The Ultimate Guide to Mailer Box

Chapter 1: Understanding the mailer boxes

1.1 What is a mailer box?

A mailer box is a specialized paperboard packaging solution designed for storing and shipping products. Its innovative design features interlocking flaps and wings, allowing for easy assembly and closure without the need for adhesive tape. With its double-sided walls, it offers enhanced durability and resistance during transportation, making it a reusable option.

This versatile and robust packaging solution goes beyond conventional shipping containers. It is carefully crafted to ensure the secure transit of products from sellers to end consumers, offering remarkable protection against potential external impacts that products might face throughout their journey. Typically crafted from corrugated cardboard, this packaging marvel guarantees exceptional safeguarding of items.

1.2 What is the materials of the mailer boxes？

1.2.1 Corrugated cardboard

Also known as corrugated cardboard, this material is composed of at least one layer of corrugated paper and one layer of boxboard, bonded together to provide good elasticity and extensibility. It is primarily used in manufacturing cardboard boxes and as a sandwich layer in packaging materials for fragile goods. Made mainly from native grass pulp and waste paper through pulping, it is transformed into raw cardboard similar to yellow cardboard. After mechanical processing, it is rolled into a corrugated shape and then bonded to boxboard using adhesives such as sodium silicate on its surface.

Corrugated cardboard forms a connected arch-like structure, with corrugations arranged side by side in rows, supporting each other to create a triangular structural body. It exhibits good mechanical strength, capable of withstanding pressure even on a flat surface, and possesses elasticity, providing excellent cushioning. It can be shaped into various liners or containers as needed, offering a simpler and faster alternative to plastic cushioning materials. It is relatively unaffected by temperature variations and offers good shading properties, resisting degradation from light exposure. While generally resilient to humidity, prolonged exposure in humid environments can weaken its strength.

Structure of corrugated cardboard

Corrugated cardboard is created by processing corrugated paper into a corrugated shape using a corrugated cardboard machine. The corrugated paper is then bonded together with adhesive applied to both sides of the surface layer, resulting in a hollow structure within the cardboard (refer to Figure below). The two parallel flat papers are called the face paper, while the wavy paper in the middle is known as corrugated or corrugated core paper.

Classification of Corrugated Cardboard

Corrugated type: This classification includes types such as A, B, C, E, and F, based on the corrugation type. Each type has different height and density, affecting cushioning and compression strength. A and B types are common in transport packaging, with B often used for beer crates. E type suits single-piece packaging with aesthetic requirements. F and G types, known as microcorrugated, are thin and used for disposable food containers or packaging for electronics.

Number of layers: Corrugated cardboard is categorized into single and double layers. Singles are for lighter packaging, while doubles offer higher compressive strength for boxes.

Flute shape: Flutes can be U-shaped, V-shaped, or UV-shaped, each with distinct properties and applications.

Special types: These include F-type corrugated and combinations like AB flute or BC flute.

Additionally, corrugated cardboards can have different layers (e.g., three-layer, five-layer) for varying carrying capacities, from lightweight to heavy-duty packaging. Fine corrugated types like E and F are replacing traditional boxes due to their sales promotion benefits. Around 80% of corrugated packaging costs come from paper, making foldable, low-cost options like corrugated aircraft boxes increasingly important in the market.

The grammage of corrugated cardboard

The grammage of corrugated cardboard varies depending on the number of plies in its construction and the type of base paper used. Here is the range of grammage based on the number of plies and type of corrugated cardboard:

Single-ply corrugated cardboard typically ranges from 125g/m² to 300g/m².

Double-layer corrugated cardboard has a grammage range of 300g/m² to 600g/m².

Triple corrugated cardboard ranges from 400g/m² to 900g/m².

E-flute (three-layer corrugated cardboard) generally ranges from 150g/m² to 250g/m².

B-flute (three-ply corrugated cardboard) ranges from 200g/m² to 350g/m².

C-flute (five-ply corrugated cardboard) ranges from 300g/m² to 500g/m².

