1 of 4
2 of 4
3 of 4
4 of 4
Advanced Machine Tool Metrology –
Achieving Optimal Performance
In the field of micro and precision engineering, the ability to measure at every stage of the production process is key. By now, anyone involved in the area of precision engineering is well aware of the much used homily, “If you can’t measure it, you can’t make it,” which is fundamentally true on every level when manufacturers are striving for efficient and cost-effective manufacturing projects.
On the 15-16 March 2017, euspen (the European Society for Precision Engineering and Nanotechnology) will be hosting the 12th International Conference and Exhibition on Laser Metrology, Coordinate Measuring Machine, and Machine Tool Performance (LAMDAMAP) at the Renishaw Innovation Centre in the UK, looking at aspects of metrology when applied to machine tools. In advance of this event, this article looks at the key issues related to advanced machine tool metrology.
The production of more and more accurate and smaller and smaller components relies and indeed is underpinned by advanced machine tool metrology, which facilitates the assessment of performance of machines. This requirement becomes more pressing as the drive in industry towards the greater use of nano-scale surface finishes and features gathers pace. It is vital that form and finish is produced consistently in small complex parts, and it is here that the key challenge for advanced metrology solutions exists today.
The euspen LAMDAMAP event is a leading source of relevant knowledge. It allows the next generation of manufacturers to use all available advances in measurement techniques to meet tomorrow's production challenges.
The machine tool is a fundamental element of a manufacturing system. The efficiency and capability of a machine tool is influenced by a number of factors including its system configuration, its operating environment, and its performance output requirements.
Designers constantly drive Increases in product performance as they specify more and more exacting manufacturing tolerances. In addition, constrained design specifications, increased product geometry complexity, and the use of higher performance materials, all effectively results in products that are getting more and more difficult to machine. From a manufacturing process perspective, engineers are continuously trying to improve machine tool capability in respect of availability, performance, and quality, with the goal of reducing the amount and seriousness of process breakdowns, as well as increasing machine uptime, material removal rates, and automation.
Because of this, a paradoxical situation arises wherein more severe conditions are being imposed on the machine tool while at the same time greater performance is expected but with reduced levels of process interruption.
It is reasonable to view a machine tool as a sub-system within a larger manufacturing system, where changes in its performance can have a significant impact on product lifecycle characteristics such as cost-to-market, final product conformance, and lifespan. Machine tool Improvements can be made through optimisation of elements contained within its system, and these include its geometry, mechanical components, electrical components, electronic components, the CNC controller, part fixturing, and cutting tools amongst many others.
It is extremely important to understand any errors contained within a machine tool system, as the configuration and variation of these errors directly impact its base level accuracy and repeatability, and therefore its overall capability.
To produce conforming products at a high level of process capability it is vital that a machine tool is demonstrably accurate. However, even a relatively simple 3 axis machine has numerous (in excess of 20) potential sources of geometric error, including squareness, straightness, and linearity to name but a few. If you were to add one or more rotary axes, this significantly increases the complexity further. Each of the errors needs not only to be fully understood, but also either corrected or compensated for before parts can be machined.
There are a numerous devices that have been used over the years to calibrate machines, but in some instances it can take as much as five days to fully calibrate a machine. This extent of downtime is massively costly and therefore not generally acceptable, so within the area of precision engineering there is a huge push to attempt to drive to down calibration time drastically and put in place rapid and non-intrusive verification systems to confirm on-going equivalence and prevent catastrophic failures.
Looking at it in a broader sense, metrology is essentially the art of measurement, and it is a fundamental and underlying capability without which products cannot be manufactured — remember, “If you can’t measure it you can’t make it!!”
Today, a massive amount of research is focused on developing new methods, techniques, and tools (be they software, instruments, or processes) to support the adoption of in-process dimensional and surface metrology for high value, precision manufactured components such as those found in engine components for aeroplanes, medical implants, optical components, and microelectronics. Some call this drive to manufacture, measure, and correct in-process the “factory on the machine”.
Much recent research (a significant amount of which eminates from the University of Huddersfield) has expanded industry’s understanding of the factors that contribute to machine tool inaccuracy. This has led to predictive methods for assessing the capability of machines to produce specific components and the development of a low-cost electronic compensation system that can increase machine tool accuracy by a factor of 10, with significant cost savings for factory temperature control.
Such rapid calibration techniques have been developed by Huddersfield University in collaboration with a U.K.-based aerospace OEM, reducing timescales from days to less than one hour. It is these sorts of initiatives that provide the core of the euspen LAMDAMAP event.
The accuracy of machine tools is fundamental to the quality of the products they make. A better understanding of why errors occur and how to minimise them is vital to ensuring higher standards of manufacturing and increased productivity.
All machine tools and coordinates measuring machines inevitably develop intrinsic deviations resulting from the inexact manufacturing of the machine components, from wear of functional parts, from ruler reading errors, as well as from elastic deformations of the structure.
The position and directional precision of the machine are affected by these geometric inaccuracies, and therefore also therefore the in-use precision of the same. Being able to measure and correct these geometric deviations in order to optimize manufacturing and measuring abilities is therefore very important in this type of system.
At the euspen hosted LAMDAMAP event, all the latest developments in this area of metrology will be discussed. Chris Pockett, Head of Communication at Renishaw explains his perspective on the state of the sector. “There is a clear trend towards higher speed and increased richness of information about machine and process — providing a greater depth of measurement data to enable more advanced forms of production control.”
“Clear recent examples of this are Renishaw’s XM-60 Multi-Axis Calibrator for machine tool production and service, and the SPRINT On-Machine Contact Scanning System. In the case of XM-60 — a tool for machine tool producers and service companies — this system provides 6 channels of measurement data for each captured point, versus only one channel for the established systems. In other words, six times improved throughput to capture the same data. Similarly, the SPRINT system brings a step change over individual discrete point measurement by introducing a full 3D stream of measurement data during probing. Such innovative new capabilities enable users to apply processes which previously were not feasible, and provide a dramatic improvement in their capability.”
At the euspen LAMDAMAP event, attendees will find on the exhibition floor an array of technology solutions targeted at the refinement of metrology techniques when applied to advanced machine tools from leading companies in this field. In addition, at the conference, papers will be presented on such topics as novel manufacturing technologies and machine tools, new developments in measurement techniques, performance evaluation for machine tools and CMMs, roughness and machine tool standards, and metrology in new fabrication techniques.
euspen has just announced that two keynote presentations have just been confirmed for the event, the first by Prof Xiangqian Jiang from the University of Huddersfield, UK looking at surface metrology for future manufacturing, and the second by Dr Josef MAYR from IWF, ETH Zurich entitled thermal error compensation of machine tools.
For more details and to register for the event please contact Dishi Phillips, Business Development Manager, tel: +44 (0)1234 754023 or email: dishi-phillips@euspen.eu