Comparison of Materials of Tool Box Mold

Injection molds can be made from a range of metals, each offering unique mechanical properties. The frequently used materials for tool box molds include:

P20 pre-hardened steel

H13 hot-work tool steel

718 (also known as 2738) pre-hardened steel

S136 stainless steel

Aluminum alloys (in limited cases)

Each material varies in hardness, thermal conductivity, corrosion resistance, and machinability, influencing its suitability for specific applications.

P20 is one of the commonly used mold materials for medium to large plastic components like tool boxes. It is pre-hardened to around 28–32 HRC, offering a good balance of machinability and strength.

Advantages:

Cost-effective for medium to high-volume production

Easy to machine and polish

Good toughness and uniform hardness

Disadvantages:

Moderate wear resistance compared to harder steels

May require surface treatment or coating for extended mold life

P20 is suitable for general-purpose molds and is often the choice when the production volume is not extremely high and surface finish requirements are moderate.

H13 is a chromium-molybdenum hot work steel known for its toughness and thermal fatigue resistance, making it suitable for high-temperature applications and molds exposed to significant thermal cycling.

Advantages:

High wear and heat resistance

Durable under prolonged use

Capable of producing complex, high-precision components

Disadvantages:

More expensive than P20

More challenging to machine

Requires proper heat treatment

For tool box molds intended for large-scale or high-precision production, H13 offers reliable performance over time, especially when thicker plastic parts are involved that demand uniform temperature distribution.

718 steel is an upgraded version of P20, offering improved hardness and polishability. It typically comes pre-hardened to 33–36 HRC.

Advantages:

Higher hardness and better wear resistance than P20

Good surface finish, making it ideal for glossy tool boxes

Good machinability

Disadvantages:

Higher cost compared to P20

Slightly reduced toughness at increased hardness

Mold makers often select 718 steel for tool box molds requiring surface quality or longer production runs, especially when appearance is a significant factor.

S136 is a high-grade stainless steel used when corrosion resistance and surface finish are necessary. It is fully hardened and suitable for demanding environments or clear plastic parts.

Advantages:

Good corrosion resistance

High wear resistance and polishability

Suitable for molds requiring high-gloss surfaces

Disadvantages:

High material and machining costs

Requires specialized heat treatment

Though not commonly used for basic tool box molds due to its cost, S136 may be chosen for specialized applications, such as storage boxes for corrosive or high-humidity environments.

Aluminum is occasionally used for prototype or low-volume molds. While not typically suitable for high-strength tool box molds, it offers advantages in rapid tooling.

Advantages:

Lightweight and easy to machine

Fast heat transfer and shorter cycle times

Ideal for testing and prototyping

Disadvantages:

Low wear resistance

Short mold life

Unsuitable for high-pressure or abrasive materials

Aluminum molds are generally not recommended for long-term production of rugged tool boxes, but they can be used effectively for early-stage product development or limited-run manufacturing.

Choosing the right mold material depends on several practical factors:

Production volume: Higher volumes require more durable materials like H13 or 718.

Product design: Complex shapes or detailed textures benefit from materials that allow fine polishing, such as 718 or S136.

Budget: P20 is the budget-friendly option, while H13 and S136 offer greater durability at a higher cost.

Environmental conditions: In humid or corrosive settings, stainless materials like S136 may offer added value.