A-flute (five-ply corrugated cardboard) has a grammage between 600g/m² and 750g/m².

The grammage of corrugated cardboard base paper typically ranges from 60g/m² to 500g/m², depending on the grade and production process.

Grade A corrugated cardboard has a grammage of 110g/m² or less.

Grade B corrugated cardboard ranges from 110g/m² to 125g/m².

Grade C corrugated cardboard ranges from 125g/m² to 140g/m².

Grade E corrugated cardboard is available in weights between 175g/m² and 250g/m².

Grade F corrugated cardboard has a weight of 250g/m² or more.

Strength standards for corrugated cardboard

(In the table, Category 1 represents superior products, while Category 2 represents qualified products.)

1.2.2 Boxboard

Boxboard paper, also known as linerboard, is the surface layer paperboard used in corrugated cardboard boxes. It requires high strength and good toughness and is made from sulphate pulp. Depending on the quality and usage requirements, boxboard paper is classified into five grades: A, B, C, D, and E. Grades A, B, and C are linerboard paperboards, while grades D and E are regular paperboards.

Grade A boxboard paper is suitable for manufacturing large corrugated cardboard boxes used for packaging fine, valuable, and refrigerated items. Grade B boxboard paper is suitable for manufacturing corrugated cardboard boxes used for export packaging (long-distance transportation). Grade C boxboard paper is suitable for manufacturing corrugated cardboard boxes used for packaging larger items. Grade D boxboard paper is suitable for manufacturing corrugated cardboard boxes used for packaging general items. Grade E boxboard paper is suitable for manufacturing corrugated cardboard boxes used for packaging light-load goods.

1.2.3 Linerboard

We separate linerboard for discussion because, in actual mailer box design, it’s crucial to meet specific packaging requirements while considering the entire printing process. The linerboard is often printed or undergoes post-printing processes before being laminated with corrugated cardboard. This approach ensures that the linerboard is not limited to simple processes like watermarking or die-cutting. It also considers factors such as flatness and impermeability after lamination. Linerboard typically requires a grammage of 150 GSM and above. Commonly used types of linerboard include:

Coated paper

Coated paper, also known as printing coating paper, is created by coating a layer of white pulp onto the original paper, followed by calendering. It exhibits several characteristics: a smooth surface, high whiteness, uniform distribution of paper fibers, consistent thickness, minimal expansion and contraction, good elasticity, strong water resistance, and tensile properties. It also boasts excellent ink absorption and acceptance.

In terms of texture, it includes cloth-coated paper, grain-coated paper, and other classifications. Regarding coating coverage, it can be divided into single-sided copper paper (coated on one side) and double-sided copper paper (coated on both sides).

A. Single copper: Used for cartons, boxes, tote bags, and medium to high-grade printing.

B. Double copper: Available in weights ranging from 80g to 400g, suitable for high-grade printing.

Note: Printing on coated paper should avoid excessive pressure and use offset resin ink and glossy ink. To prevent back sticking and dirtiness, anti-dirty agents, powder spraying, and other methods can be employed.

Matte art paper

Matte art paper differs from coated paper in that it has a matte surface. It features uniform distribution of paper fibers, good thickness, high density, excellent elasticity, strong water resistance, and tensile properties. While its ink absorption and acceptance are slightly lower than coated paper, it compensates with a slightly higher thickness. Matte art paper is primarily used for elegant, high-grade color printing, such as printing albums, cards, postcards, and exquisite product samples. It is commonly available in grammages ranging from 80gsm to 350gsm.

SBS (Solid Bleached Sulphate)

SBS is made entirely from bleached chemical pulp and fully coated with adhesive, forming a single-layer or multi-layered paper suitable for printing and product packaging. It generally has a basis weight of 150gsm or more. White cardboard consists of three layers: the top and bottom layers are white, smooth, and suitable for double-sided printing, while the middle layer serves as a filler and is made from lower-grade materials. White cardboard is rigid and has a firm texture, making it versatile for various high-end packaging boxes, cigarette cases, cups, children’s books, etc. It is commonly used for binding purposes such as softcover book covers, pamphlets, manuals, and hard linings.

