Strapping Machines 101
What is a strapping machine, and how does it work?
Sometimes known as banders, strapping machines are a staple in various industries for a range of applications as an end-of-line system to improve efficiency and the overall presentation of a packaged product. The type of production line and product to be strapped determines what machine should be used for maximum production.
What is a strapping machine?
A strapping machine secures one or more items for handling and product transport by placing a flat strap around the perimeter. The strap is held in place by various methods, including heat, friction, and ultrasonic welds. A plastic strapping machine uses multiple sizes of thin plastic strap to ensure products stay together.
Strapping machines range from small semi-automatic or “table top” units to automatic “arch” machines, sometimes called bundlers. Larger, fully automatic machine systems secure pallet loads and shipping units for transport and storage.
Types of strapping machines
Semi-automatic or operator cycled machines require an operator to manually place the product on the machine table, loop a length of strap around it, and insert the strap end into a slot to initiate the machine cycle. The machine then tightens the strap on the product, seals the strap ends, and cuts the strap off. These machines are economical and practical for light-duty, low volume requirements.
Automatic or arch machines include an arch or strap track through which the machine feeds the strap around the product, relieving the operator of that task. These units range from operator cycled via footswitch or pushbutton, to fully automatic with powered conveyors and package sensing technology that automatically positions the product in the strapping zone and applies straps without operator intervention. Throughput speeds for fully automatic EAM-Mosca equipment may approach the 60 packages per minute range depending on a variety of product and process factors.
Larger strapping machines or systems, sometimes called unitizers, because of their function of tying multi-item product groups into secure shipping units, have similar features to the automatic machines referred to above, in a larger size, utilizing somewhat different technology. They may integrate transport and handling functions upstream or downstream of the strapper as needed. Throughput speeds reflect the pace of shipping departments, typically in the 2 to 10 unit per minute range.
The Basics of Strapping Machine Operation
Every manufacturer’s equipment is different in details, but all share standard functions and features, including:
- A strap dispenser where the strap coil is mounted and where the strapping is supplied to the sealing head.
- A sealing head that feeds the strapping around the package, tensions the strap to a selected tension level, seals the strap ends together, and cuts the strap, freeing the package for movement out of the machine. The strap cycle is completed by pre-feeding the strap around the track in preparation for strapping the next package. Sealing heads may be positioned beneath, on the side, or above the product, depending on specific application conditions.
- A strap track guides the strap around the package (with semi-automatic machines, the operator performs this function). Tracks are a fully enclosed tunnel in most high-speed bundlers providing a high level of control of the strap during feeding for high cycle efficiency. Larger systems typically utilize a “spring-gate” style of track which provides good but somewhat less strict control of strap feeding but is a practical solution in larger tracks using heavier, stiffer straps that need less guidance to feed efficiently.
- Fully automatic machines include a powered conveyor that moves product into and out of the machine. These machines are paired with control systems with sensors that detect product position to determine the correct strap placement position.
- The most sophisticated systems can include web-based data transfer capability to control the strapping operation and provide an information conduit as required by the user’s overall production process.
Options for Sealing the Strap Ends
There are three types of seals used in strapping machines:
- Hot blade heat seals insert a heated tongue between the overlapping leading and trailing ends of the strap loop around the package, melt the interface and press them together to form a seal. This system is very common in smaller bundlers and is a reliable means of sealing Polypropylene (PP) strapping. The smoke given off from hot blade seals when sealing polyester strap is irritating to humans, making it a rarely used technique on Polyester (PET).
- Friction welding is a tried and true method of sealing both PP and PET straps and is widely used on larger systems. The overlapping strap ends are gripped independently, with the contacting surfaces rubbing against each other, melting and ultimately fusing the ends together. Because friction systems are mechanical, they are subject to wear over time.
- Ultrasonic sealing applies a high frequency, low amplitude vibration to the strap ends, melting the interface and generating a strong seal. Ultra-sonics eliminates the smoke issue inherent in a hot blade system and simplifies the mechanics of friction systems. It is highly effective with both PP and PET strap.
Mosca manufactures sealing heads that use all three technologies and is currently the technology leader and significant practitioner of ultrasonic sealing with its SoniXs® system. SoniXs® technology has been used in Mosca strapping machines for more than ten years and is continually refined for the highest performance. Mosca’s ultrasonic technology automatically monitors and adjusts for sealing conditions and parameters on every strap cycle, providing consistently strong seals for both PP and PET straps. SoniXs® machines come with a two-year warranty on the SoniXs® components, and the systems have a demonstrated life of up to 10 million operating cycles over thousands of machines sold worldwide.
Finding the right strapping machine for your application can be a challenge, but the machine experts at EAM-Mosca can help. With over 35 years of experience, EAM-Mosca has the knowledge and expertise to help you find the right system for your unique application. Customized systems are engineered for particular cases where standard systems don’t fit.
Contact or chat online today to find out more.