Leak tests for the automotive industry: the Movingfluid system

In this article:

• What is a leak test and why is it essential in the automotive industry?
• Movingfluid’s leak test systems: simplicity in the service of effectiveness
• All the technical and practical benefits of the Movingfluid solution
• Possible future developments

Leak-test systems for the automotive industry. Step by step, the assurance of a perfect seal thanks to Movingfluid

Safety is one of the essential aspects of the car manufacturing process, which must comply with stringent checks right from the pre-assembly stages. The engine is the heart of the car and, as such, must deliver flawless performance to safeguard the driver’s safety and ensure the brand’s reliability and credibility.

For this reason, a leading, long-established car manufacturer has chosen Movingfluid to develop a comprehensive leak test system for internal combustion engine and electric motor components. Thanks to these leak tests, the Emilia-based company is able to detect any manufacturing defects well before testing of finished engine.

A solution that is easy to use and offers significant savings in both time and money: let’s look at it in detail. 

What is a leak test and why is it essential in the automotive industry?

A leak test checks for leaks within the components or assemblies that make up the engine (conventional, electric or hybrid). This is a crucial check in the automotive industry because it certifies the quality and performance of the vehicle and its parts, confirms that it works properly, and protects personal safety.

For some years now, the plant has been home to 8 Movingfluid systems (each dedicated to a specific assembly), which are subjected to leak tests at various stages of production.  

The leak test specifically covers:  

1. intake manifolds 
2. exhaust manifolds 
3. engine heads 
4. engine block 
5. the hybrid axle (among the most recent, installed in 2022) 
6. the PHEV model (Plug-in Hybrid Electric Vehicle, also from 2022) 
7. the engine coolant circuit  
8. the engine oil circuit 

In this way, each workstation is dedicated to a single type of pre-assembled unit, making the operators’ work as easy as possible and minimising the risk of human error. But how exactly does our leak-test system work?  

Movingfluid’s leak test systems: simplicity in the service of effectiveness

Inside the plant, the components of the internal combustion engine – or those related to the hybrid powertrain – are assembled in a step-by-step process. Movingfluid’s leak-test systems, housed in compact ‘consoles’ approximately 1 metre wide and at head height, are located directly in-line, perfectly integrated with the existing equipment.

When the assembly is ready for leak testing, it is placed on the test bench – a rubber surface that fits perfectly against the underside of the part – or plugs are used if the component is difficult to handle (e.g. engine block).

The interface plate is fitted on the top side: a metal plate weighing approximately 500 gr (and therefore easy to handle), fitted with connectors for the suction pipes linked to the system.

To carry out the test, simply start the test cycle: the air inside the component is removed until the specified negative pressure level is reached.

If the value remains constant for the expected duration (a few seconds for each check), then the test is passed and the system displays a positive result (“OK”) on the control monitor.

Otherwise, the indicator will be negative (“KO”), thereby signalling that the leak test was failed. This means that there is something wrong with the coupling between the components and what should be an airtight seal is instead allowing unwanted liquids or gases to pass through. A condition that must be further inspected and rectified before moving on to the next assembly station.

To make pinpointing the problem even more accurate and immediate, some systems also include a function called ‘leak search’’, which uses positive pressure (compressed air) to identify the leak. In this case, the operator can locate the exact point of the fault by listening for sounds or by spraying soapy water onto the surface.

On closer inspection, the system is therefore very simple in terms of its design and use: a significant advantage that contributes to its efficiency and acts as a catalyst for opportunities. It is precisely thanks to its simplicity, in fact, that over time it has been able to incorporate the technological advances introduced by the company. But let us proceed in order. 

All the technical and practical benefits of the Movingfluid solution

A faulty engine at the end of the production process is a disastrous scenario for many reasons. If leaks were only detected at the final stage, this would in fact necessitate a review of all preceding processes in a ‘blind’ search for a corrective measure. This means a further investment in terms of time and money. Not to mention the extremely high risks to people’s safety and the expensive repair costs of vehicles with proven manufacturing defects.

