Ink Marking: How to choose a system for QA processes

Here, Cary Long explains more about ink marking and details some of the products available from Nordson EFD to help with the process 

When a part comes through the line and needs to be inspected in a timely manner, ink marking is a practical way to identify what passes or fails. Ink marking is widely used in the automotive and machine building markets. It helps automate the QA operation, providing a faster turnaround time for parts by preventing the need for manual inspection by an operator.

Ink marking is often used in the following processes:

Reject marking

Reject marking tells the manufacturer when a part does not meet the standard or specifications required for a part to pass. The rejected part will receive a mark and an RGB sensor will recognize the mark in order to remove the part from the production line. This method keeps faulty products from leaving the facility and prevents warranty claims and/or recalls.

Pass inspection

For many automated assembly processes, an ink mark is needed after testing at each station. The RGB sensor will verify that the mark is present before releasing the part to proceed to the next station. If no mark is present, the part is shuttled to a rework location for later inspection to either be reworked or scrapped. Typically, a reject mark is not needed for this type of process.

Nordson EFD's solutions for ink marking applications include:

MicroMark® spray marking systems eliminate maintenance, clogging, and downtime by using a programmable nozzle air delay to blow residue off the spray nozzle after each cycle. These marking systems deliver round patterns on motionless parts and stripes on moving parts. They can dispense at any angle to meet multiple application requirements. The valves can be activated manually by an operator or interfaced with a PLC, proximity switch, or other system to mark at scheduled intervals or when a signal is received.

781-SYS MicroMark Spray Marking System

This spray valve system is suitable for inks and paints that do not require recirculation. The MM781-SYS was designed to dispense transparent inks with a centipoise of 1-100. These inks are much thinner than opaque inks and do not need to be agitated. This low-maintenance system provides consistent spray patterns. Useful Tip: Transparent inks show up best on light parts, such as silver or white.

781RC MicroMark Spray Marking System

This spray valve system is designed for dispensing opaque inks with a centipoise of 30-150, using the 781RC recirculating pump. The pump keeps the pigments and solids in the opaque inks in suspension, which minimises or eliminates clogged nozzles and downtime. Keeping the pigments suspended in these types of inks is important so that no clogging or separation will take place in the system.

These spray marking systems produce uniform spray patterns while eliminating clogging, overspray, and missed shots.

Many other systems used for ink marking are not as effective as the technology that Nordson EFD offers today. Older processes include manual or handheld marking, which slows down the assembly line and is prone to human error.

Another method that is widely used is pad printing. This method involves using a felt pad that is saturated in ink and stamped onto a part. The felt pads tend to need frequent maintenance due to pad wear. In addition, they dry out very easily and have issues with clogging since the pad is always filled with ink.

Whether you are looking to dispense low- or medium-viscosity inks and paints, EFD has a solution for you.

Cary Long is an application specialist at Nordson EFD.

For further information, email: [email protected]