CCNB (Clay Coated News Back)

CCNB (Clay Coated News Back) is a type of paperboard that is white and smooth on the front side, while the back side is often grey. This paperboard is primarily used for making paper boxes after single-sided color printing, for packaging purposes, or for designing and crafting handmade products. CCNB is available in standard grammages such as 230 g/m², 250 g/m², 270 g/m², 300 g/m², 350 g/m², 400 g/m², 450 g/m², 500 g/m², and so on.

Fancy paper

Fancy paper refers to specialty papers with specific purposes and relatively low production volumes. It encompasses various types of special-purpose papers or artistic papers. Nowadays, sellers use the term “fancy paper” as a collective term for artistic papers like embossed paper, primarily to simplify the confusion caused by the diverse range of paper varieties.

1.3 Benefits of the mailer boxes

Simple structure: Conventional aircraft boxes have a rectangular shape, a straightforward structure, and are easy to assemble, which is advantageous for design, manufacturing, and use.

High strength and impact resistance: Aircraft boxes are made of thicker cardboard, providing excellent strength and impact resistance. This makes them effective in protecting contents during transport and reduces the risk of damage.

Good stability: The structural design of aircraft boxes gives them excellent stability, making them less prone to deformation. This ensures they maintain their shape and stability during transport, reducing damage due to shaking or collision.

Environmentally friendly and sustainable: Aircraft boxes are environmentally friendly and sustainable as they are primarily made from recyclable cardboard materials. This helps reduce environmental impact while meeting the modern demand for green packaging.

Good cushioning performance: Aircraft boxes typically have sufficient cushioning space inside, effectively mitigating shock and vibration during transport, thereby reducing the risk of damage.

Strong customization: Aircraft boxes can be customized according to customer needs, including size, shape, color, and printing content. This enables them to meet the packaging requirements of various industries and products, enhancing brand image and packaging effectiveness.

Low cost: Compared to other packaging materials, the manufacturing cost of aircraft boxes is relatively low. This makes them an affordable packaging option, especially for mass production and shipping.

Easy to stack and store: The structural design of aircraft boxes makes them easy to stack and store, saving warehouse space and improving logistics efficiency.

Chapter 2: Cost Control Strategies for Mailer Boxes

Bulk order principle

Firstly, larger production equipment incurs higher initial costs. Therefore, whenever possible, focus on large-scale production to minimize costs. Many manufacturers and processes waive initial costs once the quantity reaches a certain level. Otherwise, the costs of setup, mold production, etc., far exceed the cost of the product itself. Secondly, bulk orders allow for customized raw materials during production, avoiding waste from standard materials.

Overdesign principle

While adhering to design and packaging standards, aim to reduce complexity and difficulty as much as possible. This helps lower material and process costs.

Standardization principle

Where feasible, design according to standard materials, equipment, and color values to minimize extreme parameters. For example, avoid paper thickness and weight exceeding equipment parameters, and reduce manual operations. This poses significant challenges but is crucial for quality and cost control.

Maximizing space

Logistics costs are significant. Therefore, optimizing quantity for full-container shipping by coordinating warehousing and logistics can lead to substantial savings.

Chapter 3: How to customize the mailer boxes

3.1 Types of the mailer boxes

Regular mailer boxes

Mailer boxes with safety clips

Mailer boxes with handles

Mailer boxes with different flaps

3.2 Die-cut Design

This is a self-locking mailer box with ear locks, double front panels, and double side panels. This box type belongs to the 0427 box type within the international standard box types. The 04 box type is a folding box or shallow tray made from a single piece of cardboard. The bottom panel extends to form the body panel and lid panel, requiring no nailing or gluing, only folding to shape. The diagram below is a design example of a die-cut for an aircraft box with dimensions of 30020050MM. Dashed lines represent fold lines, solid lines represent cut lines. In this example, the material is E-flute, and the thickness is adjusted to the corresponding thickness or multiples of thickness for different materials.

