Aluminum profiles that are extruded cannot be used as finished products if they are not aged and the hardness is low. Therefore, generally speaking, all aluminum profiles must be aged to increase their strength. Usually there are two kinds of aging—natural aging and artificial aging. At the moment, production of 6xxx series aluminum profile basically uses the latter kind.

So, how do we prevent it that aluminum profile’s artificial aging hardness is not high enough? After long-term tracking and investigation we conclude as follows:

Production technique control:

1. Ingot temperature control: The ingot temperature shall be tested before it is carried onto the extruders. It can not be extruded unless it meets the technical requirements. 

2. On-line quenching process: Solution quenching is the basic premise for aging. Aging is meaningless without solution quenching. Therefore, to ensure quenching cooling speed can meet the aluminum quenching sensibility requirements, quenching technique shall be chosen according to ingot number, aluminum profile thickness, extrusion speed and quenching equipment conditions.

3. Aging oven’s temperature setting and control: Usually aging oven’s temperature is different from that is shown on the oven meter. When setting the oven’s temperature, it shall be done according to the oven’s actual temperature and pay close attention to the fluctuation of temperature.

4. Aging heat preservation: Aging shall be done strictly according to technique requirements. Heat preservation time shall be appropriate to prevent the aluminum profile’s lower hardness caused by short-of-aging or over-aging.

Ingot framing and entering oven:

1. When framing aluminum ingot, it shall not be too dense. Space is needed between ingots, especially unventilated small profiles and thick profiles. Their space shall be bigger. If tube profiles, small profiles and board profiles are framed together, tube profiles shall be placed at the bottom, which is good for aging loop ventilation.   

2. Before entering the oven to get aged, 6xxx special aluminum shall be separated from common 6063 aluminum. If they have to be aged together in the same oven because of production arrangements, the technique for special aluminum shall be applied for aging.