Annual Issues of Cargo Damage, Wrong Materials, and Mixed Batches? —— Five Steps for In-Plant Logistics Quality Control

1. Introduction: Quality Departments Focus on Production Lines but Overlook the "Transport Team" in the Workshop

Many factories distribute their quality management in the following way: incoming quality control (IQC) guards the entrance, process inspection monitors each step, and final inspection oversees the finished products. Each workstation on the production line has work instructions, first article inspection, and regular patrols. However, how products move between processes, how they are stored in the warehouse, and how they are allocated for production are often neglected—bumps and scratches go unrecorded, different batches of the same specification are mixed without notice, and materials for Model A are delivered to the workstation for Model B, only to be discovered after assembly. By the time customers complain or return products in bulk, the root cause is often traced back to these "unmanaged logistics processes."

In-plant logistics is the "blind spot" in quality management: it does not directly generate value but directly determines the product's condition; it does not produce inspection data but creates quality risks every day. The five steps outlined in this article aim to manage the quality of the "in-plant transportation line."

2. Recognize the Four "Quality Killers" in Logistics

Before taking action, let's look at the four most common issues in in-plant logistics and see if they apply to your facility.

Handling Damage. Scratches, dents, deformations, and drops often occur during material transfer: parts are stacked without packaging, turnover containers are overloaded, forklifts make sharp turns, and materials fall from heights. The hidden nature of handling damage is that minor scratches are not visible on-site but are discovered during assembly at the client's end, making it difficult to trace back to a specific handling incident.

Wrong Material Issuance and Allocation. Similar materials are stored adjacent to each other, picking relies on "looks like," and allocation depends on experience to identify workstations. This often leads to wrong materials being issued. Wrong material issuance is often accompanied by mixed batches: incorrect parts are assembled into products, leading to batch accidents.

Mixed Batches and Broken Traceability. First-in, first-out (FIFO) is not strictly followed, with new batches overloading old ones; batch labels fall off or are covered by oil during transfer; and flow cards are separated from the actual materials. When quality issues arise, the inability to trace batches and determine the scope often results in the entire batch being scrapped.

Storage Time and Environmental Control. Temperature and humidity-sensitive materials are left in direct sunlight by windows, anti-static components are transferred in ordinary plastic bags, and materials with expiration dates, such as adhesives and rubber parts, are stored for long periods beyond their shelf life. If the storage environment is not controlled, products can be "damaged" even before they reach the production line.

These four issues share a common characteristic: they occur in areas not directly visible to the quality department and are only exposed after causing losses. The first principle of in-plant logistics quality control is to manage logistics as a process, not just as "moving things."

3. Step One: Handling Control —— Prevent Defects During Transportation

To manage handling as a process, establish four basic requirements:

1. Handling Methods Match Material Characteristics. Precision components and appearance parts must have dedicated turnover containers, with parts separated by dividers or foam to prevent stacking; anti-static components should use anti-static containers; liquids and powders should be in sealed containers. The type of material should determine the type of container, as specified in the packaging guidelines, rather than using whatever is available on-site.

2. Standardized Turnover Containers. Turnover boxes, material racks, and pallets should have uniform specifications, colors, and load capacities. Physical restrictions should prevent overloading, and stack height limits should be marked with color-coded lines. The condition of the containers should be inspected: using damaged turnover boxes is like leaving the door open for handling damage.

3. Controlled Handling Paths and Speeds. Plan fixed handling routes to avoid high-traffic areas and areas with precision equipment; reduce speed when turning, passing through doors, and on slopes; and specify dedicated routes and speed limits for fragile and precision materials.

4. Loading and Unloading Standards and Training. Each action, from loading and unloading to placing and removing materials from shelves, should have a standard: handle materials gently, avoid throwing, and stack neatly. Handlers should undergo training and certification before starting work—since they handle more parts than many operators, the standardization of their actions directly affects the appearance quality of the product.

4. Step Two: Storage Control —— Ensure "Storage" Does Not Alter Product Condition

The core of storage control involves four key areas: clear differentiation, traceability, FIFO execution, and environmental compliance.

Clear Differentiation. The warehouse should be divided into areas for qualified, pending inspection, nonconforming, and isolated materials, with clear physical boundaries and labels. Similar materials should be stored in separate zones and racks, with each storage location uniquely coded to match the material code, ensuring "one slot, one material, fixed location." Pending inspection materials should not be moved to the qualified area until they are released.

Traceability. Inventory records, cards, and physical items should be consistent, with real-time inventory tracking and complete batch information registration: supplier, production date, entry date, and inspection report number. Materials that cannot be found or traced are themselves quality risks—traceability can break at any moment.

FIFO Execution. FIFO should not rely on "voluntary compliance" but on mechanisms. Automated立体库 (立体库 can be translated as "automated立体库" or "automated立体仓库" depending on context, but since it's not in the glossary, I'll leave it as "automated立体库") allocate storage locations based on batch numbers, and the system enforces the release of older batches first. For flat warehouses, use "left in, right out" storage rules, color-coded labels to distinguish entry months, and dual storage locations for rotation to make FIFO visible and verifiable. Weekly checks of FIFO execution rates should be included in storage performance evaluations.

