To gain traction in the aerospace industry, Australian manufacturer of rotary shank cutting tools, Sutton Tools, has been using linear motor technology. Article by Anca.
Jeff Boyd, export manager at Sutton Tools says, “By really focusing on how we could improve the surface finish, and with the added capabilities of the linear motor, we have created a product that is delivering significant productivity gains for our customers. The team is now consistently achieving a longer tool life and faster cycle times in some of the higher strength materials such as titanium.”
Jeff added that improvements in the surface finish of the cutting tools have been achieved by moving away from the traditional ball-screw movement on machines to a linear motor. The company also conducted a direct comparison and experimented with different grinding wheel grades and grinding parameters for the best finish.
“A better surface finish has also mean we get better adhesion of the coating and stable performance to the cutting tool which is important for our customers. Tool stability is important because it means our customers can confidently forecast their production schedules and reduce machine down time,” says Jeff.
Optical 3D Scanning
In order to validate their grinding methods, an optical 3D scanning technique is used to measure the area surface roughness on the rake face and the cutting rake on the tools.
Anca has combined linear motion motor technology from its sister company Anca Motion to its own rigid grinding machines. The LinX cylindrical linear motors prevent loss of preload or rigidity when grinding tools and reversal errors are eliminated and higher contouring accuracy can be maintained due to a unique control algorithm.
Simon Richardson, ANCA Product Manager explains, “When machining softer or ductile materials, chips can stick to the carbide. If the chips created are not removed faster than they are being produced – the tool may not perform effectively. However, a better surface finish on the flute prevents the swarf from sticking onto the flute face of the tool while reducing the amount of heat that is generated when machining.
“We realised that having a highly rigid machine with a cylindrical linear motor that boasts a smooth axis movement, would greatly improve the final surface finish on the tool. The research and development team conducted many hours of test grinding to rigorously test our assumption of what surface finish quality we thought was possible.”
An Alicona infinite focus XL metrology machine in ANCA’s Grinding Centre of Excellence was used to verify the results to Nano metre accuracy finding that a surface finish roughness average as low as 164.7nm (which translates to 0.16 Ra) was achieved.
Highly Polished Surfaces, Better Cutting Edges
Paul Bocchi, General Manager of ANCA Motion says, “An advantage of knowing ANCA’s customers so intimately is that we could immediately see how our technology would work seamlessly to improve performance.
“The LinX cylindrical linear motors ensure there is no loss of preload or rigidity when grinding tools. As well as that, reversal errors are eliminated and higher contouring accuracy can be maintained due to a control algorithm we use which is unique to ANCA.”
Simon concludes, “Tools with highly polished surfaces means better cutting edges which will ensure extended tool life and improve the finish on the machined part. We have seen the demand for tools with a superior surface finish continue to increase and cutting tool manufacturers are producing more highly polished tools in larger quantities.”
Tips on achieving a superior tooling surface finish:
- The quality of the grinding wheel is critical in achieving a high-quality surface finish. A fine-grit wheel can form small chips during grinding which could impart fine marks on the flute face and gash.
- Using a fine-grit also poses a challenge as the wheel must be fine enough to produce the required surface finish while maintaining a good toroid radius over a batch of tools.
- Ensure the wheel is properly trued and dressed so that it performs as expected.
- Ensure efficient coolant delivery and fine filtration systems are in place.
- Ensure the grinding wheels are balanced correctly using iBalance
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