This article presents will present detailed information about plastic coatings and dip molded plastics. Read further to learn more about:
Applying liquid polymers or plastics to a workpiece through methods like dipping or immersion is known as plastic coating. This process results in a robust plastic layer that serves both protective and aesthetic functions. It enhances the material's resistance to scratches, abrasion, corrosion, and environmental factors. By increasing the durability of metal components, plastic coatings contribute to a longer lifespan. Additionally, these coatings offer practical benefits such as improved grip and insulation for users.
Plastic coating is commonly found on hand tools, grips, and handles. For instance, pliers often feature plastic-coated handles, which enhance user comfort and efficiency by making the tool easier to handle and more durable. This coating also benefits various other items by providing additional rigidity and protection, including shopping carts, baskets, forceps, covers, caps, and plugs, among many other applications.
Plastic coatings are effective as both thermal and electrical insulators. They are frequently used on various hand tools, like tongs and spatulas, to provide extra protection when handling hot items. Additionally, these coatings are crucial in electronic applications, insulating components such as wires, cables, and digital meter probes.
The technique of applying a plastic layer to an existing metal object is known as dip molding. In this process, the metal part serves as a mold for the plastic or polymer. The item is first treated and preheated before being immersed in the liquid polymer. Once submerged, the polymer bonds to the metal and solidifies as it cools.
Dip molding is akin to dip coating but includes an extra step for removing or unloading the molded part. This method produces single, hollow, and double-walled components, reducing the need for extra finishing processes like trimming or deflashing. By minimizing these secondary operations, dip molding conserves raw materials. Examples of dip molded items include latex gloves, fashion accessories, cups, plastic caps, and components for recreational equipment.
Common polymers used for coating include plastisol, latex, neoprene, polyurethane, and epoxy. An important feature of these polymers is that they should be available in a liquid state at room temperature without requiring extra preparation. Additionally, for effective dip coating and dip molding, the liquid polymer needs to have a sufficient viscosity to prevent it from dripping off the mold surface. This ensures that the polymer stays in place until it sets and cures.
Plastisol is a widely used polymer in both dip molding and dip coating. It consists of finely ground polyvinyl chloride (PVC) resins suspended in a liquid plasticizer. Upon heating, plastisol transforms into a soft, flexible material with a rubber-like texture as it cools. Known for its durability, resistance to corrosion, and impact strength, plastisol is also valued for its high dielectric properties, making it ideal for electrical applications. To achieve desired finishes, colorants can be incorporated into the plastisol.
Latex is a dispersion of tiny polymer particles, with a significant portion consisting of rubber. It serves as a foundational material for producing both natural and synthetic rubber. While this polymer is widely accessible and safe for most users, there are concerns about allergic reactions that can arise when the latex degrades into a powdered form, which has led to a decrease in its popularity among some users.
Neoprene, created through the polymerization of chloroprene, serves as an alternative to latex. It is recognized for its resistance to chemicals and its flexible properties.
Polyurethane consists of urethane groups connected through carbamate linkages. It is celebrated for its flexibility and exceptional resistance to deformation.
Epoxy is a thermosetting polymer that, once its molecular chains are cross-linked, creates coatings with high strength, and resistance to chemicals and heat.
As discussed earlier, dip coating and dip molding share a similar operational principle. This chapter will explore the procedures involved in both processes.
Pre-treatment is essential for effectively applying plastic coatings to metal substrates. These steps are crucial for ensuring proper adhesion in both dip coating and dip molding processes.
In dip coating, pre-treatment is more intricate compared to dip molding because the polymer must permanently adhere to the metal, which serves as the mold. The pre-treatment procedure includes the following steps:
Impurities can hinder the polymer’s ability to bond with the mold or part, creating weak spots where damage may begin and spread.
Oils and greases on the metal substrate surface can act as contaminants, reducing water resistance and hindering the proper adhesion and application of the plastic coating. These contaminants are typically removed through alkali or acidic washes, or by thermal degreasing.
When re-coating parts that have already been coated, it is essential to completely remove the existing layer before applying a new one.
In addition to cleaning the surface, various properties can be added to achieve specific desirable traits. These enhancements may benefit both the dip coating process and the final application of the product.
Phosphating, also known as phosphate conversion, involves applying a thin layer of phosphate before applying the plastic coating. This phosphate layer enhances the substrate's corrosion resistance, particularly in situations where the plastic coating may be damaged. Common types of phosphate layers used in dip coating include zinc phosphate, iron phosphate, and tricationic phosphate.
Shot peening involves bombarding a surface with spherical particles to induce cold working. This process creates compressive residual stress on the substrate's surface, which helps to strengthen it and alleviate any pre-existing residual stress. Such stress can lead to microcracks, which may be exacerbated by subsequent processes.
