Featuring ADVANCED INPUT, MEMTRON, and LRE MEDICAL Products
In Mold Decorating of Injection Molded Parts
In Mold Decorating of Injection Molded Parts
IMD offers many design flexibility and productivity advantages versus other decoration methods done after molding. These benefits include design flexibility, multiple colors and effects, textures with a single operation, long lasting graphics, manufacturing productivity, and systems cost reductions. Steps in the IMD Process
In-mold Decoration (IMD), also known as Film Insert Molding (FIM), is a versatile and cost effective method of decorating and manufacturing durable plastic parts. The process of in-mold decorating a plastic component consists essentially of 4 stages: Printing, Forming, Cutting and Molding Printing: The printing operation is used to create the decorative appearance of the product. While a variety of standard technologies can be used for this stage, silk screen printing is most commonly used. Forming:
Film is screen printed (decorated) on first and/or second surface.
Film is then formed to shape and cut to final size.
The forming process converts the flat 2D-printed image into a 3D part which is sometimes referred to as a formed appliqué. This process is sometimes referred to as ‘thermo-forming’ which is a catchall term to include vacuum forming, hydro forming and high pressure forming. In all three of these techniques, the flat printed image is shaped over or into a tool using negative or positive pressure. The tool can be either male or female, and each type has its own advantages and disadvantages. Cutting: Cutting of the 3D film may be performed before or after the molding operation depending on a number of factors and usually specified by the IMD supplier. Molding:
Film is inserted into special mold tool and part is injection molded, permanently bonding decorated film.
The IMD foil(s) is then placed in the cavity of the mold tool and the required resin is injected behind it. The foil can be manually or robotically placed into the tool depending on the volume required and the need for a fast cycle time. The molding process itself will almost certainly have to be optimized to suit the foil. Since all IMD techniques are intended to create cosmetically attractive parts, it will be clear that care in handling of the product is a key issue.
Advantages - Disadvantages - Applications One of the most efficient and cost-effective ways of decorating a part is to do it during the molding cycle. In Mold Decoration (IMD) can provide several important advantages over other decoration methods.
Advantages: • Design Flexibility allows customers to express their personalities while the products are easily manufactured. • Multiple colors, effects and textures with a single operation that are complete when the part comes out of the mold. • Legend/graphics wear is almost indestructible with second surface printing. • A cost effective solution over alternative decorating techniques. • Changing legends / languages / graphics is very easy by simply changing the printing.
Disadvantages: • Time to market issues with necessary developmental iterations. • Some graphics such as concentric circles, long lines and parallel lines should be avoided because of the unavoidable distortion induced by the IMD process.
Keytops, Buttons and Key Pads
• Some shape limitations.
• For multi-color legends and graphics.
• Materials are limited to non V-0 rated Polycarbonate and ABS resins.
• For art graphics/decoration
• For scratch/abrasion resistance legends and graphics.
• Translucent legends for back lighting.
Panels • For scratch/abrasion resistance legends and graphics. • For art graphics/decoration. • For multi-color legends and graphics. • Integrating components such as a lens / window & a panel.
Common Terms
Abrasion Resistance - Ability of a printed image to withstand wear and tear during handling and general product usage. Artwork - Name given to the image to be transferred to the plastic component during the decoration process. Carrier Film - Film material used to temporarily carry a printed image. The carrier film does not become part of the finished product and is discarded during the cutting process. Cavity side - Term used to describe one half of an injection mold tool. Generally this side will form the external surface of the product and is most often the fixed half of the tool. Core side - Term used to describe one half of an injection mold tool. Generally this side will form the internal surface of the product and is most often the moving half of the tool. Draft Angle - Slight angle introduced on nominally vertical walls of a molded component to ease the process of ejection from the mold tool. Draw Depth/Draw Height - Depth/Height to which a decorated foil is formed (drawn) prior to cutting and molding. Dual Layer construction - See laminated film construction. Ejection - The process of pushing a molded component off of the core side of a mold tool. Female Tool - Negative impression forming tool into which a decorated film is pushed to create an FIM foil. Film - Raw material onto which the decorative image is printed in the FIM process. Generally this will be a polycarbonate type material. FIM (Film Insert Molding) - IMD process in which a pre-decorated, pre-formed foil is placed in the cavity of a molding tool prior to resin injection. During the molding cycle, the resin and the foil fuse together.
