Custom Injection Molding Services for Plastic Parts Production

Top Proto delivers injection molding services for product teams and manufacturers that need plastic parts produced with consistent wall thickness, accurate surface detail, and repeatable dimensional quality across every production cycle. We handle the complete process from mold design review and tooling production through to part inspection and shipment, covering low-volume prototype molding and high-volume production runs from our manufacturing facility in Shenzhen, China.

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What Is Injection Molding?

Injection molding is a manufacturing process in which molten plastic material is injected under pressure into a closed mold cavity, allowed to cool and solidify, and then ejected as a finished part. The process is highly repeatable — once a mold is qualified, every subsequent shot produces a part with the same geometry, wall thickness, and surface finish as the first.

At Top Proto, we use injection molding to produce plastic components across a wide range of thermoplastic materials, from commodity resins such as ABS and polypropylene to engineering-grade materials including PEEK, Nylon, and polycarbonate. The process is suitable for parts with complex internal features, thin walls, snap-fit interfaces, and surface textures that cannot be achieved cost-effectively by other manufacturing methods at production volumes.

Our Molding Services

Injection Molding

Standard thermoplastic injection molding for prototype and production parts. We produce single-cavity and multi-cavity molds in aluminum or steel, with shot weights and cycle times optimized for your part geometry and required production volume.

Tool Mold

Mold tooling produced in aluminum for rapid prototyping or hardened steel for long-run production. We design and machine mold cavities, cores, runners, and ejection systems to suit your part geometry and material requirements.

Insert Molding

Insert molding encapsulates metal inserts — threaded fasteners, pins, bushings, or electrical contacts — within a plastic part during the molding cycle. The result is a single-piece component with a mechanically locked interface between the plastic and metal elements.

Overmolding

Overmolding applies a second plastic or rubber material over a pre-formed substrate in a sequential molding operation. The process creates parts with soft-grip surfaces, multi-material interfaces, and integrated seals without mechanical assembly.

Why Choose Us for Injection Molding Services?

Top Proto manages the full injection molding workflow in-house, from mold design and CNC tooling production to part molding, inspection, and delivery. This integrated approach gives you direct communication with the engineering team responsible for your mold rather than working through intermediaries who do not control the production process.

Our mold shop produces both aluminum rapid tooling for prototype and low-volume programs and hardened steel production tooling rated for high-volume cycles. Every mold is measured dimensionally before the first production shot to confirm cavity geometry matches your approved part drawing. Our quality management system is certified to ISO 9001:2015 and ISO 13485, supporting applications across general industrial, consumer, and medical device sectors. First article inspection reports, material certifications, and Certificates of Conformance are provided with every order.

Materials for Injection Molding Services

Material selection for injection molded parts determines mechanical performance, thermal resistance, chemical compatibility, and appearance. Top Proto processes a broad range of thermoplastic resins to match the functional requirements of your application.

Metal Materials

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SPI A1 / A2 Polish

A semi-gloss finish produced by fine grit paper polishing of the mold cavity. Suitable for consumer product housings and parts where a smooth, slightly reflective appearance is required without full mirror polish.

SPI C1 / C2 Finish

A matte finish produced by stone polishing the mold cavity. Used for functional parts where surface gloss is not a requirement and production cycle time is prioritized.

Texture (EDT)

Electro-discharge texturing creates a uniform grain pattern on the mold cavity surface, producing parts with a consistent textured appearance. Available in multiple grain scales for different tactile and visual outcomes.

As Molded

Parts delivered in the condition produced directly from the mold without additional surface treatment. Surface quality reflects the condition of the mold cavity, which is maintained and monitored across the production run.

Painting / Coating

Post-mold painting or coating applied to molded parts for color matching, UV protection, or additional surface hardness. Applied in our in-house finishing department with color matching to RAL or Pantone specifications.

Injection Molding Surface Finishes

The surface finish of an injection molded part is determined by the mold cavity texture and any post-molding surface treatment applied. Top Proto offers a range of mold cavity finishes and secondary treatments to meet your appearance and functional requirements.

