How to perform setup time reduction in Reconfigurable Manufacturing Systems?
Reconfigurable Manufacturing Systems or simply RMS are potentially the answer to manage mass customization, since the system can be continuously reconfigured in accordance with the volumes and products required.
One of the requirements of a highly Flexible Manufacturing Systems is the use of small batches, potentially single piece.
On the other hand, one of the main differences between Ford’s Taylorism and Toyota’s Lean lies in the concept of one-piece flow, that is, working in a single piece instead of in batches. Working at one-piece flow entails a series of advantages but also a series of challenges to face.
The main one is the reduction of set-up times, especially in the presence of a high production mix.
Indeed, the production mix will be the key to remain competitive on the market: the trend is towards an ever greater product customization, which leads to more and more product varieties and in general in smaller quantities than in the past.
Benefits of One-Piece Flow
One-piece flow has a number of advantages over batch flow:
- Lower Lead Time
- No buffer needed, therefore less waste of space
- Better parts traceability
- Potential defects emerge more easily
In particular, a shorter lead time is based on an important initial condition: the setup time is 0.
The setup is the preparation phase of a process, in which a machine tool is reconfigured to adapt to the production of a particular. In the case of a production line that only processes one product, this condition is automatically verified as the line is designed to work the product in an optimal way.
However, in the case of a line that processes multiple types of products, the machinery must be set to each product, so it is essential that the set-up time is as short as possible.
Importance of setup time reduction
Based on what has just been said, it is evident that the setup time reduction is fundamental to enable a one-piece flow in the presence of a production mix.
The greater this mix, the greater the benefits brought by the reduction of setup times.
Conversely, for long set-up times, one-piece flow might not be the most advantageous, but it will then be necessary to size the batch appropriately to amortize the set-up costs.
The goal is therefore to ensure that the machine stop is as short as possible due to a change in setup.
The first thing to do is to analyze the manufacturing steps.
These processes must be as standard as possible to make sure that the number of set ups required is minimized.
This can be done in the following ways:
- grouping the products into families
- working on the method of manufacturing, for example changing the geometry of the parts in the specific phases of the process to standardize the necessary equipment and tools
- if necessary, modify the final product.
The second thing to do is to use a technique called SMED, i.e. Single Minute Exchange of Die, a methodology which aims at reducing setup times. Shortly, the SMED consists of the following steps:
- identify the set-up operations that can be carried out while the machine is working (OED, or Outside Exchange of Die) and those in which the machine must necessarily be stopped (IED, Inside Exchange of Die);
- convert the IED operations into OED;
- optimize set-ups, especially IED ones.
How to optimize the set-up operations? In this case, technology comes to our aid. Some commonly used solutions are:
- Use of quick exchange systems (e.g. jaws for spindles or tool holder clamping methods)
- Use NFC/RFID systems to communicate to the tool what configuration is needed, thus automatically changing clamping parameters
- Use robots / cobots for loading / unloading parts
- Use cameras or infrared sensors for alignment or parts identifications
- Use additive manufacturing to create adaptable systems. Examples are 3D printed grippers actuated by pneumatic systems
- Use Augmented Reality to support the operator to identify the operations to be performed through appropriate human-machine interfaces
- Use of IoT systems (e.g. Smart Torque wrenches) able to self-update based on the specific parameters required.
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