| SPI Finish | Description | Typical Applications Surface | Roughness (Ra µm) |
|---|---|---|---|
| SPI A-1 | Grade #3, 6000 Grit Diamond Buff | High polish or transparent parts, optically clear | 0.012 - 0.025 |
| SPI A-2 | Grade #6, 3000 Grit Diamond Buff | High polish or transparent parts | 0.025 - 0.050 |
| SPI A-3 | Grade #15, 1200 Grit Diamond Buff | High-to-medium polish parts, non-optical lenses | 0.050 - 0.100 |
| SPI B-1 | 600 Grit Paper | Medium polish parts | 0.05 - 0.10 |
| SPI B-2 | 400 Grit Paper | Medium polish parts | 0.10 - 0.15 |
| SPI B-3 | 320 Grit Paper | Medium - low polish parts | 0.28 - 0.32 |
| SPI C-1 | 600 Stone | Low polish parts | 0.35 - 0.40 |
| SPI C-2 | 400 Stone | Low polish parts | 0.45 - 0.55 |
| SPI C-3 | 320 Stone | Low polish parts | 0.63 - 0.70 |
| SPI D-1 | Dry Blast Glass Bead | Satin finish | 0.80 - 1.00 |
| SPI D-2 | Dry Blast #240 Oxide | Dull finish | 1.00 - 2.80 |
| SPI D-3 | Dry Blast #24 Oxide | Dull finish | 3.20 - 18.00 |
Plastic Injection Molding
CAPABILITIES
Plastic Injection Molding
A faster, easier way to order high-quality injection molded parts that accelerates iteration, testing, and scaled production. Upload your designs for DFM feedback and pricing in 1 business day.
Our Injection Molding Process
Injection molding is the most economical method for mass-producing plastic parts. This process involves injecting molten plastic into a mold, where it solidifies before being ejected. This cycle repeats rapidly, allowing the cost of the mold to be spread across hundreds or thousands of parts, reducing the cost per unit to just a few dollars or less. Using the same mold for each part ensures consistent quality across all units. Injection molding offers the widest range of materials, colors, finishes, and surface textures, surpassing the options available through CNC machining or 3D printing. Long Shen's custom plastic molding service provides on-demand prototyping and production molding. We prioritize a customer-first approach, ensuring we deliver the perfect injection molding solution to meet your needs.
Design Validation and Production
Steel tooling with rapid lead times and no minimum order quantities—ideal for prototyping, design validation, and bridge production.
Overmolding
For applications such as buttons, grips, or seals, overmold rubber or silicone onto an existing plastic part.
Insert Molding
Mold plastic around a preformed insert, often metal-threaded, to create components with integrated metal parts.
Plastic Injection Molding Materials
Can mold any commercially available thermoplastic. Please reach out with your specific resin needs.
Plastic Injection Molding Finishing Option
SPI Finishes (Society of the Plastics Industry):
MT (Moldtech):
Common Mold-Tech Injection Molding Finishes
| Mold-Tech Serial Number | Texture Depth (inch) | Application | Minimum Draft |
|---|---|---|---|
| MT-11010 | 0.001" | Dull matte finish | 1.5° |
| MT-11020 | 0.0015" | Coarse matte finish | 2.25° |
| MT-11030 | 0.002" | Coarse matte finish | 3° |
VDI (Verein Deutscher Ingenieure):
Common VDI Injection Molding Finishes
| VDI Value | Description | Applications | Surface Roughness (Ra µm) |
|---|---|---|---|
| VDI 12 | 600 Stone | Low polish parts | 0.40 |
| VDI 15 | 400 Stone | Low polish parts | 0.56 |
| VDI 18 | Dry Blast Glass Bead | Satin finish | 0.80 |
| VDI 21 | Dry Blast # 240 Oxide | Dull finish | 1.12 |
| VDI 24 | Dry Blast # 240 Oxide | Dull finish | 1.60 |
| VDI 27 | Dry Blast # 240 Oxide | Dull finish | 2.24 |
| VDI 30 | Dry Blast # 24 Oxide | Dull finish | 3.15 |
| VDI 33 | Dry Blast # 24 Oxide | Dull finish | 4.50 |
| VDI 36 | Dry Blast # 24 Oxide | Dull finish | 6.30 |
| VDI 39 | Dry Blast # 24 Oxide | Dull finish | 9.00 |
| VDI 42 | Dry Blast # 24 Oxide | Dull finish | 12.50 |
| VDI 45 | Dry Blast # 24 Oxide | Dull finish | 18.00 |
YS (Yick Sang)
Require YS Finish? Contact us, and we will look into accommodating you to meet your requirements!
