模壓復合井蓋就是將模塑料加入鋼筋在一定溫度和壓力下壓制成型。這種復合井蓋因增強材料采用的是短纖維(30-50mm短纖維形成復合材料的強度只有連續纖維20-30%)，復合井蓋結構上采用的是平板底部加肋，這種增強材料及復合井蓋結構導致復合井蓋承載能力嚴重不足，只能加入鋼筋以增加荷載。而鋼筋的加入，形成材質具有兩大缺陷：①鋼筋表面有銹，往往導致材料界面結合不好(如果復合材料界面結合不好，就不會產生1+1>2的效果);②鋼筋是金屬材料，SMC/BMC是非金屬材料，兩種材料因熱膨脹系數的差異。在不同溫度下(早、中、晚、冬天、夏天)材料界面將會形成應力，加之車輛反復碾壓，會導致鋼筋與SMC/BMC脫離，最后導致復合井蓋失去承載能力(具體多長時間失去承載能力，取決于企業制作過程中復合工藝和使用條件，也許2-3年，也許更長)。優點：A、防盜;B、外觀精致;缺點：A、承載能力不夠;B、因加入鋼筋，界面脫離后會導致失去承載能力。2、分層復合井蓋這種復合材料復合井蓋是用不飽和聚酯樹脂作基體材料，用玻璃纖維作增強材料，輔以一定剛性材料。結構上采用鍋底結構，底部抗拉材料受力均勻;材質上分上下兩層，上部采用耐磨、耐老化材料，產品的使用壽命長。下部采用連續玻璃纖維增強，可以使復合井蓋具有足夠的承載能力，而不需任何鋼筋增強。是幾種復合材料復合井蓋中綜合性能較好的一種材料復合井蓋。優點：A、防盜;B、承載能力高;C、外觀漂亮。缺點：A、表面硬度高、而脆性稍高;B、價格稍高。

模壓井蓋：是用不飽和樹脂作基本材料，用30-50mm短纖維和鋼筋作增強材料，用碳酸鈣作填充材料，在一定溫度下壓制而成。由于鋼筋是金屬材料，而BMC是有機材料，BMC的熱膨脹系數是鋼筋的兩倍，且因鋼筋表面生銹，而使BMC與之復合時界面結合不牢，溫度發生變化時，鋼筋與BMC材料之間界面會形成應力，加之車輛反復碾壓，會導致鋼筋與BMC界面分離，最后復合井蓋喪失承載能力。并且表面為BMC和碳酸鈣材料混合物，因而耐磨性較差。玻纖增強復合井蓋：從結構采用鍋底型結構(均勻承載)，這種結構與加肋型(集中承載)相比，底部受力面積增大幾倍;其次，多層加筋，層層相扣，受力均勻，因此，結構上使產品承載能力更強;從材質方面，耐磨層采用多色彩石英沙作耐磨材料并加入穩定劑，使產品耐磨性能使用壽命成倍提高;采用連續增強纖維骨架，確保了產品的高承載能力，而其他復合井蓋有的不用纖維增強，即使使用纖維增強也是使用短纖維(短纖維的強度僅為連續纖維的20%-30%)，強度不夠時，只好用鋼筋彌補，產品整體材料為有機材料，在復合井蓋不同部位使用不同增強材料，從材質上避免了其他復合材料產品因使用鋼筋等增強材料而出現的分離、脫落現象。采用分層復合工藝，滿足機構創新和材質創新的要求，在復合井蓋不同部位使用不同增強材料，使復合井蓋不同部位使用不同增強材料而出現的分離、脫落現象。

Molded composite covers with reinforced plastic is to die at a certain temperature and pressure compression molding . This result covers the composite material used is of short reinforcing fibers ( strength of the composite 30-50mm staple fibers are formed only continuous 20-30 % ) , a composite structure using a bottom covers stiffened plate , such a reinforced composite material , and manhole covers bearing capacity of composite structures lead to a serious shortage , only adding reinforcement to increase the load . The steel joined to form the material has two flaws : ① steel surface rust , often resulting in poor interfacial bonding material (if the composite interfacial bonding well, it will not have an effect of 1 +1 > 2 ); ② reinforcement is metallic materials , SMC / BMC is non-metallic materials , the two materials due to thermal expansion coefficient differences . At different temperatures ( early, middle and late winter, summer ) will form a material interface stress , coupled with the vehicle rolling again , will lead to steel and SMC / BMC detachment, leading to loss of carrying capacity of composite covers (specifically how long to lose carrying capacity, depending on the production process complex business processes and conditions of use, maybe 2-3 years , maybe longer ) . Advantages : A, anti-theft ; B, the appearance of fine ; Disadvantages : A, carrying capacity is not enough ; B, by adding steel, the interface will result in the loss from carrying capacity . 2 , layered composite covers this composite material composite covers are made with unsaturated polyester resin matrix material reinforced with glass fiber materials, supplemented by some rigid material . Structures using structural pot bottom material tensile force uniform ; divided into two layers on the material, the upper part of long life wear, anti-aging materials, products. The lower part of a continuous glass fiber reinforced composite covers can have enough carrying capacity, without any reinforcement enhanced. Is one of several composite materials composite covers in a better overall performance composite materials covers. Advantages : A, anti-theft ; B, high carrying capacity ; C, beautiful appearance . Disadvantages : A, high surface hardness , brittleness and higher ; B, higher prices .

Molded covers : unsaturated resin as a base material , with 30-50mm staple fibers as a reinforcing material and reinforced with calcium carbonate as filler , at a temperature of repression. Since steel is a metal material, and BMC is an organic material , the thermal expansion coefficient is twice BMC steel , and because steel surface rust , leaving the BMC interface when combined with the composite is not strong, when the temperature changes , reinforced with BMC material will form the interface between stress , coupled with the vehicle rolling again , will lead to reinforcement and BMC interface separation , the final composite covers loss of carrying capacity. BMC and the surface of the material and a mixture of calcium carbonate , which is poor wear resistance. Glass fiber reinforced composite covers : from structure using pot -type structure ( uniform load ) , this structure with ribbed type ( centralized load ) compared to the bottom of the force area increased several times ; secondly , multi- reinforced layers interlocking , even by force , so that the structure of the product bearing capacity; multi color quartz sand from the material, the wear layer for abrasion-resistant material and add a stabilizer so that the product wear life doubled ; continuous reinforcing fiber backbone ensure high bearing capacity of the product , and not some other fiber-reinforced composite covers , even when also using short fiber reinforced fiber ( short fiber strength of only 20% -30 % of the continuous fibers ) , the intensity of when not enough , had to use steel to make up the overall product material is an organic material , in different parts of the reinforced composite covers the use of different materials , to avoid the separation of other products due to the use of reinforced composite materials such as reinforced material appearing from the material , shedding phenomenon . Layered composite technology , innovation and material innovation to meet the agency 's requirements, to enhance the use of different materials in different parts of the composite covers , so that different parts of the composite covers the use of different materials to enhance the emergence of separation , shedding phenomenon .