Page 27 - MetalForming Magazine May 2023

Special Section: FABRICATION PRESS BRAKE TRAINING
ernize their training to keep pace with technology.
Many people responsible for train- ing, says NIMS executive director Mon- tez King, begin by defining the training materials associated with a particular job—a necessary step, but not neces- sarily the first step.
“Many employers do not provide
enough deliberate and targeted training for their employees,” King says, “and instead rely on time and chance for learning—learning by osmosis, if you will. This method of learning intro- duces people to new workplace tasks with enough direction to operate, or do what they are told to do. However, all of the knowledge and skills required
to make decisions, configure or set up these activities are learned haphazardly over time.”
The problem, King explains: Trainers become stuck between the pressure of completing their own work and shoot- ing from the hip when transferring their skills and knowledge. This conflict results in training for some and no
Need Help with Press Brake Operator Training?
If so, PMA has your back, thanks to the recent introduc- tion of new courses to its METALFORM EDU online training platform. To develop the new press brake operator courses, PMA partnered with subject-matter experts to review and update its existing press-brake training materials. The result: 12 new courses with topics covering tooling, gaug- ing, safeguarding, proper operation, measuring devices and more.
“PMA is excited to roll out the new press brake courses for the metal forming industry,” says Connie King, PMA workforce development director. “We look forward to con- tinuing to expand the METALFORM EDU library with addi- tional modules for key industry jobs and skill sets.”
One area covered by the courses is the basic machine types and where they’re best applied by metal fabricators. For insight, we spoke with one of the primary content con- tributors to the courses, Dean Phillips. Now a sales engi- neer with press-control manufacturer Link Systems, Phillips previously spent over a decade working for press brake manufacturers, designing and supporting their sheet metal fabricator customers.
“Fabricators should understand the fundamental differ- ences between older-style mechanical press brakes, tried and true and still in use today,” says Phillips, “as well as the more popular and advanced hydraulic up- and down-acting machines, hydromechanical press brakes, and the newest machines on the market—servo-electric, which continue to grow in popularity. The courses we developed for PMA cer- tainly do that.”
Hydraulic down-acting hydraulic machines are the most- used press brakes, Phillips says, equipped with a cylinder on each side of the machine. A hydraulic press brake pro- vides the ability to dwell at bottom and control ram speed, not possible with mechanical models. Typically, the machine’s cylinders are synchronized via an electrohy- draulic circuit to ensure positioning accuracy and repeata- bility. The disadvantage, says Phillips: Locating a tool set to one side of the bed can reduce the available tonnage.
“For example,” he explains, “a 200-ton machine provides 100 tons under each cylinder, so if you’re tooling is located closer to one side of the brake than the other, you’re not able to generate the full 200 tons.”
Also popular are hydromechanical press brakes that combine the versatility of a hydraulic machine with an added mechanical advantage, which compared to a hydraulic press enables the use of smaller hydraulic cylin- ders while generating the same amount of tonnage. “Smaller cylinders are less expensive,” shares Phillips, “and easier to maintain.” Also noteworthy: Most hydromechanical models are not synchronous machines, instead relying on
independent control of the left and right cylinders. Hydromechanical models come in two basic styles, with
the cylinder positioned either laterally or vertically. Both machine styles often will employ a pre-crowned bed to adjust the force curve during forming. “This works fine for fabricators forming longer, nearly full-length parts,” Phillips says, “but when forming small parts or off-center tooling setups, quality may be inconsistent as tonnage can vary at different points along the bed.” In these cases, look for machines with dynamic CNC hydraulic crowning.
Most recently introduced to the market are servo-elec- tric press brakes, which use electric motors to drive the ram. To produce motion, motors can be attached directly to the drive screw or can drive belts and pulleys. These machines provide numerous advantages in term of stroke control, accuracy and repeatability—and of course they eliminate the need for hydraulic circuits. However, they’re somewhat limited in terms of tonnage (300 tons or so) and, therefore, their capacity to bend higher-strength materials and thicker workpieces. Phillips also notes that these machines often are easier for newer press brake operators to learn, “also true for hydraulic press brakes with modern, ‘smart’ controls,” he adds, “that manage most if not all of the bending process and require very little if any operator knowledge about how materials form.”
Also available are hybrid machines combining a servo- electric drive with a hydraulic power-generating system. “These are preferred primarily for air bending rather than bottoming or coining,” Phillips says.
How does a fabricator decide which style of press brake is right for its applications? “If you’re doing multiple tool setups across the bed, that can start to eliminate the hydromechanical models because of the number of pivot points and inaccuracies,” Phillips says. “In these cases, a synchronous hydraulic or a servo-electric machine is the best choice. Fabricators performing mostly basic, simple bending operations generally can make do with simpler machines, but in most other cases you’ll need a more modern and capable machine. And, most shops today also seek machines equipped to handle faster tool change “and suppliers have added automation to quicken changeovers and improve throughput. More-efficient material and tool handling holds the key to optimum press-brake throughput.
“When talking about training operators and calling them press brake operators,” Phillips continues, “this can add to confusion because operators may be trained on one type of machine but would have limited experience on the other styles. Consequently, it’s important to develop standard assessments for your specific machines.”—Brad Kuvin
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