Contact versus Non-Contact Dispensing

How to Choose the Optimal Micro-Dispensing Method for Your Application

Producing and assembling small components and micro-technology in vehicles, electronics, and medical devices requires precision. Tiny amounts of adhesives, lubricants, and other assembly fluids must be applied to specific, often complex, locations within tight tolerances to manufacture the highest quality parts in the shortest time with the least amount of costly rework, rejects, and downtime.

The two most common methods of micro dispensing are contact and non-contact dispensing (also known as jet dispensing or jetting). While both micro-dispensing methods work in many types of applications, the degree of precision, repeatability, and speed are key considerations manufacturers make when trying to decide the best choice for a project.

Deciding which method also depends on the application, the type of fluid dispensed, the manufacturing environment, and the production process itself. Understanding pros and cons of contact and non-contact dispensing can greatly support your decision-making process.

Non-Contact Dispensing – Jetting!

Jetting often utilizes a quasi-volumetric method to apply fluids. This combined with proprietary design elements and controlled manufacturing processes allow some jet valves to deliver extremely precise, repeatable deposits as small as 5 nL within exacting tolerances of +/- 1%.

Because jetting does not require Z-axis movement, dispensing speeds up to 1000Hz (deposits per second) and 1500Hz bursts can be achieved. Fluid is applied without contacting the workpiece surface. This protects fragile substrates from damage caused by other methods such as contact dispensing. This also makes it possible to dispense consistently onto uneven workpiece topographies and to accommodate varying part tolerances without added process time for position adjustments.

Non-contact dispensing also eliminates dispense tip damage because there is no contact with the workpiece. There is no need for downtime to replace broken tips.

Cons of jet dispensing include the fact that some fluids, such as highly-abrasive or particle-filled fluids, are tricky to jet and therefore require special setup processes. Therefore, it’s important to speak to an experienced application specialist when deciding which method to choose.

Other cons of jetting include the possibility of deposit satellites and splashing that may require dispensing parameter adjustments and a slightly more sophisticated setup that may require special operator training.

Contact Dispensing

Contact dispensing often utilizes either a time-pressure or volumetric method to dispense fluids. Unlike non-contact dispensing, contact dispensing requires Z-axis movement to bring the valve very close to the surface of the workpiece to dispense. It also often requires a dispense tip fastened to the fluid body.

A wider range of fluids can be dispensed via the contact dispensing method, though not within as strict deposit tolerances. There is a reduced risk of deposit satellites and splashing. Set-up and training are relatively quick and easy.

Cons of contact dispensing include the need for Z-axis movement, which results in slower dispensing speeds. A maximum of 80 deposits per second (with an optional actuator) can be achieved with contact dispensing compared to 1000 deposits per second with non-contact dispensing. There is also the risk of part and dispense tip damage since the workpiece surface must be touched. Dispense tips can bend or break. These situations can cause unwanted downtime.

In addition, there are several variables that can be difficult to control such as air fluctuations and residual material adhering to the dispense tip. Both impact deposit repeatability.

Download the Micro-Dispensing White Paper

Download the Contact vs. Jet Dispensing White Paper for more technical information, tables, application examples, and other useful resources designed to help you decide which method is best for your application.

If you have any questions or would like to speak with an experienced application specialist, don’t hesitate to email us at [email protected].

About Claude Bergeron

Claude Bergeron is the Senior Global Product Line Manager of Jetting Systems at Nordson EFD. He uses his extensive application and product knowledge to lead the development of some of the most innovative dispensing valves on the market. Claude has more than 40 years of fluid dispensing experience. He joined Nordson EFD in 1981.