Quality Assurance
Home Quality Assurance for Investment Cast and CNC Machined Parts
Quality Assurance for Investment Cast and CNC Machined Parts
At Zeren, quality control is built into every stage of investment casting, CNC machining, heat treatment and surface finishing.

From material verification and first article inspection to in-process checks and final dimensional reports, we help ensure that custom metal parts meet drawing requirements before shipment.
Quality assurance inspection for investment cast and CNC machined metal parts
Quality Management Built Around Every Production Stage


Our quality management is built around drawing review, process control, in-process inspection, final verification, and continuous improvement. When a quality issue is identified, we analyze the root cause, adjust the related process, and update inspection requirements to help reduce repeated defects in future production.

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Quality Control Built Around Your Drawing Requirements
For custom metal parts, quality control starts with understanding the drawing, material grade, tolerance requirements, surface finish and application environment. Our team reviews these requirements before production and applies inspection controls throughout casting, machining, heat treatment, surface finishing and final packing.

Whether the project involves a prototype sample, a small production batch or repeated orders, our goal is to reduce dimensional variation, material risk and surface quality issues before parts leave our factory.
Drawing-based inspection planning
Material and chemical composition verification
Dimensional checks for critical features
Final photos, videos and reports when required

Certifications and Compliance Support

Zeren operates under an ISO 9001:2015 quality management system and supports project-based inspection and compliance documentation when required. For specific materials, surface finishes or export applications, third-party test reports and RoHS-related checks can be arranged according to customer requirements.
ISO9001 2015 - Foshan Zeren Precision Casting Co., Ltd.



ISO 9001:2015 Quality Management:

Our quality management process supports consistent production control, inspection procedures and continuous improvement across casting, machining and finishing projects.


Third-Party Testing Support:

SGS or other third-party test reports can be arranged when required for material verification, chemical composition or special project documentation.


RoHS-Related Compliance Support:

For applications requiring hazardous substance control, RoHS-related testing or documentation can be supported based on the material and surface finishing requirements.

SGS test report

Inspection Equipment for Cast and Machined Parts

Different parts require different inspection methods. Zeren uses dimensional measuring tools, material testing equipment and visual inspection methods to check critical features, material properties and surface quality before shipment.
CMM inspection for cast and CNC machined parts

CMM Inspection

Used for critical dimensions, hole positions, flatness, perpendicularity and machined interfaces on precision parts.

Spectrometer testing for investment casting material verification

Spectrometer Testing

Used to verify chemical composition and confirm that the material meets the required grade specification.

Hardness testing for heat treated metal parts

Hardness Testing

Used for heat-treated parts or applications requiring specific strength, wear resistance or mechanical performance.

3D scanning for complex investment cast metal parts

3D Scanning / Profile Checking

Used for complex shapes, sample comparison, reverse-engineered parts or profile verification when required.

HeigHeight gauge dimensional inspection for machined metal components

Height Gauge & Manual Measuring Tools

Used for routine dimensional checks during sample inspection, in-process control and final inspection.

Microscope surface inspection for precision metal parts

Microscope / Surface Detail Check

Used to check small features, edge details, surface defects, cracks, burrs or visual quality issues.

Ask for Dimensional Inspection Support

Upload Drawing

Quality Control Process from Sample to Shipment

Quality control is not limited to final inspection. For custom cast and machined parts, we review requirements before production, verify key parameters during manufacturing and check critical dimensions before shipment.

Quality control workflow for investment casting parts from raw samples and inspection to packed finished components ready for shipment
Step 1
Drawing & Requirement Review
We review material grade, tolerance, surface finish, heat treatment, application environment and inspection requirements before production starts.
Step 2
Sample or First Article Inspection
For new parts, sample dimensions, key features and production feasibility are checked before batch manufacturing.
Step 3
Material Verification
Chemical composition can be checked by spectrometer according to material grade or customer requirements.
Step 4
In-Process Inspection
Casting, machining, heat treatment and surface finishing steps are checked during production to reduce batch variation.
Step 5
Final Dimensional & Visual Inspection
Critical dimensions, threads, holes, machined surfaces, burrs, defects and surface finish are checked before packing.
Step 6
Reports & Pre-Shipment Confirmation
Inspection reports, photos or videos can be provided before shipment when required by the customer.

Send Drawing for Review

Request Inspection Report

Quality Control Across Every Manufacturing Stage

Many custom parts require more than one manufacturing step. Zeren controls quality across investment casting, CNC machining, heat treatment and surface finishing, helping customers reduce supplier coordination and inspection risks.

