Quality Control
Quality control at Yongjie is integrated into material receiving, mold validation, injection molding, product inspection, and final release. Each project is inspected according to its drawings, material requirements, critical dimensions, appearance standards, and functional specifications.
For medical injection-molded components, pen injector parts, and other precision plastic products, inspection activities are matched to the product structure and manufacturing stage. Material lots, production batches, mold information, and inspection results are recorded throughout the process to maintain clear traceability from incoming material to finished shipment.
Quality Control Throughout the Manufacturing Process
Incoming Material Verification
Plastic resins and purchased components are checked before they are released to production. Verification covers the specified material grade, batch identification, supplier documentation, and consistency with the project requirements.
Packaging condition and material labeling are also reviewed to prevent incorrect, damaged, or contaminated materials from entering the molding process. Materials that do not match the required specification are identified and isolated before production begins.
Mold Trial and First Article Approval
Every new mold, modified mold, or restarted production project begins with a mold trial and first article inspection. Initial samples are checked for critical dimensions, surface condition, molding completeness, and fit with related components.
For multi-cavity molds, parts from different cavities are reviewed separately to confirm cavity-to-cavity consistency. Mold settings are adjusted when flash, short shots, deformation, sink marks, or dimensional deviation are detected. Continuous production starts only after the first molded parts meet the confirmed requirements.
In-Process Inspection
During injection molding, key process settings are maintained within the established production range. Temperature, injection conditions, holding time, cooling time, and molding cycle are checked to keep the process stable.
Parts are inspected during production for dimensional consistency, appearance, weight variation, and complete formation. Additional checks are carried out after material replacement, mold adjustment, production interruption, or equipment restart.
When an abnormal result is found, the affected production period and mold cavity are identified before production continues. This prevents parts produced under unstable conditions from being mixed with released products.
Finished Product and Functional Testing
Finished parts are checked for critical dimensions, molding appearance, assembly fit, and product-specific functions before packing. Dimensional inspection focuses on features that directly affect positioning, movement, sealing, or connection with other components.
For pen injector components and assemblies, inspection can include cartridge positioning, mechanism movement, component engagement, and project-defined operating or sealing requirements. Other precision molded parts are checked according to their structure, including thread fit, clip engagement, connector alignment, gear movement, or assembly stability.
Batch Traceability and Final Release
Each production batch is connected to its material lot, production order, mold, manufacturing date, and inspection records. Where cavity identification is required, parts and inspection results can be traced to the corresponding mold cavity.
Before release, the finished quantity, product identification, packaging condition, and inspection status are confirmed. Batches with incomplete records, unresolved deviations, or incorrect labeling are held until the issue has been corrected and verified.
Inspection Capabilities
Dimensional Inspection
Dimensional inspection is selected according to the feature size, geometry, and drawing requirements of each product. Critical dimensions such as hole positions, wall thickness, mating surfaces, internal and external diameters, and assembly locations are checked to confirm that the part fits and functions as intended.
Visual and Functional Inspection
Molded parts are examined for flash, short shots, sink marks, deformation, burn marks, contamination, scratches, black spots, and visible color variation. Appearance acceptance is based on the project specification or approved reference sample.
Functional inspection focuses on the actual use of the component. Assembly fit, mechanical movement, locking features, sealing interfaces, and repeated operation are checked according to the product design and project requirements.
Quality Records and Traceability
Inspection results are recorded by production batch. Depending on the project, quality documentation can include first article inspection records, dimensional results, material identification, in-process inspection records, and final inspection status.
These records connect the finished product with the corresponding material, mold, production period, and inspection activity, allowing a specific batch or production stage to be reviewed when required.
Nonconforming Product Control
Products that do not meet the specified requirements are identified and separated from released production. The affected scope is determined using material lot, production time, machine record, mold cavity, and inspection results.
The cause is reviewed across the material, mold condition, molding parameters, inspection method, and handling process. Corrective actions are then carried out through process adjustment, mold correction, sorting, rework, or rejection.