First Surface Decoration - Components in which the decorative image is on the outer surface. Generally such components will be liable to abrasion and may have additional lacquers applied to protect them from this. Flow Direction - The direction of travel of molding resin during the injection molding process. Flow line - Visible defects on molded components caused by the flow pattern of the resin during the injection process. In many cases this feature can be masked by the presence of an IMD foil. Foil - Name given to the printed film in the IMD (FIM) process once it has been decorated, formed and cut. Form Tool - Male or female tool used to shape the flat, decorated film into a 3D foil. Forming - The process of shaping a flat decorated film into a three-dimensional format. Often this process is referred to as “thermo-forming” since heat is generally used. Gate/Gating - The location on a mold tool where the resin is injected into the cavity to create the component. Hardcoat - Lacquer applied to a film or foil to increase the abrasion resistance. This can be applied either as a sprayed coating on a 3D component or as a pre-coating of the film used in the decoration process. Generally, hard coating will be an essential requirement with first surface decorated parts. Height to Space Ratio - Ratio used to specify the required distance between adjacent raised areas on a formed foil. Particularly important in the design of IMD keypads where it governs the pitch between adjacent keys depending on the height of the key.
Common Terms
HPF (High Pressure Forming) - Forming technology in which flat films are converted into 3D foils using a combination of heat and high pressure air in a sealed chamber.
Post-Molding - Operation carried out on completed moldings to complete the production process. Can include, de-gating, de-flashing and several decoration techniques.
Hydro forming - Forming technology in which flat films are converted into 3D foils using a liquid in a sealed bladder.
Profile Tool - 3D cutting tool used to stamp out 3D formed films into foils suitable for insertion into the injection mold tool.
Injection Molding - The process of injection molten plastic resin into the cavity of a mold tool to create 3D plastic components.
Registration - The process of controlling the position of the printed image (decoration) on the completed plastic component.
Insert Molding - The inclusion of additional components during the plastic injection molding process. Typically used to produce moldings with mechanical components such as threaded metal bosses. Film Insert Molding is a variant of this process.
Second Surface Decoration - Components in which the decorative image is on the inner surface of a layer of plastic material. Such components are more difficult to manufacture than first surface types but have far superior abrasion resistance.
Image - Term used to describe the decoration, graphics or legend to be applied to a plastic component. See also artwork.
Solvent based ink - Thermally curing (drying) ink used in the decoration process.
IMD (InMold Decoration) - Catchall term used to describe any one of a number of processes used to decorate plastic products during the injection molding cycle.
Substrate - Term used by the printing industry to describe the material onto which the images are printed. Surface Finish - The level of texture, or polish, on the surface of a plastic component. This can be controlled by the texture on the mold tool, and/or the texture on any foil used in the IMD process.
IML (InMold Labeling) - IMD process in which a flat (2D) decorated foil is placed in the cavity of a molding tool prior to resin injection. Generally this process is used where the finished component is flat or only slighted shaped. It can also be used to decorate flat localized areas on a product.
UV Cured Ink - Ink used in the decoration process which is cured (dried) using UV light.
Ink Blow/Ink Wash - Defect in IMD components in which a portion of the image is distorted or displaced during the injection molding process.
Vacuum Forming - Well established thermoforming technique in which a heated film is drawn down onto a forming tool.
Male Tool - Positive impression forming tool over which a decorated film is shaped to create an FIM foil.
Wall Thickness - The nominal wall thickness of a molded plastic component.
Parting Line - The point on a molding tool at which the core and cavity halves of the tool meet.
Weld line - Cosmetic defect on a molded plastic component caused by the coming together of different mold flow fronts.
Thermoforming - The process used to convert flat 2D decorated films, into 3D foils.
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