3.3 Post-press processes

There are many post-press processes, and here we list only a few of the more commonly used ones in the design and production of mailer boxes.

3.3.1 Varnishing

After printing, the surface layer of the paper does not have strong adhesion to the ink, making the printed pattern susceptible to slight friction and color fading. To better protect the printed materials, we apply varnish or adhesive coatings.

Generally, when the quality requirements for printed materials are not particularly high, we apply varnish, also known as printing varnish. This involves coating (or spraying, printing) a layer of colorless transparent varnish on the surface of the printed material, which, after leveling and drying, forms a thin and uniform transparent glossy layer on the surface.

In fact, what we call printing varnish and varnishing are collectively referred to as varnishing processes in post-press techniques, but they use different types of varnish. The coatings used in varnishing processes also include blister oil, full-sheet UV varnish, and others.

Based on surface gloss, there are gloss varnish, matte varnish, and satin varnish. The difference lies in the surface glossiness of the finished product, with gloss varnish having a brighter appearance, matte varnish resembling a matte finish, and satin varnish providing a more textured feel with minimal reflection under light. The protective effect of varnishing is slightly inferior to that of coating.

Although we often consider varnishing and coating as similar processes, they are different.

Varnishing involves applying a colorless transparent coating (or spraying, printing) on the surface of printed materials, which, after leveling, drying, calendering, and curing, forms a thin and uniform transparent glossy layer on the surface. This process enhances the smoothness of the carrier surface and provides protective finishing for printed graphics and text, known as varnishing. The varnishing process for paper printing includes coating varnishing, UV varnishing, and pearl varnishing.

From a definition perspective, varnishing and coating may not seem different. However, let’s take a look at the process flow for both:

Varnishing: Printed item → Application of varnish → Infrared drying → Air drying → Calendering → Finished product

Coating: Printed item → Application of coating varnish → Infrared drying → Air drying → Finished product

Indeed, the varnishing process includes calendering, where a metal plate with an extremely smooth surface treated with polishing is heated using electric wires. This plate is then pressed onto the surface of the printed item coated with varnish under a pressure of 100-200 kgf/cm2, gradually cooling to form a glossy surface film layer. However, products that have undergone varnishing may experience discoloration in blank or light-colored areas.

3.3.2 UV varnish

The reason this needs to be pointed out is that it requires using screen printing technology to apply UV ink or various UV varnishes to the surface of the substrate. Although it involves screen printing, it is considered a post-press process.

There are many classifications of UV, which can be applied by offset printing or directly onto ink, using different types of ink. Due to the numerous classifications, they won’t be individually discussed here. Generally, if UV is applied on varnish-coated products, a matte varnish is preferred. Even when using UV varnish film with glossy varnish, the effect may not be very noticeable.

If using UV on film, a special UV film is required to prevent issues like UV peeling, bubbles, or adhesive failure. Combining this with embossing, hot stamping, and other special effects can enhance the overall result.

3.3.3 Laminating

Laminating, also known as “plastic coating,” “mounting adhesive,” or “film laminating,” refers to the process of applying a transparent plastic film to the surface of printed materials through heat and pressure. This process enhances protection and glossiness, commonly referred to as varnishing. It involves applying adhesive onto the plastic film using a roller coating device, heating the film with a hot press roller to soften it, and then pressing the coated film onto the printed material to create a laminated product. The laminating materials are categorized as gloss film, matte film, and textured film, among others, based on the type of finish.

Its functions include:

• Enhancing the smoothness and glossiness of laminated printed materials, improving their durability and extending their lifespan. The plastic film also provides protection against moisture, water, stains, abrasion, folding, and chemical corrosion.

• Using transparent gloss film can make printed colors more vibrant and three-dimensional, especially suitable for packaging green food products and similar items.

• Using matte film significantly enhances the grade and added value of product packaging.

• Utilizing textured film provides a high-quality, lightly sandblasted effect, offering a tactile feel and enhancing the product’s business attributes.

• Laminating can effectively cover up quality defects in printed products. Many surface defects that occur during printing can be concealed after laminating, especially when using matte films.

