Testing plays a key role in the manufacturing process of products, software and many other solutions. It is especially important in the manufacturing automation and robotics industry, because it affects the quality, reliability and performance of final products. What is testing on production lines? What are selected processes on electronic device assembly lines? These questions will be answered in the following article.

What is testing on production lines?

It is a process that aims to verify, evaluate and secure quality and compliance with specified requirements. It makes it possible to detect possible problems before products reach customers. Today, in-line testing is no longer just an optional step in the entire production process. It is a fundamental element. It provides a guarantee that manufactured products are as expected and meet specific quality requirements.

Functional and electrical tests

There are many different types of tests that can be carried out on production lines. Of course, depending on the type of product and industry. Once the various phases of assembly are completed, the product or its components must undergo testing. It is necessary to check that they work properly. Tests can include checking functionality, insulation test (HiPOT), measuring electrical parameters, and detecting possible defects or damage.

Housing leakage testing

Devices that are exposed to adverse external influences must undergo leakage tests. This mainly concerns enclosures. What does it look like in practice? This type of test is carried out on a bench with an appropriately adjusted receptacle or chamber to ensure tightness. The main measuring instrument is a programmable leak detector with leak measurement by pressure drop method. In addition, the bench can be equipped with additional resources. Among others, a marking or sticking code station and boxes or containers. Pieces that fail the test will go into them.

Protection against ESD, or static electricity

Damage to electronic components and circuits resulting from electrostatic discharge is often discernible only under an electron microscope. They make themselves known, if not at the first attempt to start the device then after some not-so-long period of its operation. For the manufacturer, this is a potentially large cost associated with warranty service.

Therefore, the principles of ESD protection should be followed. Appropriate ESD protection measures are used to avoid damage and ensure the integrity of electronic components.

What is ESD?

The acronym is derived from the English term “electrostatic discharge.” It means a rapid flow of electric current between two objects with different electrical potentials. In industrial settings, it is generated by motion or friction. Small voltages that do not cause visible discharges can damage sensitive components.

Requirements for implementing ESD protection have been collected in the form of DIN EN 61340-5-1. It defines the conditions necessary for establishing, implementing and maintaining a static electricity protection program.

A holistic view of the issue requires thinking not only about procedures and measures inside the plant, but also about choosing the right supplier of production lines or machines. The supplier must be familiar with the concept of an electrostatic protected area (EPA). It can range from a single station to an entire building.

In addition, the supplier should use protective elements such as grounding strips on stations, anti-static ties, grounding cables, washers, anti-static transport systems, chains for intralogistics vehicles and others.

Why is testing on production lines so important?

First, quality assessment. Testing allows you to verify that the product meets the standards specified in the design. Second, testing prevents possible defects. Detecting defects and problems allows you to eliminate them at the production stage. Third, testing on production lines is an optimization of the entire production process. It allows monitoring the efficiency and effectiveness of the entire production line.

The electronics industry uses many processes to manufacture equipment. These processes have a significant impact on the quality and efficiency of production. Automation of processes reduces production costs and errors. The dynamic development of technology and increasing market demands are forcing electronics manufacturers to invest in improving assembly processes, increasing productivity and reducing the risk of delivering defective products.

Robotic mechanical assembly

Mechanical assembly of a module or device from semi-finished products is worth robotizing. Often these are pick & place operations with assembly into the housing of finished PCBs and additional components such as washers, seals or spacers. SCARA-type robots prove themselves here. The advantage of such a solution is precision, repeatability and speed. The appropriate design of the robot gripper allows it to match the type of product and integrate various operations in a small space. The gripper is equipped with manipulators, vision systems for guidance or verification, and screwdrivers and screw feeding systems. The robotic stations can be designed to operate independently or in line with a conveyor system. The right number of robotic stations and the right software to manage the movement of transport pallets allows production to be optimized over time.

