CNC Lathe: A 'turn' of events

  • By Ron Abma

At Electram we work with various customers - from engineers to manufacturers and to the lone wolf business owners who have a lathe in their garage.

We often encounter issues requiring troubleshooting, particularly with phase converters and 3-phase power, and this specific instance was no different.

A customer purchased a CNC lathe and a digital phase converter. The nature of using a lathe requires a lot of stopping and starting, often on a dime. When stopping a high-speed chuck, the workpiece has a lot of inertia, so it requires a lot of energy to slow it down quickly. The lathe's motor slows down the chuck by turning itself into a generator and back feeds the excess energy (inertia) as electricity back towards the electrical panel.

This particular customer had a digital phase converter between their electrical panel and their lathe. The voltage that the customer's lathe back fed towards the phase converter when stopping was too high and caused the converter to trip to protect itself.

Instead of back-feeding electricity towards the electrical panel, a machine could also use something called a dynamic brake. This is essentially a big resistor that the lathe's motor can dump excess energy into instead of back feeding. We like this option because making a resistor hot does not affect the other motors, lights and electronics that you may have in your building.

When the customer purchased their lathe and phase converter they did so based on a model number but didn't talk to a 3-phase expert so there was no consideration as to how the digital converter would work with this particular lathe. The manufacturer did send additional components to increase the capacity of the converter - this did not work.

Situations like this are rather common. Most people who are buying lathes and phase converters are not electricians. This is where Electram really steps it up. Our sales staff are journeymen electricians who have pretty much seen it all and we can walk you through the process. We use to run the tools but now we run a desk :)

Give us a call and we can talk it through.

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