3.Machining and processing HPL
Forming over heated bars (contact heat)
For forming over heated bars, the HPL is clamped to a sturdy fixture. A heated rail with the desired forming radius is attached flush with the front edge. The heated rail has to ensure a constant temperature. The postforming HPL is clamped in the bending fixture accordingly. The area to be formed has to protrude over the heated rail. When the HPL has reached the required forming temperature, a pressure roller is slowly rolled over the protruding HPL area.
1 Heating using contact heat | 2 Mechanical forming | 3 Curing with
a cold air supply
Forming with heated bars (infrared)
HPL can be formed in a single-stage or two-stage process by using an infrared radiator. In the two-stage process, the material is heated in the first step with an infrared radiator in the area to be formed later on. Immediately after reaching the required forming temperature, the part is placed in a fixture which consists of a holder and a bending flap. The fixture should be made of wood to avoid accelerated heat dissipation. The mould has to be formed in such a way that overforming is prevented. Forming has to take place immediately after insertion of the HPL into the fixture, in which cooling takes place afterwards.
1 Heating | 2 Forming | 3 Cooling | 4 Postformed HPL
Forming with heated bars (infrared) in a machine
For the single-stage process, the HPL is clamped to a sturdy fixture. The HPL area protruding over a mould is heated with infrared radiators. Immediately after reaching the required forming temperature, the infrared radiator has to be swivelled out of the forming zone and the HPL has to be formed with a manually or automatically operated flap. Then the postformed HPL has to cool down in the fixture.
Bonding of preformed HPL
Only the recommended adhesives may be used for bonding preformed HPL. The required contact pressure can be generated either with corresponding negative moulds or by applying a vacuum (vacuum bag).
