What is Plastic Injection Molding?

Plastic injection molding is a cost-effective method for mass-producing plastic parts. It involves injecting molten plastic into a mold and then ejecting the solidified part. This process ensures consistent quality and offers a wide range of material options, colors, and finishes compared to other methods like CNC machining or 3D printing.

At ThesunIndustry, we provide custom plastic molding services tailored to your needs. Our customer-centric approach ensures quality without compromising on design, all at a reasonable cost. We specialize in various industries, with expertise in medical injection molding and liquid silicone rubber (LSR) molding.

Our team has accumulated substantial expertise in numerous industries, with a notable emphasis on medical injection molding, plastic molding, and liquid silicone rubber (LSR) overmolding.



Choose ThesunIndustry for Parts of Any Complexity, Ranging from 3 mm to 1 m in Size. Experience industry-leading lead times as fast as 20 days. Our extensive manufacturing employs injection machines ranging from 60 to 1300 tons, catering to various part sizes, complexities, and volumes. For precision requirements, tighter tolerances are available upon request. Partner with us for top-quality parts delivered on time and tailored to your specific needs.

Plastic injection molding

Injection molding is a high-pressure manufacturing process that involves injecting thermoplastic materials into a mold. It is the ideal choice for high-volume production, offering cost-effective and efficient manufacturing solutions.

Plastic 2-shot molding

Two-shot injection molding, also known as two-color or dual-material injection molding, refers to the process of injecting two different materials into the same mold to create a single, integrated part.

Plastic and metal Insert molding

Insert molding is an injection molding process that works especially well for parts that have threaded holes. It can also help you create better wheels, pulleys, fan blades, and other similar parts.

Plastic and LSR Over-molding

Plastic and LSR (Liquid Silicone Rubber) over-molding is an innovative manufacturing process that combines the advantages of both plastic and silicone materials to create high-performance, multi-material parts.

Advantages of Our Plastic Injection Molding Technology

High Precision and Complex Geometries: Through precise mold design and advanced injection molding techniques, we can produce plastic parts with high precision and intricate geometries. Whether you require fine details or complex structures, we can meet your requirements.

Mass Production and High Efficiency: Plastic injection molding allows for the simultaneous production of multiple identical or different parts, increasing production efficiency. Our advanced equipment and automated processes reduce production cycles and minimize manual intervention, resulting in cost-effective manufacturing.

Material Diversity and Customization: We offer a wide range of plastic materials to meet the requirements of various industries and applications. Depending on your project needs, we can select suitable materials and accommodate color adjustments, surface treatments, and special requirements.

High Quality and Reliability: We prioritize quality control and process monitoring to ensure that the produced plastic parts meet stringent quality standards. By utilizing plastic injection molding, we provide consistent, dimensionally accurate, and reliable parts.

Our Plastic Injection Capabilities

Service Details
Lead Time Our services offer fast quote responses with design-for-manufacturing (DFM) feedback within 5 business days.
Production Options Domestic and international
Machines Available We provide a wide range of molding options, including single, multi-cavity, and family molds, with press tonnage capabilities ranging from 60 to 1,300+ tons.
Inspection and Certification Options Includes FAI, FMEA, and PPAP. ISO 9001,, ISO 16949, UL, Class 8 Medical Clean Room molding.
Tool Ownership Customer-owned with mold maintenance
Mold Cavity Tolerances a tolerance of +/- 0.005mm during mold machining while considering the shrink rate.
Part to Part Repeatability +/- 0.01mm or less
Critical Feature Tolerances ThesunIndustry ensures critical features are milled to a steel-safe condition for optimal precision..
Available Mold Types Single-Cavity Molds, Multi-Cavity Molds, Family Molds, and the production cycles will be under 1000 cycles, under 100,000 cycles, under 500,000 cycles and over 1000,000 cycles

ThesunIndustry’s Related Technology of Plastic Injection Molding

ThesunIndustry is a leading company with outstanding technological advantages in the field of plastic injection molding. We combine the latest advanced technologies and innovative solutions to provide customers with high-quality injection molding services. Here are the technological advantages of ThesunIndustry in the plastic injection molding field:

Advanced Mold Design: 

We have an experienced engineering team proficient in Computer-Aided Design (CAD) and Computer-Aided Engineering (CAE) technologies. We use advanced simulation analysis during the mold design phase to optimize plastic flow, minimize potential defects, and ensure the accuracy and consistency of part molding.

High-Performance Mold Materials: 

To ensure the durability and stability of the molds, ThesunIndustry adopts high-strength mold materials and state-of-the-art coating technologies. These materials and coatings offer excellent wear resistance and thermal conductivity, ensuring the molds operate reliably in high-volume production environments.

Precision Injection Control: 

Our injection production lines are equipped with advanced injection machines and control systems, enabling highly precise injection processes. Precise control of temperature, pressure, and injection speed ensures that each part meets the strict requirements of our customers.

Technological Innovation:

ThesunIndustry continuously drives technological innovation and closely follows the latest technologies and trends related to plastic injection molding. We maintain a leading position in areas such as micro-injection molding, gas-assisted injection molding, and actively research eco-friendly plastic materials to meet customers' demands for sustainable development.

Smart Manufacturing Applications:

We integrate the concept of Industry 4.0 into our production process, adopting intelligent manufacturing technologies. Through the use of sensors, data analytics, and real-time monitoring, LingshanTech achieves intelligent control and optimization of the production process, enhancing production efficiency and product consistency.

