Injection Molding Hot Stamping Process

Hot Stamping Injection Molded Parts the Right Way

Hot stamping is a secondary process to injection molding that is used to add logos, color accents, or instructional information to plastic parts. Hot stamping plastic parts can also be done to achieve a specific color, texture, or metallic finish. The process can be done with a press (hot stamping) or without a press (tipping). Hot stamping plastic parts uses high temperature to fuse the ink to the plastic. The high temperature allows the part to be cured at room temperature. This results in a strong bond and durable finish. The ink is essentially being melted into the plastic, making the decal, logo, or other finish a part of the plastic piece, as opposed to a sticker, which is held to the plastic part with adhesive that can easily fail.

Foils and specialty films are used when a metallic finish is desired. Sheen and layers of protection can also be added by selecting the correct film. Compatibility and chemical adhesion must be taken into consideration. Not all plastics will accept hot stamping. The experts at ICOMold by Fathom can help you select the correct plastic material for your project as well as the appropriate hot stamping process to bring your products to life.

Plastic Stamping Process

Hot stamping plastic is a dry process that uses a film or foil. The film is actually a thin sheet of plastic comprised of several layers. The simplest film has three layers. The bottom layer is the adhesive. The middle layer contains the coloring for the logo. The top layer is a protective finish. The logo itself is machined onto a metal die. The film is pressed between the heated die and the plastic piece. The heat and the pressure of the die adhere the logo to the plastic. The heat from the die will activate certain layers of the film, causing it to stick to the plastic part. The film is not punched out of the plastic sheet; rather, the logo is essentially fused to the plastic, making hot stamping one of the most durable and cost effective secondary processes. Unlike spray paint, the color, image, or logo only appears where the die touches the plastic part.

It should be noted that the name foil is a bit of a misnomer. The colored layer can be metallic like aluminum foil or gold leaf. However, the colored layer can also be any color the customer desires with a finish that ranges from matte to gloss.

Hot Stamping Dies: Hard vs. Soft

Hot stamping is usually done with a heated die and a press. Die materials are termed either hard or soft. Hard dies are made of metal like copper, brass, magnesium, or steel. Soft dies are made of flexible silicone. Hot stamping on flat surfaces with a press is typically done with hard dies. Soft silicone dies are more versatile and can be used on curved or unconventionally shaped surfaces. Silicone dies also require less pressure, making it easier to hot stamp odd-shaped plastic parts. However, silicone dies do require more heat. The excess heat will eventually render the silicone die useless as it stiffens and begins to lose its flexibility. Hard dies require more pressure but less heat. Silicone dies can be used without a press in a process called tipping.

Hot Stamping vs. Tipping

Tipping is a hot stamping process that does not need a press. Instead, the part itself is used as the die. This process works well for plastic items that have raised lettering or a raised logo. Only the raised lettering or logo will receive coloring while the rest of the plastic part remains untouched. A large soft die is used to administer the film to the plastic part. A silicone die that is larger than the part is heated. It then presses the film over the entire part. Only the raised sections of the part will come away with color. Tipping is also used to apply texture to a large flat surface. Faux wood grain is a popular texture that can be applied with the tipping method.

Hot Stamping Process On Unconventional Plastic Parts

Hot stamping plastic is not limited to flat surfaces. As noted above, silicone dies can be used to hot stamp irregularly shaped plastic parts. There are also hot stamping presses that can accommodate curved items. In this instance, the plastic part is placed in the press and brought to the heated die. The plastic part is then rotated against the stationary die while the film is applied.

What Materials are used for Hot Stamping?

Custom hot stamp dies are machined from copper, brass, magnesium, steel, or silicone. Hot stamping uses a dry ink or metallic foil. Material choice is determined by the detail of the artwork and the expected part production volume. Hot stamping plastic is a way to achieve high-end decorative results. Hot stamping foils are available in a wide array of colors and finishes, from matte to high gloss, including specialty foils that are holographic or metallic.

Is Hot Stamping Durable?

Hot stamping plastic parts is one of the most durable post-processing options available. Hot stamping plastic is more durable than paint. Paint is applied to the surface of the plastic part. Hot stamping fuses the color, design, or logo into the plastic itself. The hot stamp film or foil effectively becomes part of the plastic. Hot stamping will not chip or melt away. Hot stamping is resistant to most chemicals that would remove paint. Extra layers of protection can be added to the film applied to parts that will encounter harsh conditions.

