How to select materials for plastic moulds

How to select materials for plastic moulds

Selecting the right materials for plastic molds is critical to ensure the molds’ durability, performance, and cost-effectiveness. Here are the key steps to follow when choosing materials for plastic molds:

  1. Understand Mold Requirements: Start by understanding the specific requirements of the mold, including the type of plastic material to be used, the expected production volume, molding process conditions (temperature, pressure, etc.), and the desired mold life.
  2. Identify Mold Material Categories: There are several categories of mold materials, including tool steels, stainless steels, aluminum, and high-performance alloys. Each category has different properties and suitability for specific applications.
  3. Consider Steel Types: If opting for steel molds, consider factors like hardness, wear resistance, thermal conductivity, and corrosion resistance. Common steel types used for molds include P20, H13, S136, and 420SS.
  4. Evaluate Aluminum Alloys: Aluminum molds are often used for low-volume production or rapid prototyping. They have good thermal conductivity and are easier to machine compared to steel. However, they are less wear-resistant and have a shorter mold life.
  5. High-Performance Alloys: For high-volume production or demanding applications, consider high-performance alloys like beryllium copper or nickel-based alloys. These offer exceptional wear resistance and can withstand harsh molding conditions.
  6. Cost Considerations: Evaluate the cost of materials and factor in the expected mold life. Sometimes, opting for a higher-cost material with longer life can be more cost-effective in the long run.
  7. Surface Finish Requirements: The material selected should allow for the desired surface finish of the molded parts. Some materials might require additional coatings or treatments to achieve the desired finish.
  8. Production Volume: For low-volume production or prototyping, aluminum molds might be more suitable due to their lower cost and quicker machining time. For high-volume production, more durable steel or high-performance alloys are preferable.
  9. Corrosion Resistance: Consider the presence of corrosive plastics or processing conditions that might cause corrosion. Opt for materials with good corrosion resistance in such cases.
  10. Machinability: Evaluate the machinability of the chosen material, especially if complex mold geometries are required.
  11. Thermal Conductivity: For molds subjected to rapid cooling or temperature-sensitive plastics, choose materials with high thermal conductivity to ensure efficient cooling and minimize cycle times.
  12. Consult with Suppliers: Work closely with mold material suppliers and manufacturers to get expert advice on the most suitable material for your specific application.

Ultimately, the selection of mold materials should be a well-informed decision based on a thorough understanding of the mold requirements and the properties of different materials available. A carefully chosen mold material will contribute to the success of the plastic molding process, leading to high-quality molded parts and efficient production.

In today’s world, with the rapid development of high technology, various electronic products emerge in endlessly. The production of these electronic products is inseparable from plastic molds. Therefore, how to choose the material of plastic mold has become a very important issue.

First, we need to understand the basic concepts of plastic molds. Plastic mold is a tool used to manufacture plastic products. It is composed of various metal materials and plastic materials. During the production process, plastic molds need to withstand high temperature, high pressure and high speed working environments, so the selection of their materials is crucial.

When choosing plastic mold materials, we need to consider the following aspects:

  1. Wear resistance: Plastic molds need to withstand high-speed, high-pressure working environments during the production process, so the wear resistance of their materials is very important. Generally speaking, materials such as cemented carbide and ceramics have better wear resistance.
  2. Heat resistance: Plastic molds need to withstand high temperature environments during the production process, so the heat resistance of their materials is also very important. Generally speaking, metal materials such as steel and aluminum have high heat resistance.
  3. Chemical corrosion resistance: Plastic molds may be exposed to various chemicals during use, so the chemical corrosion resistance of their materials is also very important. Generally speaking, materials such as stainless steel and nickel-based alloys have better chemical corrosion resistance.
  4. Processing performance: The manufacturing process of plastic molds requires fine processing, so the processing performance of its materials is also very important. Generally speaking, metal materials such as steel and aluminum have better processing properties.
  5. Cost factors: On the premise of meeting the above performance requirements, we also need to consider the cost factors of plastic mold materials. Generally speaking, the cost of metal materials such as steel and aluminum is relatively low, while the cost of materials such as cemented carbide and ceramics is relatively high.

