Lost core method

Core melting process in three steps: The metal core is covered with plastic and then removed.

The solution for particularly sophisticated, highly complex geometries.

Use the lost core method in order to create every conceivable part contour. Joma-Polytec is one of the few manufacturers worldwide to have mastered this special process. Firstly, we produce the metal core in the shape of the cavity specified for the moulded component. In the second step, plastic is sprayed onto the core. And finally, the metal core is melted-out.

  • Development of complex, "impossible" geometries
  • Series production in injection moulding, applying a special technology
  • ISO-certified quality management
  • In-house tool-making and mould making

Areas of application and benefits

The lost core method is particularly demanded in the automotive industry. It allows the design of complex geometries, such as multi-bent pipes for media routing of oil or exhaust gases.

The Benefit: The internal design of the components can be influenced and structured with a special purpose in mind. This is an impossible task and cannot be achieved with conventional injection moulding processes.

Component facts
  • Materials: Polyamide, PPA, PPS
  • Part dimensions: 250 x 350 x 500 mm
  • Clamping force: 250 to 350 kN


  1. Casting the metal core
  2. Spraying the cast metal core with high-temperature material
  3. Melting-out the metal core.
  4. A plastic part remains

Firstly, we produce a metal core. This core is sprayed with a high-temperature material such as polyamide, PPA or PPS. In each case, the melting point of the plastic must be higher than the melting point of the metal. In a thermal melt-down basin, we remove the metallic core by melting it out. What remains is a plastic part, which fulfills every desired geometry.

Do you have any questions or need more detailed information?

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+49 7471 706-0

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