Custom Plastic Injection Molding Services
SAMSHION manufactures custom plastic parts for small-batch and repeat production, including electronic housings, transparent covers and structural components. Mold making, injection molding and inspection are handled in-house.
- No minimum order quantity
- DFM review and approval before mold manufacturing
- Customer-approved samples before batch production
- ISO 9001:2015-certified quality management system
Injection Molding Service Overview
Review our manufacturing capabilities, order quantities, quotation timing and tooling terms to plan your custom injection molding project.
In-House
Mold making, injection molding and inspection are carried out in our own factory.
No Minimum Order Quantity
We accept small-batch and repeat-production orders. Tooling requirements and costs are assessed for each project.
Up to 800 Tonnes
Machine selection is based on part geometry, mold dimensions and processing requirements.
Within 24 Hours
After we receive complete project information. Weekends and public holidays are excluded.
From 15 Business Days
Lead time is measured from mold design approval. The T1 schedule is confirmed for each project.
Customer-Owned
Once tooling fees are paid in full, you own the mold and may request its collection or transfer.
Injection Molding Options for Your Project
SAMSHION supports prototype, low-volume and repeat production. Depending on your part design, these projects can also use insert molding, overmolding, multi-cavity molds or family molds.
Prototype Injection Molding
Prototype injection molding produces early-stage plastic parts using the selected thermoplastic material. Use these parts to assess fit, assembly and appearance, with DFM review and trial samples helping you evaluate the design before moving into repeat production.
Explore our rapid tooling services for prototype molds and bridge-production tooling.
Low-Volume Injection Molding
Low-volume plastic injection molding supports pilot builds, limited-demand products and repeat small-batch orders, including electronic housings. Tooling and material requirements are reviewed against your part design and batch quantity to define an appropriate manufacturing route.
Compare our low-volume manufacturing options when selecting a process for limited quantities and repeat small-batch orders.
Production Injection Molding
Manufacture custom injection-molded components for recurring orders, including automotive, medical and optical equipment applications. Batch production begins after sample approval, with molding and dimensional inspection planned around the agreed part requirements and production schedule.
See our production mold making services for tooling planned around repeat orders and expected demand.
Insert Molding
Metal insert molding integrates pre-positioned inserts into a plastic part during molding. This option suits designs that combine plastic geometry with metal mounting or fastening features. Insert specifications and positioning requirements are reviewed with the part design.
Overmolding
Overmolding adds a second material layer to an existing plastic component, including soft material over a rigid plastic base. We review material compatibility, coverage and interface requirements to determine a suitable molding approach for your part.
Family and Multi-Cavity Molding
Multi-cavity molds produce multiple identical parts per cycle, while family molds produce different parts in the same cycle. We assess the arrangement against part designs, material requirements and required quantities to propose a suitable tooling approach.
Injection Molding Project Examples
Explore injection-molded parts produced by SAMSHION for vehicle electronics, medical applications, optical equipment and automotive lighting. Each example outlines the material, production stage, quality priorities and dimensional inspection method.
ABS Vehicle Recorder Housing Components
ABS injection-molded housings, front frames and buttons for vehicle recording electronics. This small-batch project focused on the appearance of the plastic components and the dimensions of their assembly interfaces.
PP Components for Medical Applications
Polypropylene injection-molded components for medical applications, featuring tubular openings and branch connections. This batch-production project focused on the dimensions of the features used to connect with mating components.
PA+GF Optical Equipment Structural Component
A glass-filled nylon injection-molded structural component for optical equipment, featuring a ring-shaped body, mounting brackets and connection holes. This batch-production project focused on the dimensions of the assembly interfaces.
Transparent PC Automotive Lamp Cover
A transparent polycarbonate automotive lamp cover produced by injection molding, featuring a curved body and a raised perimeter edge. This batch-production project focused on clear appearance and the dimensions of the molded component.
Why Choose SAMSHION for Injection Molding?
From mold design approval to repeat production, SAMSHION provides clear review points, trial samples and documentation options for your custom plastic injection molding project.
DFM Before Mold Making
Our DFM review assesses your plastic part design before mold making. We submit the mold design for your approval, so tooling begins with an agreed design.
Sample Approval Before Production
Trial samples are provided for your review before batch production. This approval step lets you assess the molded parts against the agreed appearance and dimensional requirements before the project moves forward.
Documentation on Request
CMM inspection reports and material documentation are available on request. Tell us what your project needs so the required documents and dimensional checks can be discussed before production.
Mold Care for Repeat Orders
Routine mold care includes cleaning, rust prevention and lubrication for continued use. For repeat injection molding orders, mold maintenance arrangements are discussed according to the needs of your project.
Injection Molding Workshop and Tooling
See the production environment behind SAMSHION’s custom plastic injection molding services, from molding equipment and robotic part handling to injection mold tooling and storage.
