--- id: "material-selection-en" title: "Material Selection & Incoming Quality Control | Zhongde Precision" description: "Material source, grade verification, incoming inspection and lot traceability." source: "/en/quality/material-selection" language: "en" generated: true --- # Material Selection & Incoming Quality Control Controlled Sources · Grade Verification · Incoming Inspection · Traceability Material grades, conditions and stock forms are selected according to strength, thermal, corrosion, wear, weight, finishing and machining requirements. Materials are sourced from major producers and approved suppliers, supported by certificates, lot information, incoming inspection and batch control. - Major producers and approved suppliers - Grade, condition and certificate verification - Heat-to-production batch traceability ## Key Figures - Controlled Source · Major producers and approved suppliers - Mill Certificate · Grade · composition · properties - Incoming Check · Size · condition · risk-based retest - Lot Traceability · Heat · work order · finished batch ## 01. Four Foundations of Material Quality Assurance Material quality is not controlled only after machining. It begins with supplier selection and purchasing specifications. Source, grade, condition, heat number and documentation must correspond to the actual incoming material. The same grade can have significantly different strength, hardness, residual stress, machining distortion and finishing behavior in different tempers or processing conditions. Grade verification alone is therefore insufficient. ### Capabilities and Engineering Points #### 01. Reliable Sources Materials are sourced primarily from major producers and approved suppliers to reduce uncertainty and lot-to-lot variation. ##### Details - Major producers - Approved suppliers - Controlled purchasing #### 02. Verified Grade Grade, temper, dimensions, applicable standard and purchase requirements are checked against the incoming material. ##### Details - Grade and temper - Dimensions - Applicable standard #### 03. Complete Documents Mill certificates, heat numbers, chemical composition, mechanical properties and inspection records are matched to the material. ##### Details - Mill certificate - Composition and properties - Incoming inspection record #### 04. Batch Traceability Heat labels, barcodes, storage locations, issue records and work orders maintain traceability through production and delivery. ##### Details - Heat identification - Barcode and location - Work order and finished lot ### Temper Examples - 6061-T6 - 7075-T651 - SUS304 solution treated - SCM440 quenched and tempered - Copper soft / hard temper ## 02. How to Select the Right Material Material selection should begin with part function, service environment, manufacturing process and quality risk—not with a material catalog. We identify the critical performance requirements first, then determine the appropriate grade, condition and stock form. Customers usually need to know whether a material is suitable for their structure, environment and downstream processes—not merely whether it can be machined. - Advice: Select the material that is most suitable, controllable and stable for the design target, service environment, manufacturing route and production risk—not simply the strongest or cheapest option. ### Capabilities and Engineering Points #### Strength & Stiffness - Judgment: Load, wall thickness and structural deflection - Applications: Robot joints and load-bearing parts #### Thermal Performance - Judgment: Heat path, contact surface and weight - Applications: Cold plates and optical heat sinks #### Corrosion Resistance - Judgment: Coolant, humidity and salt exposure - Applications: Liquid cooling and outdoor equipment #### Wear & Fatigue - Judgment: Friction, cyclic loading and service life - Applications: Gears, shafts and transmission parts #### Machining Stability - Judgment: Residual stress, thin-wall distortion and tool load - Applications: Precision housings and thin-wall cavities #### Finishing Compatibility - Judgment: Anodizing, coating, plating and DLC - Applications: Appearance parts and functional surfaces ### Common Material Selection Questions - Why is 6061 commonly used for liquid cold plates? - Is 7075 suitable for anodizing? - What is the difference between ADC12 and 6061? - How should copper and aluminum be compared? - How can residual-stress distortion be reduced in thin-wall parts? - Should robot load-bearing parts use aluminum or titanium? ## 03. Common Materials & Typical Applications These eight common material families support early-stage material selection and engineering discussions. Final selections must be confirmed against part function, drawing requirements, manufacturing processes and applicable standards. | Material Category | Representative Grades | Typical Parts | Key Control Points | | --- | --- | --- | --- | | Aluminum Alloys | 5056, 6061, 6063, 7075, ADC12 | Cold plates, housings, flanges and heat-dissipation structures | Temper, residual stress and anodizing results | | Zinc Alloys | Zamak 3, Zamak 5, ZA-8, ZDC | Die-cast housings, brackets, connectors and small structural parts | Porosity and shrinkage, plating adhesion, corrosion and dimensional stability | | Magnesium Alloys | AZ91D, AM60B, AZ31B | Lightweight housings, brackets, frames and structural parts | Oxidation and corrosion, distortion control, chip safety and surface finishing | | Stainless Steel | SUS303, SUS304, SUS316 | Shafts, connectors and fluid-handling parts | Material mix-up, work hardening and corrosion resistance | | Carbon & Alloy Steels | S45C, SCM415, SCM440 | Gears, shafts and load-bearing parts | Heat-treatment condition, hardness and decarburization | | Copper & Copper Alloys | C1100, C1020, brass | Thermal blocks, conductive parts and liquid-cooling structures | Electrical and thermal conductivity, oxidation and soft-material distortion | | Titanium Alloys | Commercially pure titanium, Ti-6Al-4V | High-strength lightweight connectors | Cutting heat, tool life and surface integrity | | Engineering Plastics & Composites | POM, PEEK, PA, carbon-fiber composites | Insulators, wear-resistant parts and lightweight structures | Moisture absorption, anisotropy and thermal deformation | ### Important Note Specific grade designations and equivalencies are governed by customer drawings, BOMs, purchasing specifications and applicable standards. Materials with similar names in different national or standards systems must not be assumed to have identical chemical composition, properties or condition. When comparing materials across countries or standards systems, verify the grade designation, chemical composition, mechanical properties, delivery condition and applicable standard item by item. ## 04. Material Sources & Applicable Standards Stable sources are established with major material producers and approved suppliers. Material grade, condition and documentation are confirmed against customer drawings, purchasing