A well-designed label with catchy captions and all the relevant information about the product is the key to making a good first impression and attracting customers.
While there are many labeling options available for manufacturers today, in-mold labeling takes the front seat for injection molding and similar production processes. It offers a range of benefits for high-volume production, including convenience and affordability.
If you are wondering if in-mold labeling is the right choice for your product, this guide is for you. With an introduction to the process, we cover the benefits, disadvantages, and applications of in-mold labeling, followed by a comparison with other labeling solutions.
What is in-mold Labeling?
In-mold labeling is a technique designed to label products during production. Introduced in the late 1970s, it differs from traditional labeling methods that take place as a separate phase post-production.
In-mold labeling (IML) refers to a process in which the product is covered with a label in the mold itself. A pre-printed paper or plastic film label is placed in the mold before injecting the plastic into it.
When the thermoplastic cools and solidifies, the label binds with the product effectively. The idea is to unify the molding and labeling process, eliminating the need for a separate post-processing solution.
Overview of the IML Process
1. Selecting the substrate for the label: It’s vital to select the right material to ensure maximum adhesiveness to the product. Polypropylene and polyethylene films are common materials used for IML.
While plastic substrates are preferred, paper coated with a heat-sensitive adhesive can also be used.
2. Designing the label: The next step is to create a label that matches your brand’s theme and is visually pleasing for the customer. You can incorporate a variety of elements to design it.
Note that the design should ensure the product’s name and other information are clear.
3. Printing and preparing the label: The proper choice of ink is essential to obtain the best results. It should not smudge during the labeling process and should be able to withstand the heat and pressure during the molding process.
Molding and Labeling Stage
Here’s a brief overview of the in-mold labeling process.
- The decorative plastic film (label) is placed in the mold using a vacuum or static charge.
- Molten thermoplastic is injected into the mold.
- The product and the plastic film fuse during the curing process.
- The end product is ejected from the mold.
- A new label is inserted automatically for continuous production.
The final stage involves preparing the labeled product for shipping by examining the quality of the label in each unit, eliminating defective products, and packaging them carefully.
The quality-control inspection is vital to ensure only the correctly labeled products reach the customer.
In-mold Labeling Processes
In-mold labeling is possible with the following product processes.
The injection molding process uses a specialized machine to melt thermoplastic pellets and feed them into a mold at the end. In this case, the label is placed in the mold before injecting the thermoplastic.
Then, the product is left to cool and solidify. After curing and ejecting the part, a new label is placed before the mold closes again.
Blow molding is the process of inflating a molten thermoplastic tube using compressed air to form hollow plastic products. In blow molding, the plastic label is placed around the inner wall of the mold.
As air blows into the cavity and the plastic expands to form the required shape, it fuses with the label. After the plastic solidifies, the product is ejected, and a new label gets placed inside.
Thermoforming is the use of semi-melted thermoplastic sheets and drawing them over a mold and allowing them to set and form the desired shape. As thermoforming involves the use of heated plastic sheets as opposed to plastic in liquid form, the in-mold labeling process is different here.
The label gets placed in the forming tool (mold) before the forming process. When the heated sheet is pressed against the mold to create the shape, the label fuses with the sheet.
So, the formation of the finished product and labeling happens simultaneously.
Benefits of IML
In-mold labeling offers a range of benefits to manufacturers.
Better Branding and Customization Options
If you want a vibrant label with high-resolution graphics, IML is the ideal choice. Manufacturers can make the labels more attractive and aesthetic while having design variations in the same label without much-added costs.
IML also allows you to match the texture of the product. IML design offers the use of,
- Colors: Any combination of colors, including metallic shades
- Textures: Stainless steel, woodgrain, fabric, leather, marble stone, and more.
- Finishes: High gloss, semi-gloss, matte, and more.
You can have the label cover the entire product or a part of it. IML technology allows the label to take the shape of the product seamlessly without any shrinkage, bubbles, or other imperfections.
A report by IMARC Group shows that the use of IML has increased globally due to the rise in demand for more aesthetically pleasing labels for commercial products. In-mold labeling also offers better visual quality and clarity than direct screen printing.
IML is a budget-friendly choice for mass production. The manufacturing process is fast as the molding and labeling are combined in one stage. If labeling is done separately, there will be added costs for labor and raw materials like adhesives.
As in-mold labeling doesn’t require them and can be automated, it’s cheaper. The availability of many substrate materials also makes it easy for you to select a choice that fits your budget.
We also like to emphasize that outsourcing your IML requirements from a trusted manufacturer is a cost-effective way of accessing its benefits than investing in a fully-resourced facility. This is especially true for startup businesses.
Durable and Long-Lasting
In-molded labels can withstand extreme temperatures, abrasion, chemicals, and moisture. They won’t tear, fade, or shrink over time.
They also won’t peel, unlike labels pasted using adhesives, because they bond permanently with the product. Their longevity matches the service life of the product itself.
