Plastic caps and similar products like plastic seals and plastic plugs are very common items, made to seal the open ends of products like pipes, tubes and containers. These popular devices come in a wide variety of shapes, sizes and colors and their material options are many. Formed during dip molding or plastic coating, plastic caps have applications in food service, chemical, medical and consumer industries alike.
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Advantages of Plastic Dip Molding
Plastic dip molding and plastic dip coating present many advantages to those seeking the services of plastic caps. First, since the leftover molten polymer from a dipping process can easily be reused, dip molders create very little material waste. This makes the use of dip molders very economical for manufacturers, as well as a good choice for those who wish to keep their use of fossil fuels to a minimum. In addition, the use of automatic dip machines ensures relatively low labor costs. Another reason that dip molding and dip coating are so popular of methods with plastic object manufacturers is that they offer such versatility.
Dip Molding Process
The process of dip molding usually involves the engagement of dip molders, which take a mold or mandrel, which is a cylindrical rod around which material is forged or shaped, and lower it into a molten polymer, where it sits for a predetermined period of time. As the mold sits in the molten polymer, which is usually plastisol or PVC, the liquid sets and takes its shape. This allows the mold to become a precisely sized cap or plug. The longer the mold stays in the liquid plastic, the thicker the walls of the cap will be. Once the prescribed period of time is up, the mold is slowly removed from the polymer and allowed to harden and cool. The speed at which the mandrel is removed is very important, because removing it too quickly could cause irregularities on the surface of the cap. After the cap has solidified and cooled, it is removed from the mold. Dipped products rarely require secondary finishing processes. If at all, the most likely secondary process required is the heat treatment of some plastic coatings.
Plastic Coating Process
Plastic coating is a process very similar to dip molding that also uses dip molders to achieve its purposes. The goal of plastic coating is to provide a protective or insulative surface for manufactured products, including plastic caps. Other parts and products that plastic coating serve include wire form, tool handles, sports equipment, medical equipment and electrical components. Plastic coated parts undergo the same dip molding process, though objects to be dip molded may be coated in a primer before being lowered into the molten plastic. Primers ensure that objects receive full and ideal plastic coverage. Plastic coatings may be as thin one quarter of an inch, though they are usually thicker than that. Just as before, the thickness of the coating is determined by the length of time that the object is immersed in the molten plastic. As noted, the most common polymers used for plastic dipping and coating are plastisol and PVC. However, a host of other polymers are available for use, such as latex, neoprene, urethane, epoxy and silicone. UV resistant coatings are available for products with outdoor applications. Plastisol, a vinyl compound, reigns as most popular because it becomes liquid at room temperature, therefore requiring a very low amount of energy to undergo dip manufacturing. Also, once it is heated, plastisol hardens permanently, a feature that is ideal for bulk manufacturing.
Plastic Cap Customization
The reason that most plastic caps and other dip moldings do not require secondary processes is that plastic cap manufacturing demands the diligent adherence to high precision standards. High precision is necessary to make sure that plastic caps have the tight fit needed to seal containers. Manufacturers create high quality caps using precisely controlled ovens, dip times, dip speeds and withdrawal speeds. Also, automatic dip machines help ensure process consistency. Due to the nature of the materials and process used, manufacturers have a lot of freedom to custom design aspects of plastic caps, such as length, material hardness, color, texture and wall thickness. In addition, caps other products, such as plastic plugs and plastic closures, may have a round, vinyl hex or pull tab design, widening their field of applications and uses. Another type of common plastic cap is the threaded cap, which is a twist-on cap that provides a tighter seal, one that is sometimes even water-tight. Another common custom features a tamper-proof capability, common with medicine bottles. Because they are so commonly used and because so many plastic containers that require sealing and closures are produced in standard sizes, warehouses also usually carry a wide variety of stock plastic caps. These caps can be shipped at a moment’s notice to those seeking them for use with their standard containers.