How to Choose the Right Tube for Flexible Film & Packaging

When it comes to flexible film and packaging applications, selecting the right cardboard tube or core is essential. The right choice ensures product integrity, uninterrupted production, and efficient handling. As a leading packaging tube supplier in the UK, Stell has over 150 years of experience manufacturing cardboard tubes for flexible film and film winding cores that deliver performance and reliability. 

• Spiral and convolute tubes are the main types of tubes offered by Stell for the flexible film and packaging industry. 

• Dimensions and strength of the tubes you choose is critical.  

• Delivering an ultra-reliable service founded on the best equipment, super-efficient processes, carefully researched materials, high quality training and great people differentiates Stell from its competitors. 

• Stell can supply bespoke, durable and consistent tubes at low cost and with metronomic reliability to meet your exact needs. 

In our latest blog, we share our expertise to help you choose the right cardboard tube to suit the needs of flexible film and packaging.  

1. Spiral vs. Convolute Tubes

At Stell, we offer two main types of packaging cores: 

• Spiral – These are manufactured by winding ribbons of board around a steel mandrel. They offer excellent crush strength, dimensional accuracy, and a smooth finish. This makes them ideal for tubes being used, for example, in film converting which involves high speed wind/un-wind and high consistency of crush strength. 

• Convolute – These tubes are produced by wrapping a single sheet around a steel mandrel. Owing to grain alignment of the paper this creates a high beam strength for their weight (compared with spiral tubes) and the single sheet construction creates a tube structure with a higher resistance to internal pressure. Convolutes are therefore often chosen for applications where the higher beam strength is needed such as for bolts of fabric or in pyrotechnic/explosive applications where the higher capacity for internal pressure creates a larger bang/flash/burst. 

If you need high accuracy, crush strength or surface quality, spiral is usually optimal. For beam strength or applications where internal pressure capacity is important convolute tubes can offer the most cost-effective option. Our team have extensive knowledge of the tubes, materials and processes we can provide. We’re always happy to discuss your application and help you find the best solution. We have many options for further customisation such as printing surface finish which can add further value to your particular application.  

2. Get the dimensions & strength right

When customers come to us, we can often offer a more efficient tube in terms of material used because of our high expertise and knowledge of tube winding technique and the optimised materials we use for manufacture.  

When discussing specifications with our customers we primarily consider the following: 

• Inside diameter (ID) – this is often determined by the customer’s process/product. To ensure we get this right we will often use samples or measure existing products with gauges to ensure an exact match. 

• Wall thickness & outside diameter (OD) – the wall thickness of the tube determines its strength, while OD determines the wall thickness for a given ID specification. We will use either wall thickness or OD in our specification. Our ‘default’ is to use wall thickness but where the external fit of the tube is very important or minimal OD variation is critical, we’ll specify the OD instead.  

Strength performance matters, too: 

• Crush strength – The resistance to crush force on the tube. For many applications, and particularly so for flexible film manufacture, this is a more critical specification than the wall thickness or OD – the tube must not crush during the customer’s process and the wall thickness (or OD) required to match this required strength is a function of it.  

• Beam strength – The resistance to bending, which is important if rolls are supported only at their ends during use or transport. Our team can provide further advice during consultation. Often, for flexible film applications, if the crush strength requirement is fulfilled, the beam strength requirement will be also. 

Stell manufactures packaging cores to the precise strength requirements your business needs, and each tube is tested in-house as part of our rigorous quality control, in line with our ISO 9001 accreditation. 

3. Materials & finishing options

The chosen material and finish of your flexible packaging tubes affect its function and appearance. At Stell we can offer a range of materials – including a range of board strengths and grades – combined with tailored adhesives, to achieve the right balance of strength, weight and cost to suit your business’ needs. 

Finishing options we can provide include: 

• Printed or coloured covers, designed to match or include your business’ branding. 

• Wax dipping for water resistance. 

• Specialist features such as notching, pull-apart functionality, flaps, or release liners. 

This means our tubes can be tailored for technical performance while supporting your brand presentation across your products. Without compromising its durability.  

4. Sustainability considerations

Cardboard is 100% recyclable, renewable, and biodegradable, making cardboard tubes for flexible film an environmentally responsible choice. For applications exposed to moisture, we can provide wax-dipped treatments to extend the life of your cardboard tube, while maintaining its recyclability and maintaining sustainability commitments. 

5. Why choose Stell as your packaging tube supplier

With one of the largest tooling libraries in the UK and a 100,000 sq. ft facility, Stell can support your business’ exact needs. Our team manufactures over 16,000 km of cardboard tubes annually, providing an expert knowledge of high-performance cardboard tubes. 

We can also offer rapid turnaround on both high-volume and short-run orders from our facility which operates 24/7 throughout the year, and a technical expertise to meet the bespoke requirements to match your product standards and specifications. 

Our factory is heated using sustainable bio-mass fuel, our machines are powered by self-generated solar power, our lighting is from the latest gen high-efficiency LEDs, and we encourage our people to cycle, walk, use public transport or lift-share for their commute to work. 

At Stell, we’re proud to offer a consistently ultra-reliable service founded on the best equipment, super-efficient processes, carefully researched materials, high quality training and great people. 

Don’t let your packaging fail your business 

Choosing the right cardboard tubes for flexible film or packaging starts with understanding your application. From tubes for film rolls with tight tolerances, to heavy-duty flexible packaging tubes, our team at Stell offers tailored solutions which are backed by deep technical knowledge and sustainability credentials. 

If you need a cardboard tube supplier who can deliver on spec and on time, every time, Stell is your business’ ideal partner. Get in touch with our team today.