Essential Injection Molding Supplies: A Complete Guide

Table of Contents

Consumables and supplies might constitute a minute part in quantity relative to equipment and tools like the molds themselves, but they are a major reason plastic injection molding succeeds or fails. So, whether you are just starting out in the world of injection molding or you’re an industry ‘black belter,’ understanding the essential supplies for injection molding gives you better leverage. 

Thermoplastic Pellets

This guide aims to walk you through the essential supplies ranging from tools to personal protective gear to help you achieve a smooth injection molding procedure. Having this go-to resource, we’re about to share with you also helps you achieve your injection molding goals especially if one of those goals is quality manufacturing. So, if you are ready to enhance your plastic injection molding production then let’s dive in together. 

1. Mold Materials and Components

1.1 Mold Base and Cavity Inserts

The success of every injection molding process begins with the selection of mold materials and components. High-quality mold manufacturing ensures that the rigors that are attached to injection molding process can be effectively sustained by the mold. 

And while selecting the mold materials, an understanding of the considerations that will offer durability, compatibility, precision, and seamless machining is essential. The mold base and the cavity insert which are the major components of the mold must be compatible with the plastic resin selected along with the molding process. 

Furthermore, the intensity of the repeated cycles requires the molds to withstand the stress, hence extending the lifespan of the mold and reducing flaws. 

1.2 Mold Steel and Alloys

Coming to this part of selecting the right mold material and component, there’s no textbook model of selection as different applications require different tools and materials. Nonetheless, certain materials provide specific qualities. 

Steel for example offers strength and durability, which are two qualities considering the stress of the process. Steel-based tools are best utilized for molding abrasive plastics and can handle high-volume productions. 

In contrast, stainless steel can sometimes be preferred due to its corrosion-resistant properties. The reason for this is because some materials have corrosive additives. A highly humid environment could also necessitate the use of corrosion-resistant tools. Stainless steel is equipped with the ability to withstand rust, especially with projects that require the utmost cleanliness.

It is important to note that a very popular feature of stainless steel is thermal conductivity. This property ensures the steady transfer of heat which maintains the mold temperature throughout the molding process and with that, consistency is achieved in the part quality. 

1.3 Mold Release Agents

What is a mold injection without a smooth surface finish? This is a crucial part of the injection molding process. And with that comes the use of release agents. These are mediums that ensure efficient and smooth part removal from the mold. They create a separation mode that permits the easy ejection of the part from the mold. 

Mold-release agents are in varying forms. This includes liquids, sprays, and semi-permanent coatings applied on the walls of the mold to aid separation while maintaining part elegance and functionality. Their applications however differ and can be reliant on the material being used and specific molding conditions. 

The semi-permanent coating is a type of release agent that creates durable mold surface layers. It’s a cheap release agent with fewer applications, which makes it a top-choice release agent for manufacturers. Additionally, it suits high-volume production runs.

In the high-quality mold manufacturing industry, liquid mold release agents are employed for intricate design moldings. Owing to the complex dimensions involved in some injection molding operations, liquid release agents can be applied by using a brush and this affords better control. 

Spray release agents are the most labor-saving release agents among them, and it provides a consistent coating on the mold surface. Spray release agents like the liquid release agents are suitable for intricate geometries. 

polystyrene pellets

2. Plastic Resins and Additives

2.1 Thermoplastic Resins

As part of the essential supplies for injection molding, plastic resins are at the foundation of the injection molding process. Their different types and properties allow moldability, the ability to melt efficiently, and maximum functionality for various applications. Thermoplastic resins are the most popular materials in injection molding. Exploring the different types of resins will broaden our scope and understanding of their contributions to injection molding. Let’s go 

  • Polypropylene (PP): A common thermoplastic resin applicable in consumer goods, automotive, and packaging industries with features such as versatility, lightweight, immense impact strength, and outstanding chemical resistance. You can understand why it is so popular in injection molding and a widely used plastic resin among manufacturers. 
  • Polystyrene (PS): Another type of thermoplastic resin with high moldability, clarity, and affordable qualities. Polystyrene like polypropylene is likewise applicable in the packaging industry and other consumer products like disposable cutleries, and electrical products. 
  • Acrylonitrile Butadiene Styrene (ABS): This thermoplastic resin provides impressive tensile strength and excellent mechanical properties. It’s valuable in making electrical enclosures, toys, and automotive parts due to its moldability and post-processing capacities.

