Guide To In-Mold Labeling (IML): Everything You Need To Know

In-Mold Labeling

In-mold labeling is a unique process for decorating molded plastic parts.

In-mold labeling primarily provides rubber plastic products with high quality and colorful labels. IML is cost-effective and enhances the quality of plastic molded products.

In this article, I will help you to fully understand everything about in-mold labeling.

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    What is In-mold Labeling (IML)?

    In-mold labeling was first developed by Owens-Illinois in cooperation with Procter & Gamble, and was first applied to pre-labeled bottles. Now, it is becoming more and more popular and used by many molding factories in various industries.

    When using in-mold labeling technology, the pre-printed paper label or plastic film label is placed in the mold, and the label is seamlessly fused to the thermoplastic material during the molding process, thus integrating the production and labeling process, no need for post-labeling. After curing, the container and label will become a single waterproof and scratch-resistant piece.

    Why In-Mold Labeling Is Important and Popular?

    in-mold labeling example

    Product labels are very critical to the success of rubber plastic products. High-quality labels add a lot of value to products. Quality label or design makes a rubber product durable and increases its lifespan.

    The design of a plastic product has the power to attract people and even entice them to buy.

    Modern psychology has proven that most people primarily buy based on their emotions. Most people buy based on how they feel about a product before even thinking about the benefits they will get.

    How people feel about a product is linked to how they see a product. If the label is quality and beautiful, people mostly feel good about it. This good feeling ultimately drives potential customers to buy a product even when they have no idea of the product’s quality.

    Sadly, a high-quality product with a poor and unattractive appearance is likely to fail on the market. A low-quality product with a highly attractive label or design can easily attract more people to buy.

    This is why manufacturers need to pay massive attention to their product design and appearance.

    In-mold labeling is one of the most cost-effective processes that help brands to get high-quality designs for their products.

    The Principle of In-mold Labeling

    The main principle of in-mold labeling is to coat a product with a layer of label or design.

    The in-mold labeling process begins with selecting a unique material for labeling. Some of the materials used as labels include paper, polypropylene, and polystyrene. A material similar to the molded part can also be used as a label.

    A cavitated material can be also used as a label. A cavitated label material is a spongy layer that is bonded between two thin solid layers. A laminated film is used as a label when high resistance to wear is of great importance.

    The selected label is directed into an open mold. It is firmly placed into the mold cavity by either a clamp, vacuum, compressed air, or static electricity.

    The selected plastic material is melted and injected into the mold. The injected plastic material binds with the label after cooling to form a single product. This produces a beautiful design on the molded product.

    Advantages of In-mold Labeling

    It Provides Various Decorating Options

    This method of decorating plastics has quick design changeovers and it makes use of multiple color printing and lithography printing to produce products with higher quality which does not get abraded during use.

    It Improves Appearance

    In-mold labeling greatly enhances the appearance or beauty of products. It provides products with virtually impressive designs and eye catchy pictures. This easily draws the attention of potential customers. Product information is printed on the labels. The product is made even more beautiful because the corners of the label do not appear on the product.

    Also, the structure of the product is improved because both the label and the product are formed together, they naturally touch together and this improves the structure of the product. The label is permanently fused with the product. The label remains intact throughout the product’s lifespan.

    It Increases Production Efficiency

    IML has a shorter production time and its production cost is very low since containers can be produced and decorated at the same time. This makes the storage of blank containers unnecessary and eliminates the cost of storage and transport.

    It Prevents Counterfeit Products

    In-mold labeling requires the use of uniquely designed molds. Manufacturing molds for in-mold labeling requires a lot of expertise and high capital. The expertise and high cost involved in manufacturing molds greatly reduce the tendency of fraud. The variations in mold design, film printing, and label formation processes make it almost impossible to copy. This helps to preserve brands.

    Disadvantages of In-mold Labeling

    Forming Methods For In-Mold Labeling

    In-Mold Labeling molding

    There are numerous ways through which in-mold labeling can be done. In this article, we will look at the top three  IML forming methods. They are injection molding, blow molding, and thermoforming. All these three methods are effective. The only difference is the way the labeling is done.

    Injection molding

    Injection molding is the most popular in-mold labeling method. It involves heating plastic material and injecting it into a mold for it to cool. The molded plastic part fuses with a printed label placed inside the mold cavity. The results in a single decorated plastic part. The injection in-mold labeling method begins by printing a uniquely designed label.

