In recent years, several industries have benefited from the wide range of possible uses and versatility of the pad printing process. Designers and manufacturers in various product developments often use this technology to create 2D images of parts with different surfaces and structures.
The pad printing process is very popular due to its high quality, compatibility, economy and numerous color options. This article explores the pad printing process, how it works, applications and factors to consider to make the most of the technique. Dive in!
What is pad printing?
Pad printing uses flexible silicone to transfer ink from an engraved plate or base plate to a workpiece or product. It is sometimes called pad printing or pad printing. This technique is suitable for printing fine details and high-quality images on smaller, irregularly shaped components and at higher speeds.
Although this process works well on flat surfaces, it is suitable for printing products with recessed or raised areas and concave or convex surfaces.
Pad printing process principle
This section explains the principles of the pad printing process under the following headings.
1. Pad printing step by step process
The printing plate used in pad printing goes through a pre-process that involves engraving depressions. The image for printing is etched onto the surface of the flat plate using a laser or photoengraver. Built-in engravings hold the ink in place, while a smooth silicone pad collects the ink from the plate and transfers it to the desired object.
The following steps demonstrate the pad printing process with a closed cup printer:
Step 1: Starting position
This step involves placing the paint container over the engraved flat plate so that the engraving is hidden. The ink container then opens and fills the engraved area with ink.
Step 2: Air Exposure
The ink cartridge removes excess ink when closed, revealing the engraved plate. At this point, the printing plate remains exposed while the engraved portion contains the deposited ink. When the paint comes into contact with air, its top layer becomes sticky, which makes it easier to adhere to the silicone pad and the workpiece.
Step 3: Print
The silicone pad compresses the ink-filled plate to lift the image and release trapped air. The silicone pad with the raised image then moves to the workpiece to apply it.
Step 4: Next Cycle
After the pressure pads move the image, the ink cartridge returns to its original position. It then reloads the printing plate and ensures it is ready for the next printing cycle.
2. Basic components of pad printers
There are different configurations, designs and printing styles for pad printers. However, they have almost similar components. Here are some of the standard parts of a pad printer:
2.1 Block printer
There are three variants of pad printing machines: open inkwell, rotogravure and closed inkwell. These machines have different configurations with different printing styles. Open cartridge technology is extremely versatile. This involves using a spatula and flooding the printing plate with ink.
Rotogravure printing machine is similar to open inkwell and is good for 360 degree printing around a workpiece. Closed paint container technology utilizes the common technique of storing paint in an inverted container.
2.2 Ink cups for pad printing
The pad printing ink tank stores the ink and slides over the engraved part, scraping the edge of the plate and leaving ink on it. This component consists of two parts – the ring and the container. The ring does the scraping while the container contains the paint. Typical materials used for the ring are plastic, metal, or ceramic. Ceramic is the most commonly used material of the materials listed. It does not scratch the plate when scraping and controls the smooth movement of the printer.
2.3 Pad printing ink
This component is another important part of the pad printer. It is composed of diluents, pigments and resins. The diluent is responsible for the viscosity/adhesion of the paint. The pigments give different colors to the paint, while the resin/binder provides mechanical properties such as scratch resistance, adhesion and abrasion resistance.
There are several series of paints, each suitable for specific industries and objects. Typical paint selection criteria include wear resistance, lightfastness, chemical resistance, opacity, gloss or dullness, and adhesive properties.
2.4 Pressure pads
The printing pad uses silicone to lift the ink from the flat printing plate to the workpiece. It transfers the image by pressing itself onto the ink-filled printing plate and moving closer to the object and pressing it against it. The printing pad creates a high-quality impression on a part because the silicone pad adapts to the shape of the part as the image is transferred to the object.
Silicone is the standard material for making impression pads. However, depending on the application, printing pads often have different mechanical properties such as shape, hardness and size.
2.5 Pad printing plate
The pad printing plate is an important component that captures the image that needs to be transferred to the object. Standard printing plates are thin metal plates on light-sensitive plastic. They are commonly used in small and medium productions and are known for their easy printing, low price and flexibility. Steel plate is another type of printing plate with good durability, robustness and effectiveness for large productions.
Pad printing vs. screen printing: What are the differences?
Screen printing is a unique process that transfers ink through a screen/mesh and a stencil that blocks the ink. The printed material remains under the screen while the ink is pushed through the stencil openings using a squeegee or roller.
Screen printing is good for printing on all types of materials – paper, wood, metal and especially fabric. It is also very compatible with different colors, allowing for high color saturation/consistency and opacity. Manufacturers often use this process to print canvas bags and t-shirts. Screen printing is ideal for large-scale printing projects due to the detailed, high-quality results it provides.