These are a few of the many thermoplastic resins with top-quality features responsible for major numerous plastic parts and products you see around you. 

2.2 Additives and Colorants

Additives and colorants play their part in the injection molding process by offering reinforcements and colorful plastic materials. Some plastic resins are modified to improve specific qualities of the plastic resin to suit the prerequisite properties desired of the plastic resin in creating enhanced parts. 

  • Fillers: Fillers are special kinds of additives employed in injection molding to upgrade the strength and stiffness of a plastic resin without increasing cost. Common fillers deployed for this cause are glass fibers and mineral fillers. 
  • Reinforcements: These are like fillers that include carbon and glass fibers. They enhance the mechanical characteristics of the injection molded parts to attain extraordinary performance levels. Such reinforcements are employed in the injection molding of aerospace and automotive parts.
  • Impact modifiers: Additives that boost the toughness and impact resistance of thermoplastic resins are typically called impact modifiers. They are suitable for applications in aerospace where impact resistance is of huge importance. The ability for load bearing is also enhanced with such additives. 
  • Colorants: Aesthetically, colorants improve the visual appeal of injection molded parts especially since it achieves the same effect as using 3D printing technology but at reduced cost. Customized products may need market identity and colorants contribute hugely to customizing such products. Manufacturers can choose various dye options as colorants to match company product identities.
Plastics Injection Moulder

3. Injection Molding Machinery and Equipment

3.1 Injection Molding Machines

Without molding machinery, there would be no injection molding in the first place. The injection molding machine starts the melting of the thermoplastic material, injects it into the mold, and cools and solidifies it to shape into the final product. Even so, they are split into different types.

  • Hydraulic machine: This is a conventional type of injection machine that operates by the hydraulic system. Its high tonnage application capability makes it a robust option for high-volume production. Its hydraulic system is responsible for the clamping and injection and then allows it to function with heavy molds.
  • Electric machine: As the world is going electric and seeking more renewable energy ways of operating their machines, so is injection molding. The electric machine uses an energy-efficient electric motor to control the clamping and injection processes, delivering precise control and quicker response time.
  • Hybrid machines: This combines both the hydraulic and electric systems of injection machining. The advantage of a hybrid injection molding machine is to maximize energy consumption while benefiting from the technologies adopted by both types of machines. A balance between efficiency and performance is achieved and performance is fully optimized.

3.2 Auxiliary Equipment

In addition to injection molding machines, there are specific instruments that exist for the sole purpose of ensuring efficient production and smooth finishes. These auxiliary equipment are charged with separate tasks that prepare the materials for injection molding and ensure perfect process finishes. These auxiliary machines include

  • Material dryers: Machine dryers are important to injection molding because it ensures bubble-inducing moistures are mopped clean from the thermoplastic resins in preparation for melting. Moistures in a plastic material can lead to voids and bubbles which affects the overall integrity and performance of the part produced.
  • Hopper loaders: This loader is a feeding mechanism that initiates the transfer of the plastic resins to the barrel where they are melted. The hopper loaders are crucial to injection molding as they continuously feed the injection molding barrel. 
  • Temperature controllers: The function of the temperature controllers is to regulate the temperature of the melting and cooling process. The controller ensures the appropriate temperature is maintained for excellent part production.
  • Robots: the need for robotic systems in injection molding is to facilitate the removal, stacking, and packaging where automation is needed. This reduces the use of manual labor, increases efficiency, and reduces production time thereby saving cost. 

The effective use of all these auxiliary machineries reduces the chances for human error, upholds standards of quality production, and ascertains the mechanical structure integrity for safe use.

cutting tools injection molding

4. Tooling and Mold Maintenance Supplies

4.1 Cutting Tools and Abrasives

It is paramount to itemize the role of tooling and mold maintenance in injection molding. For molding of intricate angles or even simple designs and ensuring part consistency a mold maintenance system is essential. Like high-quality CNC machining, cutting tools and abrasives are some of the necessary tools available for mold maintenance.

