Infrared heating for local annealing of injection molded parts

During the cooling process, injection molded parts may generate internal stress due to uneven shrinkage, resulting in deformation or cracking. Local annealing eliminates stress and improves dimensional stability by heating specific areas. Traditional annealing uses an oven for overall heating, but it is inefficient and may affect the performance of other parts of the part.

Infrared lamp selection: fast medium-wave infrared (wavelength 1.4-2μm), with moderate penetration, suitable for fast and uniform heating of ABS materials.

Heating process: The part enters the infrared heating zone through a conveyor belt, and the focused lamp radiates the target area, and the temperature is set to 110-130℃ (lower than the melting point of the material).

Heating time: 10-15 seconds, and precise temperature control curve is achieved through PLC control.

The annealing cycle is shortened from 30 minutes in a traditional oven to 20 seconds, and production efficiency is increased by 90%.

The part yield is increased from 85% to 98%, and no secondary processing is required.

Shortwave infrared (1.0-1.4μm): suitable for rapid surface heating (such as deburring)

Short Wave Single Tube Infrared Lamp is made of round single quartz tube. The heating filament is tungsten alloy which can resist up to 2600°C. We have 10mm, 11mm, 12mm, 14mm, 15mm and 19mm quartz single tube. The total length of single tube IR lamp can be up to 2.5 meter.

Shortwave Twin Tube Quartz IR Lamp is made of 23×11mm or 33×15mm quartz double tube. The heating filament is tungsten alloy material. Twin tube shortwave infrared heating lamp can be designed with high heating power, the range of radiation wave is 1.0-1.4μm, it is particularly suited for fast response heating processes. This short wave infrared radiation penetrates more deeply into materials, as they can obtain infrared radiation full-efficiency within seconds.

Fast medium-wave infrared (1.4-2.0μm): balance penetration depth and heating uniformity (such as rapid annealing)

Fast response medium wave infrared lamp can be switched on/off the same as short wave lamps in a short time, and the range of IR radiation wave is 1.4-2.0μm. The especial fast medium wave can heat the surface and thin layers quickly, like drying ink and coatings on the surface of objects in a short time. The heating filaments can be desinged and work in 1200～1800℃, so the FMW IR lamp are widely used for fast heating application which needs heating temperature from 50～500℃. We have single tubes with sizes of 10mm, 11mm, 12mm, 14mm, 15mm, 19mm. 

Twin tube fast response medium wave infrared heating lamp can be controlled and adjusted the output power by PLC or SCR regulator automatically, so we can have accurate（±1 ℃）IR heating temperature in industry process. The heating filaments can be desinged and work in 1200～1800℃ with 1~2 seconds fast response time, so the FMW IR lamp are widely used for fast heating application which needs heating temperature from 50～500℃.

Power density: usually 10-50 W/cm², adjusted according to the heat capacity of the material.

Comparison with Conventional Methods