A shift on the sliding-head lathes

At the back of our main shed in SIDCO Kurichi, six sliding-head lathes run almost without pause. They make our smallest parts: knurled pins, sleeves, valve stems and connectors, often less than 12 mm across and sometimes thousands in a day. Here is what a morning shift looks like in that section.

The shift starts at 6 am with a handover. The night operator tells Prakash, who leads the morning shift, which machines are running which jobs, how many parts are done and any tool that is near the end of its life. Prakash walks the line, checks each machine’s counters and pulls the first parts off each to measure.

A sliding-head lathe works differently from an ordinary lathe. The bar, three metres long, is fed through a guide bush, and the headstock slides the bar forward while the tools stay close to the bush. This holds slender parts rigid while they are cut, so a pin 2 mm across and 30 mm long can be turned to within a hundredth of a millimetre. When one bar is used up, an automatic bar feeder pushes in the next.

Through the morning, the operators load bars, empty the chip bins, change worn inserts and measure a sample part every half hour with micrometers and a profile projector. Results go into a log beside each machine. Every two hours, the inspector takes a sample to the CMM room. At 2 pm, the next shift takes over, and the handover begins again. A good shift is a quiet one.