Designing a High-Speed Overwrapping and Case Packing Line for Rigid Products

The Challenge: Protecting High-Value Rigid Products at Speed

In the personal care and pharmaceutical industries, many products come in rigid block formats—such as bar soaps, cosmetic boxes, or solid dosage forms. These products often require a premium finish, physical protection, and strict weight compliance before being packed into shipping cartons. When a line is required to handle over 100 individual items per minute, manual bundling and packing become severe bottlenecks.

The challenge is to design an end-of-line system that can group these rigid items, overwrap them in a protective film, weigh them with high precision, and pack them into corrugated cases—all without exceeding the footprint of a standard factory floor.

Stage 1: 3D Transparent Film Overwrapping

For premium presentation and surface protection, 3D transparent film overwrapping is the standard. Unlike shrink wrapping, 3D overwrapping folds the film tightly around the product like a traditional gift wrap, leaving neat, clean fold-corners with no loose film tails.

In a typical high-speed configuration, products are grouped (e.g., 2x2x1 blocks) and overwrapped using BOPP or PVC film (typically 20–30 microns thick). The machine uses a fully servo-driven mechanism for feeding, stacking, and folding. The heat-sealing side flaps are PLC-controlled to ensure a secure seal without damaging the product underneath. A well-tuned system can run at speeds of 10 to 35 bundles per minute, depending on the film thickness and bundle size.

Stage 2: Dynamic Checkweighing and Rejection

Once the bundles are sealed, they move to a dynamic checkweigher. This is a critical control point for compliance. Modern checkweighers use a high-precision load cell (such as Mettler Toledo) coupled with an FPGA hardware filter.

Because the bundles are moving at high speed, the system must distinguish between the actual product weight and environmental vibrations. The checkweigher automatically compares the measured weight against the target. If a bundle is missing a piece or the film roll ran empty, the weight falls outside the tolerance band, and a pneumatic pusher (reject device) removes the bundle before it reaches the case packer.

Stage 3: Integrated Case Erecting and Packing

For the final secondary packaging, a compact, integrated case erector and case packer (such as the ZC-IT600) is highly efficient. Instead of separate machines for erecting and packing, this unit combines them into a single frame with a balcony-style design, making it easy to inspect and maintain.

Equipped with a dual-servo robotic arm and imported linear guide rails, the packing mechanism picks the overwrapped bundles and places them into the carton. The system is highly adaptable:

• Flexible Box Sizes: Handwheel adjustments allow for quick format changes.
• Complex Insertion: It can automatically insert instruction manuals, cardboard dividers, or certificates of conformity alongside the product.
• Stable Handling: The robotic arm uses vacuum suction and precise positioning sensors to ensure the product is placed neatly, layer by layer.

With a box forming capacity of up to 8 cases per minute, the packing station can easily keep up with the upstream overwrapping speed.

System Integration and Control

Connecting these stages requires strict synchronization. A continuous flow of loose products cannot be fed into a batch-packing case erector without a buffer. The infeed conveyor must have accumulation capability and photoelectric sensors to meter the flow of bundles.

For maximum reliability, the entire line is typically equipped with a unified control architecture. Using Siemens PLCs, servo motors, and Schneider electrical components ensures that the overwrapping machine, checkweigher, and case packer communicate seamlessly. If a downstream jam occurs at the case packer, the upstream machines automatically pause, preventing product from piling up and spilling onto the floor.

System Specifications Summary

For more details on integrating overwrapping and case packing into your production line, contact our engineering team.