All personnel in the injection molding process implement a "first article inspection + in-process sampling + last article comparison" system. After mold installation and at the start of each shift, the operator first injects 5-10 green parts. An electronic balance is used to weigh the individual part weight (requiring a deviation from the standard value of ≤ ±0.005g), and a vision measuring system is used to inspect critical dimensions (length, width, wall thickness, etc.). Mass production is only authorized after all parts pass inspection. During production, the injection molding machine control system monitors parameters in real-time, including barrel temperature, injection pressure, holding pressure, injection speed, mold temperature, and cooling time. If any parameter exceeds the upper or lower limits specified in the process card, the system immediately triggers an audible and visual alarm and automatically pauses the equipment. Every 2 hours, a quality inspector takes 5 green parts from the running machine for weight and dimension re-inspection and records the data on an SPC control chart. If a unidirectional drift trend is observed in the weight of 3 consecutive parts, an early warning is issued, and a technician is notified to adjust the holding pressure or switching time. During shift changes between night and day shifts, a comparison between the last article and the first article is required to ensure product consistency between shifts. All sampling inspection data is entered into the MES system, allowing real-time monitoring of the operating status and quality trends of each injection molding machine.

The debinding process uses nitric acid or oxalic acid catalytic debinding furnaces. Each unit is equipped with a high-precision gas mass flow controller and a sheathed thermocouple to monitor the nitric acid/oxalic acid flow rate (within ±5% of the set value) and the furnace temperature (within ±3°C of the set value) in real-time. When each batch of parts is loaded into the furnace, the quantity, loading position diagram, and support plate number are recorded. The debinding cycle is divided into three stages: heating, holding, and cooling. All parameters are automatically recorded and saved to the equipment's industrial computer and cannot be manually modified. After debinding, the operator randomly selects 5 parts, weighs them before and after debinding using an analytical balance, and calculates the weight loss rate (the theoretical loss rate should be over 90% of the binder content in the feedstock; the actual loss rate must be within ±2% of the theoretical value). If the loss rate is below the lower limit, it indicates incomplete debinding, requiring an extension of the debinding time or an increase in catalyst flow rate. If the loss rate is too high, it may cause micro-cracks in the parts, and the batch must undergo fluorescent penetrant inspection for confirmation. All debinding records and weight loss data are uploaded to the MES system, serving as the basis for subsequent sintering release.

The sintering furnaces are dual-purpose vacuum/atmosphere furnaces. The sintering program strictly follows the heating curve validated by the process. Three thermocouples (top, middle, bottom) and a vacuum gauge are installed inside the furnace to monitor temperature uniformity (temperature difference within the same layer ≤ ±5°C) and vacuum level (debinding stage requires ≤10Pa, sintering stage requires ≤10⁻²Pa) in real-time. Each sintering run is accompanied by a complete temperature-time curve, vacuum-time curve, and protective atmosphere (e.g., hydrogen, argon) flow rate curve. These curve files are automatically stored and numbered corresponding to the furnace run. After sintering, the quality department samples each furnace load: at least 5 parts are taken (10 parts per furnace for larger furnaces) to test the sintered density (using the Archimedes method or a densitometer), requiring a density ≥ 97.5% of the theoretical density (above 7.65g/cm³ for stainless steel); Rockwell or Vickers hardness is tested to meet the material specification requirements; metallographic samples are cut and examined under a microscope for grain size and pore distribution (porosity ≤ 3%, maximum pore diameter ≤ 10μm). Additionally, at least 3 parts from each furnace are randomly selected for critical dimension inspection, and the shrinkage rate is calculated to ensure it is within the control limits (shrinkage rate CPK ≥ 1.0). If any item is non-conforming, the entire furnace load must be isolated for review and, if necessary, scrapped.

If sintered parts require secondary processing (CNC turning, milling, drilling, tapping, grinding, etc.) or outsourced heat treatment and surface treatment (PVD, electroplating, passivation, sandblasting, etc.), the company has established strict supplier qualification and process control procedures. For internal secondary processing, detailed Standard Inspection Procedures (SIP) are prepared for each process, specifying processing parameters, clamping methods, tool specifications, and inspection standards. Mass production is only authorized after the operator's first article passes inspection. During processing, dimensional sampling inspection is conducted every 100 parts. For outsourced processing, suppliers must pass Fangchi's qualification audit, sign a quality agreement, and submit inspection reports per batch. When each batch of outsourced products returns to the factory, the quality department conducts dimensional re-inspection and visual inspection according to the sampling plan (AQL 0.65), with critical characteristics subject to C=0 sampling (zero defects). Surface-treated parts undergo additional adhesion testing (cross-cut test), thickness testing, and salt spray testing (as per customer requirements). All secondary processing records and inspection results are uploaded to the MES system, ensuring the traceability of post-processing quality.

All finished products must undergo 100% dimensional inspection and visual inspection before packaging and shipment. This is Fangchi's solemn commitment to its customers. The company is equipped with 5 fully automatic CCD optical inspection devices, each capable of simultaneously measuring over 12 critical dimensions (including length, width, thickness, hole diameter, position tolerance, etc.) at an inspection speed of 700 parts per hour. Using template matching and edge detection algorithms, the CCD devices automatically determine whether the product is within the tolerance range. Parts exceeding tolerance are automatically ejected by air nozzles into a reject bin. Simultaneously, visual inspection (including scratches, dents, burrs, deformation, color variation, etc.) is performed on each batch of finished products according to the normal single sampling plan of GB/T 2828.1-2012, and samples are taken for packaging integrity checks (labels, quantity, desiccant, etc.). After OQC inspection is passed, the quality department issues an "Outgoing Inspection Report" before the products can be warehoused and shipped. All CCD inspection data and visual inspection records are automatically uploaded to the MES system, allowing customers to query the outgoing inspection results of any batch online.

Fangchi has established a full-process quality traceability system centered on ERP+MES. Starting from raw material receipt, each batch of powder, binder, and mold is assigned a unique batch barcode. During production, the operators, equipment numbers, process parameters, and inspection results for each process step—injection molding, debinding, sintering, secondary processing, and inspection—are collected via barcode scanners or automatically by the system and uploaded to a cloud database in real-time. A traceability label is affixed to the outer packaging of each finished product, containing information such as the order number, batch number, production date, and quantity. Once a customer reports a quality issue, the quality engineer can use the batch number of the finished product to perform a one-click query in the MES system for the complete process record of that batch: raw material inspection report, injection molding process parameters, debinding and sintering curves, inspection data from each process step, archived CCD inspection images, operator and machine information, etc. A preliminary traceability analysis can be completed within 30 minutes, allowing for the rapid formulation of corrective and preventive actions. The system also supports remote customer access to certain quality data (with authorization), achieving quality transparency and enhancing customer trust.