Cutting tools such as drills and end mills are important to injection molding because they are required to remove excess materials, fashion complex geometries on the mold, and amend faulty exteriors of a mold. 

They were made to resist the rigors and stress of mold machining processes as they are made from quality carbide or steel. These sharp-ended tools are necessary for achieving an outstanding, flaw-deficient surface finish.

For molds to be completely rid of blemishes such that molded parts can be greatly affected, imperfections such as rough spots are smoothened out on the molds by using abrasives to eliminate them. 

Abrasives are such excellent polishing tools to even out mold surfaces with distortions liable to affect a part’s outcome and aesthetic appeal. 

4.2 Cleaning and Lubrication Products

Maintaining mold integrity is one part, ensuring efficient production is another part. Ultimately, these are parts of mold maintenance that can be heavily influenced and assisted by the cleaning and lubrication product applied to ensure both functions are met. For that reason keeping molds well lubricated and cleaned is an essential part of maintenance of tools and molds which is likely to either adversely affect or positively contribute to a successful injection molding process. 

Mold cleaners are one of the various ways of achieving this feat. They actively remove residues such as contaminants from mold surfaces. Mold cleaners when clinically applied ensure smooth mold operation, eliminate the chances of defects in parts, and ensure mold longevity. Mold cleaners clear the path for component manufacturing with precise and accurate dimensions.

Rust preventives are another way of keeping molds from corrosive tendencies. This is why selecting the material for making molds is crucial in carefully selecting corrosion-resistant materials. When molds are stored and not in use they run a risk of corroding. But with rust preventive lubricants, mold surfaces can be kept intact and maintenance cost is reduced.

Mold release agents are lubricants that foster the smooth release of molded parts from the mold as earlier discussed in this guide. They lubricate the mold surface and prevent the stickiness of plastic resins to molds, thereby enabling a smooth and consistent surface finish. 

safety glasses for protecion during injection molding

5. Safety Equipment and Personal Protective Gear

Safety equipment and personal protective gears are not to be overlooked in any injection molding space. Especially given the imminent exposure of operators to high-temperature, enormous tools and machines, and undoubtedly dangerous biohazard materials. On that note, protective gear and safety standards must be top-priority to manufacturers. 

  • Safety glasses: every operational worker in any injection molding production factory must be provided with many protective gears and safety glasses are one of them. These can protect workers from sudden chemical splashes, debris of plastics, and melted plastic flying unexpectedly. Furthermore, it is essential to provide impact-resistant glasses to personnel for sufficient protection.
  • Gloves: These are required to protect the hands from chemical exposures or when working with hot materials. Gloves are appropriate for safely protecting workers from cuts and burns, and the best kind of gloves are nitrile gloves renowned for their puncture and chemical-resistant properties. 
  • Ear protectors: earmuffs and noise cancellation ear plugs are necessary to counter the effect of loud noises. To prevent ear damage or potential deafening in injection molding factories earplugs are greatly advised.
  • Respiratory protective gadgets: respiratory protective equipment is necessary to guide against inhaling harmful chemicals to the body. Moreover, airborne particles and fumes are likely to fill the air during the injection molding process. 


In summary, injection molding essential supplies all work towards the success of every injection molding exercise. From selecting the best mold material which recommends considering mold base and cavity inserts, mold steel and alloys, and mold release agents to considering the different plastic resins and additives. In addition, injection molding machinery and equipment helps us gain more insight into the different types such as the hydraulic, electric, and hybrid, in connection to auxiliary equipment involved in the injection molding process. Ultimately, for all to work smoothly and in unison, tooling and maintenance supplies cannot be neglected. Conclusively, the safety of workers and injection molding operators actively involved in the process must be catered to by providing safety tools and protective gear. With all the knowledge gained from this guide, you are good to go. 


Gary Liao

Gary Liao

Gary Liao is the Engineering Manager of TDL Company and has more than 20 years of mold design experience.

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