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Marking on metal surfaces is a critical aspect of many industries, from metal packaging, medical devices to automotive. Metal manufacturers need to mark metal parts and products to identify different models, trace parts, control supply chain, and source logistics. This article explores the challenges of marking on metal, the types of metal substrates that require marking, and the industrial marking methods available, focusing on inkjet printing and laser marking technologies.
Marking on metal surfaces presents several challenges. Direct marking on raw metal can be difficult due to its smooth and reflective nature, which can hinder ink adhesion. Coated metals add another layer of complexity, as the coating itself may not always be compatible with certain marking methods. Additionally, marking on uneven or flexible metal surfaces can cause issues with consistency and legibility, making it crucial to choose the right technology for the application.
Various metal substrates require marking for identification, tracking, and compliance purposes. Here are some commonly used metal metarials in electronics, batteries and coatings, aerospace, automotive, medical implants, and other applications:
- Aluminum Alloys
- Stainless Steel
- Iron
- Titanium
- Zinc
- Brass
- Alloy Steels
- Copper Alloys
Two primary methods for marking metals are inkjet printing and laser marking. Each method has its specific applications, benefits, and limitations.
Inkjet printing mainly includes three types of technologies: Thermal Inkjet (TIJ), Continuous Inkjet (CIJ), and Drop on Demand (DOD).
TIJ: TIJ printers utilize heat to create ink droplets, suitable for high-resolution printing on porous and non-porous surfaces.
CIJ: CIJ inkjet printers are ideal for high-speed marking applications. Its contactless printing process allows for printing on surfaces whether flat or curved. Supporting both porous and non-porous surfaces, too.
DOD: Inkjet printers adopting this technology are known as Large Character Printers (LCP). Designed for printing large, bold characters, often used in packaging and bulk marking.
Each type has distinct advantages depending on application speed, resolution, and substrate compatibility. Here's a simple comparison chart of TIJ, CIJ and DOD inkjet printers. Take it just for reference, because models from different manufacturers differ a lot.
| Printer Type | Pros | Cons |
| Thermal Inkjet (TIJ) | High DPI options (up to 1200 DPI); Accessible price point; Compact size; Easy to install and move; Handheld models available | Lower coding speeds compared to CIJ; Cannot code curved surfaces; Limited ink options; |
| Continuous Inkjet (CIJ) | High printing speeds (over 300 m/min); Capable of printing on curved surfaces; 24/7 operation; Compatibility with various specialty inks | Requires periodic professional maintenance; Higher initial investment than TIJ; More complex installation |
| Drop on Demand (DOD) | Versatile applications; High quality for large characters; Various ink options; Low maintenance; Handheld models available | Slower than CIJ in high-speed applications; May require more frequent adjustments; Initial cost can vary based on model |
Both TIJ and DOD are available with inline inkjet printers and handheld inkjet printers, such as Meenjet MXPro/MXPlus/MXLite series 1 to 4 heads inline printers and Meenjet M6 handheld inkjet printers.
The effectiveness of inkjet printing on metal is influenced by several key factors, particularly the type of ink used. Choosing the right ink is vital for ensuring the quality and longevity of the printed mark. Options include:
- Solvent-Based Inks: These inks are designed for adhesion on metal surfaces and provide good durability. Numerous companies that require printing on metal substrates utilize printing systems that leverage HP technology. The different solvent inks offered by HP deliver high-quality results for printing on a range of metals, including foils.
- Curable Inks: UV and LED-curable inks offer fast drying times and resistance to various environmental factors, making them suitable for long-lasting marks on metal surfaces. These inks enhance high-resolution printing capabilities on metal, offering improved durability, quick drying times, and more sustainable.
Water-based inks are usually not designed to print on metal surfaces. Some special purpose water-based inks might print on metal, but that's a rare case.
Find Meenjet ink cartridges models in this catalog: Meenjet TIJ 2.5 Ink Cartridge Guide
Laser marking machines are popular for marking metals, with various machines available for different production needs:
Small Laser Engraving Machines: These include mini handheld laser markers for small-volume applications and static desktop laser markers for more consistent results. Below is a picture of Meenjet handheld and static laser markers.
Large Volume Laser Marking: Flying laser marking machines are used for high-speed production, meeting the needs of industries with high output requirements. Below is a picture of Meenjet flying laser marking machines.
Different types of lasers, including Semiconductor, Fiber, CO2, and UV lasers, each have specific advantages and are selected based on the material and required marking quality. To learn more about the difference of fiber, CO2, and UV lasers, you can read: The difference of laser marking machines: Fiber, CO2 and UV
Industrial manufacturing prints product IDs, serial numbers, and barcodes on metal parts for easy tracking and inventory management.
Food and pharmaceutical packaging must print consumer information and tracking codes on metal containers and foil packaging.
Metal packaging, like tin cans, often has bright designs printed directly, eliminating the need for labels, while including barcodes and expiration dates.
Medical device makers prefer direct marking on metal to meet Unique Device Identification (UDI) regulations instead of using labels.
In the automotive industry, marking and coding help track parts throughout the supply chain.
The aerospace and defense sectors often print directly on metal parts, like those for aircraft engines and structures.
The marine industry needs precise markings on products like oxygen cylinders for tracking and expiry dates.
Architectural metals, such as iron and aluminum, often feature decorative printing for aesthetic purposes.
Construction materials require marking on plumbing items, window frames, and other building products.
The electronics industry uses inkjet and laser marking to label printed circuit boards, electrical contacts, and other components for clear identification.
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