If the laminated paper is too thin, it may curl due to the different surface tensions on both sides after single-sided lamination. Therefore, for print products requiring flatness, laminating is necessary, and the paper should be at least 200gsm. When encountering solid color areas with fold marks, laminating is a must.

What does this mean? Many heavy-duty cardboard boxes, when folded, can cause the color to crack at the fold lines, revealing the white base, which looks unsightly. Lamination can solve this problem.

However, laminating requires a high standard of production environment and paper cleanliness. Dust on the surface or insufficient flatness of the paper can easily result in lamination failure or potential bubbling later, affecting overall aesthetics.

Some people may not distinguish between varnishing and laminating products well. When the film thickness is very small and combined with different levels of transparency, it becomes difficult to distinguish based solely on glossiness. The simplest method is to take a sample and scratch the printed area with a fingernail. If the coating is scraped off to reveal the white base, it is varnishing; if the laminating film starts to wrinkle or bubble due to excessive stretching, it is laminating.

3.3.4 Embossing/debossing/linen texture

Embossing refers to the process of creating patterns on a substrate by applying pressure, resulting in localized changes. It involves using metal dies, one for embossing and one for debossing, after etching from a metal plate. There are two types: cost-effective conventional etching plates and expensive laser embossing plates.

Embossing: Using a convex template (positive template), pressure is applied to create a raised, three-dimensional pattern on the surface of the printed material (localized protrusions).

Debossing: Using a concave template (negative template), pressure is applied to create a depressed, three-dimensional pattern on the surface of the printed material (localized depressions).

Embossing and debossing are suitable for paper weighing 200gsm or more, especially for heavyweight specialty papers with a distinct texture. They are not suitable for large-area patterns, fine fonts, or small images, as the effect may be subpar, and the cost is high. It’s also best to avoid near the edges of the product. Therefore, this technique is commonly used for emphasizing logos, trademarks, brand names, and other highlighted areas.

Linen texture: Using engraved patterns on metal rollers, pressure is applied to leave a full-page textured pattern on the surface of the paper.

After linen textured, the printed material surface shows varying depths of patterns and textures, with a distinct embossed three-dimensional effect, enhancing the artistic appeal of the printed material.

3.3.5 Hot stamping

Hot stamping is currently divided into cold stamping and hot stamping.

Cold stamping is named in contrast to traditional hot stamping technology. Both methods can achieve the printing effects of stamping, but cold stamping does not require heating in the initial stages of the process, hence the name “cold stamping.”

Cold stamping uses a flexible plate to apply UV adhesive locally or across the entire surface of a paper strip, which is then combined with a transfer film. After exposure to UV light, the adhesive quickly solidifies. The laser layer on the transfer film is then transferred onto the paper strip according to the pattern on the plate, creating a gorgeous packaging effect. The term “cold stamping” (or cold transfer) comes from the fact that it does not require heating, unlike traditional hot stamping. Advantages: Compared to traditional hot stamping technology, cold stamping technology has several significant advantages, mainly in the following aspects.

(1) Low plate-making cost. Cold stamping does not require expensive metal stamping plates like hot stamping, and it also avoids the pollution caused by the plate-making process in hot stamping.

(2) High stamping precision. Cold stamping has a high resolution (basically reaching printing resolution), making it excellent in stamping fine dots and lines, as well as achieving hollow effects.

(3) Larger stamped area. Hot stamping is generally limited to stamping small areas such as logos and trademarks, while cold foil has a larger width and can even match the width of printing machines. Therefore, it is more suitable for stamping large areas of graphics and text.

(4) Wide range of applicable substrates. Cold stamping can transfer cold foil at room temperature using adhesive and pressure, without the need for special temperature adjustments and controls like hot stamping. It is suitable not only for stamping on paper, cardboard, and other common substrates but also for heat-sensitive materials like thin films.

(5) Easier implementation of stamping before printing. In the process of stamping before printing, cold stamping has low operational difficulty, high efficiency, and low waste rate.

(6) Achievable continuous production, faster speed, and higher efficiency.

