Appunti Optimization and innovation of production processes in inglese (parte 6)

CPS

CPS (Cyber-Physical Systems) can represent a solution for very specific tasks. Artificial

intelligence is the core of the decision-making process for most CPS and enables a CPS to

become autonomous.

Possible advantages:

- Improved material removal rate (MRR – Material Removal Rate)

- Enhanced safety and reliability in unattended operations

- Reduction of tool wear caused by vibrations (chatter)

- Retrofit device, installable on existing systems

CPS – InteFix

Competitive advantages:

- Generic use (general-purpose)

- No need for a model (model-free)

- Autonomous control logic

Device Testing

Test case:

- Material: tool steel DIN 1.2312

- Mold for a ventilation component under optimal actuation

- Learning phase for identifying optimal actuation

- Control performance

- Synthesis of optimal linear actuations along the X–Y axes

- Control performance during milling of the test case lasting approximately 1 hour

Results obtained

The active clamping device operated with:

- 15% higher speed and reduced vibration level

- High temperature and presence of hot chips

- Occasional fluid splashes

- Frequencies up to 2 kHz

- Cutting forces up to 1 kN

Predictive Maintenance of the Machine Tool

Data acquisition via PLC (the PLC manufacturer was a project partner)

1. Objective of predictive maintenance (cost, OEE, frequency): not all components can

be monitored

2. Design of the data flow (required measurements, sensors, data acquisition – DAQ)

3. Design of data storage (Big Data may be generated)

4. Design of the Artificial Intelligence-based solution

5. System training

6. Reporting and data visualization

IoT Solutions

The architecture of the Internet of Things (IoT) is typically composed of three fundamental

elements:

- Things: devices, i.e., the “things,” connected via wired or wireless networks

- Network: the network that connects all the “things” to the cloud

- Cloud: servers in a remote data center that securely store the data

The Internet of Things refers to a set of technologies that enable any type of device to be

connected to the Internet. The main purpose of these solutions is to monitor, control, and

transfer information, and then perform corresponding actions.

1. Increasing level of complexity:

2. Network-connected devices capable of sensing data and transmitting it

3. Network-connected devices capable of sensing multiple types of data and

transmitting them

4. Devices capable of performing a first level of local processing (selection) and

transmitting only relevant data

5. Devices capable of collecting data, performing selection, and acting based on

received instructions

Devices capable of: sensing data, selecting and transmitting only the data needed for the

project, acting both on received instructions and on local processing capabilities.

Additive manufacturing

New technologies aim to produce a component in a simple way, starting directly from the

geometry without having to integrate all the parameters of traditional manufacturing

processes.

The concept behind additive manufacturing (AM) is the elimination of fixed costs (there are no

molds and programming is fast; these processes are generally cost-e?ective for small

batches). However, there are limitations in terms of materials and process logic.

We will analyze AM for metallic materials, since for plastics it has already been in use and

developed for more than 20 years.

AM is seen by many as a technological revolution, although it presents some constraints,

such as not being applicable to all components.

Towards AM

- Step 1: evaluate the use of AM to incrementally improve products

- Step 2: AM as a technology to change and streamline the supply chain

- Step 3: radical and widespread product innovation (designed for AM)

- Step 4: supply chains and products transformed to create new business models

Advantages of Additive Manufacturing: complexity for free, customization for free, material

saving, production cost reduction.

DFAM

It is time for DFAM (Design for Additive Manufacturing) as a strategy to make the production of

AM components more e?icient. This includes:

- Selecting the most convenient technology

- Optimizing geometries (also dependent on the first choice)

Hybrid technologies

Most technologies involve multiple production steps: generally, an initial material deposition

phase is followed by consolidation methods (HIPping) and/or finishing of functional surfaces

using machine tools.

Is it worth it? AM opens up incredible possibilities in terms of freedom of design and

achievable geometric features. It becomes advantageous to produce components even in

small batches at competitive costs. But how small and how competitive? Traditional methods

(e.g. milling or molding) are not cost-e?ective for small batches. Why? Fixed production costs

– independent of the number of parts produced – significantly increase the production cost of

very small batches. A few components will NEVER be more cost-e?ective than a batch

produced using mass production strategies, even when using AM.

