The complete Guide To In-Mold Labeling (IML)

Table of Contents

I. Introduction

Labels on manufactured goods serve many purposes, including proper usage and handling instructions. However, it has evolved into an integral aesthetic contributor to most products. Fortunately, technological advancement has provided innovative techniques like in-mold labeling, making it possible for products to carry labels easier, quicker, and more durable. Consequently, manufacturers looking for cost-effective labeling methods that add a bit of glamor to their products have found in-mold labeling extremely attractive and rewarding. This guide gives you all the knowledge you should have on in-mold labeling, including its merits, limitations, and environmental impact.

II. Understanding In-Mold Labeling

To successfully implement in-mold labeling for products, specific parameters need to align. The reason is that in-mold labeling incorporates pre-printed labels with manufacturing molds by inserting them before carrying out mold injection with the product material. The result is often a monolithic product of labels and plastic production material with an excellent finish and outstanding durability. This method offers many benefits to the product manufacturer, especially the significant cut in production time, making it quick to achieve a high production output. The impact of the reduced production is reflected in the increased bottom line, as more output means more profit. Again, since the mold design integrates the label and product manufacturing into one process, the number of personnel required for the job is also reduced, further saving cost. Efficiency increases, reducing the probability of manufacturing errors since there is a reduction in the number of manufacturing activities. Also, in-mold labeling improves the quality of the manufacturing process, given that the process is seamless, resulting in a better finish for the product. Furthermore, in-mold labeling is an effective way of ensuring that the labels are adequately protected from water, which is usually unfavorable to many labels causing tearing, color washing, and fading. 

Nevertheless, you must understand limitations if you plan to use in-mold labeling in your project. Chief among these limitations is its unsuitability for some products, including products with intricate shapes and designs. Also, it is quite expensive when setting it up initially, especially relative to other labeling methods. Additionally, it is only cost-effective for mass production, and people with smaller production budgets and quantities might be unable to justify its use.

Yet, in-mold labeling enjoys widespread application across several industries, including logistics and packaging, food processing, consumer goods, and electronics. Its numerous advantages and aesthetically pleasing finish are major reasons for its huge acceptance among manufacturers. 

III. Types of In-Mold Labeling

While in-mold labeling is highly beneficial and can reduce production costs, it is essential that you know the distinct types available so you can choose the most suitable one for your project. There are three types, injection, blow, and thermoforming in-mold labeling. However, understanding their unique processes and specific applications will let you know which is appropriate for your project. 

  1. Injection Molding IML: This type is often suitable for mass production because it involves injecting molten plastic material after inserting the label in the mold’s hollow space. This gives the product a high-quality finish without the need for post-production labeling. Its main advantage is its excellent accuracy, which is especially useful for labeling complex structures in huge quantities.
  2. Blow Molding IML: The unique application of the blow mold IML is in labeling plastic containers and bottles, where the air is used to blow the mold into shape. However, placing the labels in the blow molds is the first step, after which the air is blown into the mold producing a monolithic product with its label in place. It is essential to ensure the proper placement of the labels in the blow molds such that they are safe from abrasion and scratches during production. 
  3. Thermoforming IML: Thermoforming mold is an essential component of this in-mold labeling, given that the labels must be placed in the thermoforming mold before they form the plastic product. This type of IML is applicable in manufacturing plastic lids, covers, and trays which are often small in thickness. Its major merit is its versatility allowing labels with diverse types of materials. 

The advantages of each IML type make them unique and suitable for specific applications, including complex shapes and designs. Hence, considerations like material type, shapes, and design are required when selecting the appropriate IML type. A quick consultation with seasoned IML manufacturers will help you make the right choice. 

IV. Materials and Substrates

Not all materials may be used for in-mold labeling. Hence choosing the right material for the in-mold labeling type for your project is critical. 

For in-mold labeling projects, materials with excellent molding properties are often favored. Polypropylene is one of the leading materials used for IML due to its strength, thermal properties, and versatility. Also, polyester and polyethylene are popular materials with high durability, flexibility, and printability. All three materials are suitable for molding projects with high temperature and pressure requirements as they can maintain their internal structural integrity in extreme temperatures. 