    This printed label is placed into an open injection mold cavity through a polymer carrier. The printed label is held in place by air pressure or mechanical means in the mold cavity.

    Selected plastic material is heated and injected into the mold cavity for molding. The mold has a small opening that the melted plastic passes through. The injected plastic is allowed to cool in the mold. Upon cooling, it takes the shape of the mold and binds with the inserted label.
    The molded plastic part is permanently bonded to the printed label to form a permanent decoration on the plastic part.

    Injection in-mold labeling is cost-effective and provides great design flexibility. It provides long-lasting product labeling solutions and increases productivity.

    Because the labeling of the plastic mold is done during the molding cycle, post labeling and other secondary processes are eliminated.

    Many plastic containers use the injection molding method. A typical example of a product that uses injection molding labeling is ice cream tubs. Other products that utilize injection molding labeling are computer keyboards, cell phone keypads, smaller plastic paint buckets.

    Blow molding

    Blow molding is the second popular in-molding labeling method. This process involves heating plastic material and stretching it into a tube. The plastic tube is placed into a mold. Air is then blown into the plastic tube. This makes the plastic tube to fill the mold cavity. The plastic tube takes the shape or form of the mold.

    Just like in-mold injection, the label for decoration is first fixed into the cavity wall of the mold. As the molded plastic cools, it fuses with the label inside the mold cavity. The fusion is made possible because the glue on the label’s surface is activated by the heat from the heated plastic. The blow molding in-mold decoration process results in high durable labeled plastic products.

    This process is mostly used for manufacturing hollow plastic parts. This process was used to produce glass bottles. Today, this method is used for producing plastic bottles. This manufacturing process is used to produce liquid containers like containers for shampoos, dishwashing detergents, liquid soap, ketchup, sauces, etc.

    Blow molding in-mold labeling can be classified into three main types. They are extrusion blow molding, injection blow molding, and injection stretch blow molding.


    In thermoforming, plastic sheets are heated and formed into a unique shape using a forming tool. The plastic sheets are not completely heated like injection and blow molding. The heated plastic sheets are stretched around a forming tool. The heated plastic sheets take the shape of the forming mold after it cools and becomes solid.

    Before the heated plastic sheets are placed around the forming tool, a printed label is inserted into the mold. As the heated plastic sheets cool and solidify in the mold, it binds with the printed label.
    This results in a fully decorated plastic part or product.

    Thermoforming is mostly used for rigid plastic packaging. It is used for producing plastic cups. Plastic cups like coffee cups, ice cream cups are also made through this process. Thermoforming is also used for making plastic tubs that are used for ice cream packaging. Among other products that can be produced by thermoforming include lids, trays, and blisters. Other products for the food, medical, and retail industries are made through thermoforming.

    Application Examples

    in-mold labeling example 3

    Below are some of the industries that make use of in-mold labeling:

    • Food packaging cups, trays, lids, containers, tubs
    • Consumer handheld devices
    • Storage containers
    • Consumer products.
    • Plastic housings
    • Medical devices
    • Computer
    • Telecommunication

    In-mold Labeling Markets

    Over the years, there has been an impressive growth in in-mold labeling due to the great benefits it provides. The in-mold decoration market is even expected to enjoy massive growth in the coming years because of the following reasons.

    The first major reason is the massive reduction in labeling costs. Secondly, in-mold labeling products are 100% recyclable. The process eliminates all secondary processes associated with post-molding labeling methods. Another major reason is in-mold labeling’s ability to produce highly appealing and impressive designs on products. The problem of label tampering is eliminated form in-mold decoration. Higher adhesion is assured in in-mold labeling.

    Many brands across the globe have seen the need to produce products with high-quality packaging and instructive labels. On top of that, many brands are in high demand for a labeling method that makes their products highly durable and long-lasting. In-mold labeling can provide high quality, clearly instructive, and damage-resistant labels at a reasonably lower cost. This strategically positions in-mold labeling to significantly contribute to the labeling markets in the coming years.

    The materials used for in-mold labeling make it suitable for a wide range of markets which include food, pharmaceutical, computer, telecommunication, automotive, personal care products, etc markets.

