Charting the Changes: Yaw Control Error

Accurate, repeatable, ISO certified precision is what our clients’ customers expect from them– and that kind of perfection doesn’t happen overnight. Problems, however, sometimes can appear overnight.

We last visited this particular client’s shop in 2017. During our preventative maintenance (PM) check, we calibrated a few of their key machines, including one particular VTL machine that had a few (small) errors. When we left, the client had a machine that delivered on that expectation of accurate, repeatable precision. Sometime between that visit and our return visit his year, though, something happened.

“In 2018 KES Machine was called in for an annual recalibration but at this time the customer was recently experiencing quality issues on their parts,” explains KES’ Tom Prytko. “KES Machine performed testing of angular pitch, yaw, and roll. We discovered that the angular yaw error was excessive compared to last year’s results, showing the machine now had a misalignment of the X axis rails.”

 

Visualizing Yaw Error

The most likely cause of the error was some sort of impact, says Prytko, but it was fixing the problem that was on KES’ mind– and it was a problem. “This 1 Yaw error on a two axis VTL can affect X axis linear positioning of up to 0.012″ (twelve thousandths) on the diameter of a part. That’s with the ram extended only 20 inches.”

Twelve thousandths of an inch may not sound like much, but in a high-precision racing engine, aerospace part, or medical device, it can be a serious problem. Worse, this error also produced a change in Z-X squareness, as well as squareness errors in the relationship of the X to the Table and Z to the table.

Finding the problem was just the start for KES Machine. Next, KES will service the machine and recalibrate it using the latest laser-based tools from Renishaw. We’ll post a follow-up story once it’s back to normal– which is to say: back to thousandths-of-an-inch perfection.

 

Original content from KES Machine.