Posted on: 16 Aug 2022 Posted by: MAXON® Comments: 0

Top 3 Ways to Pressure Test Complex CNC Parts

Trusted and reliable CNC businesses utilize cutting-edge inspection tools as an essential part of their quality assurance management framework. These facilities must use various techniques to test components that retain pressurized gases or fluids due to the development of certain metal defects.

Such defects deteriorate the product’s quality and performance and can lead to structural corrosion or surface flaws. That’s why they must be pursued more actively, as far as sophisticated CNC machined components are involved. 

Pressure testing is the optimum solution to address these defects. Let’s find out more.

When Should We Do Pressure Testing?

Generally, we perform pressure testing after product assembly, machining, or vacuum impregnation, which is an operation of encasing the porosity of castings and leak trails with an under-pressure sealant. This technique aids in the containment of gases and vapors, preventing any leakage. 

Leak and Pressure Test Machines and Solutions | TQC Ltd

Assembly is the most preferred step in the process after which testing is conducted. At this phase, testers employ the poka-yoke approach to determine the precision of the process and the overall quality of the CNC machined part. 

Testing may remain within constraints or attain maximum level if the customer needs exceptional accuracy in the final component. An important thing to note is that greater testing demands attract higher manufacturing costs. 

Top 3 Ways of Pressure Testing Employed for Complex CNC Parts

1. Air Decay 

This method employs a pressure test control module that keeps track of air pressure alterations inside the part. Pressurized air is then used to fill it up after it has been firmly clamped into a fixture. Pressure varies depending on the size of the pores inside the component and usually ranges from 5-90 psi.

Approximately half a minute after the motion of air molecules ceases, a measurement is taken to determine the drop in pressure and evaluate whether the result meets the customer’s specifications.

Also, the level of complexity of a machined component directly affects how long it takes to run the test. If the volume of the machined component is significant and the client has high standards for precision, a test could take quite some time.

High Pressure Air Decay Leak Testing Methods | TQC Ltd

2. Mass Flow

In this technique, the air gets injected into the component by mass flow at a pressure of around 20 psi. The pressure levels are monitored with a gauge, which shows whenever the component is fully filled and at 20 psi.

A null reading indicates that the CNC component has reached the limit of its capability to accept more air. If there’s a reading greater than zero on the gauge, the component allows more air to enter when the air inside it escapes through pores. This confirms the existence of a leakage.

3. Air under Water

In this precision testing method, pressure testing is done without a gauge and relies on visual examination. Both the execution and leak detection of this procedure is straightforward.

It involves submerging an air-filled component with all entrances enclosed in a water container. The bubbles rising to the water surface indicate the presence of a leak.


While manufacturing complex CNC parts with a CNC router or any other CNC equipment, optimal pressure testing helps us cater to the end-customers demands, achieve high-efficiency benchmarks, and meet the highest product quality standards. In addition, if the customer does not demand high accuracy standards, manufacturers must sustain a cost/value proportion while maintaining product quality and minimizing manufacturing costs.

<img alt="<strong>Peter Jacobs
Peter Jacobs

Peter Jacobs is the Senior Director of Marketing at CNC Masters. He is actively involved in manufacturing processes and regularly contributes his insights to various blogs on CNC machining, 3D printing, rapid tooling, injection molding, metal casting, and manufacturing in general.

Top 3 Ways to Pressure Test Complex CNC Parts was last modified: December 15th, 2022 by MAXON®

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