Micromachined parts are the components that most require dimensional measurement. It is important to know the most effective methods for addressing specific measurement applications.
Micromachined parts and their features present challenges for the application of new technologies in part manufacturing and measurement. The requirements fall into two main categories: small components that can be measured within a single field of view, and larger parts with micro-features that require high precision and high speed. This article will examine two distinctly different measurement systems designed to meet these varying challenges.
Small Parts, Big Challenges
These days, everything is getting smaller—except expectations. It is now standard to expect this year’s new models to be at least 10% smaller, lighter, faster, and cheaper. This steady trend toward miniaturization and cost reduction presents manufacturers with significant challenges. Manufacturing tiny, intricate products requires tighter dimensional tolerances, more complex tooling and fixtures, and higher inspection accuracy. Inspection and measurement are part of the challenging tasks in the workshop, requiring new technologies to address micro-scale manufacturing and assembly processes.
How Small Is a Micrometer?
There is no single definition of “micro,” so there is no single solution for measuring “micro” components. Micro parts come in a wide range of sizes and conditions, and process metrology must adapt accordingly. Generally, we classify micro measurements as ranging from a few micrometers to a few millimeters, but even so, this range is vast when you consider that a human hair is approximately 90 micrometers in diameter.
Micro-mechanical parts can be small and simple or small and complex. They can be fragile or robust, expensive or disposable. A common characteristic of micro-parts is that they have very tight tolerances, thus requiring high precision. They are also typically manufactured in high volumes, necessitating high throughput. The primary distinction regarding micro-parts lies in whether they require high-precision, high-speed measurement or ultra-high-precision, high-speed measurement.
The choice of micro-part measurement technology ultimately comes down to the requirement for sufficient accuracy and speed to provide rapid feedback to the manufacturing process. This choice is not straightforward, as simultaneously meeting both accuracy and speed requirements is typically costly. Selecting the appropriate micro-measurement tool is crucial, and making trade-offs is equally important.
It is often said that an “ideal” measurement system would be a device resembling a microwave oven. You open the door, place a part inside, press “Measure,” and moments later, a comprehensive measurement report pops out.
Obviously, this ideal scenario overlooks some practical details, such as creating a measurement program that meets drawing specifications, establishing part positioning and reference points, performing measurements without distorting or damaging the part, and ensuring that relevant features can be detected. The concept of this “magic measurement box” is highly appealing, and its realization is getting closer.
The Real World
A key step toward the ideal measurement system is the emergence of new digital measurement equipment, also known as ultra-wide-field-of-view measurement systems. These measurement devices, equipped with digital, megapixel sequential imaging, and advanced image processing technologies, are becoming increasingly precise and suitable for measuring small parts.
For many small parts, simply placing them within the imaging window and pressing a button allows for the easy measurement of common geometric dimensions. QVI Group’s SNAP system features an imaging window exceeding 3 inches and supports simultaneous measurement of multiple parts. Place several parts randomly on the glass stage, press “Run,” and the system will automatically measure them. First, the system captures an image of the parts; the software then automatically identifies them and executes the corresponding program.