Thanks to the above strengths, IML is preferred for microwavable and frozen consumer products and parts exposed to harsh environmental conditions. The durability and prolonged lifespan of the label also enhance the reputation and brand image of your business.
Efficient and Time-saving
As the labeling and production are completed at the same time, it reduces lead time significantly and improves the efficiency of the manufacturing process. The lack of a second step also means there’s no need for extra labor to label the products.
As the process is automated, the process can go on without interruption, and you can complete the order faster. There’s no fatigue involved, and hence, no requirement for breaks in between.
IML helps you cater to large orders productively and will boost the revenue of your business.
Versatility and Adaptability
For IML, the shape of the product and the contours in the exterior doesn’t matter. It can cover curves, ridges, and other features of the product while offering a smooth and perfect finish. It is one of the main limitations faced by other labeling solutions, as discussed below in the guide.
Also, one IML system can take up multiple products and helps you label an assortment of goods with ease. It is also fully adaptable to your needs.
In-mold labeled products are also more sustainable and eco-friendly compared to labels attached separately to the product. As the label and the product are of the same material, the recycling process is easy and efficient. As the raw materials, storage and transportation facilities, and other resources are also reduced, IML lowers the carbon footprint of your production too.
The same report by IMARC Group also pointed out that consumer preference for sustainable packaging is another factor boosting the demand for IML. Hopefully, it will also increase the recycling rate of this product, reducing the impact of plastic pollution.
IML can also make your product tamper evident and prevent counterfeiting effectively. As the label can cover the product entirely, it’s easy to identify a broken seal. The label is permanently attached to the product, making it difficult to replace it with a fake one.
Moreover, you can also include a watermark or a code to ensure the products are original. IML can make your products more reliable and trustworthy.
The permanence of the label also improves the safety of the product, especially if it’s a food or medical item. No one can change the manufactured and expiry dates or any other information included in the product.
Disadvantages of IML
As convenient as in-mold labeling is, there are also potential drawbacks and challenges attached to the process.
Compatibility of Label and Product Materials
It’s paramount for the pre-prepared label to withstand the conditions of IML to guarantee a flawless output. Therefore, the substrate, inks, adhesives, and lacquers used to create the label should be chosen carefully.
Not every material will react well when it contacts molten polymers at high temperatures. In this regard, there’s also a limitation of choice when designing labels.
Moreover, the film substrate should be compatible with the polymer used to manufacture the product for optimal adhesion. Otherwise, it can lead to peeling, delamination, and a poor result.
It also means that in-mold labeling may not be the best choice for all types of thermoplastics. In some cases, the manufacturer has to use a different plastic for the labeling film for better adhesion purposes, and it can result in increased costs.
The thickness of the label is another determining factor for adhesiveness.
Cost of Equipment and Expertise
Although in-mold labeling simplifies the production process, it calls for specialized and efficient machinery for a smoother operation. Robotic systems and clamping stations are required to position each label in the mold after ejecting a completed unit.
Also, the mold designed for the product should be accurate for the labeling to be accurate.
IML also requires seamless collaboration between design and engineering teams to execute the task well. They should have in-depth knowledge and understanding of how the process works and how to avoid the drawbacks successfully.
Not every manufacturer would be able to carry out an efficient task due to the complexities involved in the process. In this regard, the initial investment for in-mold labeling is quite expensive.
Potential for Labeling Errors
The defect rate of IML is quite high compared to alternative labeling solutions. Some common issues reported are ink washout, wrinkles, weld lines, sink marks, and the presence of bubbles.
Defects can arise due to low compatibility between the label film and the product material or label alignment issues. It can also happen if the label film is too thin to stay upright when it’s placed in the mold.
A higher rate of defects means you will have to work on the product again or manufacture new units to achieve the required quantity. It increases your production costs and leads to a waste of resources.
As concerning as these disadvantages may sound, IML remains one of the best labeling solutions for high-volume manufacturers. As long as your order is in good hands, meaning with a reliable and reputed manufacturer, the chances of defects are minimal.
Applications of IML
Food and Beverage Packaging
IML is a popular choice for food and beverage packaging because it doesn’t get affected by exposure to very cold or hot temperatures. It also allows for great flexibility in design, allowing manufacturers to design creative and colorful labels to attract customers.
In-mold labeling is particularly ideal for thin-walled disposable and reusable products and containers. Applications include,
- Dairy containers
- Ice cream and butter tubs
- Drink cups
- Beverage bottles
- Sauce and ketchup bottles
- Milk cans
Medical and Healthcare Products
IML is more hygienic when compared to other forms of labeling because the label is integrated into the product’s surface. It doesn’t leave room for the growth of bacteria or the spread of infections.
More importantly, IML on medical products can help medical professionals identify originals from counterfeited products. The permanence of the label makes it difficult, if not impossible to remove, preventing the drug or equipment from being replaced with a duplicate label.