Injection Molding Capabilities

Feature	Specification
General Tolerances	ISO 2768-M for standard features; tighter tolerances available on critical dimensions specified in your drawing
Minimum Wall Thickness	0.5mm for rigid engineering resins; 1.0mm recommended for consistent fill and reduced sink marks
Maximum Part Size	Up to 800 x 600 x 400mm depending on resin and mold configuration
Production Volume	Low volume: 100 to 10,000 parts; High volume: 10,001 parts and above
Lead Time — Rapid Tooling	7 to 14 days for aluminum tooling; first shots within 3 to 5 days of mold approval
Lead Time — Production Tooling	25 to 45 days depending on mold complexity and steel grade
Cavity Configuration	Single cavity, family mold, and multi-cavity configurations available

Our Injection Molding Gallery Parts

The parts shown here were produced at Top Proto using our injection molding capabilities across a range of materials, mold configurations, and industries. Each part was produced from a qualified mold, inspected against the approved drawing, and delivered with full quality documentation. The gallery reflects our production capability across single-cavity, family, and multi-cavity mold configurations.

Rapid Tooling

Rapid injection mold tooling at Top Proto is produced in aluminum alloy, typically 6061 or 7075, using our in-house CNC machining centers. Aluminum tooling is designed and machined to produce functional plastic parts quickly, typically within seven to fourteen days from drawing approval. This approach is used for design validation, fit-and-function testing, regulatory submission samples, and early-market pre-production runs before the full investment in hardened production tooling is made.

Production Tooling

Production injection mold tooling at Top Proto is machined from hardened steel — P20, H13, or S136 depending on the resin being molded and the required tool life. Hardened steel tooling is rated for production cycles of one million shots and above, maintaining consistent cavity geometry and surface finish across the full tool life. Multi-cavity configurations with hot runner systems are available to maximize output per cycle and reduce material waste in high-volume programs.

How We Works – 3-Stages Workflow

We guarantee that CNC parts are delivered on time and that the process is completely transparent in the following 3 simple steps:

Upload Your Files

Instant prices with DFM feedback for many file types.

We Manufacture Your Parts

You can select from many materials and methods.

Tracking and Receiving Your Parts

View the QC documentation and inspection photographs.

Pros of Injection Molding

Long Lasting:Made with guide tool steels, these molds last a long time..
Accuracy: Ideal for product consistency and quality over long production runs.
Cost Efficient : Perfect for short to long runs with little variation in product needs.
High-quality Finish: Provides high-quality surfaces.
Design Variety:Can accommodate detailed geometries and additional components.
Short Turnaround: More efficient cooling systems and part ejectors produce in less time.

Frequently Asked Questions

What is the minimum order quantity for injection molding?

Top Proto accepts orders from 100 parts upward for rapid tooling programs, and from 1,000 parts for production tooling. For low-volume requirements below these thresholds, vacuum casting may be a more cost-effective alternative — our team can advise based on your part geometry and volume requirements.

How long does injection mold tooling take to produce?

Aluminum rapid tooling typically takes 7 to 14 days from drawing approval to first shots. Hardened steel production tooling takes 25 to 45 days depending on mold complexity, number of cavities, and steel grade specified. Lead times are confirmed at the quoting stage before production begins.

What plastic materials can you injection mold?

We mold a broad range of thermoplastic resins including ABS, PP, PE, PC, Nylon PA6 and PA66, PEEK, POM, TPE, and TPU. Material selection should be based on your part’s mechanical requirements, operating temperature, chemical exposure, and surface finish specification.

Can you produce both the mold and the parts?

Yes. Top Proto manages the complete process from mold design review and tooling production through to part molding, inspection, and delivery. You work with a single supplier for the entire program, which simplifies communication and reduces the risk of specification mismatches between tooling and production.

What quality documentation is provided with injection molded parts?

Every order includes a first article inspection report, dimensional measurement data for critical features, material certification for the resin used, and a Certificate of Conformance. Additional documentation including process capability data and appearance inspection records is available on request.

CNC Manufacturing Resources

Technical guides and process comparisons from the Top Proto engineering team, covering material selection, process decision frameworks, and manufacturing design principles for engineers and product developers.