Inspection of inner holes for porosity using a borescope

At the Cimos plant in Slovenia, where mostly automotive center housings, exhaust manifolds, compressor brackets, differential covers and other engine parts are produced, the client wanted to inspect bores of turbine central housing for porosity that sometimes appeared on the surface after it had been machined. These surfaces are sealing surfaces so the presence of porosity can lead to oil leakage or damage of O-rings, which are assembled later.

The issue is that, in the event of bad sealing, oil leakages cannot be detected before final assembly in the car, whereby removing the deficient piece at that stage of the assembly is costly and time-consuming.

Our challenge

The bores are narrow, some of them with diameters no larger than 9mm. The optical challenge is to illuminate such narrow holes and get close enough with the optical system.

Solutions

A custom, inline machine vision solution for optical inspection of bores was developed. Special assembly and measuring device were devised, where the optical measurement of the bores was one of the supported processes.

The borescope optical device, including custom lens and lighting system was completely designed and developed in house.

Features

• Cycle time: 15s
• Inspection parameters:
  • Inpection of inner holes with diameters ranging from 9mm to 25mm for porosity
  • Detection of those pores that manifest on the surface as anomalies with a surface area upwards of 0.05mm2.
• 100% attributive MSA.

Benefits

Thanks to the 100% quality inspection of parts, returns due to oil leakage defects dropped to almost zero.