Nonetheless, the compatibility of label material with different plastic materials is a critical consideration for IML procedures, knowing that some materials are incompatible with plastics. A case in point is using PP labels with suitable plastic materials like polyethylene and polypropylene, which are polyolefin plastics but not suitable for crystalline plastics like PET nylon and polycarbonate plastics. It is standard practice to carry out compatibility tests to ascertain the adhesion of the label and plastic materials to avoid defects like warping and other anomalies. As a substitute for popular label materials, certain substrate materials with suitable properties, including flexibility, good reflective properties, and strength, can be used in their stead. These substrate materials can be paper, metals, or even cardboard. Still, specific surface treatment will require these substrates to bond properly with the plastic material. 

In the end, knowing the right label materials to use depends on the plastic material selected for the product. Also, critically considering compatibility issues will ensure a quality finish with excellent durability for your in-mold label application. 

V. Design and Artwork Considerations

In-Mold Labeling (IML) offers unique branding opportunities that traditional labeling methods cannot match. With IML, graphics are integrated into the product, providing a durable, high-quality finish. However, designing for IML requires careful consideration of several factors to ensure the final product meets branding and functional goals.

One of the primary design considerations is the choice of colors and artwork. Because IML is a printing process, selecting colors compatible with the printing process and the substrate is important. Color matching and uniformity should be carefully considered to ensure that the final product fits branding criteria. Furthermore, the design should be considered for the incorporation of barcodes and QR codes, which can give crucial product information and ease product tracking.

Graphic design rules are especially important in IML since the sort of visuals utilized is limited. Simple and bold graphics with sharp contrast are ideal for IML. Designs with intricate details or gradient colors may translate poorly in the IML process. The placement of graphics should also be carefully considered to avoid interference with the product’s function or appearance.

In summary, design and artwork considerations are essential to successful In-Mold Labeling. A clear understanding of the printing process, substrate compatibility, and graphic design guidelines can help ensure that the final product meets branding and functional goals.

VI. IML Manufacturing Process

The numerous benefits of in-mold labeling are largely based on the efficiency of the automation process involved, especially since the two processes are combined. However, understanding the various steps involved in-mold labeling – that is, besides mold manufacturing, is critical to optimizing the production process. 

Preparing the label is generally the first step in any IML procedure. The label’s material must be flexible and robust despite its thin dimensions. That’s why polyester materials are some of the most popular materials used, given that they are flexible yet able to withstand the stress of the process. Printing the design on the material is a significant part of the label preparation process. It is done before the label is loaded into the machine. After printing, inserting the label in the robot-controlled IML machine is time. The molten plastic is injected into the mold once the label has been inserted. The mold serves as an encasement for ensuring that the label and the plastic resin material come out as a single block before it is passed along for further processing and packaging.

 The equipment engaged in IML is automated and highly sophisticated, considering that it uses a robotic arm that requires a high level of expertise to operate. Also, the labeling arm is connected to the robot’s end using a vacuum system. This component secures the label while printing, ensuring high precision and alignment of the label and product. Furthermore, the cooling of the molten plastic injected into the mold is handled by a cooling system. This system reduces the time it takes to unmold the solidified final product, increasing efficiency and output. 

Besides its increased efficiency, integrating the labeling and molding processes obtained with IML increases manufacturing options for manufacturers with the ability to use IML for various applications. These applications also include a variety of products with different complex geometries, shapes, and dimensions with high branding accuracy. 

VII. Quality Control and Inspection

Ensuring the quality of a product is a critical part of most production processes, as defective products can hurt the company’s reputation and, ultimately, the bottom line. IML, being a complex manufacturing technology, is likewise not free from quality processes in its implementation. However, because it is primarily automated, it is simple to implement a quality management system to assure the creation of a long-lasting product with a well-bonded label. 