Quality control across casting CNC machining hardness testing and surface finishing for custom investment casting parts
Investment Casting Quality Control
Wax pattern quality, shell condition, pouring control, casting appearance, shrinkage risk and key casting dimensions are checked according to part requirements.
CNC Machining Quality Control
Critical machined features such as holes, threads, sealing surfaces, mounting faces and assembly dimensions are inspected according to the drawing.
Heat Treatment Verification
For parts requiring improved strength, wear resistance or mechanical properties, hardness testing and deformation checks can be performed after heat treatment.
Surface Finishing Inspection
Blasting, polishing, passivation, plating, powder coating and black finishes are checked for appearance, coverage, surface defects and project-specific requirements.
Need casting, machining and surface finishing to meet the same drawing and inspection standard?
Inspection Reports We Can Provide

For projects requiring documented quality control, Zeren can provide inspection records and supporting documents based on the part, material, production stage and customer requirements.

Dimensional Inspection Report
First Article Inspection Report
Chemical Composition Report
Material Certificate / Material Test Report
Hardness Test Report
Heat Treatment Report
Surface Finishing Inspection Photos
Pre-Shipment Photos and Videos


Report format and inspection items can be discussed before production. For critical parts, please mark key dimensions, tolerance requirements and special inspection points on the drawing.

Inspection reports and measuring tools for precision investment casting and CNC machined metal parts
Example: Chemical Composition Verification and Adjustment

During melting and material verification, chemical composition can be checked by spectrometer before pouring. If an alloy element needs adjustment, the melt can be corrected and re-tested to help reduce material risk before production continues.

Chemical composition verification and adjustment for investment casting metal samples
Step 1 — Melt Sampling
A metal sample is taken after the raw material is melted.
Step 2 — Sample Preparation
The sample is cooled and polished for spectrometer testing.
Step 3 — Composition Verification
The chemical composition is checked against the required material specification.
Step 4 — Adjustment and Re-Test
If adjustment is needed, alloy elements are added and the sample is tested again before pouring.
Customer Feedback on Quality and Repeatability
The parts met our contract requirements, and the repeatability between samples was very good. Communication was professional and efficient, and issues were resolved quickly. We would recommend Zeren for its reliable quality and client-focused support.
-Automotive Customer

Working with Zeren has been a very positive experience. Their communication is clear and responsive, and the quality of the castings has been consistently strong. Their proactive approach helped us stay on schedule and solve design and production challenges efficiently.

-Industrial Machinery Customer

We were pleased with both the quality of the product and the overall service. The team was easy to work with, responsive throughout the process, and the parts were delivered on time. We are confident in their ability to meet high quality expectations.

-Agriculture Customer
FAQ About Quality Inspection and Reports
Q1: Can you provide dimensional inspection reports before shipment?
A: Yes. Dimensional inspection reports can be provided when required, especially for critical dimensions, machined features, holes, threads and assembly surfaces.
Q2: Can you check chemical composition for investment casting materials?
A: Yes. Spectrometer testing can be used to verify chemical composition according to the required material grade or customer specification.
Q3: Do you inspect both cast parts and CNC machined parts?
A: Yes. We can check casting appearance, key casting dimensions, machined holes, threads, sealing surfaces, assembly faces and other critical features according to the drawing requirements.
Q4: Can you provide photos or videos before shipment?
A: Yes. For custom orders, pre-shipment photos, videos and inspection documents can be provided when required.
Q5: How should I mark important inspection requirements?
A: Please mark key dimensions, tolerance requirements, material grade, surface finish and special inspection points clearly on your 2D drawing or technical document.

Send Your Inspection Requirements

Need Quality-Controlled Custom Metal Parts?
Send us your drawings, material requirements, tolerance details and surface finishing needs. Our team can review the manufacturing and inspection plan before production and provide reports, photos or videos when required.

Request a Quote

Upload Drawing

Quality-controlled custom investment cast and CNC machined metal parts with engineering drawing and inspection tools
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Quality-Controlled Manufacturing Support

Start Your Drawing-Based Manufacturing Review


For custom investment cast and CNC machined parts, send us your drawing, material requirements, tolerance details, surface finishing needs, and expected quantity. Our team will review your project and provide practical feedback for quotation, production, and inspection planning.


·  Drawing-based review before production
·  Material and chemical composition verification
·  In-process inspection for casting and machining
·  Dimensional reports and FAI support when required
·  Surface finishing and packing checks before shipment
·  Flexible support for samples, small batches and repeat orders
Send Us Your Drawing
Please send us your drawing, material, quantity, tolerance requirements, surface finishing needs, or inspection report requirements. Our team will review your request and respond within 6 hours.
Request a Quote
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