Applying adhesives and sealants

Depending on the type of component parts and the purpose of the product, it is necessary to dose and apply substances with different properties. These can include adhesives, sealants, thermally and electrically conductive compounds. In the assembly line of components for PTC heaters, dispensing of thermally conductive adhesive with compensation of the actual position of the component on the pallet was used. The solution, based on a vision system, servo drive and scales, allows correct application of the layer with a precision of ±0.0125g and a droplet diameter of about 1.9mm. The correct adhesive composition is ensured by a dispensing needle system with a mixing tube with a constant mixing ratio. Servo-controlled dispensing pistons feed the substrates into the mixing tube. The combination is stablized at a thermal fixation station by heating the component to about 100-120°. A second automatic glue application system, handles the sides of the component with a dispensing precision of ± 0.005g.

Infrared welding

Infrared welding is a clean process for assembling plastic components, using a special moving head with a lamp and a reflective inner surface. The head is slid onto a plastic pin that positions the parts to be attached. The reflective interior of the head focuses the infrared energy from the lamp onto the plastic peg and heats it up. The plastic becomes soft, so the tip inside presses down on it, which flattens and molds the peg, fixing the parts.

ELPLC SA machines and lines

We specialize in designing and building machines, complete robotic assembly lines and developing software for industry. We offer our expertise to many industries. We provide Industry 4.0 / Smart Factory solutions.

The requirements that arise in systems using CO2 as a refrigerant do not bypass air-conditioning tubing either. One method is to manufacture a duct from AEM rubber [2] reinforced with a steel braid, which contains a corrugated, flexible stainless steel tube inside. A duct made in this way can operate with an operating pressure of 170 bar at a temperature of -40÷150°C. It provides zero permeability, high pressure and temperature resistance and meets DIN 74106 specifications.

Rubber hose production line with corrugated steel hose inside

Start of the process – precision cutting of corrugated hose

The stainless steel corrugated hose is supplied in reels on drums with different burl diameters. The length of the hose on a single reel is 400÷1100m. Transport of the cutting component is provided by decoilers with an auxiliary feeding system that regulates the tension and thus minimizes the effect of material stretch on the actual length of the cut piece. A chipless cut must be made precisely on both sides at a specific point in the wave, which is tested using a vision system. The manufacturer’s specifications specify ranges for the length and outside diameter of the cut piece. The infeed roller system ensures optimum distance from the cutting head and proper tensioning of the hose to reduce the possibility of deformation.

Nipple assembly, welding and electrochemical passivation

Sections of corrugated hose of the appropriate length then go to an automatic station for assembling nipples on both sides. These are also made of stainless steel. The process of TIG orbital welding in an argon atmosphere takes place here. After the electric arc is extinguished and the protective atmosphere is emptied, the turntable with the component is automatically returned to the base position. The workpiece moves to the next station for electrochemical passivation of the welds. An electric drive puts the component into rotary motion and a pneumatic system moves the weld cleaning heads closer. Electrochemical passivation is particularly effective for stainless steel welds and provides optimal corrosion resistance. Excess liquid used in the process is collected by a system of acid-resistant tanks. A number of parameters are measured and checked, such as the path of the nipple assembly, the speed of electrode rotation during orbital welding, the welding current, the rotation speed of passivation heads or the conductivity of the passivation bath.

Mounting the steel hose in the rubber hose

The steel hose prepared in this way can be mounted inside a rubber hose of adapted length. A special hole is also made in the rubber later secured with a silicone band. Finally, D-rings are put on the steel nipples. The machine ensures that the parts are assembled without deformation or scratching, and at the right level of cleanliness. The assembled workpiece is blown out and any impurities go into the appropriate chamber. The extension of the nipples from the rubber hose is checked using a profilometer. The presence of D-rings is also checked and the path and, optionally, the strength of the assembly of the steel hose into the rubber hose is measured.