The bonding between the plastic substance and the label is one of the most important quality factors in IML. The success of the molding process is dependent on the label’s great adherence to the product. To determine the integrity of the label’s bonding with the product, you may need to check for particular characteristics. The label’s compatibility with the product’s plastic substance is a critical inspection criterion. Ensuring the label has high adhesion with plastic means you’ll need to use materials like polypropylene and polyethylene, some popular IML materials with outstanding adhesion and flexibility. These materials can also handle the rigorous process involved in IML, which is also a critical quality concern. Also, the color and design are an essential part of quality checks which ensure the accuracy of the design’s graphics and the product’s aesthetic appeal.

The previously mentioned checks are pre-printing quality assessments. However, post-printing quality evaluation, which includes checking the material and design specifications of the label to ascertain it meets all design parameters, is also crucial. Defects like warping and bubbles that often reduce the label’s adhesion properties are some defects to check. Production quality checks, including equipment inspection, label positioning, and optimization controls during production, are essential to avoid anomalies. Finally, post-production quality inspection is needed to ensure that there are no defects with the label and product bonding and that the product meets end-users’ requirements. These post-production checks include durability checks, label bonding, and the label’s aesthetic appeal. 

VIII. Environmental Impact and Sustainability

The environmental impact assessment of every production is becoming a concern considering the carbon footprint of most production equipment. Also, the waste generated during production is another environmental concern seeing the vast amount of non recyclable waste on dumping sites and the amount of untreated harmful chemicals released as wastewater. However, in-mold labeling, the reduction of the processes involved, especially in merging the labeling and manufacturing, helps to reduce energy consumption and carbon footprints. It is also an efficient way of reducing the waste generated during production, given that there is no separate application of labels to products that often require so many packaging materials. 

Most in-mold labeling materials can be recycled into materials for other products making them more sustainable than most other manufacturing materials. Again, the thin dimensions of the labels in IML are an efficient use of materials, further reducing the wastage associated with different product labeling methods. This also means cost-effectiveness as you use less material for IML relative to other labeling techniques. In all, the environmental impact assessment of IML is more favorable than most other labeling techniques, and there is even more potential as technological advancements increase and more sustainable materials emerge. 

IX. Cost Factors and ROI

The initial purchase price, maintenance cost, and the cost of operating a machine are important considerations manufacturers often evaluate before adopting a production method or equipment. These parameters help assess the equipment’s financial feasibility, including its return on investment (ROI) over time. Considering these factors before adopting IML for your labeling projects is also essential. However, the most significant aspects will be highlighted here.

  • Equipment and setup: The two most expensive expenditures for IML machines are the cost of acquiring one and setting it up. Nonetheless, the long-term return on investment may be enormous due to the multiple benefits such as cost-effective production, decreased material waste, greater production efficiency, and reduced negative environmental impact.
  •  Operational and maintenance costs: After setting up the IML equipment, operating it daily and the periodic maintenance cost is also substantial. This cost includes acquiring labeling materials, hiring operators and technicians, and repair or maintenance fees, all of which should be carefully considered before purchasing IML equipment.
  • ROI assessment: When analyzing its ROI, the major factors are the long-term advantages and cost-effectiveness of embracing IML techniques and equipment over alternative ways. Its advantages, such as improved aesthetics, higher manufacturing efficiency, and cost savings, can have a beneficial influence on ROI.

X. Choosing the Right IML Partner

In many cases where manufacturers are bogged down with limited budgets, finding an IML partner seems the way to go if you must enjoy the numerous benefits of IML for your product. Finding the perfect IML partner who is dependable and devoted to quality, on the other hand, might take time and effort. However, there are specific factors and attributes that you can use in your checklist to confirm the suitability of an IML partner. 

