Mold part blanks, also known as workpieces, are preformed materials shaped according to the size and shape requirements of the final part, serving as the foundation for further processing. These essential components determine the manufacturability, quality, and lifespan of the mold itself. In modern manufacturing, universal plastics have become increasingly important in blank production due to their versatility and cost-effectiveness.
The selection of appropriate blanks directly impacts production efficiency, material utilization, and final product performance. This guide explores the various types of mold part blanks, their characteristics, and the principles governing their selection in industrial applications, with special consideration for universal plastics and their unique properties.
Types of Mold Part Blanks
1. Profiles
Profiles refer to materials such as steel, non-ferrous metals, or universal plastics produced through rolling, drawing, extrusion, or other processes, maintaining a consistent cross-section along their length. After cutting to size, profiles can serve directly as blanks for further surface processing in the workshop.
In mold manufacturing, rotating surface components like guide pillars, guide sleeves, ejector pins, and push rods typically use bar stock directly as blanks. Plate-type components such as core plates, cavity plates, ejection plates, stripper plates, and square inserts generally come from cut sections of steel plate profiles.
Hot-rolled profiles, with their larger dimensions and lower precision, are often used as blanks for general parts. Cold-rolled profiles, featuring smaller dimensions and higher precision, find application in medium and small parts requiring greater blank accuracy. Universal plastics profiles have gained popularity for their consistent dimensions and ease of machining.
2. Castings
Castings are ideal for creating blanks for complex-shaped mold parts, especially those difficult to form using other methods. In mold manufacturing, common castings include upper and lower die bases for stamping dies, mold bases for large plastic molds, and die bases for automotive panel molds, typically made from gray cast iron HT200 and HT250.
Upper and lower die bases for precision blanking dies usually employ cast steel ZG270-500, while convex dies, concave dies, and blank holders for large panel drawing dies utilize cast alloy steel. Universal plastics have also made inroads in casting applications, particularly for non-structural components requiring complex shapes.
The casting process allows for intricate geometries that would be challenging or impossible to achieve with other manufacturing methods, making it indispensable for certain mold components. Modern casting techniques combined with universal plastics have expanded the possibilities for lightweight, corrosion-resistant mold parts.
3. Forgings
Forgings are suitable for manufacturing blanks for mold parts requiring high strength and having simple shapes. Due to the plastic deformation involved in forging, the internal grain structure becomes finer, and there are no internal defects typical of cast blanks, resulting in better mechanical properties than castings.
For example, punch and die components in stamping dies generally use high-carbon, high-chromium tool steel as material, with forgings serving as the blanks. Tool steel inherently contains a large amount of eutectic network carbides distributed unevenly throughout the material. These carbides, being both hard and brittle, can reduce the material's mechanical properties and heat treatment process performance, thereby shortening the service life of mold parts.
Only through forging can these eutectic network carbides be broken up, their distribution homogenized, and the grain structure refined, thereby improving the material's mechanical properties and extending the service life of mold parts. While universal plastics typically don't require forging, some reinforced plastic composites benefit from similar deformation processes to enhance their structural properties.
Large-sized parts generally use open die forging, while medium and small parts employ closed die forging. Complex-shaped steel parts are not suitable for open die forging. However, the forging method has limitations in producing complex shapes, especially those with intricate internal cavities, where universal plastics often provide a more practical alternative.
4. Semi-finished Products
With the increasing specialization, specialization, and standardization of mold manufacturing, various components such as upper and lower die bases for stamping dies, guide pillars, guide sleeves, universal fixing plates, backing plates, various mold handles, pilot pins, guide plates, and standard mold bases for injection molds have become standard mold components, with their applications becoming increasingly widespread.
These standardized components, manufactured according to national and ministerial standards, are the semi-finished products of molds. These semi-finished products can be purchased from specialized manufacturers and then used after processing the forming surfaces and related parts. The application of semi-finished products can significantly reduce mold costs and shorten mold manufacturing cycles.
Universal plastics have played a significant role in the standardization of mold components, offering cost-effective alternatives to traditional metal parts in non-load-bearing applications. The availability of standard semi-finished plastic components has further accelerated mold development cycles and expanded design possibilities.
The use of semi-finished products represents a key trend in modern mold manufacturing, enabling greater efficiency, consistency, and cost-effectiveness. Manufacturers increasingly combine metal semi-finished components with universal plastics parts to optimize both performance and production costs.
Principles for Selecting Blanks
Numerous factors influence the selection of appropriate blanks for mold parts. The decision-making process should consider several key aspects to ensure optimal performance, cost-effectiveness, and manufacturability. With the growing use of universal plastics in mold manufacturing, these principles must also account for the unique characteristics of plastic materials alongside traditional metals.