Plastic Secondary Operations Processes
All finishes meet SPI standards
Heat Staking
Heating plastic to reform it and insert a component (e.g., a threaded insert).
Laser Engraving
Engraving text or a design with a laser.
Pad Printing
Applying an ink-based, 2D design to a 3D surface
Painting
Applying primer, topcoat, EMI (copper) paint, in both standard and Pantone colors.
Ultrasonic Plastic Welding
Joining or reforming thermoplastics with a high-frequency welder
How it Works
1. Submit Your Designs
Upload your 3D CAD and 2D technical drawings to our secure platform.
2. Receive a Quote
Configure your projects in our quote-to-order system and get pricing within one day.
3. Review Your T1 Samples
During the trial phase, view the T0 sampling and receive T1 samples within 2-3 weeks for review before production begins.
4. Order Parts
After sample approval, production starts with an average lead time of 4-7 business days.
5. Begin Production
Utilize our mold library to select and order your parts.
6. Ready to Begin?
Plastic Injection Molding FAQs
Injection molding could absolutely be used for prototyping, but it depends on the project requirements. Typically, for projects that require less than 10 prototypes, injection molding may not be the most cost-effective option. We are happy to meet with you to discuss your needs and help determine if injection molding is the correct process for you.
Long Shen is happy to offer you injection molding services with NO minimum order quantity.
Absolutely. As long as you are able to supply project requirements and part specifications, Long Shen is happy to provide a no-obligation quotation.
Of course! Long Shen will maintain your mold for 2 years after your most recent order and allow you to re-order parts for the duration of the mold life.
Long Shen does not charge any inventory fees for holding your molds, as long as you order off of the mold within 2 years. After 2 years of inactivity, Long Shen will ship/destroy the mold at the customer's direction.
Long Shen has the ability to build both aluminum and steel molds.
A part manufactured through 3D printing is orders of magnitude more expensive than the same part manufactured through injection molding, assuming the design is a fit for injection molding. As long as you produce enough of that part to offset the mold cost, it would be worth it to pursue injection molding. Long Shen provides you with DFM on your design and options for mold architecture to give you the best cost-benefit balance. Request an injection molding quote for your 3D-printed part design to get a no-obligation quotation and DFM and assess your options at no cost to you. It is recommended that you get an expert involved early on in the design process if you intend to use injection molding for production. Many customers invest significant time in creating 3D-printed prototypes and making revisions without taking into account the specific manufacturing constraints associated with injection molding. This oversight can lead to wasted resources, both in terms of money and time. By providing Design for Manufacturability (DFM) guidance tailored to injection molding, Long Shen can help you avoid such pitfalls, resulting in significant savings in time and costs.
Long Shen does not conduct mold flow analysis as a standard DFM analysis for injection molding, however, to get an Enhanced Design Validation, it can be done, upon request, as an additional service.
The tooling lead time can vary depending on the complexity of the part. In some cases, it can be as quick as 10 days, while in a more complex design, it may extend to around 21 days (calendar days). For parts larger than 300mm, the lead time might be further extended due to the additional complexities involved in manufacturing larger components.
Once the materials and molds are prepared and in place, the injection molding process allows for the production of several hundreds of molded parts per day.