Environmental Compliance. Temperature and humidity, cleanliness, and static protection requirements should be written into storage guidelines, with daily recording and automatic alerts for exceeding limits. Materials with expiration dates should have an expiration ledger, with warnings issued before expiration and re-inspection after expiration, and nonconforming materials should be immediately isolated. Storage is not just a "place to put things" but a "place to maintain product condition"—any change in condition is a quality incident.

5. Step Three: Distribution Control —— Deliver the Right Material to the Right Workstation at the Right Time

Distribution is the interface between logistics and production and is a high-risk area for wrong material issuance. Distribution control involves three key areas: error-proofing during picking, timely delivery, and controlled line-side storage.

Error-Proofing During Picking. Material requisition forms are generated by the system based on work orders, and pickers verify each item by scanning—material barcode, storage location code, and work order number. If all three match, the material can be released from the warehouse. For smaller factories, at least achieve "one form, one vehicle, one label": each material requisition form is paired with a dedicated turnover vehicle, with the form hung on the vehicle and materials placed in designated slots, eliminating "memory-based picking." A verification step should be set up after picking, with the verifier checking each item and signing off on the release.

Timely Delivery. Distribution timing should align with production rhythms—delivering too early occupies line-side space, and delivering too late causes production delays. Implement timed and quantified distribution: calculate distribution frequency based on production plans, and fix the time window for material arrival at the line side. Any deviation from the time window is considered an anomaly. Establish a rapid response channel for distribution anomalies (missing materials, wrong materials, delays) to notify production and planning immediately.

Controlled Line-Side Storage. Line-side material racks should be fixed and clearly marked, following the same "one slot, one material" rule as the warehouse. Verify batch numbers and work orders before materials are loaded onto the line; clear the line and confirm during changeovers, ensuring all materials from the previous product are removed. Set upper and lower limits for line-side inventory levels—replenish when below the lower limit and alert when above the upper limit. Uncontrolled inventory is a precursor to mixed batches and expiration.

6. Step Four: Packaging and Labeling Control —— Ensure Products "Carry Their Identity" Throughout the Process

Packaging and labeling are two critical areas in logistics quality that are often overlooked.

Packaging Protection. Inner and outer packaging and cushioning materials should be designed based on product characteristics and validated through drop, stack, and vibration tests—packaging validation is not a one-time task but should be repeated when suppliers change packaging materials or transportation methods. Materials with damaged packaging should be inspected separately upon receipt and not directly used in production.

Complete Labeling. Each turnover unit should have a unique label, including the material code, batch number, quantity, and date. Labels should accompany the materials, and any detachment, blurring, or covering during transfer should be treated as an anomaly, with immediate relabeling and batch verification. Prohibit "unlabeled materials" from entering the production line—parts without labels are like people without IDs, and any issue can become a traceability black hole.

Error-Proofing in Labeling. Use barcodes, QR codes, and RFID to replace handwritten labels, with uniform label templates and machine-printed batch information to prevent the classic "unreadable handwritten batch number" incident. Label integrity checks should be included in daily logistics inspections.

7. Step Five: Measurement and Closure —— Logistics Quality Also Needs "Accounting"

Managing without measuring is like not managing at all. Establish a set of visible metrics for logistics quality:

• Cargo Damage Rate (the proportion of damaged items during handling and storage out of the total flow, broken down by process; focus on improving areas with higher damage rates)
• Wrong Material Issuance Frequency (the number of wrong material issuances during picking and distribution; the target should be zero)
• FIFO Execution Rate (the rate of FIFO compliance, with a target of at least 95%)
• Traceability Success Rate (the proportion of randomly selected work-in-progress items for which the batch, source, and condition can be clearly identified within three minutes)
• On-Time Delivery Rate (the proportion of materials arriving at the line side within the specified time window)

In addition to metrics, a closed-loop mechanism is essential: logistics anomalies (bumps, wrong material issuance, label loss) should be managed through anomaly reporting, similar to production line quality anomalies—analyze root causes, develop countermeasures, and verify effectiveness. Conduct a monthly logistics-specific audit, scoring across handling, storage, distribution, and packaging and labeling dimensions, and include these scores in departmental performance evaluations. Continuous improvement in logistics quality should follow a "discovery—analysis—countermeasure—verification" cycle, not just a scolding of handlers when issues arise.

8. Conclusion

Every segment of a product's "journey" within the workshop is part of the quality formation process. Handling, storage, distribution, packaging, and labeling—these five processes may seem insignificant, but they determine whether the product reaches the customer in perfect condition or with visible damage. By managing in-plant logistics as a process, establishing rules, setting standards, measuring metrics, and following a closed loop, the "blind spot" of transportation can be transformed from a breeding ground for accidents into an extension of the quality defense line.

In-plant logistics is the "blind spot" in quality management: manage handling, storage, distribution, packaging, and labeling as processes, and issues like cargo damage, wrong material issuance, and mixed batches will lose their breeding ground.

Knowledge code: 7.4.2

Version: v20260823

? Complementary Training Materials: Five Steps for In-Plant Logistics Quality Control Practical Training (Complete PPT) —— handling, storage, distribution, packaging and labeling, measurement and closure, transforming the blind spot into a quality defense line, suitable for 1.5 to 2 hours of internal training.

Author: Quality Think Tank Quality Think Tank is dedicated to providing systematic professional knowledge, methodologies, and practical tools for quality management practitioners, helping enterprises continuously improve their quality capabilities.