with a mold temperature sensor should be used to ensure consistency and spraying effect.
Auto Mold Release Agent Spray by CEX Casting
Mold Maintenance and Monitoring
Per-Shift Mold Cleaning
Molds are prone to residual release agents, aluminum slag, and oxides during operation, affecting the size and surface quality.
It is recommended to use a brush, compressed air, or ultrasonic cleaning of key areas such as the cavity, exhaust groove, and gate every shift to keep the mold clean.
Regular Maintenance
In addition to daily cleaning, the mold surface wear should be checked, sliding parts should be cleaned, demolding areas should be polished, and aging seals should be replaced every week.
Establishing a maintenance cycle table can help detect problems in advance, reduce sudden downtime, and extend mold life.
Use a Sensor Monitoring System
Install temperature, pressure, or cycle count sensors at key parts of the mold to monitor the operating status in real time.
Set thresholds to trigger alarms, intervene in abnormalities in time, prevent mold damage, and achieve predictive maintenance.
Mold Handling and Storage Specifications
Handle Molds Carefully
During the process of hoisting or moving the mold, the corners and precision surfaces are easily damaged by collision.
Use lifting tools with cushions to ensure uniform force and avoid direct contact with hard objects. Even minor cracks may expand during use and shorten the life of the mold.
Control the Storage Environment
Humid or temperature-difference environments are prone to rust and thermal fatigue.
Molds should be stored in a dry, constant temperature area and covered with anti-rust film or sprayed with anti-rust oil.
At the same time, regular inspections should be carried out to prevent surface degradation.
Sealing Idle Molds
If the unused mold is not sealed, it is easy to be damaged by air corrosion or accidental contact.
It is recommended to apply anti-rust oil after cleaning, wrap it with VCI film, and mark the storage status to avoid confusion, stacking, or damage.
CEX Casting‘s Practice of Extending Mold Life
Mold Design Optimization
We introduce mold flow analysis and DFM reports in the mold design stage to identify potential stress concentration areas in advance and optimize the layout of gates, runners, and cooling systems.
By predicting risks and improving structures, we can reduce mold wear and failure rates from the source and effectively extend the service life.
Raw Material Purification Treatment
A centralized smelting system is used to effectively remove oxide inclusions and gas impurities, significantly reducing the erosion and corrosion of the mold surface by the liquid aluminum.
This can make the aluminum liquid purer and the mold more durable, while also improving the quality and consistency of die casting parts.
Robotic Loading and Unloading
The production process fully uses robotic arms for automatic loading and unloading operations to maintain a stable beat and avoid bumps, side loads, or over-force ejection caused by manual operations.
It helps to reduce mechanical damage and ensure the continuous and stable operation of the mold in high-paced production.
Standardized Mold Storage
All molds are classified and numbered and stored in standard mold racks to prevent damage caused by stacking, moisture, or misoperation.
The mold rack is convenient for daily inspection, positioning, and management, improving storage safety and maintenance efficiency.
Mold Storage Racks by CEX Casting
Regular Maintenance and Renovation
We have established a systematic mold management mechanism, regularly clean, inspect, and renovate key parts, and formulate maintenance plans based on usage records to achieve preventive maintenance and extend the life of the mold.
Conclusion
Extending the life of die casting molds depends on comprehensive strategies such as high-quality materials, scientific design, precise process control, surface treatment, and standardized maintenance.
As a leading aluminum alloy die casting manufacturer, CEX Casting has strong mold development and manufacturing capabilities to help customers improve the production efficiency and product stability of aluminum die casting.
Contact us now to learn how we can turn your next high-pressure die casting products into reality.