How does it work?
Automatic bagging and wrapping equipment enclose sliced loaves of bread in bags. Typical bags are low density polyethylene plastic, 1 mm thick, and open at one end (ponytail design). Some bakeries double wrap variety breads with an inner wrap prior to bagging.
Depending on how the product and packaging material are put together, two types of bagging and wrapping systems are available:
- Equipment in which product is pushed into the bag
- Equipment in which the bag is pulled over the product
Wrapping is achieved by cutting a piece of plastic film, forming it into a tube around the product.
A length of wrapping material is drawn or fed through a reel or cut off. The product is pushed into and the ends and folded around the product to form a “tube” where its open ends are tucked in and sealed by heat seals.1
Bread can be bagged by using wickets or stacks of bags. A bag is blown open by air and a scoop enters the open mouth, expands, grips the bag, and pulls it from the wicket over a properly positioned loaf. The open end or bag mouth is gathered together to form a neck that is closed by using a wire twist-tie or a plastic-clip.1
Wire twist-tie closure
Bag-closing equipment can run at 60–100 packages per minute. Wire ties are typically 4.0 inches (10.2 cm) long. The wire is wound over replaceable reels or cut-offs of a certain length, providing thousands closures per reel that keep up with the line speed. The wire is cut to required length as it is attached to the bag’s neck. Colors are available for coding and traceability purposes.
Wire ties are available with all-plastic, laminated plastic/paper, along with all-paper covers over the wire core. Frequent maintenance should ensure laminations are intact and do not separate from the bare wire to expose sharp edges.2
This bag-closing equipment runs at 100–130 packages per minute. These closures are also wound over reels that provide several thousands of closures per reel. Imprinting can be done on the plastic clip to provide information about price or ‘‘sell by’’ date.
Plastic-clip closures are produced from resilient polystyrene. Their aperture size can form an almost airtight package to help preserve products’ shelf-life. Clips are also available in colors for coding and traceability.2
Aspects to consider when buying packaging equipment:
- Maintenance requirements (e.g. lubrication, repair, replacement of mechanical parts)
- Amount of product waste generated
- Hygienic design
- Crumb collection system
- Level of automation required
- Human-machine interfacing
- Pneumatic requirements (bag opening by air jetting)
- Speed (units per minute) must be balanced against production line needs
- Static versus moveable design
- Excess capacity for future demand growth
- Acquisition and commissioning costs
Production checks for bagging equipment:
- Bag integrity
- Timing between product/bag pushing or pulling
- Bag fit
- Loaf volume (size)
- Loaf thickness
- Product shape
- Absence of sharp edges that may tear the bag
- Orientation and positioning of product at inlet
- Gap between loaf slices
Adjustments to bagging settings
Bagger adjustments rely on basic operational factors, these are:
- Air supply (pneumatic system): cleanliness, pressure and flow direction
- Packaging and machine settings: scoop size, width of side guides, conveyor speed
- Paine, F.A. “Packaging Machinery.” A Handbook of Food Packaging, 2nd edition, Springer Science+Business Media Dordrecht, 1992, pp. 126–131.
- Good, G.E. “Closures, Bread Bag.” The Wiley Encyclopedia of Packaging Technology, 3rd edition, John Wiley & Sons, Inc., 2009, pp. 284–285.