Tectra Automation recently assisted a small business, Milled Shapes & Profiles, in building a custom CNC milling machine for precision 3D milling of rigid foams, plastics and associated materials.
Tectra supplied the aluminium structure for the frame, the ball screws that move the spindle and the axes, the high precision linear guides, and the complete electric drive and control package.
The motor control centre, a Bosch Rexroth MTX Micro CNC controller, was the first to be installed in the country. This controller combines ease of use with advanced performance and precision. “Bosch Rexroth’s IndraMotion MTX control platform is ideal for automating up to four feed drives for turning or milling machines as a CNC controller with integrated PLC,” explains Georg Venter, Electric Drive and Control divisional manager, Tectra Automation.
The user panel offers various standard functions that enable commissioning and optimisation without a programming unit. The control centre can be either manually controlled from the human machine interface (HMI), or with a mobile hand-wheel. Further commissioning functions, such as axis commissioning and backing up or reproducing the controller and drive data, have been added and can now be used straight from the control panel. Graphic input masks enable intuitive programming technology cycles, thus making the reading of input parameters unnecessary.
Built for versatility, the milling machine has machining capabilities of 3500 mm on the X-axis, 1250 mm on the Y-axis and 900 mm on the Z-axis. It also has a thermal guillotine using a hot wire on the z- or x-axis for precise, clean cutting. Special longer length tools had to be made for the spindle on the machine, believed to be the first of its kind in South Africa, as it requires longer lengths that are not readily available in the market.
“Because the table needs to be very accurately levelled to enable precision milling, we use an engineers’ level to line it up perfectly. The machine can handle up to 7 m long pieces in one go. It also has vacuum plug fasteners to safely hold pieces down while milling and to machine more than one piece at a time,” says Robin Murgatroyd, co-owner of Milled Shapes & Profiles.
The MTX Micro CNC controller is pre-programmed via a personal computer during the day. The motor control centre then receives the data so the machine can work throughout the night. With the help of the specialised Bosch Rexroth control centre, the machine switches itself off once a program has been completed. “As the programs we use contain a lot of data, downloading can be time consuming. We plan to install cabling direct from the computer to the controller to save on the download time,” says Murgatroyd.
Milled Shapes & Profiles can now offer its clients a one stop service. This includes translating a client’s initial design idea into a fully fledged CAD model; developing a CAM model that maps out the tool paths and programming overlays; and ultimately machining the product according to client specifications.
“One of the advantages of the Bosch Rexroth system is its flexibility. It does not tie one down to a specific program, which allows for a wide range of functions and makes it ideal for our specialised applications,” explains Murgatroyd.
Milled Shapes & Profiles’ customised machine is perfect for cutting intricate patterns and moulds with high accuracy from complex surfaces that cannot be done manually. A recent project involves a vehicle body pattern for a Unimog vehicle. “The client was quoted R300 000 by a patternmaker for the Unimog bonnet system, while we will be able to do it for him at around R10 000,” concludes Murgatroyd.
For more information contact Georg Venter, Tectra Automation, +27 (0)11 971 9400, [email protected], www.tectra.co.za
| Tel: | +27 11 971 9400 |
| Fax: | +27 11 971 9440 |
| Email: | [email protected] |
| www: | www.boschrexroth.africa |
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