TPE, TPR wrapping material eight considerations

  • Time of issue:2022-01-08
  • Views:387

TPE, TPR wrapping material eight considerations

  • Categories:Elastomer knowledge
  • Author:SPP
  • Time of issue:2022-01-08
  • Views:387

1. Different substrates to choose different materials of TPE, TPR cover material. For example, the package PP material can not package ABS, package ABS material can not package PA, etc.. Now on the market TPE wrapping, can be divided into the following categories: PP wrapping class, ABS wrapping class, PETG wrapping class, PC wrapping class, PA wrapping class, etc.

  2.TPE,TPR overmolded layer thickness. In most overmolding applications, the wall thickness range of 1.5-3.0mm will ensure a good bonding effect, if the TPE bit is too thin, injection is more difficult, the bonding strength is lower, the feel is also poor. The wall thickness of TPE should be as uniform as possible in order to achieve the best forming cycle. The transition between different wall thicknesses should be gradual to reduce the problems arising from fluid flow, such as air lines and bubbles.

  3. Curvature (minimum radius of 0.5mm) should be used at sharp corners to reduce local stresses. Deeper closed air chambers or arched sections that cannot be vented should be avoided, and if necessary, sufficient venting slots (0.015-0.025mm) can be added at the end of the TPE adhesive bit. Insufficient venting may cause trapped air, burning glue, insufficient adhesion and other undesirable phenomena.

  4. In the base material to add buckle or make some properly designed deeper concave and convex part, to improve the TPE bonding effect is very helpful.

  5. Treatment of mold surface.

  1)The mold should be polished to get a smooth or clear surface.

  2) In order to produce the kind of lusterless appearance of thermosetting rubber surface, a rougher mold surface is needed. Generally speaking, the rough surface produced by electrical discharge machining (EDM) of the mold cavity will produce a good appearance of the part and make it easier to release the mold. Abrasive methods such as steam blasting, sand blasting or shot blasting, and chemical etching can also be used to produce a surface with a different luster and appearance.

  3) For easy release, a release coating can be applied to the mold cavity or core, for example, a layer of PTFE (polytetrafluoroethylene) impregnated nickel after it has been sandblasted or electro discharge machined (EDM).

  6. The substrate should avoid the use of mold release agents. The surface of the substrate should be clean and avoid contact with dust as much as possible.

  7. The processing temperature of TPE,TPR overmolded material should be based on the actual measured melting temperature of the adhesive, not on the display temperature of the injection molding machine.

  8. If you require TPE,TPR wrapping on the metal parts, you can use the appropriate adhesive as an aid.

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