Material Properties Requirements
Generally, once a part's material is selected, the type of blank and processing method are largely determined. For example, when the material is cast iron, due to its excellent casting properties, cast blanks should be chosen. For small-sized, simple-shaped steel parts with modest mechanical property requirements, profiles can be directly used as blanks. For important steel components requiring sufficient mechanical properties, forged blanks are appropriate. Universal plastics blanks are selected based on their unique properties like corrosion resistance, weight, and thermal characteristics.
Shape, Structure and Dimensions
The part's shape, structure, and dimensions directly influence blank selection. For example, stepped guide pillars with slightly differing diameters can use bar stock as blanks. For large stepped cores with significantly different diameters, forgings should be used. Die bases for stamping dies and large automotive panel mold frames typically use cast iron blanks. Universal plastics excel in complex shapes where intricate geometries would be costly or difficult to achieve with metal processing.
Production Volume
For small-batch production, blank manufacturing methods with lower precision and productivity are generally used, such as hand-molded castings and open-die forgings. For mass production, high-precision and high-efficiency blank manufacturing methods should be employed, including machine molding for castings and die forging for forgings. Universal plastics offer particular advantages in medium to high production volumes due to their faster processing cycles and lower tooling costs compared to metals.
Production Conditions
The selection of blank types and manufacturing methods should consider the equipment, technological level, and workers' skills available in the blank manufacturing workshop.同时，还应考虑采用先进工艺制造毛坯的可行性和经济性。Universal plastics often require different processing equipment than metals, so production facilities must be evaluated for compatibility with plastic processing techniques when considering these materials for mold part blanks.
Additional Considerations in Blank Selection
Cost Efficiency
The overall cost, including material costs, processing costs, and scrap rates, must be considered. Universal plastics often provide cost advantages in certain applications due to lower material costs and faster processing times, though this must be balanced against performance requirements.
Lead Time
The time required to produce or acquire blanks can significantly impact overall production schedules. Semi-finished universal plastics components often have shorter lead times than custom metal forgings or castings.
Environmental Factors
Modern manufacturing increasingly considers environmental impact, including material recyclability and energy consumption during production. Universal plastics offer varying environmental profiles, with many now available in recycled or biodegradable formulations that can reduce the ecological footprint of mold production.
Material Availability
The availability of materials, especially during supply chain disruptions, is a critical practical consideration. Universal plastics generally maintain more stable supply chains compared to specialty metals, providing greater production reliability.
Practical Applications of Different Blanks
Automotive Industry
In automotive mold manufacturing, large components like panel mold bases typically use cast iron blanks for their rigidity and vibration damping properties, while precision components often utilize forgings. Increasingly, universal plastics are used for non-structural mold components and prototypes.
The high production volumes in automotive manufacturing favor standardized semi-finished components to reduce costs and ensure consistency across production runs.
Consumer Electronics
Molds for consumer electronics often require high precision and complex geometries. This sector frequently uses a combination of precision forgings for critical components and universal plastics for less stressed parts, taking advantage of plastics' excellent surface finish capabilities.
The small size of many electronic components makes cold-rolled profiles economically attractive, providing the necessary precision without excessive material waste.
Packaging Industry
Packaging molds often utilize a high proportion of universal plastics blanks due to their corrosion resistance, ease of cleaning, and ability to replicate fine details. Profiles are commonly used for structural components, while custom castings handle more complex geometries.
The high-volume nature of packaging production makes the cost advantages of standardized semi-finished components particularly valuable in this sector.
Future Trends in Mold Blank Technology
The field of mold part blanks continues to evolve with advancements in materials science and manufacturing technologies. Several key trends are shaping the future of blank selection and production, with universal plastics playing an increasingly prominent role.
Advanced Materials
New alloy compositions and enhanced universal plastics formulations are providing improved strength-to-weight ratios, better thermal stability, and increased wear resistance. These materials allow for longer mold life and expanded application ranges.
Additive Manufacturing
3D printing is revolutionizing blank production, enabling complex geometries that were previously impossible. Both metal and universal plastics are being used in additive processes to create near-net-shape blanks with reduced material waste.
Smart Manufacturing
Digitalization and AI-driven design are optimizing blank selection based on performance requirements and production conditions. This intelligent approach ensures optimal material utilization and performance while minimizing costs.
Sustainable Practices
Environmental considerations are driving the development of recyclable universal plastics and more efficient manufacturing processes. Closed-loop material systems are emerging, reducing waste and energy consumption in blank production.