When a packing line in a large-scale facility stutters, the root cause isn’t always a mechanical failure or a software glitch. 

Often, the culprit is the Coefficient of Friction (CoF) of the plastic bag. 

At UPAC, we don’t just manufacture ‘bags’. We engineer high-performance liners designed to interface perfectly with your plant’s automation. Here is why understanding ‘slip’ levels is critical for your operational efficiency and your bottom line. 

What is ‘Slip’ in Packaging Science? 

In technical terms, slip refers to the ease with which two surfaces slide over each other. This is measured by the Coefficient of Friction (CoF): 

• Kinetic CoF: The force required to keep the film moving over a surface. 
• Static CoF: The force required to get the film moving in the first place. 

For a food-safe plastic bag, we optimise these levels using specialised additives that ‘bloom’ to the surface of the film. This creates a microscopic lubricating layer. Without this, your film would be too ‘tacky’ to run through a machine. 

Why ‘Slip’ Levels Matter for Automation 

1. High-Speed Feeding and Opening 

On automated Vertical Form Fill Seal (VFFS) or pouch-loading machines, bags must be ‘plucked’ and opened in milliseconds. 

• Too Much Friction: Bags stick together, which is known as ‘blocking’. Your vacuum cups might grab two bags instead of one, leading to jams or ‘dry cycles’. 
• Optimised Slip: Bags separate cleanly. This ensures the machine hits its rated cycles per minute (CPM) without your team having to intervene. 

2. Travel Over Forming Collars 

As the plastic film moves over the metal forming collars of a packing machine, it encounters resistance. If the CoF is too high, the film ‘drags’. In a heavy-duty processing environment, this leads to: 

• Misaligned Seals: The film stutters, leading to wrinkled or weak seals that won’t pass a QA pressure test. 
• Material Fatigue: Excessive tension can stretch the film, thinning the barrier and potentially compromising the shelf life of your product. 

3. The ‘Anti-Block’ Balance 

While high slip is great for movement, too much slip is a safety hazard. If a bag is too slippery, finished products will slide off conveyors or, even worse, cause pallet instability in the warehouse. 

At UPAC, we engineer a ‘Balanced CoF’. We typically aim for a range between 0.2 and 0.3. This is slick enough for your machines, but grippy enough for your pallets. It means no jams on the line and no collapsed loads on the highway. 

The UPAC Difference: Technical Precision for Local Industry 

We provide technical consistency that protects your OEE (Overall Equipment Effectiveness): 

• Batch Consistency: We ensure the CoF remains identical from the first bag to the millionth. Your fitters won’t have to recalibrate sensors mid-shift. 
• Application-Specific Formulas: A bag for frozen peas requires different slip characteristics than a bag for fine flour or bulk protein. 
• Climate Resilience: Australian humidity can affect film tackiness. Our formulations are tested to perform in the varying temperatures of Aussie processing plants, from humid Queensland to chilled Victorian facilities. 

When you prioritise the slip levels of your food-safe liners, you aren’t just buying plastic. You are buying uptime. You reduce wear and tear on your equipment, prevent film breakage, and ensure your goods arrive at the distribution centre safely. 

Is your current packaging causing ‘stutters’ on your line? Contact the UPAC Technical Team today for a CoF analysis of your current liners. Let’s find the perfect grip level for your specific machines: slick enough to run fast, but grippy enough to stay stacked.