Frequency Converters for High-speed Spindles Tailored to the Needs of the Customer

The Schmoll Maschinen GmbH has specialized in machines for mass production solutions for electronic and micro structuring applications. The solution portfolio covers all performance relevant steps for mechanical and laser micro machining. Production capacity can be increased by automation technology. "Customers in the PCB electronic industry and related markets like solar and LED appreciate our comprehensive experience in laser processing", Marcus Winterschladen, technical manager at Schmoll Maschinen GmbH, explained. "We are one of the leading manufacturers in the world of production solutions for the electronic industry. The name Schmoll stands for reliability, innovation and technological market leadership."

PCB drilling systems for mass production

The product range of Schmoll covers PCB drilling machines for mass production. These machines are basic machines for maximum drilling productivity. Top of the class is the Speedmaster series. Here the most powerful spindles are used. The machine capacity starts with spindles at 60,000 rpm and ends with types at 300,000 rpm. These different types of spindles cover the customer requirements over a very wide range.

High-quality linear motors are used for XY-drives. Together with a high quality granite base, the customers receive a production machine with high accuracy and high process reliabilty combined with low energy and maintenance costs. Depending on the configuration and the size of the panels, machines with typically five or six, but max. eight spindles can be realized. Furthermore, the machine components can be customized according to customer specific requirements.

High-speed frequency converter for multi-spindle operation

In PCB drilling machines equipped with T180 or T200 asynchronous spindles, Schmoll uses an individually adapted frequency converter of the Lueneburg based company SIEB & MEYER. "The central frequency converter must allow sensorless operation of up to 8 high-speed spindles in the speed range of 480,000 rpm", Michael Schulz, key account manager CNC Europe / USA at SIEB & MEYER, explained the requirements of the customer. "Furthermore, the power supply of the frequency converter shall be realized via the DC link of the available drive package".

The customized solution is based on the serial device FC2 by SIEB & MEYER that features a device topology with controlled DC link. This permits the operation of low-inductive asynchronous motors without additional motor chokes via pulse amplitude modulation (PAM) up to an output frequency of 8,000 Hz (480,000 rpm). Low motor heating and dynamic speed control are also ensured.

Well-proven standard, individually adapted

The functional spectrum of the standard device already includes the parallel operation of up to eight asynchronous motors as well as the separate evaluation of the temperature sensors. SIEB & MEYER adapted the electronics of the power supply unit and the device construction to the machine conditions. During this process, the engineers were able to reduce not only the installation space but also the wiring work. "Unlike the standard version the customized frequency converter does not include an integrated power supply. This makes the housing more compact", Michael Schulz explained. "This allows mounting the frequency converter directly into the drive package – in this case adjacent to the servo amplifiers. As a result, the central supply voltage of up to 350 VDC available in the machine can be used to supply the frequency converter." The basis software of the serial products is upgraded and modified in close cooperation with Schmoll. The important feature for Schmoll: The parameters of the frequency converters can easily be set via the software –reconfiguring of the machines to other spindle types is no problem.

"SIEB & MEYER provides customized solutions in the field of high-speed frequency converters as well as intelligent drive amplifiers", Michael Schulz explained. "Our know-how is based on our standard modules which are well-established on the market." The benefit for the customers: They receive tailored products to a very good cost/performance ratio. Schmoll is perfectly satisfied with the individual solution: The customized FC2 can easily be mounted into the machine without any additional components. The compact system adapts itself to the available space and is produced in series by SIEB & MEYER, which leads to stable costs and a high availability of the components and allows flexible response, if requirements at Schmoll should change.

"The frequency converters by SIEB & MEYER run very smoothly, which contributes to the positive drilling results of our machines", Marcus Winterschladen explained. "The engine power and performance are always optimal." Besides, the technician praises the good cooperation with SIEB & MEYER – in particular the high expertise and professional advice. No wonder that the cooperation of the partners will continue to exist: The newest machine generation also uses frequency converters "Made in Lueneburg".

Info box:

The individual frequency converter for Schmoll

• Compact and low-cost
• supply voltage 350 VDC
• PAM modulation, controlled DC link
• output: 3 x 0..230 VAC, 0..8,000 Hz, S1: 13.2 kVA
• integrated evaluation of up to eight temperature sensors
• sensorless operation of up to eight asynchronous motors