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Guide to Mold Manufacturing & Its Processes

Jul. 28, 2025

Guide to Mold Manufacturing & Its Processes

Mold manufacturing is instrumental in producing a wide range of products, from simple plastic and silicone parts to complex medical devices. Knowing the ins and outs of its operation and the materials involved is key for understanding modern manufacturing. Whether you’re an industry professional, looking to design your own prototype, or simply curious about how things are made, this comprehensive guide will provide you with essential insights into the molding process.

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What is Mold Manufacturing?

Mold manufacturing is the process of shaping molten or pliable materials into parts using hollow molds. These molds are versatile, used with various materials like silicone, metals, plastics, ceramics, wood, and foam. This process ensures precise and consistent results, leading to high-quality products and efficient production of complex parts.

What Materials are Used in Making Molds?

Steel, aluminum and alloys are commonly used materials in mold production. Steel molds are known for their durability and ability to withstand high temperatures and pressures, making them suitable for high-volume production. Aluminum molds, despite their cost-effectiveness, have a shorter lifespan compared to steel and often need to be replaced. When selecting materials for mold manufacturing, factors such as production requirements, budget, and desired product characteristics should be considered.

Other materials used for mold manufacturing include plastics, ceramics, wood, and foam. These materials are typically used for less intensive applications, such as prototypes or low-volume production. They offer advantages such as lower cost, faster production, and easier modification. However, they also have drawbacks, such as lower durability, higher wear and tear, and lower precision. Therefore, these materials are not suitable for long-term or high-volume production.

Mold Manufacturing for Different Molding Processes

Mold manufacturing is essential for various molding processes. Each process has its own advantages and disadvantages, depending on the application, material, and production volume. Although there are many different molding processes, some common ones include:

Injection molding: This process involves injecting molten material into a mold cavity under high pressure to achieve the desired shape. It’s especially effective for manufacturing parts from thermoplastic, silicone, or rubber, and it offers high efficiency for large-scale production.

Compression molding: This involves compressing material into a mold under high pressure and heat. It’s suitable for simpler designs and medium series production, and is often used for rubber and silicone products. It offers benefits such as low cost, high strength, and low shrinkage. However, it also has disadvantages, such as longer cycle time, higher waste, and lower precision.

Blow Molding: This is common in creating hollow plastic objects by inflating a heated plastic tube in a mold. It is commonly used for packaging, such as bottles, containers, and jars. It offers advantages such as low cost, high speed, and flexibility. However, it also has limitations, such as lower precision, higher waste, and limited design options.

Casting: This involves filling a mold with molten metal or other uncured materials. The material then solidifies to create the desired product. This method is widely used in industries such as automotive, aerospace, and jewelry. Casting enables the production of intricate and high-quality products while minimizing waste and ensuring durability. However, it is important to consider that casting does have some drawbacks, including high energy consumption, labor-intensive processes, and long cycle times.

Thermoforming: This process involves heating plastic sheets and forming them over molds. It is commonly used for packaging, such as trays, cups, and clamshells. (In fact, we use this process to create many of the blisters used to package our parts.) It offers advantages such as low cost, high speed, and easy modification. However, it also has drawbacks, such as lower quality, higher waste, and limited design options.

When choosing the right manufacturing approach for each process, factors such as the complexity of the part, production volume, material properties, and cost considerations need to be taken into account.

What are Injection Mold Components?

Injection molds consist of several essential components that work together to shape and form materials. These components include:

- Mold Base: Provides the foundation and support for the mold components.
- Mold Cavity: Creates the desired exterior shape of the final product.
- Mold Core: Works with the mold cavity to form the internal shape of the final product.
- Sprue: Facilitates the flow of material into the mold cavity.
- Runner System: Channels the material from the sprue to the mold cavity.
- Gate: The entry point from the runner system into the individual part cavity.
- Ejector Pins: Help remove the molded part from the mold.
- Cooling/Heating System: Regulates the temperature of the mold during the manufacturing process.

Each component plays an essential role in successful production.

What’s the Difference Between Soft Tooling vs. Hard Tooling?

In mold manufacturing, two common approaches are soft tooling and hard tooling.

Soft Tooling:

Soft tooling is ideal for prototyping and testing purposes, as it allows for quick and easy mold creation and modification. It’s also suitable for low-volume production, reducing initial investment and maintenance costs. However, soft tooling has limitations, such as lower durability, higher wear and tear, and lower accuracy. Therefore, soft tooling is not recommended for high-volume or long-term production, as it can compromise the quality and consistency of the products.

Hard Tooling:

Hard tooling is preferred for high-volume and long-term production, as it offers higher durability, precision, and consistency. It’s also suitable for complex and intricate designs, as it can achieve higher quality and detail. However, hard tooling has drawbacks, such as higher initial investment, maintenance, and longer lead time. Therefore, hard tooling is not advisable for prototyping or low-volume production, as it can increase the cost and time of the project.

Mold manufacturing is a critical process in producing plastic and metal components. Understanding the intricacies, including materials selection, injection mold components, different molding processes, and tooling approaches, is key to successful manufacturing.

Pros and Cons of 6 Injection Molding Materials - RJG, Inc.

One of the first decisions that needs to be made when designing a new injection molded part is which material to use. The material (and additives) you choose has a huge impact on how plastic will flow through the mold, what the process will be, and the look and feel of the final product. Here are some pros and cons of 6 common injection molding materials.

