Project Description

Quality inspection report of a CNC turning part

Part description

This aluminum drum cover is a thin-walled CNC turning part. It is about 130mm in diameter and the wall thickness is 2mm in most places. The material is aluminum 6061-T6. There are no tight tolerances required for this part, however, this is still a challenging job due to its thin wall feature.

Analysis of possible quality issues prior to production

Surface waviness

Thin-walled parts are prone to have waviness on the machined surface due to vibration in the cutting process. On the picture below, you can see a typical waviness of CNC machining.

Surface waviness of thin walled turning parts

Less smooth radius on the edge

We have to use 2 cutting tools to cut the outer radius, there could be a step where 2 cutting paths meet, as shown below:

changing cutting tools along the cutting path

This is exactly what happened with our first trial.

We did it with more attention on the second time, the small step almost disappeared.

the small step caused by tool changing disappeared

Quality inspection report

  • dimensional quality inspection report 2
  • dimensional quality inspection report 1

We take the measurements several times to be more accurate

We usually will take several readings for each dimension. For example, when we measure the OD44.10, we will take the measurement from 3 or 4 different spots at a 30° or 45° interval, that is why you see the readings are like 44.14~44.16mm instead of one simple number. This way, not only that we can make the measurements more accurate, but also we will know if the roundness is within an acceptable range.

several readings measuring OD