Blasting alters the substrate surface by creating tiny cavities, which enhances the surface area available for adhesion of primers, undercoats, and plastic coatings. Common blasting techniques include sandblasting, metal grit blasting, glass bead blasting, and plastic bead blasting.
De-embrittlement is a heat treatment process designed to eliminate hydrogen that has diffused into the metal substrate, reducing the risk of brittle fractures under stress. This hydrogen often comes from previous pre-treatment steps, such as acidic washes and phosphate applications.
The following treatments are applied to the substrate surface to enhance the quality of the coating:
Primers act as a preparatory layer that enhances adhesion between the substrate and the plastic coating. They also provide extra protection to the substrate being coated.
Undercoats are additional layers that impart specific properties to the final product, such as UV and scratch resistance. Typically, undercoats are not used independently but function effectively when combined with the primary plastic coating.
In the dip molding process, a mold release agent is applied to the mold's surface to facilitate the removal of the molded part. Common mold release agents include silicone and permanent polytetrafluoroethylene (PTFE).
After completing the pre-treatment steps, the mold is dried to eliminate any moisture. Retained moisture can lead to expansion when exposed to heat during subsequent steps, causing the formation of voids or bubbles in the finished product.
The mold is heated in an oven to a specific temperature for a set duration. The heating temperature is a key factor in determining the coating thickness of the part. The effectiveness of heat distribution is influenced by the mold's design and the airflow within the oven. Uniform heating is crucial to ensure an even coating thickness throughout the material.
The heated mold is either partially or fully dipped into the liquid polymer, allowing the polymer to adhere to its surface. The outer dimensions of the mold define the internal shape of the part. The dwell time, or the length of time the mold remains submerged in the liquid polymer, is a crucial factor in determining the final coating thickness. Longer immersion times result in thicker coatings.
The speed at which the mold is immersed and withdrawn from the liquid polymer is another crucial factor, influenced by the properties of the polymer used. These rates are optimized by manufacturers during the process development phase. Generally, these movements should be slow to regulate the flow of the polymer and achieve a smooth finish. Rapid withdrawal after the dwell time can cause surface irregularities, while overly slow immersion and withdrawal can result in an excessively thick coating.
Some advanced facilities use a fluidized bed of fine polymer powder as an alternative to traditional liquid polymer solutions. In this method, the process is similar to conventional techniques: the fine powder melts and bonds to the heated mold surface upon contact.
Any excess liquid polymer is allowed to drain off the mold's surface. To achieve a thicker coating, multiple dipping cycles may be used, or a specialized coating may be applied.
The coating is cured in an oven to set the polymer more thoroughly and completely evaporate the excess moisture, solvents, and additives. In this step, the final mechanical properties of the polymer such as rigidity and flexibility are acquired. In thermosetting polymers, the curing step allows the polymeric chains to become completely cross-linked.
The cured coating is cooled either by immersing the mold in a water tank with temperatures ranging from 122 to 1112°F (50 to 600°C) or by using forced or natural air convection. The cooling rate is generally less critical compared to other molding processes.
Once the coating is cured, the finished parts are taken out of the frame. For dip molding operations, the plastic-coated part is separated from the mold either manually or using mechanical methods. This process yields a finished plastic component or part.
The dip molded plastic or the plastic coating may undergo additional finishing steps such as notching, punching, printing, and decorating.
The dip coating and dip molding techniques are quite similar, leading to the use of nearly identical machinery for both. In either process, a range of machines and parts is required to create dip molded plastic. Below is a list of the equipment and tools commonly utilized in an industrial setup for dip coating and dip molding.
In this stage, the mandrel or metal item is heated to get it ready for the dipping procedure. The preheat oven employs blowers or fans to facilitate forced convection, ensuring effective hot air circulation within the chamber.
In dip molding, the tool used is known as a mandrel. This custom-designed male mold defines the three-dimensional shape of the part being produced. The exterior shape of the mandrel determines the interior form of the final product. Similarly, in dip coating, the metal piece being coated serves as both the mold and the mandrel. Mandrels can be made from various materials, including machined solid metal blocks, cast aluminum from wooden patterns, or formed sheet aluminum.
Mandrels are moved through the process and submerged in a tank filled with polymer solution. After dipping, they are allowed to rest on a carrier frame before the curing stage. This frame can hold several mandrels and is often connected to a computer-controlled mechanical arm, which helps optimize the molding cycle time.
The dipping tank holds the polymer solution in which the mandrels are immersed. To maintain consistent temperature and concentration, the solution bath is frequently agitated. De-aeration equipment is employed to eliminate air and moisture from the mixture. Prior to being moved to the dipping tank, the solution is typically prepared in an offline tank with a mixer, where the resin, additives, and colorants are blended together.
