Blistering or whitening in hot bending of PC board? No!!
PC board bending is an essential process in endurance board processing and production. Also known as hot press forming, is a process in which the PC sheet is heated to a certain temperature and plastically deformed after softening according to its thermoplastic properties.
Hot-bent or cold-bent both popular in the market. But because the latter can only perform simple processing such as straight-line bending, can not meet complex needs required radians, so there is no much discussion.
The heat deformation temperature of PC endurance board is about 130 ℃ (1.18MPa), and the glass transition temperature is about 150 ℃. Above this temperature, the board can be thermoformed.
Two general methods for heating sheet equipment as following
1. Acrylic bending machines. Place the part of the PC sheet over the heating tube or wire, and after heating to soften, bend along the straight line position of this heating and softening.
2. Oven.Make the PC board flat surface curved, first put it in the oven and heat it.After soften, take out and put it on the pre-made female mold, then press it with male mold. Wait for the plate cool down and taken out and the whole setting process is completed.
Pls kindly pay attention to these two following factors
1. If the PC plate is heated for too long or with too high temperature, it will blister (Because of high temperature, the interior starts to melt and the exterior gas enters into the plate.). Generally, during the post-processing, it does not have same precise temperature and heating time control as during production.Only be judged manually, so generally bended by experienced professional workers.
2. PC sheet itself absorb moisture (At standard atmosphere pressure, 23℃, 50% relative humidity, the water absorption rate is 0.15% ). Therefore, if the finished plate is stored for a long time, it will often absorb moisture in the air. If the moisture is not removed, the product will have bubbles and misty micropores after molding, which will affect teh appearance.
According to the specific requirements, comprehensively consider to select which process and control the key points to avoid problems so as to make size-standard products without any blistering!
