Finding The Right Painting Service For Injection-Molded Parts

Painting injection-molded parts is a popular post-processing procedure that offers several benefits, including enhanced aesthetics, scratch resistance, and protection from UV light and chemicals. However, finding a suitable painting service for injection-molded parts can be challenging due to factors such as cost, quality control, and the expertise required to achieve long-lasting adhesion between paint and plastic. When choosing a painting service, it is essential to consider the specific needs of the plastic material, the desired finish, and the experience and equipment available at the paint shop. In-house painting facilities, such as those offered by Universal Plastics, can provide custom colours, finishes, and printing options, while companies like Boyan Manufacturing Solutions offer essential preparation advice and guidance on navigating the diverse options available in the market.

Painting process benefits

Painting injection-moulded parts is a cost-effective way to ensure uniformity in texture and colour across a large number of parts. This process offers several benefits, including:

Covering Flaws and Imperfections

Paint can conceal inconsistencies in the resin and any imperfections resulting from the injection moulding process, such as those caused by the mould or design geometry.

Enhanced Aesthetics

Painting can provide colours and glossiness beyond the natural capabilities of plastic materials, significantly improving the visual appeal of products.

Stain and Chemical Resistance

The paint acts as a protective layer, preventing staining from environmental factors and contact with certain chemicals, thus extending the lifespan of the product.

Scratch and Abrasion Resistance

Many types of paint offer a hardness that surpasses that of the underlying plastic, making the surface more resistant to scratches and general wear and tear.

UV Resistance

The paint acts as armour, shielding the plastic from the degrading effects of UV light and prolonging its lifespan.

Easy Clean-Up

Painted surfaces are easier to clean than unpainted ones, as paint protects against staining and chemical damage.

Soft Touch and Feel

Specialised paints can add a degree of softness to the surface, creating a unique tactile experience for the user.

Protection from the Elements

For parts used outdoors, paint provides an extra layer of protection from harsh weather conditions and physical abuse.

While painting offers these benefits, it is important to consider the challenges, such as additional costs, recycling concerns, and the risk of higher scrap rates due to increased quality requirements.

Choosing a paint type

Painting injection-molded parts is a cost-effective way to ensure a uniform look and protect the newly manufactured parts. The right type of paint will ensure aesthetic appeal, long-term performance, and adherence.

There are several types of paint and processes to choose from. The best process for your project will depend on how and where the part is used, and what environmental factors may impact the part.

Spray painting is the simplest and most cost-effective painting process used to add color or character to plastic parts. Some paints are two-part and self-curing, while others require UV curing to increase durability.

Powder coating is another option, which can provide a hardness surpassing that of the underlying plastic, making surfaces less prone to scratching. This type of paint also adds a degree of softness, offering a unique tactile experience.

In-mold painting may be an option, but it may not be as cost-effective as painting after the fact. Coatings that provide shielding against electromagnetic interference (EMI) are also considered to be post-process painting.

When choosing a paint type, it is important to consider the specific needs of the plastic. For instance, if the part will be used outdoors, the paint should offer protection from UV light and the elements. If the part is likely to come into contact with chemicals, the paint should offer chemical resistance.

It is also important to consider the molding process, mold type, mold surface, and part surface preparation to achieve long-lasting adhesion between the paint and plastic.

Preparing the product surface

Firstly, the product surface must be thoroughly cleaned to ensure it is free from any contaminants. This includes removing any mould release agents, greasy residues, soil, dust, fingerprints, static, or other debris. Handling the products with gloves during this process can help maintain surface readiness for painting. It is also important to note that certain additives used in the injection moulding process, such as plasticizers, can negatively affect paint adhesion, so their use should be carefully considered.

Secondly, a meticulous pre-painting inspection is vital to identify and rectify any flaws or imperfections. Painting enhances the appearance of the product, making even minor defects more noticeable. Therefore, addressing these imperfections before painting is essential.

Additionally, pre-treatment steps like sanding or plasma treatment may be necessary, especially for plastics with low surface energy. These treatments increase surface energy, creating a stronger bond between the paint and the plastic.

Finally, choosing the right type of paint is crucial. Specific paints are designed for certain plastics to meet their unique needs. Consulting with paint suppliers can provide valuable insights and recommendations to ensure the paint selected ensures not only aesthetic appeal but also long-term performance and adhesion.

Overall, preparing the product surface for painting injection-moulded parts requires careful consideration and attention to detail. By following these steps, a high-quality and durable finish can be achieved.

Alternative post-processing methods

Post-processing is necessary to address aspects not fully achieved during the molding process, such as removing excess material, improving aesthetics through surface finishing, adding colour or texture, and incorporating additional components or inserts. Here are some alternative post-processing methods to painting for injection-molded parts:

• Laser marking: This is a fast, tool-less process that can impart high-resolution effects to plastic injected molded parts. It is often used to produce logos or apply unique identifiers to parts that require traceability, such as medical devices and aerospace parts.
• Pad printing: This is a conventional marking process that transfers a two-dimensional (2D) image onto a three-dimensional (3D) object.
• Heat staking: This process involves melting plastic around a non-plastic part to join them together.
• Ultrasonic welding: This process uses high-frequency ultrasonic acoustic vibrations to join two components, usually plastics, together. It eliminates the need for chemical solvents and adhesives, making it useful for medical devices.
• Texturing: Texturing can be achieved through Mold-Tech, which enables specific sections of a part to be textured differently than the rest of the component.
• Assembly: This involves integrating additional components or inserts during the molding process to enhance functionality or create multi-material parts.

Finding a painting service

Painting an injection-molded part is a cost-effective way to ensure a uniform look and protect the part from scratches, UV light, and stains. It can also cover up any imperfections from the molding process.

When looking for a painting service for your injection-molded parts, there are several factors to consider. Firstly, you should ensure that the painting service has experience in painting injection-molded parts specifically. This process requires an in-depth knowledge of the chemistry and characteristics of plastic materials, as well as the molding process and the various variables involved.

You should also consider the specific type of paint you require. Different paints have different properties, such as hardness, scratch resistance, and UV and chemical resistance. It is important to choose a paint that will ensure not only aesthetic appeal but also long-term performance and adherence. Consulting with paint suppliers can help you make an informed decision about the type of paint that will best suit your needs.

Additionally, you may want to look into the quality control measures that the painting service has in place. A meticulous pre-painting inspection is crucial to identify any flaws in the injection-molded parts, as paint can enhance the appearance of defects, making them more noticeable. Consider whether you will need a member of your team present on-site to supervise the painting process and conduct random follow-up checks.

Cost is another important factor to consider when choosing a painting service. Painting is a post-processing procedure that will incur additional costs. These costs can vary depending on the size and equipment of the painting shop, so it is worth comparing prices from different providers.

Finally, it is essential to ensure that the painting service can meet your specific requirements, such as the desired color, finish (e.g., matte or gloss), and any additional treatments or coatings that may be needed.

Some companies that offer painting services for injection-molded parts include Universal Plastics, Boyan Manufacturing Solutions, and ICOMold by Fathom.

Frequently asked questions