Effective component marking is a key part of manufacturing quality management, but how do you pick the right marking approach for your application? Vice President at Pryor Technology Alastair Morris explains.
In December 2019, a major company in the aerospace industry was fined $4 million for allowing faulty parts to be installed on aircraft. While the number of affected parts was relatively small, identifying and rectifying the problem proved to be a costly and time-consuming exercise for end customers. The fix was harder than it should have been because the supplier that made the components had not followed the agreed part marking protocol. Critical identifying marks on potentially affected components were frequently obscured or illegible.
Clear and accurate part marking is a fundamental part of modern manufacturing quality management. Companies rely on marks to track components through their internal production processes. Customers insist on marks to identify components on assembly lines and associate them with the right digital records and the ultimate end users need marks to source replacement parts. When quality issues arise, proper part marking ensures that defective or suspect components can be spotted, checked and rectified or replaced.
Identification marks can only do their job, however, if they are clear, legible and accurate to begin with, and they remain so throughout the lifecycle of a component. The quality of a mark depends upon the choice of marking technology, and the way that technology is applied in production.
Laser Marking
Laser-based marking systems are fast, flexible and versatile. Lasers can produce almost any combination of marks, including data matrix codes, text in a choice of fonts, or manufacturer logos. Laser systems can be mounted on robots to permit the marking of large parts in multiple locations, or can be used for on-the-fly marking of moving components in high speed production applications.
Laser marking systems offer a high degree of tunability. The power of the laser, the frequency of laser pulses, the motion of the beam across the surface of the part and its speed of movement can all be adjusted to affect the appearance of the mark. That flexibility allows lasers to produce clear marks in a wide range of circumstances. It is possible, for example, to generate data matrix codes with a high contrast background for improved readability.
Mechanical Marking
Despite their versatility, laser systems are not the optimum answer for every application. If a component is to receive coatings or surface treatments after mark application, for example, it can be desirable to create marks that indent the surface of the component using a mechanical process. Laser based systems are also relatively high cost, which can limit their use in low-volume applications.
Dot peen marking uses a stylus that rapidly actuates to indent a series of dots on to the surface of a material. This approach is ideal for the creation of 2D data matrix codes, but it can also be used to generate human-readable text. The depth of the generated mark depends on the hardness of the material, the force programmed into the marking system controller and the angle and gap between the stylus and workpiece.
Scribe marking uses a pneumatically actuated pin that is driven into the component surface, then moved through the metal-engraving an inscription in a continuous line. The process is slower than dot peen marking but it is also quieter and can produce clearer, human-readable text. Like dot peening, the depth of the mark can be adjusted by altering the pressure applied by the scribe, the geometry of its tip and its angle against the workpiece. Because dot peening and scribe marking both use mechanical force to generate the mark, the component must be securely held while marking takes place.
Electrochemical Marking
Electrochemical etching uses an electric current to create marks on metal surfaces. A stencil of the design that is to be marked is placed between the electrode and the surface, and a low voltage current is then passed through an electrolyte to etch the material. Chemical etching does not deform the material that is being marked, which is important when marking thin, delicate components or in applications where surface finish tolerances are a primary concern.
Selecting the most appropriate part marking system for a given application depends on multiple factors, including the characteristics of the part and the required mark and the cycle time available. Modern marking systems offer a high degree of flexibility in their configuration, making it essential that users take the time to understand the parameters available to them and to identify the combination of settings that provides the best trade-off between speed, clarity and reliability.
Authored by Alastair Morris, Vice President, Pryor Technology Inc.
For more information contact:
Pryor Technology Inc.
303A Ashcake Road
Ashland, VA 23005
804-496-6669
sales@pryortechnology.com
www.pryortechnology.com