- Syringes and syringe barrels
- Pill containers
- Laboratory tubes
- Plastic surgical equipment
Automotive and Industrial Parts
As IML is very durable, it is a solid choice for labeling and decorating vehicle components. The label will last as long as the vehicle component and won’t peel, crack, or fade in color with time.
It also allows a smooth operation of the in-built controls in the car, making it user-friendly and attractive. It’s also possible to derive different effects like metallic, gloss, or matte textures from IML. Some popular applications include,
- Control panels
- Car emblems
- Switch indicators
- Remote keys
- Decorative fixtures
Consumer product brands are increasingly using IML technology to label their products because it’s long-lasting and wear-resistant. IML also allows for advanced designs through the use of different textures, colors, and images and can be done on different shapes of containers.
As the label and the product material are usually the same, these consumer products are also easy to recycle. So, it’s a very sustainable choice. The use of IML in consumer goods is extensive. Some examples include,
- Decorative phone cases
- Control panels and interfaces in home appliances
- Skincare products and cosmetics
- Kitchen utensils
- Computers and electronic devices
- Storage containers
Comparison of In-mold Labeling with Other Labeling Methods
Pressure Sensitive Labeling
Pressure-sensitive labels have a layer of adhesive on the back. It is similar to a sticker and requires pressure to be applied onto a surface. It can be done manually or through an automated system.
This labeling method is easy to apply, compatible with most surfaces, and offers a smooth finish. The investment for these labels is low, and the choice of suppliers is high.
However, unlike IML, pressure-sensitive labels are easily prone to damage and can tear or peel with constant use and exposure to extreme temperatures.
It’s also difficult to stick these labels on contoured surfaces, whereas IML can cover the entire product if needed. IML can also mimic the texture of the product’s surface.
Shrink Sleeve Labeling
Shrink sleeve labeling is the process of wrapping a label around a product using heat. The label is usually a plastic film material, and the technology allows the label to be wrapped flawlessly around the product. Shrink sleeve labels can make a product tamper-resistant and attractive.
As there’s no glue holding them to the product, they are easy to remove and recycle.
However, that also happens to be a drawback. The removable nature makes the label unreliable. These labels can tear easily and have a short service life.
As you have to label the products post-production, it’s also costly compared to IML.
Wet Glue Labeling
Wet glue labels or cut-and-stack labels are the classic forms of labeling. They are paper labels that need to be stuck on the product using glue. The method doesn’t require advanced technical know-how, unlike IML.
There’s a lot of design freedom, and you can create an attractive label for your product easily. Also, wet glue labels are ideal for plastic, metal, and glass products.
However, wet glue labels are easily subject to depreciation. They can peel and fade in color over time. It also increases the product lead time. Unlike IML, wet glue labels are only meant for smooth surfaces and are not very water-resistant.
Heat Transfer Labeling
In heat transfer labeling, the design is imprinted on the product’s surface with the help of a heat-reactive material.
A heat transfer printing machine is used for this purpose, and this method is popular for printing garments and plastic products. Heat transfer labels are durable, long-lasting, and compatible with many materials.
Unlike IML, heat transfer labeling cannot cover the whole surface of the product with the label. The print can fade with time, even without exposure to harsh environmental conditions.
Heat transfer labeling is also more time-consuming than IML, as it’s a separate process that happens post-production.
Direct Print Labels
Direct print labeling is a more innovative method than IML because they require fewer resources and materials for the labeling task. An automated system will print the design directly on the surface.
It offers a wider variety of design, color, and customization options than IML. It is also faster, more efficient, and guarantees a better quality output.
However, direct print labels can fade or discolor over time, especially when exposed to extreme weather conditions. So, while it is a sustainable choice, it’s not the most lasting option for labeling.
Also, direct print labeling is only ideal for parts with a smooth surface or slightly curved products.
Kemal: The Best Choice for Quality Plastic Injection Molding Services
If you are looking for an experienced manufacturer offering high-quality injection molding and in-mold labeling solutions, look no further. Kemal is one of the top manufacturing companies in China, with nearly three decades of experience.
Some of our solutions are mold design and manufacturing, plastic injection molding, CNC machining, and 3D printing. We cater to the prototyping and high-volume manufacturing requirements of leading brands worldwide.
Our state-of-the-art production facilities, paired with the in-depth expertise of our team members, help us deliver the best output for our customers.
You can use our online quotation system to determine the cost of your injection molding or in-mold labeling requirement easily. If you have any questions, don’t hesitate to get in touch with us! Our experts can help you select the right material and manufacturing solution for your needs.
We hope our guide helped you understand the process and requirements for IML comprehensively. It’s one of the most efficient labeling solutions available today.
However, you should factor in the benefits and the limitations of IML before deciding whether it’s the right choice for you. You can also talk to your manufacturer, compare it with other labeling methods available, and make a decision.