Mold Structure System
When designing a mold, there are four key objective factors to consider:
1. Structural Rigidity: The hardness, tensile and compressive strength, toughness, and stress distribution of the mold core, mold frame, sliders, repeat-positioning pins, and mold base must be analyzed.
2. Physical and Chemical Properties of the End Product’s Material: Select appropriate mold core materials based on the physical and chemical properties of the material used in the final product.
3. Establishment of Mold Processing Systems and Techniques: Set standards for mold processing, verification of technical processes, inspection norms, and component measurement systems.
4. Physical Properties of Mold Materials: This includes analyzing the thermal conductivity and coefficient of expansion at different temperatures.
During rough processing, measurements are rarely taken after machining is completed, especially for mold bases and support plates, where residual mechanical stress from large-scale cutting processes can result in dimensional changes or deformation due to stress release after a few days. This leads to inaccurate machining tolerances, particularly for multi-cavity plastic mold bases, progressive dies, or precision punching base plates.
Applications of Molds
Categories of Mold Applications:
1. Pre-hardened mold steel for medium and large molds: These require large cutting volumes, large areas of polishing, and either etching or engraving.
2. High-hardness mold steel for small and micro-precision molds: These require heat treatment, high wear resistance, mirror polishing, micro-engraving, and are suitable for high-production quantities.
3. Precipitation-hardening mold steel: Easily machined and polished, with no need for post-machining heat treatment.
4. High thermal conductivity mold materials: This includes aluminum alloys and beryllium copper alloys.
5. Components for plastic injection molding machines: Such as screws, check valves, and extrusion machine screw tips and mold heads.
Plastic Mould Steels
Since 1990, plastic products have constituted 60-65% of daily consumer goods, ranging from nano-sized medical instruments like endoscopes to large items like aircraft doors. Different molding methods are chosen depending on the plastic and product size.
Plastic and rubber molds can generally be divided into four main categories:
1. Large Molds
Mold Tolerance: 0.05mm–1mm
Mold Base Weight: 1 ton–15 tons
Applications: automotive bumpers, dashboards, motorcycle exterior parts, car interior door panels, refrigerators, washing machines, plastic chairs, airplane doors, and storage racks.
2. Medium Molds
Mold Tolerance: 0.01mm–0.05mm
Mold Base Weight: 500kg–2 tons
Applications: LED TV housings, car lights, liquid containers, household appliances, automotive parts, and computer casings.
3. Small Molds
Mold Tolerance: 0.005mm–0.01mm
Mold Weight: 300kg–1,000kg
Applications: mobile phone housings, connectors, computer accessories, and external parts of consumer electronics.
4. Ultra-Precision Molds
Mold Tolerance: 0.005mm–0.01mm
Mold Weight: 50kg–500kg
Applications: medical instruments, plastic lenses, mobile phones, digital camera lens modules, Blu-ray, and DVD modules.
Perspectives and Benefits of Plastic Injection Molding Plants
Plastic raw materials must meet aesthetic and functional demands, such as color, tactile feel, temperature resistance, durability, heat dissipation, eco-friendliness, optical transparency, and mechanical strength. As a result, various additives, flame retardants, carbon fibers, and glass fibers—amounting to 60–65%—are mixed into plastics to enhance their mechanical and physical properties.
1. Yield: The introduction of many synthetic chemical ingredients results in high corrosion elements, which can release gas during the melting process and corrode the mold materials. This can cause issues like yellowing in transparent parts or underfill, leading to higher defect rates, which in turn reduce production efficiency and yield.
2. Production Cycle:
Injection molding plants prioritize production cycles. When product demand exceeds 5.1 million to 20 million units, production cycle efficiency becomes critical. For products like mobile phone lenses, digital camera lens modules, PET bottles, and bottle caps, machines need to handle 1 million to 3 million mold cycles at the very least.