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

1. Polypropylene (PP)

Polypropylene (PP) is one of the most popular materials for injection molding because of its moldability. It is versatile, offers a wide array of uses, and has various unique properties that make it an attractive option. Even though PP has a semi-crystalline nature, it has a low melt viscosity, which allows it to flow extremely well. That means you can fill the mold much more quickly, cutting down production time for each shot.

PP is also a relatively inexpensive material, making it cost effective. It is very resistant to moisture, has good chemical resistance, good impact strength, and is a good electrical insulator.

There are a few shortcomings, however. It has a high thermal expansion coefficient, which means it is limited in high temperature applications. It is susceptible to ultraviolet degradation and has poor resistance to chlorinated solvents, is difficult to paint due to poor bonding capabilities, is highly flammable, and is susceptible to oxidation.

2. Polycarbonate (PC)

Polycarbonate (PC) is one of the strongest, most durable materials, which makes it ideal for face shields, visors, or safety glasses. It is a naturally transparent amorphous thermoplastic, which means it remains transparent even if color is added, similar to glass. PC has great heat resistance properties and can be combined with flame retardant materials without material degradation.

PC also has high thermoplasticity, which means you’re able to melt, cool, and reheat it without material degradation. This allows it to easily be injection molded and, later, recycled. It is a pretty pliant material, so you can form it at room temperature without it cracking or breaking. The amorphous properties mean they gradually soften instead of quickly transitioning from a solid to a liquid.

There are a few areas where PC falls short. It is more susceptible to scratching, even though it is a highly durable substance. That’s why it is encouraged to apply some kind of scratch resistant layer in order to protect it on clear substances, like shields or glasses. PC is considered toxic when it comes in contact with food due to its release of BPA during degradation. There are many options today that are BPA free, however, for use in food and water applications.

3. Polylactic Acid (PLA)

Polylactic Acid (PLA) is a bio-degradable plastic that is manufactured out of plant-based materials, like corn starch or sugar cane. That’s why it is known as “the green plastic” or “bioplastic”. If you add in a filament recycler, you’re about as green as you can get. PLA is mostly used for food packaging, bottles, film, and medical supplies.

PLA is biodegradable and has characteristics similar to PP and PE and a bit more brittle than ABS. It constricts under heat, which makes it highly suitable for applications such as shrink wrap. PLA melts very easily, making cycle times shorter. It is not toxic and safe for food handling and medical implants.

Due to its low glass transition temperature, PLA is unable to contain hot liquids or other high heat applications, even a hot car in the summer. PLA is also slightly more costly than other options and can be more difficult to color.

4. Acrylonitrile Butadiene Styrene (ABS)

Acrylonitrile Butadiene Styrene (ABS) is an extremely popular middle-of-the-road injection molding material due to its balanced combination of mechanical toughness, wide temperature range, good dimensional stability, chemical resistance, electrical insulating properties, and ease of fabrication.

ABS is available in a wide range of grades and textures, including high-impact, heat resistant, fire-retardant, and high gloss. It is a tough, rigid material and metal coatings easily adhere to it. Plus, it looks great and can be very easily processed—it flows well and easily releases from the mold.

There are some downsides to ABS, though. It has poor solvent resistance and poor weatherability, but there is a UV additive that can improve that problem. ABS is also a poor electrical insulator and melts very easily (even when you don’t want it to).

5. Polyethylene (PE)

Polyethylene (PE) injection molding material is the most popular and commonly used plastic in the world, used in shopping bags, toys, garbage cans, and shampoo bottles. It is a lightweight thermoplastic material that has high chemical resistance, elasticity, and electrical insulating properties. PE has low hardness, so it is very ductile and has good impact strength, meaning it will stretch rather than break.

PE is water resistant and durable with high weatherability. Depending on the thickness of the material, it can be transparent to opaque, making it suitable for packaging applications. It can be easily recycled into other products, which is more cost effective than utilizing new plastic.

The downside to PE is that it is not environmentally friendly. It takes a long time to break down, which means it could be in landfills for decades. It can also be toxic if it is incinerated, which is another means of disposing plastic waste. PE is extracted from petroleum, or natural gas, which is a limited resource. The production of PE releases high greenhouse gas emissions of carbon dioxide, contributing to global warming and climate change. Sorting through the various types of PE to recycle it is complex and expensive.

6. Polyamide (PA):

Polyamide (PA), also known as nylon, is a semi-crystalline polymer with a good range of properties. It is tough and has a high melting temperature, good wear, and chemical resistance, so it is a good option for strong mechanical parts, such as bushings, gears, and bearings.

PA has a high temperature endurance for a short period of time. It is tough enough to withstand repeated impact. Its tensile strength is more than twice as high as ABS and is higher than that of metal, and its compressive strength is comparable to metal. It has a high resistance to abrasion and wear. When used as a movable mechanical part, PA is self-lubricating with low noise, and its smooth surface leads to very little friction. PA is also non-toxic, odorless, self-extinguishing, inert to biological erosion, antibacterial, anti-mildew, and has great weatherability.

The cons to PA are that it absorbs moisture, which can affect the electrical and mechanical properties, especially in thin-wall applications. This requires strict requirements for injection molding due to the need to ensure no moisture enters the part and the difficulty in controlling dimensional stability due to thermal expansion. Uneven wall thickness will cause distortion and deformation. It also requires UV stability due to its poor resistance to light, turning brown and then cracking when exposed. PA can also be attacked by strong acids or bases, causing material degradation and making it unable to be used as an acid-resistant material.

Are you interested in learning more about Automotive plastic injection molds? Contact us today to secure an expert consultation!

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