Are grinder guards over-designed?

Guards on grinding machines are particularly important for ensuring operator safety. Grinding wheels seldom burst, but when they do, there is a great risk of serious injury to the machine operator. Recent studies suggest, however, that the enclosures commonly used in gear grinding machines, for example, could be over-designed.

Investigations conducted by the VDW (German Machine Tool Builders’ Association) and the Institute of Machine Tools and Factory Management (IWF) at TU Berlin, reveal that it is possible to use safety guards which are up to 70% thinner, depending on the width of the grinding wheel. These findings are now leading to changes in ISO standardisation.
The minimum wall thicknesses for safety guards are specified in ISO 16089. For example, there is a directly proportionate link between the requirements concerning primary protective covers for gear grinding machines and those for the full enclosures located further away. The reason is that no specific safety precautions were initially specified for the safety guards of gear grinding machines as they were not explicitly included in the preceding standard, EN 13218. However, this proportionate scaling has been repeatedly questioned, including by the JMTBA, as it results in overdesigned polycarbonate safety guards and screens.
“Our burst and impact tests showed that the thickness of the enclosure wall can be reduced by up to 70%, depending on the width of the grinding wheel,” explains Simon Thom, group leader for machine tool technology at IWF (TU Berlin). “This is very good news for the machine tool manufacturers, who are keen to avoid excess weight in their machines. Reducing the thickness of a sheet steel housing by half a millimetre, for example, will save 4 kg/m2 in weight.”
For further information www.vdw.de

Entry level universal grinder

A new universal cylindrical grinding machine from Swiss specialist Kellenberger majors on providing high value at the entry level, while offering reliability, precision and high productivity via its state-of-the-art intuitive programming function.

Available in the UK from Jones & Shipman Hardinge, the Kellenberger 10 (K10) combines proven technology using many Kellenberger components and sub-assemblies from the established K100 machine, coupled with the latest programming technology. For instance, Kellenberger Blue teach/programming software enables semi-skilled operators to use the machine, thereby optimising use of the work team. Kellenberger Blue solution software is accessed through a FANUC 0i-TFP CNC control with a 19” touch screen.
In standard format, the machine can accommodate workpieces up to 1000 x 400 mm in size with a top table weight capacity of 100 kg. The table profile is also a proven Kellenberger design with the full length wheel dressing interface located on its rear to reduce re-tooling work and extend wheel dressing possibilities.
K10 models feature generous X and Z-axis strokes (365 mm in X, 1150 mm in Z), collision-free operation and dressing ratios. The low-maintenance, high-precision linear guide on the X axis and the flat sliding V guides on the Z axis are equipped with optical absolute linear position measuring systems. Furthermore, the B axis is designed as an automatic indexing axis (1° Hirth gearing) with high positioning accuracy and a +30°/-210° swivel range.
The K10 also offers the ability for users to expand or customise its capability by adding a range of optional equipment such as a second external grinding wheel, larger grinding wheels, a tailstock, gap control and balance sensors, and measurement control via probing.
For further information www.hardinge.com

£1.2m project support

The University of Derby is supporting an advanced manufacturing project that has secured a £1.2m UK Research and Innovation (UKRI) grant.

Funding has been released for a project led by engineer Ayantika Mitra of Hampshire-based firm TISICS to transform advanced materials manufacturing through digital technologies. The four-year project, named ‘RAiSE: Radical Approaches in new materials Science and Engineering’, will develop tools to enable the rapid certification and qualification of new lightweight products for spacecraft and aircraft.
The University of Derby is providing advanced materials and expert support.
For further information www.tisics.co.uk

Adding control to contour grinding

The two-machine X series of two- and three-axis surface grinders from Taiwan-based Perfect has long been a part of RK International Machine Tools’ portfolio of precision grinding machines. Now, thanks to the addition of full CNC in the form of the Siemens 828D control, these machines have gained even greater versatility, with the three-axis versions now able to perform full contour grinding as standard.

The X25 with its 250 x 500 mm table – and the larger X36 with 300 x 600 table – feature 550 mm and 600 mm clearance between table and spindle centreline respectively. Both variants are based on a construction that was developed through FEA for added stiffness and support. Spindles are also high-performance P4 units with precision angular contact bearings delivering runout of <2 μm. The spindle itself features an inverter giving users a choice of spindle speed to suit specific materials. Craig Digweed, RK International’s product manager - grinding products, says: “With the addition of full CNC control from Siemens, the X series provides, as standard, cycles to cover surface, crisscross, plunge and pitch [same pitch and same depth] grinding. However, customers can now specify optional cycles such as stair, side, profile and contour grinding, giving them much greater control over their operations.” Table speed ranges from 1 to 25 m/min, dependant on machine specification, with a cross feed of 1100 mm/min on all machines. A table mounted, three-piece dressing diamond is standard and, to accommodate the variety of additional grinding cycles, rotary and roller dressing devices can be offered for wheel forming options. For further information www.rk-int.com

Learn more about UL508a standard

UK manufacturers targeting new growth opportunities in North America are being urged to avoid costly mistakes when trying to meet specific technical standards for the territory.

PP Control & Automation (PP C&A), which provides strategic manufacturing outsourcing solutions for over 20 of the world’s largest machinery builders, has launched a new educational campaign on UL508a, a technical standard for industrial control panels in the US.
Working with specialist partners Rockwell Automation, Lutze and Product Approvals, the company is set to host a number of detailed virtual presentations that will be available to view or download, followed by an interactive Q&A platform. These presentations follow a series of blogs and short videos that have been viewed more than a thousand times by manufacturers keen to avoid the expense associated with rectifying machines to make them UL compliant, and any subsequent disruption that could impact the customer.
For further information www.ppcanda.com