A Punch Above
- February 24, 2021
Punch press specialists weigh in on streamlining setup times and keeping your turret production flowing
Unlike the many other sheet metal fabrication processes, automation has all but skipped over the punch press, which still requires lots of human involvement. Ancillary automation, such as material handling and storage towers, have improved efficiency, but it still takes a skilled operator to detect issues or malfunctions. And there are countless time-wasters when it comes to setup, maintenance and conditioning that will slow even an experienced operator.
According to Peter Visser, regional sales manager for Mate Precision Technologies, one of the biggest drags on setup time comes down to basic housekeeping. “Part of my job is auditing customers to see what they’re doing right and wrong. It doesn’t matter where I go, there are a bunch of things that always standout,” he says. “Good housekeeping is one of them. If a company calls me in to help find a problem or fix the tooling and I ask them for an Allen key, a wrench, a rag or even some oil, people always scramble to find those items.”
Having the correct tools accessible to the operator is essential for setting up the machine and making adjustments on the fly.
Visser also notes that he often sees an operator going to get material with a forklift rather than setting up his machine. “that’s bringing no value to his job. Someone else should be doing that.”
Clay Case, product specialist for Salvagnini, says, “Some of the biggest ‘time vampires’ for punch tooling is the tool storage location and tool organization. Are the punch and dies together? What is the tooling condition? Are they sharp or damaged? Are there backups or are there multiple machines waiting for a tool from another?”
To mitigate these time-wasters, Case suggests keeping the tools sharp and close to the machine in an organized fashion (have we all forgotten 5S already?). Keep track of what tools get replaced and how often, and make sure all tools are assigned to and at the machine before production. “You can also consider purchasing additional cassettes that can hold different tooling configurations for quick swapping,” says Case. “And organize your production to use the same tooling as long as possible. It’s also very important to have a tooling manager that monitors the inventory, condition and replenishment.”
Tool changeover, setup and adjustment prolong startup times. “We basically have three lines of punch press tooling,” says Rob Kolaczewski, Amada’s tooling products manager. “We have our ID style, Z style tooling and GT7 style tooling. All three are fully adjustable to increase the height of the punch and get it back into the machine.”
The ID tooling comes with a QR code that can be scanned into the compatible Amada turrets to load the tooling information automatically. “Traditionally the operator would have to load the tool and manually enter the dimensions of the tool. With this style of tooling, it cuts out the middleman. Amada’s ID Tooling system (AITS) reduces setup time and human error as it loads all the information right into the control so the tool setup is ready to go,” says Kolaczewski.
One of the biggest wastes of time for punch press operations is tool sharpening. “After awhile the punch and the bottom die will wear to a point where you might see a burr on the part itself,” he says. “It’s not punching through the materially cleanly.” He suggests using automated tool sharpeners to sharpen the tooling close to the machine, rather than sending them to a tool room for someone to manually sharpen them, which can halt production.
Automated tooling sharpeners such as Amada’s TOGU line have been on the market for a couple of decades and are well proven in these situations. The ID TOGU works in with Amada’s ID Tooling System to measure and send updated tooling heights to the control. Normally, if you’re sharpening tools as a part of a regular maintenance schedule, you want to remove six to eight thousandths of material. The TOGU can do that in three to four minutes as opposed it to a tool room, which can take a day or two before the tooling is back in production.
This is a crucial aspect of maintaining efficiency and throughput: regular maintenance. Schedule production so the tooling remains in the machine for as long as possible.
“But in doing that sometimes you leave tools too long in a machine and they get forgotten about,” says Visser. “So if you’re going to standardize tools and have tools in a machine, you need to have some kind of identifier to know when to pull those tools out to maintain them and sharpen them.”
Most machines have hit counters that alert operators when a machine needs to stop to replace a tool. “You can tell a machine to stop punching at 20,000 hits and inspect the tooling. If it’s good, punch another 20,000 and inspect the tooling again. Once you notice a tool is becoming dull you can set hit markers for that tool,” says Visser. “I would also recommend that everyone does a test sheet—every day or every week—and punch a hole for each of the tools in the machine. This will allow you to feel the burr or tell how dull the tool is and which tool needs to be pulled out, rather than pulling them all out.”
What’s really come along way for punch press machines are multi-tool magazines, making it easy to swap out several tools at once. “The multi-tool expands the capacity you can put in the turret and allows you to make quick changeovers,” adds Visser. “The other advantage is that I can take the whole cassette and sharpen all eight tools at once with a grinder because [the cassette] acts like a fixture.”
“We recommend sharpening the punches and dies every 50,000 hits,” says Kolaczewski. “They can go beyond that mark,” “But running it too long reduces the grind life of the tool by waiting instead of doing a regular maintenance schedule.”
Some shops are still pulling slugs, according to Visser. “Once you pull a slug, you damage the part you’re building. They either don’t know how to set up the tools to get the correct penetration so they don’t need to pull a slug, or they didn’t buy slug-free dies,” he says. “Essentially, a die without that feature will be less expensive. But you only saved $10 on that die and the operators are probably scrapping $200 sheets of metal.”
Visser says several of his customers have planned and unplanned scrap bins, so when a plant manager sees that the unplanned bin is full, he can investigate. It also gives companies a scale of how much waste they create.
Indeed, slugs can occur due to dull tooling or improper die geometry, but there could also be an alignment issue with the machine. Many shops don’t often check and misaligned machines chew up tooling.
“Another thing I see in shops is that they’re just not following the OEM recommendations for replacement parts. There are keys that align the upper and lower tools in the machine that need to be changed once they reach a certain wear tolerance,” says Visser. “If they don’t, they’re wearing their tools out. I’ve asked customers when they last changed their keys and they tell me they still have the original keys and they’re 10 years old. Those keys should be changed yearly.”
Just like investing in the right tooling, investing in continuous training for operators is equally imperative. “What’s important is to remember that your operators are the ones that turn your raw stock into parts… they make you money,” says Chase, referencing the age-old argument regarding the costs of training:
CFO: What happens if we spend money training our employees and they leave the company?
CEO: What happens if we don’t and they stay?
With less experienced operators entering the workforce, Chase says it’s critical to have detailed Standard Operating Procedure documents (SOPs). “Detailed SOPs are very important in these situations, as those details can literally make or break your tooling. That being said, it’s paramount to continuously review and improve these processes based on feedback from your operators, as they are performing these tasks daily.”
A good operator can hear if a tool isn’t hitting the material as it should. Investing in tooling and operators will clearly improve overall turret operation efficiencies, but by honing-in on proper housekeeping, better setup processes and regular maintenance will help shops solve many throughput issues, not to mention save money on tooling and material. SMT