Skin Packaging Machine

Overview

A skin packaging machine seals a product to a printed backing card under a tight, clear film skin. The product is placed on a coated paperboard, a sheet of clear film is heated until soft, and vacuum is pulled through the board to collapse the film down over the product and bond it to the card. The result holds the item firmly against the board with a glossy second-skin that follows its exact shape. This is how hardware, hand tools, fasteners, fishing tackle and electronics are displayed on peg hooks, and it is also used to vacuum-skin fresh meat and fish onto a board for premium retail.

The board travels through the Frame and Table on a conveyor. The Board Feed places a printed card on the platen, the operator loads product, the Skin Film Feed clamps clear film over it, the Film Heater softens the film, the Seal and Draw Frame brings it down, the Vacuum System draws it tight, and the Trim and Separate station cuts the finished pack free. The Control Cabinet cabinet times the cycle.

The platen and board

The board sits on a Perforated Platen, a bed drilled with many small holes. When vacuum is applied beneath, air is pulled down through these holes and through the porous coated board itself, dragging the softened film down with it. The board is not plain card: it carries a heat-activated skin coating, so when the hot film touches it under vacuum the two bond into a sealed pack. Without the coating the film would simply drape and not stick.

Boards are fed from the Board Feed magazine, where a Pick-off Cup cup peels one card off the stack and a Feed Pusher slides it onto the platen. On most machines the operator then places the product onto the card by hand, since skin packs cover a wide range of irregular items.

Heating the film

The clear skin film is usually a surlyn ionomer or a special polyethylene chosen because it softens cleanly, stretches deeply without tearing, and bonds to the board coating. The Skin Film Feed pulls the film off a reel, held taut by the Reel Brake, and the Film Clamp Frame grips its edges over the board.

The Film Heater then softens it. A Radiant Heat Panel of infrared heaters above the film warms it to its softening point, with a Reflector aiming the heat down and a Heater Thermocouple holding temperature. The dwell is critical: too little heat and the film will not draw over tall product, too much and it sags, thins, or burns. Once the film is soft the Heater Traverse slides the hot panel clear so it does not overheat the pack.

Drawing the skin

This is the step that gives the process its name. The Seal and Draw Frame lowers the clamped hot film onto the board and product, and the Vacuum System system opens the platen to vacuum. A Vacuum Pump feeding a Vacuum Reservoir reservoir means the Vacuum Valve can dump a strong, fast draw the instant the film is in place. The film collapses down over every contour of the product and bonds to the coated board around it, with no trapped air. A Pressure Sensor confirms the draw reached the target vacuum, which is what makes the skin tight and the bond complete.

For meat and fish the same draw removes all air from around the product, which both displays it attractively and extends shelf life by vacuum, often longer than a gas-flushed tray.

Trimming, control and use

After the bond sets the Trim and Separate station frees the pack. A Trim Knife cuts the film around the edge of the board, a Cutoff Bar severs the web between packs, and the Scrap Winder reels up the leftover film skeleton. The finished pack rides off on the Board Conveyor.

The Control Cabinet cabinet holds the PLC and the Temperature Controller for the heater, with the operator setting heat time, vacuum dwell and board size on the HMI Touchscreen.

The machine runs 4 to 12 cycles a minute, slower than a wrapping line because each cycle includes a heat soak and a vacuum draw. Buyers split into two camps: industrial and retail packers who skin-pack tools, hardware and electronics for peg display, and food processors who vacuum-skin meat and seafood onto boards for premium chilled retail. The skin pack's appeal is that it grips odd shapes securely, shows the product clearly, and needs no blister tooling, so a new product runs with only a new printed board.