According to the Global News Wire, The plastic injection molding market size is expected to reach USD 419.1 Billion in 2030. PVC is one of the most commonly used materials in plastic injection molding due to its versatility and cost-effectiveness.
As developing countries are focusing more on their infrastructure, the demand for heat and pressure-resistant materials is increasing, making PVC a popular choice for industrial products that require strength and stability.
In this article, we will take a close look at PVC injection molding, its applications, advantages, and disadvantages. We will also answer some important FAQs related to PVC injection molding and its process.
What is PVC Material?
PVC stands for ‘Polyvinyl Chloride’ – It’s a high-strength thermoplastic used for a variety of applications such as pipes, medical devices, stationary, etc. It can be reheated to mold different parts without degradation.
Every year, more than 40 tons of PVC is produced worldwide, making it the third most produced synthetic material in the world. China, being the largest PVC producer, takes about half of the world’s PVC production capacity.
The production of polyvinyl chloride involves the polymerization process of the vinyl chloride monomer (VCM).
Although PVC can be colored, it is typically used in its natural white or gray form. In its true form, it’s very brittle until the addition of a few plasticizers.
History of PVC
A German scientist Eugen Baumann made a remarkable development for the plastic industry by synthesizing PVC for the first time in 1872.
PVC wasn’t commercialized until B.F. Goodrich hired industrial scientist Waldo Semon to develop an alternative to natural rubber. Soon, the demand for PVC peaked during World War II when military ships needed insulators.
Characteristics of PVC
PVC characteristics and properties are ideal for PVC injection molding.
Let’s take a look at some of them:
| Characteristic/Property | Description |
|---|---|
| Density | 1.38 g/cm3 |
| Melting point | 212 — 500 °F (100 – 260°C) |
| Appearance | White, Brittle Solid |
| Tensile strength | Flexible PVC: 6.9 — 25 MPa (1000 – 3625 PSI) Rigid PVC: 34 — 62 MPa (4930 – 9000 PSI) |
| Young’s modulus | 3275 MPa |
| Thermal conductivity | 0.12 – 0.25 W/(m·K) |
| Odor | Odorless |
| Chemical Formula | (C2H3Cl)n |
| Solubility in Water | Insoluble |
Note: The values may vary depending on the specific type and grade of PVC used.
Can PVC Be Injection Molded?
PVC can be injection molded by melting it. In fact, it is one of the most common manufacturing processes used for PVC.
If your manufacturing process needs efficiency and cost-effectiveness, PVC injection molding is your best bet. For example, if you belong to the automotive industry, PVC injection molding is used to produce critical components such as dashboards, door panels, window frames, and interior trims.
Its ability to produce complex parts with great precision makes it a preferred choice in the manufacturing industry.
Additionally, the process can be customized to produce a wide range of shapes, sizes, and finishes, depending on the type of product you are creating.
PVC Injection Molding Processing Guide
Additives Used for PVC Injection Molding
To go through an injection molding process, PVC material may require some additives depending on the desired material properties such as:
- Plasticizers: If you need more flexibility and workability in your PVC material, you will need to add some plasticizers. They are typically added in small amounts to soften the material and make it more pliable. Common plasticizers used in PVC injection molding include phthalates, adipates, and citrates.
- Stabilizers: To prevent degradation and discoloration due to heat, sunlight, and oxygen, stabilizers are added to PVC. This prolongs the PVC lifespan and makes the products durable. Common stabilizers used in PVC injection molding include tin, lead, and calcium-based compounds.
- Lubricants: PVC sometimes creates friction during injection molding. Lubricants such as stearic acid, myristic acid, and paraffin wax are added to increase the flowability of the PVC.
- Fillers: Filler materials improve the overall part costs and add strength and stiffness to the final molding product. Common fillers used in PVC injection molding include calcium carbonate, silica, kaolin, and clay.
- Pigments: Pigments are added to PVC to provide color and improve its aesthetic appeal. They can be used to create a wide range of colors and effects, from solid colors to metallic finishes.
- Flame Retardants: Flame retardants are commonly used as additives in PVC injection molding to enhance the material’s fire resistance properties.
PVC Injection Molding Process (Step-by-Step)
The process of PVC injection molding is comparable to other types of injection molding.
Given below is a step-by-step guide on how to manufacture PVC components through injection molding machines in a professional manner:
- Material Preparation: To obtain the desired properties and color, PVC resin pellets are carefully mixed with plasticizers, stabilizers, lubricants, and pigments.
- Heating: PVC pellets or powder are heated until they liquefy and acquire a steady viscosity. The appropriate PVC molding temperature ranges from 345°F to 375°F, but it depends on various factors.
- Injection: The injection molding machine dispenses molten PVC into the mold at high pressure through a nozzle. The molds must be kept at a temperature between 70°F and 130°F.
- Cooling: In order to allow the PVC to take on the desired shape, the PVC mold is subjected to a cooling process.
