I. Root Cause Analysis of Color Difference: Accurately Locate the Problem nodes

The color difference of stainless steel color plates is usually caused by four core factors:

1.Coating process deviation：When PVD vacuum coating is applied, the purity of the target material (such as the ratio of titanium to chromium), the coating thickness (fluctuating within the range of 20-50nm), and the temperature inside the furnace (with a temperature difference of ±5℃) directly affect the color stability.

2.Substrate difference：The surface roughness (Ra value 0.2-1.6μm) and grease residue (≥5mg/m²) of 201/304/316 materials can lead to uneven adhesion of the coating, causing color deviation.

3.Batch production fluctuationCoating parameters for different batches (such as voltage(200-400V, current 50-100A) not standardized, or the coloring solution aged (with a usage cycle exceeding 3 months), resulting in poor reproducibility of the same color number.

4.Ambient light interferenceThe customer is in natural lightWhen observing colors under D65 light source, indoor warm light (A light source), and cold white light (TL84 light source), visual differences with ΔE > 2 May occur.

Ii. Full-process Control PlanSeven key actions have been implemented

1.Deep binding of the upstream supply chain: Establishing color control rights

· Supplier access criteria：

· Required to be providedSpectrophotometer test report（ΔE≤1.0, measurement conditions: D65 light source, 10° field of view), with a focus on verifying the reproduction ability of RAL color cards (such as RAL 7035 Pearl Gray) and Pantone color cards (such as 18-1663 TPX wine red).

· During the on-site factory inspection, check whether the coating equipment is equippedClosed-loop temperature control system"Precision" ±1℃）、Plasma cleaning lineEnsure that there is no grease residue on the surface of the substrate≤2mg/m²）。

· Customized color card system：

· The United Steel Plant has developed the "Special Color Card for Traders", which includes50 high-frequency color series (such as bronze, rose gold, titanium gold), with each color number markedLaThe range of b * values(Such as titanium gold:L*=60-65，a*=15-20，b*=40-45）、Standard for film layer thickness(such as25nm±2nm）。

· The supplier is required to make the products before each batch is producedStandard sample of 500mm×500mmIt will be sent to the trader's laboratory via SF Express for useKonica MinoltaCR-400 colorimeterOnly after passing the inspection can mass production proceed.

2.Digitalization of order management: Eliminating communication errors

· Online color grading system：

· On the official website"Mini-program embedding.AR color palette preview toolAfter the customer uploads the space photos, they can drag and drop different color board models (such as antique bronze, coffee gold) to view the decoration effect in real time. The system will automatically record the ones selected by the customerLa"b * value."

· The remarks column of the order is mandatory to be filled inColor tolerance range(such as ΔE≤1.5）、Light source observation conditions(such as Avoid ambiguous expressions such as "acceptance under D65 light source".

· Historical color number database：

· "Establish"Excel ledger records the order color number, supplier, production batch and inspection data of each customer. When repurchasing next time, the historical data can be directly retrieved to achieve "one-click ordering and color replication".

3.Production process transparency: Eliminate under-the-table operations

· Remote monitoring intervention：

· The supplier is required to install it in the coating workshopIndustrial cameraTraders can view production parameters (such as vacuum degree) in real time through the cloud platform≤5×10⁻³Pa, target current 80A±5A. Stop immediately if any abnormality is found.

· everyTake a screenshot every two hoursEquipment operation log(Including temperature, voltage and coating time), archived for future reference.

· First-article confirmation mechanism：

· Before the mass production of goods, suppliers need to submitThree first-piece samples(Including scraps), traders are randomly selectedOne piece will be sent to the customer for signature confirmation, and two pieces will be retained simultaneously as acceptance reference samples.

4.Quality inspection system upgrade: Building a dual defense line

· Internal quality inspection by traders：

· "ProcurementDesktop spectrophotometer(such as(X-Rite MA98), conduct on the arrived platesFull inspectionTake the first and last parts of each roll of sheet1 meter, detect 3 points, and record the ΔE value; For irregular-shaped parts (such as curved plates), usePortable colorimeter(such asBYK 4561) Detect the uniformity of surface color.