The Benefits of Hot Stamping

Hot stamping plastic is a dry process so there are no unpredictable chemicals, no need for specialized venting equipment, and no drying time to slow down production. The hot stamping process tends to decrease packaging and handling costs because the decorated parts can be volume packed without need for spacer material. There will be no damage to the decorated part surfaces since the hot stamping process effectively fuses the logo into the plastic, making it a piece of the plastic instead of just a surface treatment. This makes hot stamping a very cost effective choice for adding color or logos.

Specialist In Hot Stamping Plastic Parts

ABS, acetal, nylon, PVC, polycarbonate, and polypropylene are some of the more commonly used plastics for the injection molding process. An extensive knowledge of these plastics and their chemical characteristics is required to apply paints, labels, and foils to the parts. ICOMold by Fathom has that knowledge – we know plastics and we understand the intricate chemistry involved in molding plastics. For nearly two decades, ICOMold has developed injection-molding processes that produce consistent, high quality parts for our customer all while keeping costs low.

Thinking Ahead About Secondary Processes

It is essential to plan for secondary processes in the design phase. Talk to your ICOMold engineer about the finishes as soon in the process as possible. Early planning will help speed production and lower costs, and it can also help minimize delays down the line. Some plastics are more receptive to hot stamping than others. Be sure to discuss the parts intended end-use and part decoration during the design phase.

Preparing Injection Molded Parts For Hot Stamping

Proper surface preparation is the key for successful post-processing with any plastic part. Hot stamping plastic is no different — making surface preparation a crucial step in the process. A good bond can be achieved by understanding the many chemical- and molding-process factors involved in the part design.

Surface preparation starts before the injection molding process. The potential for contamination in the mold or on the part is always present in any injection molding process. ICOMold by Fathom has developed methods for avoiding contamination and ensuring a clean part on every cycle.

Another consideration is the surface energy of the plastics. Many plastics used in injection molding generate electrostatic surface charges. The electrostatic charges tend to attract contamination. ICOMold’s decades of combined experience will help customers avoid paint defects and maximize hot stamp foil and film bonding. The experts at ICOMold are continually analyzing the entire processes, from mold design, to material options, to mold prep, and part surface preparation.

• ICOMold strives to develop tooling designs modified to downstream painting requirements in the plastic parts that will be molded.
• Designing with as few cutouts as possible helps provide a better painting process.
• Rounded part edges can be more easily covered with paint than sharp ones.
• Residual burrs can lead to contamination all the way into the painting booth. ICOMold keeps deburring to a minimum.
• ICOMold has developed proprietary systems for keeping tools extremely clean. Clean tools avoid excessive buildup of the materials used in the injection molding process while minimizing contamination.

More Ways to Optimize Surfaces for Hot Stamping Plastic Parts

ICOMold by Fathom uses release agents, additives, filler materials, and fibers to improve the characteristics of plastic injection molded parts and the bond with various paints, foils, and films. ICOMold has developed exacting processes and procedures for keeping these agents off the plastic part surfaces and to protect against inadvertent transfer.

Hot Stamping Plastic Parts Requires Surface Energy

The plastics used in injection molding processes do not carry much surface energy. This can make the adhesion of paints, inks, foils, and films difficult to ensure. Cleaning and some pretreatments can go a long way toward preparing the surface for secondary processes. ICOMold by Fathom often pretreats plastics that are going to be painted or stamped. This allows us to increase the surface energy of the part and improve the quality of the finish.

Color Matching Methods for the Plastic Stamping Process

Presentation is important. The right color is essential to branding and will help the logo stand out. ICOMold by Fathom can custom-adjust color, finish sheen, or add multiple colors to the hot stamp design. ICOMold utilizes:

• Pantone color matching
• Physical sample color matching
• RAL color matching

Surface Etching For a Better Hot Stamping Process

Most plastic parts are smooth when ejected from the mold. Completely smooth surfaces reduce adhesion. The surface of the part can be etched to prepare for painting or hot stamping. This will improve adhesion and the look of the finish. A chemical agent is used to create mild surface roughness and gripping areas that will provide a better bond for the paint, foil, or film. Etching is a delicate process and must be done carefully to avoid parts damage.

The Hot Stamping Process on Plastic is Just One of Many Secondary Processes

ICOMold offers many different effective paint and finish options for many kinds of plastic parts following the molding process. Films, paints, powdered plastics, even metallic vapors, can be used to enhance the appearance of injection molded parts. Hot stamping plastic parts can provide a desirable appearance that is both durable and within budget.

See the ICOMold list of other Injection molding painting processes for more details and post-processing options.

A Simple Process For Creating Appealing Injection Molded Plastic Parts

ICOMold offers an easy way to take injection-molded products from design to reality. Contact the experts at ICOMold today to see how we can help make your next project the best one yet.