AM also brings additional advantages related to the component supply chain. The first real

applications of AM technologies were in the military and aerospace sectors, where the

procurement of components can be very di?icult. Added to this are the di?erent mechanical

characteristics (specific to the various processes) and the di?erent behavior in terms of

corrosion and fatigue.

While plastics have already reached a good level of performance – also thanks to the design

of specific polymers for these processes – for metallic materials there are still many issues to

be resolved. This is further compounded by the di?erent mechanical properties (specific to

each process) and the di?erent behavior with respect to corrosion and fatigue. While for

plastics a good performance level has already been achieved – again thanks to the

development of specific polymers for these processes – for metallic materials many

challenges still remain unresolved.

AM Technologies for metals

Powder Bed

Powder Bed is one of the most innovative technologies in the field of Additive Manufacturing

(AM). This process is based on the deposition of metal powders, which are then melted layer

by layer to create a component. The powders used in the Powder Bed process have

micrometric dimensions and are produced through special gas atomizers. Their fineness

makes them extremely sensitive to contamination; therefore, it is essential to store them in

airtight containers in order to reuse them safely. Among possible contaminants, oxygen

represents a particularly critical risk, as it can alter the chemical and physical properties of

the powder, compromising the quality of the final components. Careful handling of these

powders is therefore necessary to maintain the quality and consistency of products made

through additive manufacturing.

Powder Bed technology is particularly interesting because it allows the creation of complex

and highly detailed geometries with great design freedom, a feature that would not be

achievable with traditional manufacturing methods without excessive costs or extended

processing times.

One of the crucial aspects of Powder Bed is the possibility of optimizing the structure of

components. This is achieved through advanced topological optimization software, which

makes it possible to reduce the weight of the product by placing material only where it is

strictly necessary. In this way, not only is structural strength improved, but material is also

saved, reducing weight and associated costs. For this reason, lattice structures such as those

used in Formula 1 are produced using this technique: they combine high strength with low

weight. Lattice structures allow a high level of sti?ness to be achieved while maintaining low

mass. This enables topological optimization of components, adding material only where

needed, resulting in higher-performance structures with lower weight and material savings.

The Powder Bed process also allows for the highest levels of product customization, since

each component can be manufactured to measure without modifying tools or molds.

However, some limitations must be considered, such as the issue of internal porosity, which

can reduce the service life of components subjected to cyclic loads. Nevertheless, post-

processing treatments such as Hot Isostatic Pressing (HIP) are available; these increase

material density and improve surface finish.

Many software tools are available for topological optimization using “free” geometries. To

perform optimization, it is necessary to know the loads to which the product will be

subjected. In general, the objective function is weight reduction.

The process of manufacturing a component using SLM technology is very simple and allows

an almost automatic transition from the product geometry to its production.

However, some parameters that have a strong influence on product quality must still be

selected, such as:

- Layer thickness: determines the precision and surface finish of the component.

Thinner layers o?er more accurate details but increase production time.

- Part orientation: a?ects the distribution of stresses during the printing process and

the overall surface quality. An optimal orientation can improve strength and reduce

distortions.

- Number and size of supports: essential to keep the component stable during printing;

supports a?ect material consumption and the time required for removal after printing.

- Component nesting: the arrangement of components within the build volume.

E?ective nesting optimizes available space, reducing material waste and production

time.

Porosity is one of the main problems in the production of materials using PB techniques, as it

limits the fatigue life of the component. Internal porosity can result from lack of fusion and

gas entrapment. The choice of scan path influences surface finish and the density/porosity of

the material inside the component.

At high scanning speeds, the balling phenomenon occurs, causing the material to contract

into disconnected spherical droplets due to incomplete fusion of the substrate (low surface

tension). This creates a limit for process productivity. Another phenomenon that may occur is

delamination of the fused layers, due to incomplete fusion. Currently, it is possible to monitor

the melt pool and the substrate, but not yet to change process parameters in real time to

eliminate this problem.

E?ect of the process on material properties:

Fatigue life of a material manufactured using AM:

Secondary treatments are always necessary to improve product characteristics in terms of

compactness and surface finish.

The powders are micrometric and are produced using special gas atomizers. They are highly

sensitive to contamination and must be stored in airtight containers to allow reuse (oxygen is

a particularly critical contaminant). Availa