Why is embossing necessary at all and how do you decide which type of embossing to use? To better understand these questions, we have compiled some of the most important information below:
Embossing is a technique that deforms a material mechanically and without heat by exerting pressure on an embossing tool featuring positive and negative engraving. This method creates a permanent structure (shape change), which gives the material various additional properties.
The embossment fulfills various functions of packaging. On the one hand, the embossment fulfills a technical function, such as ensuring good flatness or giving the die-cut blank additional stability. In addition, it ensures the function of lid separation from a stack so that the packaging can be securely sealed on the filling line. On the other hand, the embossing also carries important marketing functions such as recognition and differentiation. The embossing allows the third dimension to be used decoratively and creatively.
sealing rim embossed - back
sealing rim embossed
1 - Destacking: In order to prevent the pre-punched lids from sticking to each other due to the vacuum effect of smooth film when destacking on the filling line, the lid must be mechanically deformed. For this purpose, a fine, relief-like surface structure is applied. This deformation causes an air cushion to form between the individual punched lids. This ensures trouble-free filling already during separation and application of the lids to the container. When designing the embossing structure, care must be taken to ensure that the repeat pattern of the embossing is never identical to the repeat pattern of the feed during die-cutting. If this is the case, the opposite of the desired function occurs and the embossing structure interlocks and reliable destacking is no longer possible.
2 - Flatness: The embossing structure can enhance the stability of the lid. However, the embossing structure can also have a strong influence on the flatness of the lid. The selected embossing structure must be adapted to the respective die-cutting substrate in order to allow a trouble-free die-cutting process.
3 - Recognition: The embossment can strongly influence the optical appearance of the product and can therefore also be used to establish exclusive customer loyalty. A unique embossing structure with a clear recognition value strengthens the brand's position on every sales shelf.
4 - Differentiation: The worm embossment and the dot embossing designs are the most commonly used embossing structures. These two structures make up a large part of the embossed products in flexible packaging. However, a unique embossing structure allows a clear differentiation from the mass.
There are many different ways to shape a material, and they depend on which function the embossing has to perform. The most important embossing methods are listed below:Full-surface Embossing
Full-surface embossing is the most widely used embossing process and is used for all types of products. For full-surface embossing a union set of steel embossing rollers with positive and negative embossing is used.Partial Embossing
In partial embossing, certain areas are deliberately not embossed. This is usually necessary when certain areas must be particularly easy to read, such as a printed EAN code.Logo Embossing
An embossed logo is the icing on the cake for every lid. With logo embossing, a 3D effect can be achieved and thus a brand or a designation can be specially highlighted. Logo embossing with 3D effect is done with special embossing plates, which are installed in the die-cutting tool.2-step embossing
2-step embossing is a combination of two distinct embossing methods. Full-surface embossing on the one hand and logo embossing on the other. 2-step embossing is used exclusively for aluminium lids. In a first step, the foil is embossed with a very fine embossing structure. Then, in a second step, the structure is pressed flat again with a logo embossing (deembossing), creating a gloss effect. In 2-step embossing, the desired graphic effect is achieved exclusively by embossing. These products are originally unprinted and convey a premium effect to the consumer.Seal Edge Embossing
Seal edge embossing was developed by BERHALTER to take account of the progress in printing technology and not to reduce the high print quality and radiance of the colours by full-surface embossing. As the name suggests, only the edge of the lid is embossed (sealing rim-embossing). This ensures on the one hand that the destacking is guaranteed and, on the other, that the entire surface outside the hot seal area is unembossed and brightly radiant. Seal edge embossing is usually done with embossing plates, which are installed in a special embossing unit.
When selecting the appropriate embossing structure, or the corresponding embossing method, it is important to answer a few basic questions in advance. The answers not only limit the wide range of different embossing structures to a minimum, but also define the most appropriate embossing method as a rule.
1. What material is used?
The material to be embossed is an important factor in the selection of the embossing pattern. Basically, all materials can be embossed, but there are differences in the result. Aluminium foil is easy to emboss and the final embossing height remains stable. Plastic film, on the other hand, has a so-called "memory effect". This means that the material must always be over embossed, as the final embossing height forms back by approx. 20-30% due to the material properties. Paper allows only a very light structure.
2. Choose the structure of the embossing (dots, lines, worms, etc.)
The standard "worm" embossing is used very often with aluminium foil. This structure is easy to handle and has good properties in terms of flatness and destacking. However, this embossing structure does not work for plastic film. In particular, "dot" or "pin" embossing is used here, which has proven itself very well in practice. It is also important to consider the desired or customer-required total embossing height when choosing the embossing design, which also has an influence on the packaging size of the stacks.
3. Is the structure one-sided or two-sided?
The choice between a one-sided or two-sided embossing design is usually made on the basis of the customer's specifications or the comparison of function, utility and appearance. The majority of the embossing structures are two-sided for practical reasons, so that in most cases this question is answered by the embossing structure.
The reasons that speak for a one-sided embossing are: - The surface on the print side is flat and, the dots are negatively embossed, which promises a good appearance. - Self-adhesive labels can be glued to a smooth surface instead of a printing it, which does not work on a two-sided embossing due to the lack of adhesion.
The reasons that speak for a two-sided embossing are: - Lower embossing height per side compared to one-sided embossing, but nevertheless a higher overall embossing height. - Good flatness of the lids, which ensures trouble-free further processing.
4. Which embossing roller is on top and which is on bottom (positive/negative)?
Here we have a situation similar to that described for the embossing structure in point 3. Depending on the desired appearance and function, the embossing roller will emboss against the material from above or below. However, in the case of multi-layered or surface-treated materials, embossing from above or from below can have an influence on the flatness.
5. Determine the total embossing height
The total embossing height is determined by the embossing structure used. Each structure has a maximum embossing height and a defined area where the embossing works particularly well. In order to roughly calculate a total embossing height, we need to know the embossing structure (and thus the maximum embossing height) as well as the material thickness.
For example: aluminium/HSC 40µ + worms embossing 90-100µ = max. 140µ. Substract 10% = total embossing height max. 126µ
6. Are technical implementations such as a logo or design element required?
If special solutions such as logo embossing or a design element have to be implemented, this must be discussed in a joint project. Technical implementations such as logos or design elements require more time and a goal-oriented approach. However, the result will be a delight and ensure uniqueness.
7. Determining the embossing structure
The easiest way for our customers to obtain the desired embossing structure, logo or 2-step embossing is to send us a sample of an existing design. Our specialists will analyse the embossing structure and develop a tailor-made plan for implementation.