· "Establish"Nonconforming product handling process：Batches with ΔE > 1.5 will be directly returned to the supplier. Batches with 1.0 < ΔE≤1.5 are marked as "Special Purchase". Customers need to be informed in advance and a discount (such as a 3% reduction) should be provided.

· Third-party testing endorsement：

· For high-end customization project (such as star hotels and luxury stores), entrustSGS/IntertekProceedColor durability test(such as200 hours of ultraviolet aging (ΔE≤3.0), with a test report issued and delivered along with the goods, enhancing customer trust.

5.Packaging and transportation damage prevention: Color guards the last mile

· Scratch-resistant packaging solution：

· "AdoptDouble-layer protective film"Inner layer"PE static film, outer layer PVC anti-scratch film, for edge usePearl cotton corner guardsWrap to prevent the film layer from being scratched or discolored due to friction during transportation.

· When packed in wooden crates, the boards are used in betweenCorrugated paper isolationAnd mark "Do not place sideways" and "Store away from light" signs. Transport vehicles are equipped with GPS positioning to monitor temperature and humidity (temperature ≤35℃, humidity ≤60%).

· Standardization of delivery and acceptance：

· Included with the goods** "Color Acceptance Guide" **, specifying the testing tools (if the customer needs to prepare a color difference meter of the same model by themselves), observation distance (50cm), and lighting conditions. It is required that the customer complete the acceptance within 48 hours after receiving the goods; otherwise, it will be considered qualified.

6.Rapid after-sales response: Minimize losses

· Color difference treatmentSOP：

· After the customer reported the color difference issue,Initiate response within 2 hours

· Step 1: Remotely guide the customer to take pictures of the color difference area with their mobile phone (under standard light source, adjust the white balance to.D65), useAdobe Color CCThe app extracts color values and compares them with the order standards.

· Step Two: If If ΔE > 2.0, a qualified sample will be reissued within 48 hours. If ΔE≤2.0, explain the industry standard (for stainless steel color plates, ΔE≤3.0 is considered qualified), and offer accessories worth 1% of the payment as compensation.

· Customer education mechanism：

· Regularly held** "Stainless Steel Color Application Lecture Hall" ** (Online Live Streaming), explaining the principles of color difference generation, acceptance criteria, and maintenance knowledge, reducing disputes caused by cognitive differences.

7.Iteration of technical tools: Replacing experience with technology

· AI color grading algorithm：

· Access the supplierIntelligent coating systemInput the targetLaAfter reaching the b * value, the system automatically calculates the target material ratio and coating time (for example, predicting titanium gold requires 50% titanium target + 30% chromium target + 200sccm argon gas flow, coating time 1200 seconds), with an error rate of no more than 1.5%.

· Blockchain traceability：

· Generate for each orderBlockchain traceability codeRecord the smelting from the base material (such as green mountainsThe entire process information, including 304 hot-rolled coil, coating parameters (such as PVD furnace number 2025-04-23-08), quality inspection data (such as ΔE=0.8), and logistics trajectory, can be verified by customers by scanning the code for authenticity and color compliance.

Iii. Cost and Benefit Analysis

Key points of execution：

1.Give priority to tackling high-value customersThe annual purchase amount exceedsFor customers with a budget of 5 million yuan, we will take the lead in implementing full-process control. After accumulating successful cases, we will replicate them to small and medium-sized customers.

2.Establish a red and black list for suppliersContinuousSuppliers with qualified color differences in three batches will be given a 5% preference in purchase volume. Those who fail to meet the standards for two consecutive times will be blacklisted and made public to the industry association.

3.Data-driven continuous improvementMonthly summary of color difference problem reports and analysisThe TOP3 color codes (such as champagne gold and sapphire blue) are frequently used, and the process parameters are optimized in collaboration with suppliers.

Through the above strategies, traders can lower the color difference complaint rate from the industry averageThe 12% has dropped below 5%, and at the same time, a differentiated competitive edge has been established through "zero color difference" services to seize the pricing power in the high-end customization market.