As a leading plastic injection molding company, ThesunIndustry not only constantly innovates in technology but also strives to provide excellent solutions and high-quality products to our customers. Our professional team will continue to work closely with customers to promote the development and advancement of the industry.

Secondary Operations

We provide various secondary operations, including painting and heat-tapping inserts, among others. For your specific needs, please mention the required secondary operations in the "custom requirements" section of your quote request.

  • Inserts
  • Pad Printing
  • Painting
  • Silk screening
  • Ultrasonic welding
  • Laser engraving
  • UV coating
  • Heat staking
  • Hot stamping
  • Post-mold machining

Custom Injection Moldings Design Guidelines

Feature Tip
Undercuts Incorporating pass-thru coring helps to minimize undercuts, thereby reducing the complexity and cost of the tool's ejection mechanisms.
Wall Thickness Maintaining uniform wall thickness in plastic parts helps prevent wall sink and voids, while thinner walls contribute to shorter cycle times and lower manufacturing costs.
Drafts Ensure parts are designed with a minimum draft angle of 0.3°, or up to 5°, for faces with medium textures.
Ribs/Gussets Ribs should be 40-60% the thickness of outer walls and should still maintain draft.
Bosses To ensure structural integrity, bosses should be designed at 30% of the wall thickness in depth, featuring a 30% edge groove, and attached to side walls or ribs.

How We Manage Your Injection Molding Project?

Step Description
1. Upload Design Submit your product's 3D design for review by our specialist team. Receive expert insights and recommendations.
2. Receive Quote Collaborate with your account manager and technical team to get a detailed quote within 48 hours.
3. DFM & Tool Approval Review the Design For Manufacturing (DFM) analysis for your approval before tool construction begins.
4. Receive T1 Samples Prior to production, receive a golden sample for approval to ensure it meets your specifications.
5. Production & Delivery Parts are manufactured to match the approved sample and promptly delivered to your location.
6. Reorder as Required Easily reorder parts by contacting your account manager for any future requirements.

Surface Finish Options

Draft angle requirements will vary by requested finish. Industry standard Mold-Tech finishes are also available.

PM-F0 non-cosmetic, finish to Protolabs' discretion
PM-F1 low-cosmetic, most toolmarks removed
PM-F2 non-cosmetic, EDM permissible
SPI-C1 600 grit stone, 10-12 Ra
PM-T1 SPI-C1 + light bead blast
PM-T2 SPI-C1 + medium bead blast
SPI-B1 600 grit paper, 2-3 Ra
SPI-A2 grade #2 diamond buff, 1-2 Ra


We’ve worked with many types of resins, including:

Property Materials
Impact resistant ABS, PMMA, PVC, PE, PC
Wear-resistant POM, PEEK, UHMW
Dimensional stability ABS, PBT, HIPS, PPS
Chemical resistance PEEK, PP, PBT, PE, LDPE, PA
Rubber like TPU, TPE, Silicone
Cost-efficient PP, HDPE, LDPE
Cosmetic ABS, PC, HIPS


The specific tolerance ranges may vary depending on project requirements, material types, and manufacturing equipment. Here are the typical tolerance range values:

For small-sized parts (less than 50 millimeters), it is generally possible to achieve smaller tolerances. Typically, tolerance values may range from 0.05 millimeters to 0.2 millimeters.

For medium-sized parts (50 millimeters to 200 millimeters), the tolerance range may slightly increase. Generally, tolerance values may range from 0.1 millimeters to 0.5 millimeters.

For large-sized parts (greater than 200 millimeters), the tolerance range may be larger. Generally, tolerance values may range from 0.5 millimeters to 1 millimeter.

Please note that these tolerance ranges are provided as general guidance and may vary depending on project requirements, material characteristics, and manufacturing capabilities. In specific projects, we assess and determine the tolerance range in collaboration with the client, considering their specific needs and design requirements.

Applications of Plastic Injection Molding


Plastic injection molding technology finds extensive applications across various industries, main including:

  • Automotive Industry: Manufacturing automotive components such as interior parts, exterior components, and functional elements.
  • Electronics and Electrical: Production of plastic enclosures, connectors, wire harnesses, and other electronic components.
  • Medical Devices: Manufacturing medical equipment and instruments like syringes, surgical tools, and implants.
  • Consumer Goods: Production of plastic containers, household items, toys, and more.
  • Industrial Components: Manufacturing plastic parts for machinery, aerospace, energy, and other industrial sectors.


How Much Does Plastic Injection Molding Cost?

Discover how to reduce the manufacturing costs of your custom parts through our injection molding guide, which explores the key factors influencing expenses such as tooling, materials, and production.

Who Owns the Injection Mold?

Customers own all custom tooling they develop, while reusable proprietary components created by the manufacturing partner (MP) become the MP's property. Custom tooling remains at the MP's facility for a minimum of two years, with the option for extension if needed. Transfers to other locations are possible at the requester's expense.

What Happens if an Injection Molding Partner Leaves the ThesunIndustry?

In the event that an injection molding partner leaves Lingshantech, we cover the cost of transferring all molds to another manufacturing partner within our network. This ensures uninterrupted production and timely delivery of your parts.

What Is the Process after Ordering?

Upon receiving the order, our manufacturing engineers review the statement of work. A case manager is assigned, and a suitable manufacturing supplier is selected. We create a thorough DFM report for approval. After approval, tooling and mold production begin. T1 samples are produced and sent for approval. Upon approval, the rest of the parts are manufactured.

What ISO Certifications Do You Have?

Having both ISO 9001 and IATF 16949 certifications showcases our dedication to maintaining rigorous quality management practices and meeting the stringent requirements of our client’s industry.