How to measure micro molded parts. A detailed look.

Creating tight tolerance micro molded components is a feat, but accurate measurement of those components is a feat in itself. Understanding how to measure micro molded parts is just as critical as making the parts. 
   

The difficulty of measurement in micro molding. 

Obviously, if micro molded parts are measured inaccurately, the results when sent to a customer are catastrophic. Parts may not work in assembly or could fail later in service. This is very costly to a project timeline or to the customer in terms of field failures that could lead to injury or warranty expenses. There’s just as much pressure to verify accurate parts as there is in the processing. 

If a micro mold quality professional measures a part within customer specifications inaccurately, that mismeasurement can prompt an unnecessary tooling change. This also delays a project, adding unnecessary costs. This is why the success of all micro mold projects, are dependent on the accuracy and success of our measurement and quality lab. 

Professional micro molders ensure the measurement method, fixtures, machines, gages, and even the actions staff take, are repeatable. The same result must be presented every time a part or feature is measured. Fully grasping how to measure micro molded parts and mastering the skill, is just as much a science as the micro molding process itself. 

The nature of measuring micro features and micro parts and technology required is remarkably complex and difficult. Accurate measurement requires state-of-the-art technology and highly trained professionals that know how to push the capability envelope of those instruments. 

How are micro mold parts measured?

To measure micro mold parts, a quality lab professional will use extremely precise equipment that can see detail and measured in microns. Quality labs professionals may use equipment like a Zygo White Light interferometer or Optical Gaging Product (OGP) Smart cope, which allow for magnification up to 400x.  

Micro molders will often utilize multi-sensor equipment with vision, laser, and touch-trigger capability to measure dimensions on mold steel and parts using X, Y, and Z coordinates. Molders will also utilize geometric dimensioning and tolerancing via Measuremind software, comparing a part’s 3D model using Zone3 software. ZYGO white light interferometers are used to measure fine details including Z heights, 3D surface finish, and optic lens dimensions.   

Lab professionals may scan surface roughness, and even verify the shapes of micro-lenses. Most measurement equipment is non-contact using lasers and optical systems. The technology in the quality lab is capable of scanning a part, comparing its dimensions to the original 3D CAD model we used to design the injection mold.

At Accumold, our staff are trained better than anyone in the world on how to measure micro molded parts. We are routinely measuring parts with tolerances less than 10 microns, so we often use laser, vision, and white light measurement techniques on a single part based on the part size, feature size, surface finish requirements, and tolerance limits.

Traditional hand tools such as calipers, micrometers, drop indicators, and many other tools are also utilized to measure features and parts when the size of the features are manageable. In the factory itself, tool-scopes, optical systems (Keyence), and automated visual inspection (AVI) is used to determine visual and dimensional part quality.

It’s important to add, an often overlooked aspect of measuring micro features and parts is the need to properly design and build fixtures that can hold the parts in the various views required for measurement. We’ve developed techniques that are repeatable time and time again to ensure measurement accuracy. 

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