Various types of flat cable molding methods have their scope of application, advantages and disadvantages. The molding method used in production depends on the processing performance of the insulating material. Some specifications of flat cables can use two molding methods, such as UL2651 can use direct extrusion method or lamination method; while some flat cables can only use one molding method, such as UL2468 and UL2877 can only use direct extrusion , UL2902 can only use the bonding method. Various UL standard flat cable forming methods are clearly defined in the UL document.
In order to produce a qualified flat cable, in addition to selecting a suitable processing method according to the processing performance of insulation, there are many specific process problems in forming (some are unique to flat cable forming, and some are encountered in ordinary cable production ) It must be solved, otherwise, the product cannot be used even though the products are similar in appearance and the electrical performance does not meet the requirements. The center distance exceeds the requirement, the wire is seriously eccentric, the insulation resistance is low and the flat cable length is short, etc. are the problems often encountered in production. The coefficient of linear expansion of plastic is large, and the soft PVC is 7.0 ~ 25X10 / ℃. As the ambient temperature changes, the size of the center distance also needs to change. When the flat cable forming mold adds soil as required, it cannot follow the temperature. In order to facilitate the operation and reduce the cost of the mold, the flat cable must be formed in an environment with a small temperature change, and the temperature of the workshop should be controlled between 15 ~ 25 ℃.
The dimensional accuracy of the flat cable is basically guaranteed by the accuracy of the mold. The dimensional tolerance, surface roughness and shape and position tolerance of the mold are all very high, resulting in high mold cost and poor versatility. When designing the mold, in addition to ensuring the accuracy of the finished product, it is also necessary to consider the manufacturability of soil adding and installation.