Robot Automation for Thin-Wall Packaging Production

Three categories of robots serve thin-wall packaging production. Take-out robots are the simplest, extracting molded parts from the mold and placing them onto a conveyor or stacking station. They use servo-driven side-entry or top-entry configurations with cycle times of 0.8 to 1.5 seconds for part extraction. IML robots are the most complex, combining label placement, part extraction, and often quality verification in a single system. They require 5 or more servo axes and cycle times under 3 seconds. Downstream packaging robots handle stacking, counting, and case packing of finished parts. For thin-wall food packaging, the choice between take-out and IML robots depends on whether the product requires in-mold decoration. Undecorated products like disposable tableware and plain food containers use take-out robots, while branded yogurt cups, margarine tubs, and milk tea cups use IML robots. HWAMDA specifies the appropriate automation level for each turnkey line configuration. The automation level is specified during the turnkey line engineering phase to match the customer's production requirements.

HWAMDA partners with SWITEK to provide fully integrated IML automation. The SWITEK SW833 serves machines from 150 to 450 tons with a crosswise stroke of 190 plus 190 mm, vertical stroke of 420 mm, and traverse stroke of 2,100 mm. It achieves take-out times of 1.2 to 1.5 seconds with an 8 kg payload capacity and weighs 1,280 kg. The 5-axis servo motor system provides the speed and precision needed for label placement at plus or minus 0.1 mm accuracy. The complete cycle includes label pickup from the magazine via vacuum suction, electrostatic charging of the label for cavity adherence, label placement into the open mold cavity, mold closing verification, injection cycle wait, part extraction from the core side, and part deposit onto the stacking conveyor. The flexible cassette magazine design allows rapid changeover between label SKUs, supporting multi-product production scheduling. The SW850 model handles larger format containers on machines up to 600 tons.

After parts are extracted from the mold, downstream automation handles stacking, counting, and packaging. For nested products like cups and containers, servo-driven stacking systems arrange parts in precise stacks of 25, 50, or 100 units. The stacking mechanism must accommodate the slight taper of thin-wall containers while preventing damage to the thin walls or any IML decoration. Automatic counting sensors verify stack quantity before routing to the bagging station. Bag-in-box or shrink-wrap packaging machines seal the counted stacks into shipping units. For cutlery and flat tableware, counting and bundling machines create sets of 100 or 250 pieces. The entire downstream line typically operates at 10 to 20 percent higher throughput than the injection molding cycle to prevent bottlenecks. HWAMDA provides downstream automation as part of the turnkey package, ensuring compatibility with the injection molding and robot systems. The complete downstream system is sized for 10 to 20 percent higher throughput than the injection cycle to prevent any bottleneck in the packaging process.

The ROI calculation for automation in thin-wall packaging compares the automation investment against labor savings, quality improvements, and throughput increases. A SWITEK IML robot system at 40,000 to 80,000 dollars eliminates 1 to 2 manual labeling operators per shift, saving 2 to 6 full-time positions in a 3-shift operation. In China, where injection molding operator wages average 600 to 800 dollars per month, annual labor savings from eliminating 4 positions total approximately 28,800 to 38,400 dollars. In higher-wage countries like Turkey at 700 to 900 dollars per month or Germany at 3,200 to 3,800 dollars per month, automation payback is proportionally faster. Beyond direct labor savings, automation improves quality consistency by eliminating human variability, enables 24-hour unattended operation, and reduces scrap rates from typical manual handling losses of 1 to 3 percent to below 0.2 percent. Total automation payback is typically 6 to 18 months depending on local labor costs.