Here, heat treatment is conducted post-molding to solidify the plastic coating. Like the preheat oven, this stage also uses forced convection to circulate hot air throughout the chamber.
To enhance production efficiency, various setup configurations utilizing the same equipment have been developed. Some examples include:
Several mechanical arms equipped with carrier frames are mounted on a rotating wheel, similar to a carousel. As the wheel turns, each arm is indexed to dip the mandrels into different depths of the solution.
The frames with mandrels are moved through the process by a precision conveyor, enabling a continuous production flow for dip coating or dip molding. The pre-heat and curing ovens are positioned on either side of the polymer solution tank, each equipped with entrance and exit doors for the frames. Additional dipping tanks for specialized coatings can also be integrated into the setup.
Plastic coating machines play a crucial role in modern industries by applying protective, insulating, or decorative plastic layers to a variety of products. This enhances their durability, functionality, and appearance across sectors such as manufacturing, construction, automotive, and electronics. Below, we explore several top brands of plastic coating machines available in the United States and Canada, highlighting specific models and their distinctive features, functions, and capabilities:
Features: The Nordson Encore LT is a manual powder coating system engineered for precision and efficiency in plastic coating. Its user-friendly operation and control make it ideal for small to medium-sized applications. The system utilizes advanced electrostatic technology to ensure a consistent, high-quality finish and includes a lightweight, ergonomic gun design for ease of use. The Encore LT also supports rapid color changes and promotes effective powder utilization.
Features: The WAGNER PEM-X1 is a manual liquid coating system known for its precision and dependability in plastic coating applications. It provides adjustable coating parameters to accommodate a range of needs. The system is equipped with advanced atomization technology for a smooth and consistent coating distribution. Its user-friendly control panel offers intuitive settings and monitoring options. The PEM-X1 also facilitates quick material changes and simplifies maintenance.
Features: The Reliant Finishing Systems PC601 is a conveyorized powder coating system tailored for high-volume applications. It provides a continuous coating process with efficient use of materials. The system boasts a sturdy conveyor for smooth and consistent movement of parts and employs advanced powder application technology for even and durable coatings. Additionally, the PC601 features automated controls and customizable options to maximize productivity.
Features: Graco provides a range of electrostatic liquid coating systems designed for plastic coating tasks. These systems deliver efficient, high-quality finishes with excellent transfer efficiency. They incorporate advanced electrostatic technology to ensure even coverage and minimize overspray. Users benefit from precise control over coating parameters such as flow rate and atomization. Graco's electrostatic liquid coating systems are recognized for their reliability, durability, and user-friendly operation.
Features: The Dymax UVC-6 is a conveyor system engineered for UV-curable plastic coating applications. It provides precise control over UV exposure and curing times, ensuring effective coating performance. The system includes multiple lamp heads to guarantee even and complete curing. It also features adjustable conveyor speed and height for added flexibility and customization. The UVC-6 is compatible with other Dymax equipment and offers user-friendly controls.
Note that model availability and features may change over time. For the most current information on models that meet your needs, please contact the manufacturers or their authorized distributors.
Dip coating and dip molding offer several advantages to manufacturers, thanks to their straightforward concepts and versatile applications. Here are some key benefits of using these methods:
These processes do not result in shrinkage, allowing for precise achievement of the desired internal dimensions. Additionally, unlike other molding methods, the cooling rate is less critical and does not require stringent control.
Dip coating and dip molding effectively create seamless, double-walled components. Unlike parts joined from multiple pieces, which can have stress points at the seams that compromise durability, these methods ensure a continuous and robust construction.
Dip plastic casting allows for the production of large plastic components by encapsulating sizable metal pieces through dip molding. Producing similar large plastic parts using injection or blow molding would necessitate large tooling and become a costly process. The primary constraints of dip molding are the dimensions of the tool, the capacity of the pre-heat and curing ovens, and the size of the polymer solution tank.
Additionally, dip coating and dip molding are capable of creating intricate designs with severe undercuts and angles.
Designers can easily add extra details to the final product, as the tooling material can be readily modified. Additionally, different coating materials and thicknesses can be achieved using the same tooling by adjusting the formulation of the polymer solution.
Dip coating and dip molding are well-suited for short runs and laboratory-scale production due to their straightforward equipment requirements. Unlike injection and blow molding, which necessitate complex machinery and extensive floor space, these processes involve simpler setups. Additionally, the tooling for dip molding is cost-effective as it does not require high pressures to operate.
