One extruder makes pipe, tubing, rod, sheet, film and wire insulation, and only the die changes: a round hole gives rod, a ring around a centre pin gives pipe or tube, and a wide slit gives sheet. Pipe is the most valuable product for a settlement, and its wall thickness is set by the gap between the die and the pin and by how steadily the product is pulled away.
Part of Plastics and Polymers
Extrusion products are the continuous plastic profiles formed by a die: rod, pipe, tube, sheet, film and coated wire.
The Die Decides The Product
| Product | Die | Notes |
|---|---|---|
| Rod, filament | Round hole | The practice product; sets temperature and cooling |
| Pipe, tubing | Ring around a centre pin (mandrel) | Gap = wall thickness; pin must stay centred |
| Sheet | Wide slit | Cooled flat on a table or between rollers |
| Film | Slit, or a ring that is inflated | Very thin; needs steady pull and cooling |
| Insulated wire | Die the wire passes through | Plastic closes around the conductor |
Plastics Manufacturing gives the first four uses: pipe, rod, sheet and film from the same machine. The wire coating route is from general knowledge, not the corpus.
Pipe Is The Priority Product
Pipe for water, drainage and irrigation is far easier to produce and install than metal pipe. The carrier’s method:
- Use a die with a centre pin so that the pipe is hollow.
- The gap between die opening and pin sets the wall thickness.
- Pass the pipe through a water cooling bath immediately after the die.
- Pull at a steady rate. A faster pull stretches and thins the wall.
- Cut to length.
Use HDPE for flexible lines and PVC where rigid, solvent-welded runs are wanted; the water-system choices are in Pipe Materials. Do not extrude PVC without a way to carry away the fume: it releases hydrogen chloride when heated.
Film And Sheet Are Harder Than They Look
Sheet needs a wide, flat slit and cooling that keeps it from curling. Film is thin enough that small changes in melt temperature or pull speed show up as holes and ridges. Thin film also degrades in sunlight; the corpus notes in Plastic Film and Alternatives that cheap film lasts about a season in sun. Aim first for pipe, rod and thick sheet.
Why The Pull Rate Matters
For a given feed, product cross-section and pull speed trade against each other. If you pull faster than the melt is delivered, the product stretches and the wall gets thinner. If you pull slower, it thickens and may bulge at the die. Hold feed and pull steady and change one thing at a time.
What You Need
- A working extruder: Extruder Design
- A cooling bath long enough to set the product before it reaches the puller
- A puller: two rollers or a belt, or a hand-drawn rope for short runs
- A cutter and a straight-edged table to check the product
Common Mistakes
- Cooling too slowly — pipe sags and ovals before it sets.
- Mixed plastic in the feed — streaks and weak walls; see Sorting and Identification.
- Using unidentified scrap for pressure pipe — test every length before burial; see Pipes and Containers.
Hot product and hot water
Fresh extrudate is hot enough to burn, and the cooling bath splashes. Wear gloves and eye protection at the die and the bath, keep the bath clear of electrical equipment, and keep ventilation on whenever the barrel is hot.
What’s Next
- Learn next: Pipes and Containers — using the pipe you make
- Combine with: Insulation and Tools — wire coating and handles