To sum up, when selecting plastic mold materials, we need to comprehensively consider factors such as wear resistance, heat resistance, chemical corrosion resistance, processing performance and cost. Only in this way can we choose the plastic mold material that best suits our needs, thereby ensuring the quality and production efficiency of electronic products.

Internal mold: mainly refers to mold core, slider, lifter, insert, etc. For plastic mold without any requirements, 45 # steel and 50 # steel materials are generally used; P20 pre hardening plastic die steel is generally selected for ordinary requirements; 718 super pre hardening plastic mould steel must be selected for the plastic mould inner parts with high requirements; For precision plastic molds with very strict requirements, 738 (4Cr2NiMnMo national standard) steel should be selected; If customers have a demand for polishing the plastic mold to mirror luster, most plastic mold factories will choose NAK80 mirror plastic mold steel; In the process of using plastic molds to produce plastic products, corrosive gases will sometimes be generated. At this time, we need to choose corrosion-resistant mold steel for production, such as M300 corrosion-resistant steel.

Mold base: generally, the minimum required mold base is also made of 45 # steel; The most commonly used mold base materials are 50 # steel; For plastic mold base with certain requirements, 55 # mold steel will be selected; GS638 (P20 American standard GS638 German standard 42CrMo national standard) die steel should be selected for the most exquisite plastic mold, which can meet the requirements for use.

Guide post: 1, 20 # (S20C) or 20Mn2B (SMn420), treatment: carburizing and quenching, hardness after treatment is greater than 55HRC 2, T8A, T10A, treatment: surface quenching, hardness after treatment is less than 55HRC 3, 45 # treatment: tempering, surface quenching, low temperature tempering, hardness after treatment is greater than 55HRC

Guide sleeve: Most plastic mold factories use H62 brass or bronze alloy to make guide sleeve.
Bushing: Most mold factories choose 45 #, 50 # and 55 # bushings. Treatment: surface quenching, hardness greater than 55HRC.
Push rod, thimble, draw bar: T8, T8A, T10, T10A Treatment: quenching, low temperature tempering, hardness greater than 55HRC 45 #, 50 #, 55 # Treatment: quenching, hardness greater than 45HRC.

All kinds of plate materials: General plastic mold factories choose to use 45 #, 50 #, 40Cr (quenched and tempered) and structural steel Q235~Q275. If large plates need to be produced, ductile iron can be used instead.

Selecting the right materials for plastic moulds is critical to ensuring the quality, durability, and longevity of the mould. There are several factors to consider when choosing materials for plastic moulds, including the type of plastic being used, the design of the mould, and the expected production volume. Here are some tips on how to select materials for plastic moulds:
  1. Determine the type of plastic: The type of plastic being used is a key factor in selecting the right materials for the mould. Different plastics have different properties, such as melting point, shrinkage rate, and viscosity, which will impact the mould design and material selection.
  2. Consider the mould design: The design of the mould is also important in selecting the right materials. The mould must be able to withstand the high temperatures and pressures of the injection molding process without deforming or warping. The design should also allow for easy removal of the finished product from the mould.
  3. Determine the expected production volume: The expected production volume is also an important factor in material selection. For high-volume production, materials that can withstand the wear and tear of constant use are needed, while for low-volume production, materials that are less durable but still effective may be sufficient.
  4. Consider the cost: The cost of the material is also a factor to consider. Materials that are more expensive may offer better performance, but they may not be cost-effective for lower volume production runs.
  5. Look for materials with high thermal conductivity: Materials with high thermal conductivity can help to reduce the cycle time and increase the production speed, making the manufacturing process more efficient.
  6. Consider the surface finish: The surface finish of the mould can impact the final product’s quality. Choosing materials with the appropriate surface finish can help to reduce defects and improve the overall quality of the finished product.

In conclusion, selecting the right materials for plastic moulds is crucial to achieving high-quality and efficient production. By considering the type of plastic being used, the mould design, the expected production volume, cost, thermal conductivity, and surface finish, manufacturers can choose materials that will ensure the durability, longevity, and overall quality of the mould.