Traditionally, gears are produced by using well-established processes in the field of machining, special processes – including heat treatments – and inspection methods.
Following, some production limits related to the gear manufacturing are presented and how new technologies can lead to more automated and at the same time more flexible processes.
Although mechanical transmissions are used in different applications and therefore with different design requirements, we can still identify some standard processes:
- Machining, mainly turning, milling and tooth cutting
- Heat treatments
- Surface finishing, when required
- In process and final inspection including dimensional, destructive and non-destructive test
Looking at the overall picture
As any good manufacturing engineer knows, the final result is guaranteed not only by the success of each individual operations, but more important by their level of intercorrelation.
In fact, the characteristics generated at each stage of the process can have a significant impact on downstream operations and such variations, if not under control, can generate inefficiencies, scraps, delays, especially when the products variety increases and the average batch decreases, as it will be very difficult to set highly repetitive standard processes.
When volumes are big enough to justify dedicated production lines, standardization guarantees a high process stability, therefore automation is the most effective technological solution.
Henry Ford had already introduced a high level of standardization in his assembly lines by applying economy of scale to the automotive sector and to produce low-cost cars, but with a very little models variety.
However, with the introduction of Lean Manufacturing principles and industrial robotics, the variety of models has gradually increased to meet customer needs, and at the same time the processes have become more and more efficient.
This is particularly true in the automotive business, where robots and automatic presses are able to manage the entire pressing, welding and painting process almost independently.
However, in the field of mechanical transmissions the flexibility of a robot cannot be exploited to its full potential: gears mostly use processes that require CNC machines and bespoked high precision equipment with set up times that are not negligible.
Although the use of robots still offers several benefits, especially in pick-and-place and inspection operations, it is necessary to achieve a greater level of automation and flexibility in a different way.
Making the production system more flexible
The increasing product variety and the shorter life cycles are leading to an ever greater gears variation with reduced production volumes.
Consequently, it is necessary to maintain a high level of efficiency and keep production costs competitive, but at the same time to introduce flexibility while maintaining the same or even better quality.
In this sense, the use of new technologies can also help us in the traditionally conservative sector of gear manufacturing: indeed, they will be essential in order not to be cut off the business.
Some examples to increase the flexibility of the gear production system while maintaining a high level of automation will be briefly reported below.
We can proceed to reduce the number of set ups needed and at the same time reduce the time of the single set up.
- Reduce the number of set-ups: the use of multi-tasking machines, capable of integrating multiple processes / operations on a single platform, significantly reduces the number of required set-ups. To date, many machine manufacturing leaders offer such platforms: there are turning machines able to integrate hobbing or special tools for gear cutting, or grinding centers for both internal and external gear, datums and bearing raceways, both internal and external, on a single platform.
- Reduce set up times: the design of smart equipment, able to adapt to different parts to be processed, can significantly reduce set up times. In this sense, hydraulic or pneumatic actuators, RFID tags and machine readable marking systems such as QR code or 2D Data Matrix can provide the right solution for greater flexibility.
Simulations are traditionally used by manufacturers to verify the correct tool path and to prevent collisions. However, simulations can offer further advantages:
- Multi-physics simulations: in the field of heat treatments for example, it is possible to predict the distortions with a high level of accuracy. This lead to a considerable advantage in terms of quality and downstream process optimization;
- Gear cutting simulation: how to define the cutting parameters correctly? Kinematic simulations, traditionally used by tool makers, do not provide all the necessary information. For example, how do variables such as lubrication, machinability and hardness influence the process? Simulations are able to optimize the parameters to increase, for example, the tool life, to control surface finish with greater accuracy and the generated residual stress.
Without an extensive data collection campaign and detailed analysis, it will no longer be possible to remain competitive on the market for long time. We have already highlighted how the manufacturing processes are linked to each other, therefore analyzing what happens upstream of the process and providing real-time feedback to the downstream processes will be fundamental.
In this sense, the Internet of Things is the ideal tool for the Big Data collection, while for their analysis, Machine Learning and more generally Artificial Intelligence can use Six Sigma statistical tools to adapt the production system in real time.
Some examples related to the upstream and downstream processes of heat treatments are:
- After the heat treatment, a gear can be scanned by optical systems and the data sent to the following process which will automatically adapt
- Once processed, the same data can provide information to upstream machining steps in order to reduce distortions due, for example, to excessive eccentricity of datums or excessive residual stress generated by the gear cutting process
In order to have a completely interconnected data transfer system, it will be necessary to size an adequate IT infrastructure to guarantee a flowless exchange of information, and to estimate the required computing power to process almost instantaneously the amount of data generated.
How to start?
If you are in the business of gear manufacturing and you would like to approach towards the implementation of Smart Factories, we recommend to have a look at our catalogue to get the proper knowledge and to fill the skills gap.
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