Injection Molding Workshop
Plastic components are produced in our injection molding workshop using molding machines and supporting handling equipment. This production floor forms part of SAMSHION’s in-house manufacturing operation.
Molding Equipment and Part Handling
This production station combines an injection molding machine, an overhead robot and a conveyor. The equipment supports part handling and collection alongside the molding operation.
Injection Mold Tooling
We manufacture injection molds in-house for custom plastic components. The open mold shown here provides a closer view of its forming surfaces and surrounding tooling structure.
Injection Mold Storage
Injection molds are kept in a dedicated storage area between production runs. This area provides space for tooling used in our plastic part manufacturing projects.
How Plastic Injection Molding Works
Thermoplastic pellets are prepared, melted and injected into a closed mold. The part then cools before the mold opens for removal.
Material Preparation & Plasticizing
The selected resin is prepared and dried where required. Barrel heating and screw action melt the pellets and prepare material for injection.
Filling & Packing
Molten plastic fills the closed mold cavity. Packing and holding pressure then feed additional material as needed to compensate for shrinkage before the gate seals.
Cooling & Solidification
Heat is removed through the mold’s cooling system. The part remains in the closed mold until it is sufficiently solid and stable for removal.
Mold Opening & Ejection
After sufficient cooling, the mold opens and the ejection system releases the molded part. Ejection is planned around the part geometry to help limit deformation and unwanted surface marks.
After ejection, gate removal, secondary operations and inspection are carried out as required by the part design and agreed project requirements.
Plastic Injection Molding Materials
SAMSHION offers custom plastic injection molding in commonly used thermoplastics, engineering plastics and high-performance materials, including PEEK, PPS and PPA. We review material selection against your part design, operating conditions and production requirements.
The applications below are general selection examples. Suitability depends on the exact resin grade and finished-part requirements.
Commonly Used Plastics
Engineering and Transparent Plastics
High-Performance Materials: PEEK, PPS and PPA
For a broader comparison of plastics and process-specific material options, explore our manufacturing materials guide.
Surface Finishes and Secondary Operations
Molded-In Surface Finishes
Surface appearance begins with the selected resin and mold surface. Define visible areas and provide finish references before mold design approval, so these requirements can be considered during production mold making.
Smooth and Glossy Finishes
Polished mold surfaces can produce smooth, glossy molded parts. The achievable appearance depends on the resin, part geometry and processing conditions. Specify the required finish using a reference standard or sample.
Matte Finishes
A matte mold finish can create a lower-gloss appearance without a separate paint layer. Provide a reference sample to clarify the intended surface, as “matte” alone does not define an exact finish.
Textured Finishes
Molded-in textures create a pattern or grain directly on the plastic surface. Identify the texture reference and its location so draft angles, parting lines and release requirements can be considered during mold design.
Post-Molding Secondary Operations
Specify any finishing or marking requirements when submitting your CAD files and drawings. These operations can be included in your injection molding project, with the delivery arrangements outlined below.
Painting and Coating
Painting and coating for injection-molded plastic parts are coordinated through external finishing providers. Include your target color and surface appearance, together with any areas that must remain uncoated.
Pad Printing
Pad printing is coordinated through external printing providers for text, symbols and graphics on molded plastic parts. Supply your artwork, print colors and locations to define the printing requirements.
Laser Marking
Laser marking is performed in-house on injection-molded plastic parts. Share the marking content, location and appearance requirements so suitability can be assessed for the selected material and part surface.
Explore our surface finishing services for more information on finishing options for custom parts.
Injection Molding Design Guidelines and DFM Review
Before mold manufacturing begins, SAMSHION reviews your plastic part design, selected material and project requirements through design for manufacturability (DFM). The review identifies potential molding risks and design details that need to be addressed before tooling begins.
Wall Thickness and Transitions
Review wall thickness, transitions and corner radii for potential filling, cooling and sink-mark risks. Recommendations depend on the selected resin grade, part geometry and functional requirements.
Draft Angles and Mold Release
Check draft angles against the mold-opening direction, feature depth and surface finish. Review mold release requirements while considering critical dimensions and visible surfaces.
Ribs, Bosses and Assembly Features
Evaluate ribs, gussets and bosses for local material buildup and assembly requirements. Identify screw, insert and mating-part interfaces that must be maintained during design changes.
Undercuts and Side Actions
Identify features that may prevent straight-pull mold release or require side actions. Consider whether geometry changes could simplify tooling while preserving the intended function.
Gates, Parting Lines and Ejector Marks
Review proposed gate, parting-line and ejector locations in relation to visible areas and functional interfaces. Define restricted areas and acceptable molding marks before mold design approval.
Shrinkage, Warpage and Critical Dimensions
Review material shrinkage and potential distortion alongside flatness, hole positions and assembly requirements. Identify critical dimensions for follow-up during tooling development and sample evaluation.
The agreed design requirements help guide rapid tooling or production mold making, depending on your project stage and production needs.