- Ejection: Once the PVC has solidified, the mold opens, and the finished product is released into a designated collection bin.
- Finishing: Depending on the intended application, the molded part may undergo further finishing processes such as trimming, painting, or assembly.
The extent of PVC shrinkage can be influenced by a number of factors, including the material’s level of hardness, holding time, melt temperature, mold temperature, and type or amount of additives utilized. Typically, PVC shrinkage averages between one and two percent.
PVC Injection Molding Conditions
| Parameter | Value |
|---|---|
| Machine Type | Reciprocating screw injection molding machines |
| Screw Compression Ratio | ≤3.0:1 |
| Clamp Capacity | 1.5 to 2.5 tons per square inch |
| PVC Melt Temperature | 345°F to 375°F (174°C to 191°C) |
| Mold Temperature Range | 70°F to 130°F (21°C to 54°C) |
| Nozzle Temperature | Adjusted based on barrel zones |
| Drying Temperature | 75°F to 90°F (23.9°C to 32.2°C) |
| Backpressure | 50 to 125 psi |
| Screw Speeds | Slow or medium to avoid degradation |
| Processing Time | 30 to 60 seconds (average), can be longer depending on part size, dimensions, and mold temperatures |
What Are the Advantages of Injection Molding PVC?
Here’s why you should admire PVC injection molding for your manufacturing parts:
Durability
Did you know that PVC pipes can last up to 100 years, according to some studies? The long lifespan of PVC pipes has important implications for infrastructure planning and development.
Thanks to its tightly bound molecular structure, which makes it resistant to corrosion and degradation over time.
The durability of PVC pipes is further enhanced through the use of additives during the manufacturing process. For example, stabilizers can be added to PVC to improve its resistance to UV radiation and other environmental factors.
Flexibility
PVC has several degrees of hardness – each degree is achieved by the addition of plasticizers. The hardness of PVC is measured in Shores. The normal range of PVC is from 35 to 90 Shores.
Flexible PVC has lower costs than rigid PVC. It also has a high impact strength, good electrical insulation properties, and requires minimal finishing.
The flexibility of PVC makes it suitable for use in a variety of applications, such as electrical cable insulation, medical tubing, and inflatable products.
However, it is important to note that the flexibility of PVC can be affected by factors such as temperature and exposure to sunlight. High temperatures can cause plasticizers to leach out of PVC, which can make it more brittle and less flexible over time.
Exposure to UV radiation can also cause the degradation of PVC, which can impact its flexibility and other properties.
Chemical Resistance
PVC’s chemical resistance can be attributed to its tightly bound molecular structure, which makes it less susceptible to degradation or chemical reactions.
Here’s a complete chart that shows the resistance of PVC against various chemicals:
| Type | Resistance |
|---|---|
| Dilute Acids | Very Good |
| Dilute Alkalis | Very Good |
| Aromatic Hydrocarbons | Poor |
| Esters | Poor |
| Boric acid | Very Good |
| Ketones | Poor |
| Soaps | Very Good |
| Gasolines | Very Good |
| Kerosene | Very Good |
| Natural Gas | Very Good |
| Chlorine | Poor |
Recyclability
PVC is 100% recyclable – which means you can use it to reduce the carbon footprint and save energy.
According to the PVC Pipe Association, the production and use of PVC pipes have a lower environmental impact than other materials such as concrete and ductile iron.
Most PVC products can be recycled up to six to seven times. Given the lifespan of PVC, which is around 100 years. The material can be recycled and used for up to 600 years which is astonishing.
Cost-Effectiveness
Items manufactured through the injection molding process using PVC are usually more economical compared to numerous other materials like copper, aluminum, concrete, and glass.
PVC’s long-lasting quality ascertains cost-effectiveness by reducing expenses linked with maintenance and replacement. Not to mention, the setup requirements for PVC are also lesser than those for other materials.
Additionally, PVC is a sustainable material, rendering it eligible for repurposing and reuse at the end of its lifespan. This recyclable attribute brings added savings for industries that can integrate recycled PVC in their manufacturing operations.
Flame Resistance
PVC possesses innate flame-resistant qualities that render it suitable for use in situations where fire safety is a priority. Its fire-retardant characteristics stem from its high chlorine content, which affords it a natural fire barrier upon exposure to heat or flames.
Moreover, the flame resistance of PVC can be bolstered by the inclusion of flame-retardant additives throughout the manufacturing process. These additives function by curbing the material’s flammability and slowing down the propagation of fire.
Additionally, PVC boasts a self-extinguishing quality, implying that it doesn’t continue to burn after the source of heat or flames has been extinguished. This feature is immensely significant because it prevents fire spread and mitigates damage in the event of a fire.
Widely Available
PVC injection molding is widely used throughout the world due to its versatility, precision, and repeatability.
The PVC injection molding market is expected to continue growing as PVC production increases, as so do the world’s demands. According to Statista, the worldwide PVC market will expand to approximately 60 million metric tons by 2025.