In contrast, pad printing is as effective as screen printing and offers brilliant results. It is suitable for printing fine details on small, irregularly shaped components compared to screen printing, which works on flat surfaces. However, pad printing is a cost-effective option because it is easier to set up than screen printing.
Advantages and disadvantages of pad printing
Advantages of pad printing
Here are some of the general benefits of pad printing:
- This technique allows you to print images with multiple colors on surfaces that have high chemical resistance.
- Pad printers use a silicone pad that easily conforms to irregularly shaped surfaces.
- The pad printing process is ideal for personalizing or individualizing products.
- Pad printing technology is compatible with various materials such as glass, metal, plastic and edible foods such as sweets.
- Provides a clear, high-quality finish on small, irregular and fragile objects such as smaller electrical components.
- The pad printing machine is easy to use and economical for the in-house pad printing process.
Disadvantages of pad printing
Despite all the advantages of pad printing, there are also some disadvantages. Here are some of those disadvantages:
- While it is suitable for printing small images on larger objects, there are limitations when printing large areas.
- The process is very slow and involves more steps than most printing processes.
- Some block printers experience tonal inconsistencies when printing large blocks of color.
What industrial applications print with pad printing?
The silicone pad in pad printing is extremely versatile and adapts to a wide range of irregular shapes, giving the process a wide range of applications in different industries.
See some of the sectors that use this procedure:
cosmetics : This industry uses pad printing to create decorative images and high-quality details on the surfaces of objects such as lipstick holders, cosmetic bottles, lids and jars.
Automotive Industry : The flexibility of the pad printing process allows industry manufacturers to efficiently decorate and mark various automotive parts with abrasion-resistant images and details. Common pad printing parts include batteries and coolers.
household appliances : Pad printing is ideal for printing identification labels, instructions, trademarks and decorating devices such as telephones, keyboards, laptops, radios and other gadgets.
electronics : Pad printer can be used to add attractive, easy-to-read branding images and details to electronic devices such as relays, cables, connectors, and other devices with complex shapes.
Medical : The medical industry precisely applies images to medical components with curved, tiny, or crooked surfaces. This facilitates identification and traceability. Common examples of block-printed medical components include insulin pens, contact lenses, syringes, inhalers, tubes, implants, and catheters. Manufacturers often print medical details using medical ink to avoid toxicity.
Factors to Consider When Block Printing
Here are some factors that should be taken into consideration when it comes to pad printing to ensure a successful process, even if it is a simple process.
1. Choose quality equipment
It would help if you always used high-quality equipment that allows for high-quality prints. Although there are three pad printers, the closed ink tank is the standard. You can also consider automation as it increases productivity and reduces the risk of errors.
2. Mix paint
Mixing paint/paint is a good alternative if you can't get the color you want. When you work with the best pad printing service provider that has the right experience, technology, and tools to determine the perfect color for your project, you have a better chance of mixing colors successfully.
3. Choose the correct pad type
Choosing the right type of block for your project impacts the success of printing on the pieces. In general, pads come in different sizes, shapes, and mechanical properties that you need to consider before choosing the ideal pad for your project.
- With larger pads, the chance of warping is minimal, minimizing deformation during printing.
- Hard pads create sharper shapes and finer lines, perfect for hard, asymmetrical surfaces.
- Steep air-trapping pads allow air to escape easily during lifting and transport.
4. Avoid excessive pressure on the pads
If too much pressure is applied during printing, excessive compression may occur, resulting in split pads. Consider adjusting the printer's downward stroke to allow the ink to run normally. Mechanical errors sometimes cause too much pressure on the pad to be applied during printing. Therefore, it would be helpful to regularly check your machine for defects.
Various finishing services for your projects
With a team of experienced specialists and modern equipment, we work with a variety of machined surfaces and are able to deliver professional final results. Simply upload your CAD files and start a new project.
Concluding
Pad printing is a reliable method for transferring 2D images to components of different dimensions and sizes. It is a versatile and precise process for your projects. However, you should not consider this process for your material and component until you fully understand the process.
Common questions
What affects printing pad life when printing pads?
Print pad life is affected by several variables, such as stray particles, improper pad use, and careless machine operation.
How accurate is the block printer?
The block printer transfers images to objects with the highest photographic precision. It provides accurate prints of critical objects with a line resolution of up to 0.0001 inch (25 µm).
How thick is the ink in pad printing?
For pad printed substrates, the thickness of the transferred ink layer is 4 to 10 micrometers. This guarantees a clear and unambiguous impression on the desired component.