Precisely to avoid this problem and to ensure the brand’s market position (as well as the vehicle’s component parts), the company in question has opted for a reliable and modular inspection system at all stages of the engine’s partial assembly process. And to do this, it turned to Movingfluid, which, compared with other solutions already in use at the company, offers many additional benefits: let’s see them in detail. 

Benefit 1) The system’s simplicity and flexibility

As we have already mentioned, the system’s primary strength lies in its structural and operational simplicity. If we were to strip it down to its bare essentials, we could say that it is based on a pneumatic pump and pressure sensors.

The streamlined design makes the systems flexible, easy to use and simple to service in-house, as well as capable of accommodating software upgrades without major hardware modifications.

In fact, all leak-test stations are now connected to the company’s MES (Manufacturing Execution System), which transmits instructions and collects production data, thereby ensuring the traceability and safety of the individual processes.  

Benefit 2) Customisation and standardisation go hand in hand

The second advantage, on the other hand, concerns the right balance between customisation and standardisation. Customisation mainly concerns the interface plates: initially produced by Movingfluid based on the design of the components being tested, these are now manufactured directly by the customer with the support of our specialist engineers.

The constant collaboration between the two technical departments makes it possible to refine the design and achieve optimum machine performance for every new application requirement or overhaul of engine components.

On the other hand, the basic structure of the systems remains standardised and replicable, thus making the solution scalable. 

Benefit 3) Production time and multi-function stations

Time is a key factor in any manufacturing sector, and the automotive industry is no exception. The leak test takes just a few minutes and falls well within the takt time available to the operator: 28 minutes per part.

In fact, the control station also serves as an assembly station:this way, everything runs smoothly without creating bottlenecks that would slow down the whole process.

When a defect in the seal is detected, the component is placed in a ‘recovery area’, where it will undergo further analysis and processing, and the line continues with the next part.   

Benefit 4) Cost-effectiveness and rapid response, both remotely and on-site

Compared with other suppliers (mostly German) who already provide similar solutions within the same plant, Movingfluid systems also stand out for reasons of cost-effectiveness. A tangible cost-saving that stems precisely from the simplicity of the facilities and processes, and which does not affect the quality of the materials or the efficiency of the machines, which are robust and wear-resistant.

The ability to provide remote support also played a key role in the company’s choice of the ideal partner. Thanks to secure access to the internal systems, we can respond promptly to resolve any issues that cannot be handled by the customer’s personnel. Although such situations are rare, on-site support is always available whenever needed. In this specific case, the close proximity between Movingfluid and the customer’s facility allows us to plan and carry out repairs even more quickly, minimizing downtime.

Furthermore, to prevent production stoppages or system errors, we carry out thorough checks on the detection sensors, issuing calibration and suitability certificates every 12 months: documentation which, in turn, is subject to periodic internal audits.

Predictive maintenance of the plates and their gaskets, on the other hand, ensures that the machine is hermetically sealed, which is essential for leak detection operations to be carried out correctly.  

Possible future developments

The current system is designed for a ‘piece-by-piece’ flow (assembly-test-assembly). The sets of components that pass the test are then sent on to the next assembly stations, followed by further tests to ensure the integrity of each additional component, until the actual acceptance testing of the complete engine is carried out.

Although it is technically feasible to carry out several tests simultaneously at the same workstation – for example, in the event of production delays – the standard procedure is to carry out one sequence at a time to ensure maximum accuracy. Furthermore, each individual group of components is tested on a dedicated test bench, specific to the type of engine that it is paired with.

All these precautions help to minimise the likelihood of human error, whether caused by working too quickly or by switching between different assemblies.

However, new production requirements may necessitate a forthcoming adaptation of the multi-purpose systems, so that pre-assembled units from different categories can also be tested on the same machine.    

Designing simple systems and installations is the most complex endeavour: but our Sfigasolvers are trained to solve even the most twisted challenges.