Hot stamping uses hot stamping foils, mainly made of electrochemical aluminum, by heating and applying pressure to transfer patterns or text onto the surface of the stamped material.

Because of its clear and beautiful patterns, bright and vibrant colors, and wear resistance, hot stamping can play a role in highlighting design themes and adding finishing touches, especially when combined with embossing for trademarks and registered names, the effect is even more significant. Special hot stamping techniques, such as holographic positioning for trademarks, are widely used for anti-counterfeiting printing.

With the development of printing technology, 3D hot stamping, also known as embossed hot stamping or three-dimensional hot stamping, has emerged.

3D hot stamping technology is a composite technique that combines hot stamping with embossing. It can be seen as a combination of “hot stamping + embossing” technology. It uses corrosion or engraving techniques to create a concave and convex mold for hot stamping and embossing, achieving both processes in one step.

It can simultaneously accomplish hot stamping and embossing, reducing processing steps and the amount of waste due to misregistration, thus improving production efficiency and product quality. Products produced through this technique have full-bodied hot stamping, fine patterns, aesthetic appeal, and no misalignment of embossing.

3.3.6 Mounting:

Honeycomb mounting

This involves processing corrugated base paper into a honeycomb structure, then using adhesive to bond the surface layers from both sides, creating a hollow core structure in the cardboard. It provides high strength, rigidity, hardness, pressure resistance, puncture resistance, elongation, and elasticity.

Single-sided mounting

This is a process where two sheets of paper are mounted bottom to bottom, with adhesive applied to the bottom sheet. After pressure is applied, the two sheets are firmly bonded together.

Multi-layer mounting

This process involves bonding two or more sheets of substrate together to increase product thickness, toughness, insulation, light blocking, anti-condensation properties, etc.

In engineering design for mounted products, the grammage of the adhesive surface material should preferably be over 300gsm. The surface paper (for automatic mounting machines) should exceed 190gsm for single copper paper and 250gsm for whiteboard. If the grammage is lower than these values, manual mounting is necessary, and the adhesive surface should ideally undergo surface treatment to avoid sticking or abrasion issues.

3.4 How to communicate customization for a mailer box

For industry-experienced buyers or repeat purchasers, direct communication of comprehensive information about the materials, processes, packaging, etc., can be initiated. This allows for more accurate price negotiations and a compact schedule from sample confirmation to mass production, ensuring high efficiency.

For buyers with purchasing experience but not packaging professionals, initial communication typically revolves around measurable information such as dimensions, weight, structure, etc. We then analyze and provide solutions for materials, processes, packaging, and transportation. Alternatively, if clients provide samples, we use them to determine the production process.

Some clients only provide usage scenarios, company culture, and design ideas. In such cases, we offer packaging solutions and materials, which may require extended periods of refinement and modifications in the early stages. This process necessitates collaboration between business, design, and production teams, highlighting the importance of effective teamwork.

Chapter 4: Production process of mailer boxes

4.1 Demand-driven matching

The process involves coordinating product design and craftsmanship, confirming prices based on packaging and transportation needs, designing patterns, confirming materials and techniques, packaging and transportation plans, and so on. Some of these tasks are provided by the client, some are entrusted to design companies, and in most cases, printing and packaging companies complete them based on the client’s requirements through their craftsmanship departments. After the design is completed, large-scale samples need to be produced, and production can only begin after obtaining client approval for the large-scale samples.

4.2 Prepress

The prepress department is often responsible for graphic design, document processing, typesetting, color calibration, standard die-cutting graphics, film output, CTP plate making, and so on, ensuring the correctness and accuracy of all documents before mass production printing, and facilitating the smooth operation of the printing department.

The process flowchart for prepress is as follows:

4.3 Printing

The main conventional corrugated cardboard printing methods are flexographic printing, offset printing, and screen printing.

