Common drive technology challenges and how to deal with them
01 December 2017
If there’s one thing that continues to hamper the UK manufacturing sector, it’s the ongoing struggle for greater productivity.
As many factories are turning to capital equipment and modern machinery in an effort to speed up production lines and improve worker output, drive technology is becoming critical to enabling better plant automation, ensuring maximum productivity, and reliability throughout the entire production cycle. In this article, Marcus Schneck, CEO at norelem UK, looks at the importance of standard components in drive technology.
True engineering automation is enabled through the perfect integration of multiple standard components and the amalgamation of multiple drive systems. Gears, motors, ball screws, and couplings integrated with frequency converters at a single source, are key to enabling effective automation in most modern manufacturing facilities. However, while the right application of these standard components can facilitate automation, the lifecycle perspective of drive technology very often depends on how these individual components are used, maintained, and brought together. To understand how to yield maximum value from drive technology, it is important for engineers to familiarise themselves with the individual components themselves.
Gears are integral to the smooth operation of most machinery equipment, transmitting rotary motion and force as required, depending on the application. To achieve this, most machinery will use a combination of standard gear components, the most common of which are spur gears, which are mainly used for transmission between a rotating mechanism and a mechanism with longitudinal movement. An example of this is in the connection of a gear wheel with a gear rack. Spur gears are suitable for form-locking and slip-free force transmissions with alternating rotation.
These components do wear over time, and must then be replaced. Nonetheless, care should be taken to specify high quality components which enable prolonged lifecycles and help to avoid costly downtime or damage to machinery. Gears made from material that is of inferior quality, unable to cope with the operating conditions or which are imprecisely machined or fitted, are likely to fail with greater regularity than better quality parts, sometimes taking other parts of the gear drive with them.
When fitting spur gears, care must be taken to align the shafts correctly, because inaccurate fitting can reduce tooth contact, causing wear and excessive noise. They must be fitted firmly, to prevent them slipping towards the shaft.
Other gears commonly seen in machinery include gear racks, which convert rotation to linear movement, and bevel gears, which transmit power between a pair of intersecting axles.
A ball screw, also referred to as a ball screw linear actuator, translates rotation into linear movement. In this it acts in a similar way to a gear rack (although the construction of the two is entirely different), but the ball screw allows for greater precision and efficiency. Ball screws consist of a threaded screw, which acts as a 'runway' for the nut element, which is actually a component containing re-circulating ball bearings, in which the balls and the ball return are integrated. Ball screws are very commonly seen in machinery, where they may be preloaded so that backlash is more or less eliminated.
These components have no self-locking due to their low rolling friction, and reduction transmissions or engine brakes are generally used as braking systems. They are common in industrial applications, and are generally quite resilient, but they do have to be replaced over time and are susceptible to contamination. Poor circulation of the ball bearing can increase servo load, while excessive backlash generated by a ball screw can compromise accuracy just where it is needed in equipment such as CNC machines.
Couplings are used to transmit torque between two shafts. Mechanical engineers often use them to separate various individual components, e.g. the motor, transmission and working machine. They are often used in machine tool construction, servo drive technology and in automation, where they are frequently installed in highly dynamic feed axes and demanding drives.
Common signs of coupling failure include abnormal 'screeching' noises and excessive vibration. Improper installation, excessive loading, contamination, lack of maintenance and inappropriate size selection are common causes.
Couplings are available in various designs, and according to those designs they may convey other benefits such as limiting torque; compensation for axial, radial and angular misalignment in shafts; vibration dampening; load interruption when maximum torque is exceeded and/or electrical insulation. Shaft couplings are flexible couplings in which inertia is minimised, these generate no backlash, can transmit torque angularly and have high torsional rigidity.
It is when these components come together in an optimum operating environment when they become most effective, enabling seamless automation in a raft of critical machinery found on almost every shopfloor. The role of drive technology is set to become even more important to growth in the manufacturing sector, as industry strives to become more productive, competitive, and effective. Automation will play an integral part in this journey but an investment in expensive machinery, however justified, can be wasted if the vital standard components that comprise it are ineffective. Frequent upkeep, maintenance, and replacement of drive technology components is the only way that machinery operators can ensure that they are continue to achieve maximum return on their investment, not just in terms of cost, but improved lead times and productivity as well.
Drive technology components can be found in THE BIG GREEN BOOK from norelem, which can be ordered at https://www.norelem.co.uk/gb/en/Download/eCatalog.html
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