In dip coating and dip molding, excess solution drains back into the dipping tank, making it possible to reuse it. This is in contrast to other molding methods, where excess polymer material often results in cut-outs and runners that need additional processing for recycling. Dip coating also offers advantages over spray coating, as some of the spray material typically ends up on the walls of the coating chamber or equipment, leading to waste.
However, there are limitations to these processes where other molding methods may offer advantages. The following are some of the disadvantages:
While the internal dimensions achieved with dip coating and dip molding are precise, obtaining an exact coating thickness can be challenging. This is because it depends on various factors, including dwell time, tooling temperature, immersion rate, withdrawal speed from the polymer solution, and the properties of the polymer solution itself. These variables can also make it difficult to achieve uniform coating thickness distribution.
Dip molding is a time-consuming process due to the extended heating, dipping, and cooling cycles required.
Plastic coatings have become an integral part of manufacturing, used to enhance the appearance and functionality of cars, tools, appliances, sports equipment, and handrails. Their adaptability and versatility make plastic coatings a valuable addition to a wide range of products. In today’s market, plastic coatings are essential for ensuring the longevity and durability of both commercial and industrial items.
The demand for plastic coatings can be summed up in three key attributes: longevity, durability, and safety. Modern producers are continually seeking methods to extend product life while ensuring safety and reliability. These critical factors drive the development of new products, influencing every
Years ago, customers expected that new products would eventually need replacement, a principle that manufacturers relied on to sustain their market share. However, with technological advancements and the increasing complexity and cost of products, consumer expectations have shifted towards durability and long-term performance. In response, manufacturers have developed techniques to extend the lifespan of their products.
As component design and capabilities have advanced, a range of exceptionally strong plastic polymers has been developed to suit the needs of modern devices. These polymers contribute significantly to the longevity of electronics, such as televisions and computers, by providing unmatched durability under challenging conditions. When used as coatings, these polymers create a protective layer around commercial and industrial tools, enhancing their durability and extending their useful life.
In both commercial and residential settings, protective coatings are essential to prevent injuries from uncovered corners or exposed edges. In industrial environments, where tools can be complex and hazardous, plastic coatings play a crucial role in safeguarding workers from dangerous materials and equipment. Plastic-coated safety walls, gates, and enclosures act as shields, providing crucial protection and reducing the risk of harm.
Moreover, plastic-coated tools offer several benefits when used with moving parts, electrical circuits, and controls. Ensuring worker safety is a core principle of modern manufacturing, and plastic coatings contribute significantly to this goal by enhancing the safety and functionality of tools and equipment.
Vibrations are an inherent byproduct of operating heavy machinery and industrial equipment. To ensure the longevity of their products, facilities work diligently to minimize and manage these vibrations. A key component of this effort involves using plastic coatings, which help to prevent direct contact between machinery parts and reduce overall vibration.
Despite numerous efforts to reduce noise in production environments, it remains a significant aspect of manufacturing due to the high forces involved in producing large quantities of products. In addition to addressing vibrations, plastic coatings are also employed to mitigate noise. They are used in various applications such as separators, gaskets, shields, controls, and enclosures to help dampen and control sound levels.
Reducing friction in industrial processes enhances efficiency and ensures smoother operation across various production tasks. Friction can cause equipment wear, abrasions, and electromagnetic interference (EMIs), all of which can be detrimental to machinery. Applying plastic coatings to different components significantly lowers friction, thereby improving safety and boosting productivity.
Modern industrial machinery often includes insulation to safeguard both workers and products. Plastic coatings are commonly used due to their durability, ease of application, and long-lasting performance. These coatings help to reduce electromagnetic fields (EMFs), prevent direct contact between metal components, and ensure the smooth operation of equipment.
Applying protective plastic coatings provides additional protection and value to industrial processes. This investment helps reduce wear, damage, and the need for frequent replacement of critical machinery, while also significantly enhancing worker safety.
Plastic caps and plugs are two distinct ways for sealing the ends, tops, and openings of tubes and containers. Caps are placed over the opening, and plugs are placed in the opening. Due to the many varieties of...
Blow molding is a type of plastic forming process for creating hollow plastic products made from thermoplastic materials. The process involves heating and inflating a plastic tube known as a parison or preform. The parison is placed between two dies that contain the desired shape of the product...
Industrial coatings are a type of substance that is spread over a surface of various derivatives like concrete or steel. They are engineered chemically to give protection over industrial products that include pipelines and...
Plastic bottles are bottles made of high or low-density plastic, such as polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polycarbonate (PC), or polyvinyl chloride (PVC). Each of the materials mentioned has...
Thermoforming is the process of heating thin plastic sheets to its forming temperature and stretching it over a mold which takes its shape. After cooling and setting of the molded plastic sheet, each part will be separated from its batch to form a single unit or product...