From Quote to Injection-Molded Parts
Follow the key stages of a custom injection molding project, from submitting CAD files and reviewing the quotation to approving samples and receiving production parts.
Upload CAD Files and Requirements
Send your 3D CAD files and available 2D drawings, together with the material, quantities, surface requirements and critical dimensions. Include mating-part information where assembly fit is important.
Project Review and Quotation
We review the submitted information and prepare a project-specific quotation. Quotations are provided within 24 hours of receiving complete project information, excluding weekends and public holidays.
DFM and Mold Design Approval
We review manufacturability and discuss design details that affect tooling and molded-part requirements. Agreed changes and the mold design are submitted for approval before mold manufacturing begins.
Tool Manufacturing and T1 Samples
The mold is manufactured to the approved design, followed by the first molding trial and T1 samples. T1 sample lead times start from 15 business days after mold design approval, with the schedule confirmed for each project.
Sample Approval and Production
Review the samples against the agreed requirements. Where corrections are needed, the changes and follow-up samples are reviewed before approval. Batch production begins after sample approval.
Inspection and Delivery
Parts are inspected against the agreed requirements, with packaging and delivery arranged for the project. Inspection methods and documentation are defined according to the agreed quality assurance requirements.
Injection Molding Quality Control and Inspection
Quality requirements are reviewed against your drawings, material specification and intended application. SAMSHION provides dimensional inspection and project-specific documentation for custom injection-molded parts, with inspection methods and acceptance criteria agreed for each project.
For further information, explore our quality assurance and tolerances and standards.
Drawing and Tolerance Review
Identify critical dimensions, assembly interfaces and acceptance requirements before production. Achievable tolerances are reviewed against the selected resin grade, part geometry and measurement requirements rather than applying one tolerance value to every feature.
Dimensional Inspection
Measurement methods are selected according to the part and the dimensions being checked. CMM inspection can be used for suitable dimensional and geometric features, with the inspection scope agreed for the project.
Sample and Appearance Review
Samples are submitted for review before batch production. Surface finish, color and acceptable molding marks are assessed against agreed requirements or approved references, with appearance acceptance defined separately from dimensional inspection.
Inspection Records and Material Documentation
CMM inspection reports and material supplier documentation can be provided when requested and agreed as part of the project. Specify the required records during quotation so the documentation scope can be confirmed before production.
Injection Molding Guides
Explore practical guidance on material selection, plastic part design and common injection molding defects. These resources can help you define material, dimensional and appearance requirements for your next project.
Injection Molding FAQs
What is the minimum order quantity for injection molding?
SAMSHION has no minimum order quantity for custom injection molding. We can review prototype, small-batch and repeat-production requirements. Tooling and part-production costs are quoted for the specific project.
How can I get an injection molding quote?
Send your 3D CAD files and available 2D drawings, together with the material, quantity, surface requirements and critical dimensions. Quotations are provided within 24 hours of receiving complete project information, excluding weekends and public holidays.
How much does custom injection molding cost?
Tooling and molded-part production are quoted for your specific project rather than using a standard price per part. Submit your drawings, material specification, quantities and any required secondary operations so we can confirm the scope and prepare a quotation.
How long does injection molding take?
T1 sample lead times start from 15 business days after mold design approval, with timing confirmed for each project. This is the first sampling stage, not finished-part delivery. Any tooling corrections, sample approval, batch production and shipping require additional time.
Will I receive samples before batch production?
Yes. Samples are submitted for your review before batch production. If agreed corrections are needed, we review the changes and follow-up samples before proceeding. Batch production begins after sample approval.
What tolerances can you achieve on injection-molded parts?
Achievable tolerances depend on the resin grade, part geometry, dimension and measurement requirements. Send your drawings with critical dimensions and assembly interfaces identified so we can review feasibility. See our tolerances and standards for additional guidance.
Which plastics can you injection mold?
We work with commonly used thermoplastics such as ABS, PP, PC, PMMA, POM and PA, including glass-filled grades. We also have experience with PEEK, PPS and PPA. The exact commercial grade and its suitability are reviewed for each project. Explore our materials guide.
Do you offer insert molding and overmolding?
Yes. We offer insert molding and overmolding for suitable projects. Insert geometry, material combinations, bonding requirements and part function are reviewed before the tooling and molding approach is confirmed.
Who owns the injection mold?
The mold belongs to the customer once the agreed mold costs have been paid in full. Mold transfer can be arranged, with the handling, shipping and associated requirements confirmed in advance.
What inspection reports and material documents are available?
CMM inspection reports and material supplier documentation can be provided when requested and agreed as part of the project. Specify the required reports and formats during quotation so the inspection and documentation scope can be confirmed. Learn more about our quality assurance.
Get a Quote for Your Injection Molding Project
Upload your 3D CAD files and share your material, quantity and key requirements. SAMSHION will review your project and prepare a tailored quotation.