specifications and applicable standards. ### Source Management #### Engineering Items - Major material producers and stable supply channels - Supplier qualification and delivery capability review - Purchasing specifications aligned with drawing requirements - Material certificates matched to physical lots - Supply deviations and substitute materials require approval ### Standards System #### Engineering Items ##### GB / GB/T. Chinese National Standards ##### JIS. Japanese Industrial Standards ##### ASTM / SAE. United States Standards ##### EN. European Standards ##### CUSTOM. Customer Corporate Standards & Drawing Specifications ### Important Note We do not claim that all materials uniformly comply with one standard. Actual purchasing and verification follow customer drawings, purchasing specifications, material form and the designated standard. When JIS, ASTM, EN or a customer corporate standard is specified, purchasing and document verification are performed to that standard. ## 05. Incoming Material Inspection Workflow Incoming inspection follows purchasing requirements and controlled documents. Receipt records, material grade, appearance, dimensions, risk-based material verification and status identification are reviewed before material is released to production. ### Process Steps #### 01. Receipt & Document Review Match the purchase order, delivery note, material certificate, quantity and lot information, and confirm document completeness. #### 02. Material Grade Verification Verify grade, condition, stock size, applicable standard and heat or lot information against drawings, BOMs and purchasing specifications. #### 03. Visual & Packaging Inspection Check for surface damage, corrosion, contamination, cracks, distortion, and the condition of packaging and transport protection. #### 04. Dimensional & Tolerance Inspection Sample-check thickness, diameter, length, straightness and other critical dimensions and tolerances as required. #### 05. Material & Property Verification Review certificate data and perform necessary composition, hardness or property retesting according to customer requirements and material risk. #### 06. Disposition, Identification & Storage Assign accepted, pending or rejected status, apply identification, and release material to storage or move it to segregation. ### Process Control Points #### Engineering Items ##### 01. Inspection Basis & Revision Control Use current drawings, BOMs, purchase orders, material specifications and inspection requirements to prevent obsolete revisions from being used. ##### 02. Sampling Rules & Inspection Frequency Define sampling plans, inspection items and frequency according to material risk, lot size, supplier performance and customer requirements. ##### 03. Nonconforming Material Segregation & Disposition Immediately segregate document, identification or material discrepancies, record the issue, and follow the approved return, concession or disposition decision. ### Records & Outputs #### Engineering Items ##### Inputs Purchase order, delivery note and material certificate ##### Inspection Records Visual, dimensional, material and property results ##### Status Identification Accepted, pending confirmation or rejected ##### Outputs Incoming inspection report, traceability number and storage status ### Important Control Material must not enter production before inspection and release. Material certificates, lot numbers and inspection records for critical materials must be retained to support subsequent quality traceability. ## 06. Material & Batch Traceability A verifiable material traceability chain is maintained by linking the supplier, material certificate, heat or lot number, storage, material issue, production, inspection and finished-product batch records. ### Execution Stages - SOURCE VERIFICATION - STORAGE & PRODUCTION - INSPECTION & DELIVERY ### Process Steps #### 01. Supplier #### 02. Material Certificate #### 03. Heat / Lot Number #### 04. Incoming Stock Label #### 05. Material Issue Record #### 06. Production Work Order #### 07. Inspection Record #### 08. Finished Product Batch ## RFQ Requirements and FAQ ### 07. Information Required for Material Quotation Complete material requirements help the engineering team accurately assess sourcing feasibility, substitution risks, inspection requirements, lead time and quotation scope. #### Engineering Items ##### Material Grade Aluminum alloy / stainless steel / copper / engineering plastics ##### Material Condition T4 / T6 / T651 / quenched and tempered / annealed / soft / hard ##### Applicable Standard GB / JIS / ASTM / EN / customer corporate standard ##### Stock Form & Size Bar / plate / tube / extrusion / casting / forging ##### Quantity & Lead Time Sample / low volume / production / required delivery schedule ##### Certification & Traceability Material certificate / heat-lot data / third-party testing / lot traceability ### 08. Common Engineering Questions #### Engineering Items ##### Where do you source materials? Materials are sourced through audited, stable supply channels in accordance with customer drawings, purchasing specifications and designated standards. When a customer specifies a brand, producer or supplier, we evaluate availability, lead time and minimum purchase quantity against those requirements. ##### Can you provide material certificates and heat-lot information? Material certificates, supplier lot numbers, heat numbers, incoming labels and related inspection records can be retained according to order and customer requirements. Whether original documents or compiled traceability records must accompany the shipment should be agreed during the RFQ or order stage. ##### Can GB, JIS, ASTM and EN grades be substituted directly? No. Similar designations alone are not sufficient for substitution. Chemical composition, mechanical properties, supply condition, dimensional range and product form must be checked together, and the substitute may be used only after drawing and application requirements are confirmed. ##### How do you proceed when the material condition is not specified? The material condition should not be assumed. Requirements such as aluminum T4, T6 or T651, annealed or quenched-and-tempered steel, and soft or hard copper should be confirmed before purchasing because condition affects strength, residual stress, machining distortion and finishing results. ##### Do you support material retesting and third-party testing? Internal testing or third-party retesting can be arranged according to customer requirements, material risk and project classification. Test items, sampling method, acceptance criteria, report format and cost should be defined during quotation. ##### Can customers specify a material brand or supplier? Yes. We evaluate supply feasibility against the specified brand, supplier, standard, purchasing quantity and lead time. If minimum order quantities, extended lead times or discontinuation risks apply, an alternative is proposed for customer approval before purchasing.