Shuttle milling machine eases the transition to five-axis machining

‘Spindle hours are what make shuttle machines so powerful’

‘Making spindle hours’ is how Harman and Geert Horstra describe the strength of shuttle machines, and the striking feature of the RS 80K is its combination of four-axis and five-axis machining capability. Five-axis production machining can be performed on the rotary/tilt table located on the left-hand table. The robust shoulder bearing provides high stiffness and precision. The right-hand part of the machine is reserved for four-axis machining of relatively long products (using rotary tables) with lengths up to 1825 mm. The Horstra brothers describe this as an ideal concept for a company that is making the transition to five-axis machining. ‘This gives us an opportunity to accumulate experience and look for optimisations without any pressure, especially for prototypes, while we can continue to perform standard production jobs on the other side. Another advantage is that we do not have to make an immediate investment in an expensive five-axis machine before we have enough work to keep it busy.’ This is the first machine of this new type that has been delivered in the Netherlands by Promas in Panningen, the Netherlands representative of HEDELIUS. The RS 80K Celox has a spindle power of 26.5 kW with a torque of 158 Nm, a maximum speed of 15,000 rpm, and a magazine with room for 56 tools. A special measuring probe determines the exact position of the clamped product, and this information is processed in the controller. This makes precise clamping unnecessary, which helps increase productivity. As five-axis machining often involves long, thin tools, we bought a shrink-fit machine at the same time to ensure zero-play clamping. Horstra Technology has also invested in a HEDELIUS four-axis C 60 shuttle milling machine specifically for prototype work.

When the partition wall is removed, this machine has a machining space of 2000 mm x 620 mm x 520 mm, and the maximum speed is 12,000 rpm.

Automation

Horstra Technology focuses primarily on CNC milling of small-run jobs and prototypes, especially for the top end of the market, which is characterised by high complexity and high accuracy requirements. Although the company is not ISO-9001 certified, it works in full conformance to the standard. Its major sales areas are the IC industry, general machine construction, the shipbuilding industry, and the packaging industry. The company also provides mechanical assembly services. Among the materials it machines, the accent is on stainless steel (40%) and aluminium (40%), with steel and plastics making up the remainder. The company started operation in 2001 with two three-axis DMC machines. As the focus gradually shifted toward longer products, they purchased the first C 80 shuttle milling machine in 2004 for products with a maximum length of 3200 mm (without the partition wall). It also incorporates a combination of three-axis and four-axis machining, the latter using rotary tables. It was followed in 2006 by the RS 80K Celox and C 60. Each of the machines is equipped with a Siemens 840D controller with ShopMill and connected to a central CAD/CAM station. The same holds true for the Mitutoyo coordinate measuring machine used to generate measurement reports. The shop equipment is rounded out by a grinding machine used when additional precision is required. Herman and Geert Horstra say that automation and low-labour production are the most important factors in the company. ‘This is why we do 3D programming off-line and configure the tools outside the machine.

We are already doing as much as work as possible using unmanned operation during our extended working hours of 6 a.m. to 6 p.m.’ In order to achieve this, they devote considerable attention to developing special clamping tables and mastering the milling processes.

The advantages of the HEDELIUS RS 80K for Horstra Technology

• Shuttle operation so the spindle remains productive during product exchange

• The combination of five-axis and four-axis machining capability: this makes it possible to accumulate experience with five-axis machining without any pressure and reduces the urgency of full capacity utilisation with products of this type.

We have uploaded a short film to www.metaalmagazine.nl that shows the HEDELIUS RS 80K in action.

Horstra Technology, Hardenberg

Horstra Technology was founded in 2001 with three employees, and by 2007 the number of employees has grown to seven. According to Harman and Geert Horstra, it won’t become much larger: ‘We can still keep track of everything ourselves, so we can operate with a minimum of overhead.’ The company presently realises 20 percent of its sales in Germany, with a lot of quasi-prototype work for machine builders. The first customer in Switzerland has already been booked. For more information, visit www/horstra-technology.nl.

Jan Oonk

metaalmagazine 2 2007

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