Aluminum seldom makes sense if a mold is fabricated in China (which we cover later). Steel is the most common injection mold material, but choosing the right injection mold steel material is similar to selecting the foundation for a building: it dictates the mold's durability, performance, and ultimately, the quality of your parts. As engineers, we understand the critical nature of this decision.

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Let's delve into the three most common types of hard steel and pre-hardened steel utilized in injection molding:

Hard Steels:

1. / / H13: This trio offers a workhorse option. After hardening, they achieve a Rockwell C hardness of 49-53 HRC, making them suitable for ordinary hardening molds. Their versatility allows for applications across various projects.

ESR: This steel takes the performance of the previous group a notch higher. It boasts the same hardness range (49-53 HRC) after hardening but excels in applications demanding both durability and a highly polished finish.

S136 / S136SUP / : Don't be fooled by the 'steel steel' reference ' these are actually high-performance stainless steels. Their strength lies in corrosion resistance, making them ideal for molds processing materials like POM and PVC, which can be corrosive to standard steels. Additionally, they hold their own when it comes to achieving a polished finish.

Lifespan: Mold tooling made from hard steels like 1.#, #, and # will usually last for around 300k-500K shots, but can reach 1 Million if the mold structure is simple.

Pre-Hardened Steels:

S50C / S55C: These steels offer a cost-effective option for mold bases, providing adequate strength and machinability. However, their lower hardness limits their suitability for high-wear applications.

718 / 718H: Renowned for their toughness and ability to achieve a good surface finish with standard polishing techniques, 718 and 718H are popular choices for mold cavities and inserts. Their well-rounded properties make them a versatile option for various applications.

738 / 738H: Offering superior rigidity compared to 718 grades, 738 and 738H excel in core and insert applications. While their polishing capabilities are considered 'ordinary,' their rigidity often outweighs this limitation for specific applications.

A Note on P20: It's important to clarify the perception of P20 steel in China. While technically encompassing a series that might include materials like 718 or 738, the term 'P20' in China often refers to a lower-grade steel with potentially less desirable properties compared to the 718/738 series.

NAK80 / XPM: The champion of pre-hardened steels, NAK80 boasts a hardness of 37-43 HRC. This, coupled with its excellent polishing capabilities, makes it the go-to choice for molds requiring high-precision parts from materials like PC, PA+GF, and PC+GF.

Remember, this is just a starting point. Selecting the optimal steel grade requires careful consideration of factors like part complexity, plastic-type, production volume, and budget. Consulting with experienced mold makers and material suppliers is crucial to ensure you make the best choice for your specific project.

Lifespan: For pre-hardened materials the mold life is usually 100K-300K shots.
In particular:

• 278#; 718#; p20#: 100k-200K;
• NAK80; XPM: 200-300K

Watch these videos on how to test steel's properties which may help you to select the types you require.

Injection Moulding: 10 most frequently asked questions

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We have collected the ten most frequently asked questions about injection moulding and answered them for you.

1. What is injection moulding and how does it work?

Injection moulding is a manufacturing process used to produce parts by injecting molten material into a mould cavity. The material is then cooled and solidified to form a finished part. The process is automated and can produce high volumes of parts with consistent quality.

Reference: 'The Process of Injection Moulding Explained' by MAKLIN

2. What types of materials can be used in injection moulding?

A wide range of materials can be used in injection moulding, including thermoplastics, elastomers, thermosets, and metals. The choice of material depends on the requirements of the part, such as strength, durability, and temperature resistance.

Reference: 'Beginners guide to Injection Moulding' by MAKLIN & 'Handbook of Applied Polymer Processing Technology' by Nicholas P. Cheremisinoff, Paul N. Cheremisinoff

3. What are the advantages of injection moulding over other manufacturing processes?

Injection moulding offers many advantages over other manufacturing processes, such as high production volumes, consistent quality, and low labour costs. The process is also versatile and can produce a wide range of part sizes and shapes.

Reference: 'Beginners guide to Injection Moulding' by MAKLIN & 'Injection Molding: An Introduction' by Walter Michaeli, Gerd Potsch

4. What factors affect the quality of injection moulded parts?

Several factors can affect the quality of injection moulded parts, including the material used, mould design, injection pressure and temperature, cooling rate, and part ejection. Any deviation in these factors can lead to defects such as warping, sink marks, and voids.

Reference: 'Injection Molding Process, Defects, Plastic' by CustomPartNet

5. How can injection moulding defects be prevented or corrected?

Injection moulding defects can be prevented or corrected by monitoring and controlling the moulding process, making design changes, using better quality materials, and maintaining machinery and equipment.

Reference: 'Injection Molding Troubleshooting Guide, 3rd Ed' by Jay W. Carender

6. How can sustainability be incorporated into injection moulding?

Sustainability can be incorporated into injection moulding by using recycled or biodegradable materials, reducing waste and energy consumption, and implementing eco-friendly practices in the manufacturing process.

Reference: 'A New Era in Regional Injection Moulding' by MAKLIN &'An Environmental Analysis of Injection Molding' by Alexandre Thiriez, Timothy Gutowski

7. What are some innovative technologies in injection moulding?

Some innovative technologies in injection moulding include 3D printing of moulds, controlled foaming, and nano-additives for enhanced properties.

Reference: 'Latest Innovations in injection molding' by Klaus Vogt

8. What are the industry standards for injection moulding?

The industry standards for injection moulding are defined by organizations such as the American Society of Mechanical Engineers (ASME), the Society of Plastics Engineers (SPE), and the International Organization for Standardization (ISO). These standards cover areas such as material selection, mould design, process control, and part testing.

Reference: 'Society Of The Plastic Industry Mold Building Standards' by Society of Plastics Engineers

9. What are some common applications of injection moulding?

Injection moulding is used in a wide range of industries, including automotive, electronics, medical, and consumer goods. Common applications include automotive parts, electronic enclosures, medical devices, and packaging.

Reference: 'Injection Moulding Applications' by Engineers Edge

10. How can injection moulding contribute to the circular economy?

Injection moulding can contribute to the circular economy by implementing closed-loop systems for material recycling, reducing waste and energy consumption, and designing products for easy disassembly and reusability.

Reference: 'Fixing Europe's plastic recycling problem' by KPMG

Are there any other frequently asked questions about injection moulding that we did not cover in this article? Let us know!

Contact us to discuss your requirements of plastic injection mold design. Our experienced sales team can help you identify the options that best suit your needs.