Good Color Retention
PVC displays a notable resistance to UV radiations, imparting a lower likelihood of fading or discoloration when subjected to sunlight or other sources of UV radiation.
This attribute is particularly crucial when using the material for outdoor applications, like building materials, where color preservation is pivotal to upholding the product’s visual appeal.
Additionally, PVC can be manufactured with varied surface finishes, for instance, gloss, matte, or textured, which may exert an impact on the color retention properties of the material.
To elaborate, the application of matte finishes may augment the susceptibility of showcasing dirt or discoloration as opposed to the glossy finishes, thereby influencing the appearance and color retention of the product.
What Are the Disadvantages of PVC Molding?
While PVC injection molding has many advantages, it does have some limitations that should be considered when choosing your manufacturing process.
High Upfront Costs
Although PVC molds cost per piece is low, setting up a complete injection molding mechanism for PVC requires a big budget. Sometimes the tooling costs can go up to $100,000+.
The injection molding process requires specialized equipment, such as injection molding machines, molds, and other tools, which can be expensive to purchase and maintain.
Therefore, this process is not ideal for small production runs, as the setup costs may outweigh the benefits of producing a smaller number of parts.
Initial Lead Time
The manufacturing of molds and tooling is a time-consuming task that may necessitate numerous design and testing stages in order to finalize the product for production. As a consequence, the lead time before commencing production may be extended.
It should be emphasized, however, that although the initial lead time for PVC molding can be long, the process can ultimately yield more efficient and expedited production in the long run.
Subsequent to the installation of the mold and tooling, large quantities of high-precision parts can be efficiently produced through the injection molding process with consistency.
Applications of PVC Injection Molding
Here are some industries and their applications of PVC injection molding:
Automotive Industry
The PVC material is strong, durable, and lightweight, making it ideal for use in automotive applications. It can produce complex shapes and sizes that are essential for manufacturing interior and exterior parts of cars.
Examples:
- Dashboard and console covers
- Door panels
- Armrests and interior trim
- Weatherstripping and seals
Construction Industry
PVC injection molding is widely employed in the construction sector to fabricate a range of items, including pipes, fixtures, and configurations. PVC, being a lightweight, sturdy, and corrosion-resistant substance, is found to be a suitable choice for application in plumbing and drainage systems.
Examples:
- Pipes and fittings
- Window profiles and frames
- Flooring and wall panels
- Electrical conduit
Healthcare Industry
The utilization of PVC injection molding has gained popularity in the healthcare sector when it comes to the production of medical equipment and devices. PVC, known for its non-toxic and biocompatible nature, is deemed resilient to sterilization and resistant to chemicals.
Examples:
- IV bags and tubing
- Blood bags and tubing
- Catheters and connectors
- Respiratory equipment and masks
Consumer Goods Industry
The technique of PVC injection molding has the ability to fabricate superior quality products with exceptional resilience, sturdiness, and tenacity that can endure abrasion and attrition.
Moreover, this production technique facilitates the creation of products in a variety of configurations and dimensions, which empowers manufacturers to devise and innovate distinctive and unique creations that cater to the requirements of the consumers.
Examples:
- Toys and games
- Household items such as hangers, storage boxes, and baskets
- Packaging such as blister packs and clamshell containers
- Electrical switch boxes and covers
Future of PVC Injection Molding
The advancements observed in technology are driving the trajectory of PVC injection molding forward. By means of the integration of computer-aided design (CAD) and 3D printing, more intricate and complex items can now be fabricated.
In order to augment the process of manufacturing, automation, and robotics have been introduced, leading to a surge in efficiency and speed.
This has eventually led to the evolution of PVC injection molding into a more agile and productive means of producing top-quality goods.
Choosing a PVC Injection Molding Manufacturer
In this discussion, we shall explore essential factors to bear in mind when choosing a PVC injection molding producer.
- Expertise: Opt for a manufacturing company that possesses several years of experience and a demonstrable history of delivering high-quality products.
- Capacity: Inquire about the array of products they are capable of manufacturing, the dimensions of their production facility, and their overall production capabilities.
- Accreditations: Possessing certifications is an indication that a manufacturer has met particular quality and safety benchmarks.
- Client Support: The organization should be readily available to address your inquiries and consistently provide updates regarding your project’s progress.
- Costing: Obtain quotations from various manufacturers and evaluate their pricing structure, capacities, and customer support prior to making a final decision.
Get a Quote on Injection Molding PVC from Kemal Today
Searching for a dependable PVC injection molding producer to collaborate with on your next project? Kemal is the ideal choice for you!
Our extensive expertise, cutting-edge machinery, and dedication to excellence make us your ultimate partner for all your PVC injection molding requirements.
Reach out to us today to obtain an estimate for your next project and discover why Kemal is the premier preference for PVC injection molding. Together, let us transform your concepts into reality!
