Does the inspection process affect my part materials, will it cause degradation in plastics?
The integrity of your components is paramount, and it is a valid and critical concern whether standard inspection processes could compromise their material properties. The short answer is that while many modern inspection methods are entirely non-destructive and safe, the risk of material degradation depends heavily on the specific inspection technique and the material composition of the part. A comprehensive understanding of these interactions is essential for protecting your investment.
Truly Non-Destructive Evaluation Methods
Many inspection techniques are classified as Non-Destructive Testing (NDT) because they do not alter the part in any way. These are generally safe for all materials, including sensitive plastics and finished surfaces.
Visual and Optical Inspection
Methods such as manual visual inspection, coordinate measuring machines (CMMs), and 3D laser scanning are completely non-invasive. They involve no chemical, thermal, or significant physical contact that could stress the material. This makes them ideal for verifying the dimensions and surface quality of components from our Precision Machining Service without any risk.
Industrial CT Scanning
Computed Tomography uses X-rays to create a 3D volumetric model. For most engineering plastics and metals used in applications such as automotive or Consumer Products, the radiation dose from a single scan is negligible and does not induce measurable degradation or lingering radioactivity.
Inspection Methods with Potential Material Impact
Certain techniques, although non-destructive in the sense that they don't physically alter the part, can potentially affect specific material properties or surface finishes.
1. Chemical-Based Inspection
Fluorescent Penetrant Inspection (FPI): This method involves applying a low-viscosity penetrant chemical to detect surface cracks. For many metals, this is harmless after proper cleaning. However, for porous plastics like some grades of Nylon (PA – Polyamide) or certain ABS blends, the chemicals can be absorbed, leading to swelling, staining, or a reduction in mechanical strength. The cleaning process can also degrade surfaces.
2. Techniques Involving Physical Contact
Coordinate Measuring Machines (CMM) with High Force: While standard CMM touch probes are very gentle, excessive probing force on a soft material can leave minor witness marks. This is a particular concern for delicate Plastic CNC Machining components or highly polished surfaces. Using appropriate probe tips and low force is critical.
3. Thermal and Energy-Based Methods
Ultrasonic Testing (UT): Standard UT requires a couplant (a gel or water) to transmit sound waves. If this liquid is trapped in pores or incompatible with the plastic—such as with Polycarbonate (PC)—it can cause clouding or hydrolysis, leading to embrittlement over time.
Specific Risks to Plastic Components
Plastics are particularly susceptible to certain inspection methods due to their polymeric structure.
Chemical Attack: As mentioned, penetrants and some cleaning solvents can cause stress cracking, dissolution, or swelling in many thermoplastics.
UV Degradation: Inspection methods using ultraviolet light (such as FPI) can, with prolonged exposure, initiate photodegradation in certain polymers, resulting in fading and embrittlement.
Thermal Stress: Although rare in standard inspections, methods that generate local heat can potentially warp or melt low-melting-point plastics.
Best Practices for Safe and Effective Inspection
To mitigate any risk, a tailored inspection strategy is developed based on the material and criticality of your part.
Material Declaration is Key: Informing us of the exact material, such as PEEK (Polyether Ether Ketone) or Acetal (POM), allows us to select compatible inspection methods.
Prioritize Non-Contact Methods: For critical plastic parts, we preferentially use non-contact methods like CT scanning or 3D optical scanning. These provide comprehensive data with absolutely no physical or chemical interaction.
Validate Post-Processing: The risk extends beyond inspection. We ensure that any required Surface Treatment for CNC Aluminum Parts or CNC Part Polishing Service is completed before final inspection, protecting the finished surface.
Use Witness Samples: For new materials or processes, testing the inspection method on a witness sample first verifies compatibility.
In conclusion, while the vast majority of inspection processes are safe, a proactive and communicative approach is essential. By understanding the specific properties of your materials—from high-performance Titanium CNC Machining parts to sensitive plastics—we can design an inspection protocol that guarantees quality without compromising the material integrity you depend on.
