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Modern Technologies for Metal Spinning

By: Peter Ulintz

Peter Ulintz has worked in the metal stamping and tool and die industry since 1978. His background includes tool and die making, tool engineering, process design, engineering management and advanced product development. As an educator and technical presenter, Peter speaks at PMA national seminars, regional roundtables, international conferences, and college and university programs. He also provides onsite training and consultations to the metalforming industry.

Friday, August 23, 2019
 
This article, the third of a three-part series on metal spinning processes and their tools, focuses on modern technologies in metal spinning.


In 2017 Abacus Maschinenbau introduced its vertical spinning machines to the North American market with polymer cast frames for better vibration dampening and a vertically mounted main-spindle that provides increased stability. Servo drives on all axes provide for high positioning accuracy and precise part reproducibility. Servo power eliminates warm-up time and the high service costs common to hydraulic machines.
An automatic metal spinning machine in its most basic form consists of a headstock, tailstock and two-axis slide compound with a spinning roller attached. The numerical controls supplied enable the tool path to be CNC programmed off-line or at the spinning machine using teach-and-playback mode—sometimes referred to as programmable numeric control.

Early automatic machines utilized a template and single roller attached to a hydraulically actuated slide for forming, which also helped eliminate physical wear on the spinner. Today, most machines have automatic tool change devices or a multistation turret with different forming rollers, and cutting or trimming tooling ready to employ.

The first programmable technologies were teach-and-playback control systems. An experienced metal hand spinner could create repeatable, production-ready spin programs in a relatively short period of time. This made spinners more efficient and adaptable to changes in the marketplace (e.g., lower volumes, more shapes, improved quality) and able to produce consistent parts over an entire production run. Software was intuitive and easy to use, even for those spinners with little or no CNC programming experience.

Software Transformation

The biggest transformation in metal spinning has been the development of user-friendly CNC programming software to generate tool paths on a computer. Point-and-click menus make quick programming possible. The use of software embedded G-code generators eliminated the need to know or learn G-code programming commands. Today, user-interface software packages can be configured for specific types of spinning machines. Such packages provide enhanced machine safety, programmable tailstock positions, axis-force control, secondary-operations positioning, and in-process and production control functions. For long production runs and heavy or awkward shape parts, robots can be incorporated to handle repetitive machine-tending tasks.

Another transformative technology: live internet connections to the machine controls to provide machine manufacturers with immediate customer service feedback and troubleshooting in a matter of minutes.

Automatic metal spinning machines can replicate most everything a hand spinner does, only faster, longer and with greater repeatability. The greatest challenge with CNC programming: The metal spinning process takes years to learn and requires an expert to create the tool-path programs, and then refine them to make the machines production-ready, which may be the reason why older teach-and-playback programming techniques remain popular.

Like many metal forming professions, metal spinning has met with little enthusiasm among younger generations. This translates to a lack of skilled workers in this area for the foreseeable future. As a result, research continues in smart-programming methods that take a CAD model of the final part and automatically calculate a starting blank diameter, blank thickness and the number of spin passes required, and generate optimum tool paths. Although software applications can perform similar calculations for deep drawing and stamping applications, metal spinning requires the blank (workpiece) to rotate and to apply tangential forming forces. The complex kinematics and numerical models required to simulate, coupled with the current lack of scientific understanding, means that the artisan portion of the spinning process will not be reduced to a fully computerized activity any time soon. MF

The author thanks Dave Grupenhagen, DG Associates, and other members of PMA’s Metal Spinning Division for their contributions.

 

Related Enterprise Zones: Tool & Die


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