    There has been a significant growth of in-mold labeling markets with light plastic labels and moisture barriers. The main reason is the major change in the way people buy products. A lot of people now buy products on the internet. This has created the need for increased shelf life. Products bought on the internet mostly spend a longer time at distribution centers shelf before reaching consumers. This demand for products with light plastic film and moisture barriers is even expected to rise in the coming years since the number of people who purchase on the internet is expected to increase.

    In-mold labeling uses digital printing to print labels. Digital printing makes it possible to print lower volume labels at a lower cost. Digital printing offers variable data printing. This makes it possible to place codes or numbers on labels in a successive manner. The capability of digital printing in printing high-quality labels at a lower cost positions in-molding labeling for greater success in the coming years.


    Here, you will find the most common questions about IML.

    Some of the noticeable plastic materials for in-mold decoration are:

    Polypropylene, Polyethylene, Acrylic, Polycarbonate, Polyamide, High Impact Polystyrene, Thermoplastic Polyurethane, Thermoplastic Rubber.

    Injection molding, blow molding and thermoforming are the most suitable and effective in-mold plastic labeling processes.

    Through In-mold labeling technology, modern plastic can be given highly appealing, durable, long-lasting, and damage-resistant decorations. This technology helps plastic product brands to cut down their cost of production to the most reasonable minimum. This is because complete labeling is achieved in the mold. This eliminates all post-molding labeling costs. It helps brands to save extra time, energy, and labor used in post-molding labeling.
    The digital printing technology used in in-mold decoration helps to print high quality, clearly instructive, and damage-resistant labels at a reasonably lower cost. Low volume product labels can be printed through digital printing at a lower cost.
    In-mold labeling has a wide range of applications in different markets. The plastic materials used for in-mold labeling make it suitable for markets such as food, pharmaceutical, computer, telecommunication, automotive, personal care products, etc markets.
    In-mold labeling highly efficient. You can mass-produce many labeled plastic parts within a short time. It provides a lot of flexibility in decorating plastic molded products with unique labels.

    Below is the list of machines used for in-mold labeling:

    ❖ Ferromagnetic in-mold labeling machine
    ❖ Extrusion blow molding and labeling machine
    ❖ In-mold labeling robot machine
    ❖ In-mold labeling robotic arm
    ❖ In-mold labeling line (IML)
    ❖ Robotic arm for in-mold labeling machine.
    ❖ Automated assembly machines,
    ❖ Pick & place mechanisms
    ❖ In-mold insertion machines
    ❖ Part insertion machines
    ❖ Robotic laser cutting machinery
    ❖ Material handling systems
    ❖ Case packing machinery
    ❖ Inspection & machine vision systems
    ❖ Specialized machines & systems
    ❖ Digital barcode printers

    There is a distinct difference between in-mold labeling and in-mold decoration even though they are mostly interchanged. It is important we understand this difference.
    In-mold Labelling In-mold labeling is used for decorating disposable products with a short lifespan. Some of these products include food containers, household containers, cosmetic, personal care products, etc. These products are only used for months and do not last for years. They also have low prices. In-mold labeling decorated products are produced by thin-walled, multi-cavity injection mold machines.
    In-mold Decoration Long-lasting products with longer lifespan are decorated through in-mold decoration. Automotive parts, medical devices, appliances, garden equipment are examples of products decorated by in-mold decoration. Thick-walled, lower cavity injection machines are used for producing these products and they last for years. In-mold decoration designs or labels have a medium cost. In-mold decoration creates very beautiful and durable labels that represent brands.

    There are two main categories of materials used for in-mold labels. The paper and plastic film. Polypropylene is a common example of a plastic film. It has a thickness of 15 to 40 micrometers. The paper used for in-mold labels is mostly covered with a heat-sensitive adhesive. When a paper is used as an in-mold label, the adhesive covering it is activated by the heat from the melted plastic. This causes the paper to bind with the molded plastic part to form a single product.

    In-mold labeling comes with a lot of costs. Molds used for in-mold labeling are complex and expensive. It requires a lot of capital and expertise to manufacture an efficient mold. The robot systems and machines used for in-mold are costly. In-mold labeling companies need to buy their machines and molds from the right suppliers. With proper guidance from suppliers, in-mold labeling technology can be maximized for profitable and efficient results.


    In this post, we have explored everything you need to know about in-mold labeling, now I think you have a clear understanding of in-mold labeling, its benefits, forming process, applications, and market potential. Hope the information provided in this article can help you make a good in-mold labeling decision for yourself or the company.

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