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Using Eddy Current for Improper Heat Treatment Testing in Automotive Manufacturing

Automotive manufacturers need eddy current for improper heat treatment testing.

Defective automotive components are more common than many realize, which is why automakers need a quality nondestructive testing (NDT) regimen to eliminate improper heat treatment. Choosing techniques less favorable to NDT could result in defective parts that incur liability lawsuits or recalls. 

With that, advanced eddy current testing (ECT) instruments featuring simultaneous multi-frequency testing capabilities can help identify multiple material structure differences. This article will showcase why ECT is the best choice for automotive manufacturers conducting improper heat treatment testing.  

The Benefits of Eddy Current Testing in the Automotive Industry

Since heat-process variations are hard to detect visually, technicians need ECT equipment that can pinpoint deviations during the inspection process. Without eddy current, technicians are relegated to ineffective means like visual testing or cumbersome sample testing procedures that include cutting, polishing, and etching. 

Eddy current technology uses coils and magnetic fields to detect irregularities and isolate deviations. Eddy current allows analysts to spot all assembly flaws: delayed/short quenches, shallow case depths, misplaced cases, or short heats. Modern eddy current technology can confirm the quality of heat treatment faster than other NDT methods. Analysts can also achieve faster inspections and a repeatable testing strategy that allows operators to conduct in-line inspections of all manufactured components. 

However, eddy current testing is only as good as the device, and the eddy current equipment should include the following features:

  • Automated multi-frequency and multi-channel test set-up. 
  • Data recording capabilities.
  • Industrial I/O for easier integration with material handling systems.

A purpose-built eddy current instrument for manufacturing can be used to test for proper heat treatment on simple parts such as ball bearings and fasteners, as well as on complex components such as gears, wheel bearings and axles. With multi-frequency, multi-channel capabilities, it’s easy to simultaneously inspect for multiple anomalies at different locations on a single component.  

How to Use Eddy Current for Improper Heat Treatment Testing

With so many variables at play, the automotive industry needs eddy current testing on all parts on the assembly line. Eddy current can detect a variety of anomalies in the form of through depth, hardness and material mix testing.Also, eddy current readings can highlight the parts that haven’t been heat-treated. 

The automotive industry’s behemoth supply is more likely to produce untreated parts that could cause malfunctions and hazards. With eddy current, technicians can test for proper heat treatment on components such as rear axle cross pins wheel bearings and gears.

Example: In 2011, General Motors recalled over 26,000 cars due to real axle cross pins that were never heated. Cross pins without heat treatment are prone to displacement or fracturing, causing the rear axle to malfunction.

Take note of the following errors that could produce a substandard product:

  • Warped coil inductions
  • Tool misalignment
  • Condensation on parts

Importantly, analysts can test an item without destroying it physically. If a technician wanted to test the hardness of a valve tip, for example, they previously relied on batch testing, which involves destroying the parts that were recently hardened. Not only is destructive testing a waste of viable materials, but it also requires additional steps (i.e. visual inspection) that don’t always produce reliable data. 

On the other hand, eddy current will validate if the material is hardened without the need to destroy materials or look for defects with the naked eye. In fact, eddy currents can identify hundreds of defective valves in a row, allowing operators to stop production and further test items to enhance quality control. It will also confirm the correct structure in the material and assess the correct alloy compositions used during assembly. An eddy current system allows analysts to compare assets, ensuring that the tested item meets industry standards. 

Testing Improper Heat Treatment with Eddy Current Technology

To avoid improper heat treatment, technicians need an NDT system that can test items rapidly, reliably and with reproducible results. Eddy current can inspect more components than other testing systems, such as cluster testing. It’s also better than destructive testing and visual testing because both systems rely on the naked eye. 

With eddy current, the currents and magnetic fields spot all discontinuities within a part, and it can confirm if an asset has been heat-treated. Operators can continue operations with peace of mind and confirm whether the manufacturing process remains up to par. With an efficient workflow, automotive plants can prevent defective items that may degrade the durability of a car or cause dangers that jeopardize the lives of consumers.

Zetec is a major provider of eddy current equipment for the automotive industry. Contact us today to get a custom inspection plan and additional guidance on your NDT needs.