Little Things Add Up
20. August 2013
Every second counts at an operation that depends on seven flexible machining cells that run nearly 140 hours per week. Shown here is the company’s latest, consisting of four Makino A51 HMCs serviced by a rail-guided pallet shuttle.
Virtually any shop visit can reveal small insights or tidbits of information that readers might find useful, yet don’t make the resulting article. That was the case when I visited Applied Engineering to explore how tight control of cutting tool inventory facilitates tight control of manufacturing processes. Courtesy of project manager Brad Bohnet, here are a few examples of small process changes that have made an outsized impact at this Yankton, South Dakota aerospace manufacturer—and might do the same for your shop, too.
- Don’t wait to rapid. For a long time, standard procedure for any of the company’s 29 HMCs was to fully stop the spindle, then rapid over to the in-machine probe to check for tool breakage or wear. Now, that move starts immediately, and it is timed so that the spindle stops revolving just prior to reaching the probe. This saves only about 2 seconds, but given that such moves occur approximately 20 times per hour per machine, and each machine runs at least 100 hours per week year-round, the accumulated time savings are substantial.
- Don’t stop the drip. Broken tool alarms are sometimes triggered not by an actual breakage, but by an anomaly, such as shaving stuck on the end of a tap. Until recently, such incidents would stop the “drip feed” of programs into the machine. This could result in anywhere between 5 and 15 minutes of downtime as the operator searched for the appropriate tool to restart the program. In response, the company developed a “soft” tool alarm that stops the machine, but allows he operator to check, clean and re-check the tool without ending the drip feed. This has increased machine availability throughout the shop floor by more than 1,500 hours per year.
- Don’t overblow it. Each machine is equipped with a fan that blows chips and coolant off of tombstones at the end of a machining cycle. Given that any given tombstone might hold a variety of different parts, each with its own program, this often resulted in running the fan cycle multiple times before the tombstone cycled out of the machine. Now, the company employs a macro that runs the fan cycle only once for every tombstone. The resulting time savings of 1 to 3 minutes per tombstone adds up to approximately 750 machining hours per year.