4.3.1 Conventional flexographic printing

Conventional flexographic printing on corrugated cardboard involves direct printing on the corrugated cardboard using water-based inks, which is why some people also refer to this process as water printing. Direct flexographic printing has the following characteristics:

• Large Format: Flexographic printing machines with wide formats can reach a maximum width of 2.5m (98.43in) to 2.8m (110.24in).
• Low Cost: Flexographic plates are highly durable and can be reused; ink prices are also relatively low.
• Integrated Production: Flexographic printing can be linked with other processes such as slotting, creasing, box stitching (or gluing), and bundling, all achievable with one machine.
• Minimal Impact on Box Strength: Flexographic printing exerts light pressure, so it has minimal impact on the strength of corrugated board.
• Lower Printing Precision: Flexographic printing typically uses lower line screens compared to conventional offset printing (175 lines per inch for offset vs. 35 lines per inch to 65 lines per inch for flexographic on corrugated boxes). It is suitable for printing text and line art; although the quality of four-color image printing has improved in recent years, there are still limitations.
• Plate Making Complexity: Plate making for text and line art is relatively easy, but it’s more challenging for four-color images.
• Inconsistent Print Quality: Flexographic printing can have issues with ink density control, leading to variations in print quality. This direct flexographic printing process is widely used in the production of Type 1 corrugated boxes in China’s box factories.

4.3.2 Offset Printing

Conventional offset printing on corrugated paper uses an indirect printing method, where the box liner is printed first and then adhered to the corrugated board.

Due to the high resolution of PS plates, very fine printing patterns can be achieved. Currently, the majority of high-end corrugated boxes used for sales packaging are offset printed products. Offset printed corrugated boxes have the following characteristics:

• Not Suitable for Inline Board Production: Offset printing is only suitable for single-face corrugated machines, resulting in lower production efficiency.
• Limited Format: Offset printed boxes generally have smaller formats compared to flexographic printed boxes.
• Very Fine Printing: Offset printing can achieve high line screens ranging from 150 lines per inch to 200 lines per inch.
• Easy Plate Making: PS plates are commonly used for plate making.
• Surface Finishing Options: Offset printed boxes can undergo surface finishing such as lamination and gloss coating.
• Higher Printing Costs: Offset printing tends to have higher printing costs.
• Stable Print Quality: Offset printing offers relatively stable print quality.

4.3.3 Screen Printing

Screen printing on corrugated cardboard employs a direct printing method. Due to the relationship between ink coverage and screen mesh size, the resolution of screen printing is not very high, and the image accuracy is low, with a typical line screen ranging from 60 lines per inch to 80 lines per inch. Screen printed corrugated boxes have the following characteristics:

• Not Suitable for Inline Production: Screen printing is not suitable for inline production lines, resulting in lower production efficiency.
• Variable Printing Format: Screen printing can be done in various sizes.
• Printing Before or After Assembly: Printing can be done before or after assembly and box formation.
• Suitable for Non-Fine Products: Screen printing produces thick ink layers, resulting in high color saturation and strong visual effects, especially for spot color printing.
• Easy Plate Making: Screen printing plates are easy and cost-effective to make.
• Low Printing Costs: Screen printing tends to have lower printing costs.
• Relatively Stable Print Quality: Screen printing offers relatively stable print quality.

4.4 Post-printing processes

Various post-printing processes are detailed in Chapter 3.3.

4.5 Die-cutting

Die-cutting is the process of using steel knives or steel wires arranged in a template to shape printed materials under pressure according to the designed specifications. International standards require tolerances to be controlled within +/- 0.005 inches/1.27 millimeters.

This process is suitable for products made from paper weighing 157 grams or more, such as stickers, labels, gift boxes, and related printed artworks.

It’s important to note that creasing, punching, and perforating are part of the same process. The entire die-cutting board is divided into cutting blades, creasing blades, and perforation blades, which are allocated based on the design.

4.6 Packaging

Packaging typically involves the following steps: waste removal, assembly of finished products, quality inspection, matching packing, and item counting. This marks the final stage in the production process, emphasizing the importance of meticulous inventory checks for accurate quantities and meeting quality standards. Additionally, adhering to requirements for affixing box and pallet labels is essential, ensuring that their size and material comply with international trade standards.