If you’ve ever ordered nylon rod from two suppliers and found that one machines beautifully while the other smears and chatters, you’ve met the difference between cast and extruded polyamide. On paper they share a name. On the shop floor they behave like different materials.

How each one is made

Extruded nylon is melted and pushed through a die. It’s fast and economical, but the rapid cooling locks in stress and limits how large a section can be. Cast nylon is polymerised directly in a mould from liquid monomer, cooling slowly into large rods, tubes and plates with higher crystallinity.

• Higher stiffness and dimensional stability

• Lower internal stress, so less movement after machining

• Available in much larger sizes, up to Ø 800 mm

• Easy to modify with oil, MoS₂ or heat stabilisers

When extruded is the better choice

For small diameters, high volumes and parts with generous tolerances, extruded nylon is often the smarter buy. It’s cheaper, widely available and perfectly adequate for spacers, washers and light-duty guides. The key is matching the material to the load, the size and how much the part can move.

Getting a recommendation

Not sure which one your part needs? Send us the drawing and the operating conditions. We’ll recommend a grade and explain why, with no obligation.