In Episode 20 of No Dumb Questions, we explain the differences between tube-on extrusion and pressure extrusion in cable jacket manufacturing.
Extrusion is the process of applying a protective thermoplastic jacket around a cable core, and the choice between tube-on and pressure techniques impacts the cable’s physical profile, weight, flexibility, and ease of termination.
Tube-On Extrusion: Tube-on extrusion applies the jacket material as a sleeve with a uniform wall thickness around the cable core without forcing material into internal gaps. This method uses less plastic, which reduces raw material costs and overall cable weight. Additionally, because the jacket does not adhere tightly into internal crevices, it is significantly easier to strip during termination.
Pressure Extrusion: Pressure extrusion forces the molten thermoplastic material directly around the cable core under high pressure, filling internal gaps (interstices) between individual conductors. This holds the inner core bundle firmly in place, making it ideal for flexible cables subject to high mechanical wear or physically demanding environments. However, pressure extrusion increases material weight and cost, and can make jacket stripping more difficult during assembly.
Key Technical Takeaways
- Tube-On Extrusion: Creates a smooth, uniform sleeve with lower material weight and easier jacket stripping.
- Pressure Extrusion: Forces jacket material into core interstices, holding internal conductors firmly in place.
- Mechanical Protection: Pressure-extruded cables resist physical wear, flexing, and harsh environments better than tubed-on designs.
- Manufacturing Tradeoffs: Pressure extrusion increases cable weight, material costs, and stripping difficulty compared to tube-on extrusion.
Keep watching! Next up, Episode 21: What is the purpose of a drain wire?
Episode 20 Transcript – Tube-On or Pressure Extrusion?
Welcome to No Dumb Questions
Tucker: Welcome to the latest edition of there are No Dumb Questions. Owen: Where the only dumb question is the question you don’t ask. Tucker: Today’s question is “what’s the difference between tube-on and pressure extrusion?”. That’s not a dumb question at all. I think that’s a great question. Would you like to…? Owen: I would like to answer that. Tucker: Thank you.
Tube-On vs. Pressure Extrusion Process
Owen: So the difference is, there’s two different types of extrusion process.
Thermoplastic materials can have a tube-on extrusion, creating a smooth, uniform thickness around the jacket. The advantage of a tube-on extruded jacket includes savings of weight and materials, and also easy stripping.
A pressure extrusion holds the core tightly in place and fills the gaps interstices of the core bundle. This is better for common flexible cables, especially where cables are used in a physically tough environment. However, the disadvantages of a pressure extrusion include potential problems with stripping, an increase in weight, and possible increase in costs.
Does that answer your question? Tucker: It does. Thank you very much. And again, please catch us next time on there are No Dumb Questions.