What Does an IMD Hot Press Do? Film Forming in IMD and IML

IMD (in-mold decoration) places a film inside the injection mold to decorate the surface of a plastic part. The IMD hot press handles one step of this chain: it heats printed, pre-cut film sheets and presses them into a 3D shape.

Two ways to do IMD

1. In-mold transfer: printed film on a roll is fed through the injection machine and mold automatically, like a label; after molding, the graphics transfer onto the part. This method normally needs no separate forming step.
2. In-mold labeling (IML): the film is printed, formed on a forming machine, trimmed and then placed in the injection mold. The IMD hot press performs the forming step here.

IML film layers

IML film usually has three layers: a substrate (mostly PET), the ink layer and an adhesive layer. After molding, the adhesive bonds film and resin into one piece; the PET with its wear-resistant coating stays on the outside, giving abrasion and scratch resistance. The original article states a surface hardness of up to 3H. Typical molding resins are PC, PMMA and PBT.

Design points of the SANSEN IMD hot press (as described in the original article)

• High-sensitivity through-beam light curtain.
• Air-over-oil booster main cylinder with ample force and smooth, responsive travel.
• Process data stored by mold number and recalled by entering the number, reducing set-up.
• PLC temperature control with touch-screen input.
• Heater plate in/out driven by a synchronous motor with an inverter for smooth movement.
• Carbon-fiber heaters for fast, even heating; compact footprint and easy mold change.

After forming, the sheet usually goes to 3D die cutting before molding. See the gas-hydraulic IMD hot press and our article IMD/IML thermoforming machines: process and applications.