  • Experience and Expertise: The number of years in business and the number of completed IML projects are ideal starting points for assessing an IML partner. These indicators will help you determine whether the partner is a good fit for your IML needs. Various industries and applications are also great indications of a potential IML partner. More is better in each case. 
  • Design Capabilities and Technical Knowledge: The technical expertise of a prospective IML partner is another critical factor in choosing the right partner. This factor shows the IML company’s ability to take on complex IML projects, including products with complex geometry and design, and the ability to use sophisticated equipment like CNC machining to execute these projects. Their technical skills also include helping you decide on the most suitable label material for your product and graphic design.
  • Customer Service and Communication: An IML partner’s ability to communicate the project’s goals, technicalities, and the timeline required are key suitability indicators. These factors give clients the confidence to trust an IML company. Hence, an excellent customer service team is an essential consideration in choosing an IML partner that is right for you. 

XI. Case Studies and Success Stories

The versatility of IML application across several industries has consistently attracted manufacturers to these labeling methods over the years. These industries include automotive, logistics and packaging, home appliances, and cosmetics.

For instance, in the production of cosmetics packages, IML provides an excellent finish for labels of products like creams, lipsticks, and powders, giving them a unique aesthetic appeal. IML also ensures the graphics on these labels are consistent and without distortion due to the stress involved in the production. The accuracy of IML for cosmetics packaging is also a huge benefit considering that small products like lipsticks can be branded with precision and enhanced product appeal. 

Again, in packaging food items like beverages and dairy products, IML has consistently provided manufacturers with durable labels that remain untouched despite preservation conditions. For instance, the freezing environment required to preserve milk and yogurt causes no defect to IML labels. Also, IML’s use of thin but high-strength label materials helps manufacturers improve their packages’ safety with tamper-proof packaging. Furthermore, IML helps food and beverage manufacturers strengthen their brand visibility with the full-wrap label designs. 

Household goods packaging is another industry with extensive use of IML. Especially for products containing harsh chemicals like detergents, bleaches, and other cleaning fluids, IML’s durable label material helps to secure these chemicals within their packages without deteriorating. These labels can also be given a unique design and shape to increase brand distinctiveness among other brands with related products. 

These are all successes of IML in several industries. However, specific industries have put a spin on IML for their unique application producing some of the most innovative ways to use IML. These innovative IML applications include peelable labels in soap bars and plastic containers. Other creative IML uses have holographic labels with advanced graphics for added aesthetic appeal. 

The numerous benefits of in-mold labeling account for its increased popularity in different industries and several applications over the years. Due to its multiple advantages, this growing trend has increased demand for IML over conventional labeling methods, especially in pharmaceuticals, cosmetics, and home appliances. More importantly, the sustainability of IML as an environmentally friendly labeling method is another reason it has become so trendy among manufacturers. 

However, with all these IML trends presently on the ground, the future of IML will be quite different from what we have now if the advancement in technology is anything to go by. The rate of technological inventions and developments keeps raising the bar of what is possible. With the development and continuous research on biodegradables, it is possible to eliminate the negative impact of waste in the future. 

The efficiency of machines and equipment has improved production speed, such as rapid prototyping and advanced digital imaging. This efficiency has made production more effective and accessible to previously disadvantaged manufacturers. Hence, IML will predictably permeate and dominate the labeling landscape with better quality and appealing labels. 

In all, it is expected that IML will continue improving efficiency and quality while finding other applications, especially marketing and promotional strategies, as the graphic design quality also continues to improve. 

XIII. Conclusion

In a nutshell, in-mold labeling is an innovative method with many advantages, including increased production effectiveness, accurate labeling for complex geometries, and increased aesthetic appeal for products. Also, the cost savings and massive return on investment have made IML attractive to many manufacturers across several industries. Nonetheless, the careful considerations of parameters like design complication, product material, and necessary product checks are important for the success of in-mold design labeling. However, you can find a suitable IML partner that meets your requirement if you are a small manufacturer and want the full benefit of IML. Still, it would help if you evaluated this potential IML partner based on their experience, technical ability, and quality of service. Ultimately the future holds more promises for IML with rocket-speed advancements in technology and the increased demand for IML by more industries. 


Gary Liao

Gary Liao

Gary Liao is the Engineering Manager of TDL Company and has more than 20 years of mold design experience.

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