Sub-assembly of the ties and crimping of the ends of the block and connector

Each complete hose consists of two lugs and a section of pre-assembled hose. Ties are put on the rubber part, which are crimped at the next station. The ends are bent into a preset shape and are topped with a block and connector. The assembly operation involves sliding the ends from the side onto the nipples and crimping the connectors around the nipple connection. Loading is done manually, while assembly and unloading are automatic. It is possible to integrate with a manipulator or robot that receives the assembled cables.

Crimping of stainless steel ties

The cable is manually pre-positioned. The machine automatically extends the ties assembled at the earlier station. The position of the ties results from the product reference. Verification of the correct positioning of the cable tie follows, and the crimping operation is performed. Ovalization is optionally checked.

Machines for wire bundling and flow test

A/C wires are grouped into bundles of different numbers, e.g., two-piece or five-piece. The picking station allows assembly by simultaneously pushing the wires against the appropriate flange. This operation is followed by a purge and automatic flow test with dry filtered air without oil mist. It is to check whether the cross-section of any of the component hoses has been narrowed or completely clogged.

Footnotes

[2] AEM – ethylene acrylic rubber

ELPLC SA machines and lines

We specialize in designing and building machines, complete robotic assembly lines and developing software for industry. We offer our expertise to many industries. We provide Industry 4.0 / Smart Factory solutions.

Air conditioning in the car is associated with comfortable use of the vehicle, especially in summer. The guarantee of its proper functioning is not only regular servicing, but also the quality of workmanship of the various components of the system: compressor, evaporator, radiator and tubes. Air conditioning hoses should ensure the tightness of the refrigerant circuit and proper pressure and temperature resistance.

Briefly about refrigerants

Until 2017, R-134a refrigerant was very popular due to its good thermodynamic properties and high auto-ignition temperature (770°C). Unfortunately, it turned out that its GWP factor [1] is as high as 1430. This resulted in Directive 2006/40/EC, which banned the use of the refrigerant in newly manufactured vehicles from January 1, 2017. R134a was replaced by R1234yf with a GWP=4 and very similar cooling efficiency, unfortunately at the cost of a dangerously lower auto-ignition temperature (about 405°C). Alternative green compounds have also been selected for use in automotive air conditioning systems. The leading alternative here is paradoxically CO2 (R744), which ranks among the so-called natural refrigerants. It is non-toxic, non-flammable, colorless, inert and has no negative impact on the ozone layer. However, it places greater demands on the pressures and temperatures found in air conditioning components.

Production of air conditioning tubes

The various components of the air conditioning system are attached to various body or engine components. This exposes them to vibrations and mutual displacement, so sections of flexible ducting are used to connect them. The hoses can come in bundles of different numbers with the appropriate mounting flange. The cable consists of a rubber hose, metal ends (usually aluminum) and various types of connectors that allow their subsequent installation.

The metal end is formed from a tube so that it can be connected to the rubber hose. Mounting blocks are soldered to facilitate attachment and ensure tightness. An important stage of production is bending the aluminum tubing to the appropriate shape. It is determined by the vehicle model, type of engine, etc. Sometimes the tubes are equipped with heat exchangers to further accelerate the cooling of the air and thus reduce the load on the engine. After the metal tubes are formed, sealant is sprayed onto them. A vision system verifies the correct application of the sealant. The next step is to connect the metal parts to the rubber hose by means of clamping with metal bands.

The grade of rubber used should be characterized by its ability to dampen vibrations and ensure the tightness of the connection. The finished hoses undergo flow and leakage tests. Tightness is important due to high environmental standards, hence air is pumped out of a special chamber and helium is injected into the tubes. A spectrometer is used to detect leaks.

ELPLC air conditioning duct assembly and testing lines

Over the course of more than a dozen years, ELPLC has gained extensive experience in implementing stations and entire lines for manufacturers of automotive air conditioning components. They handle a range of processes found in the production of air conditioning ducts: induction brazing of aluminum components, chipless cutting of corrugated steel hose, TIG orbital welding with electrochemical passivation, band crimping, bundle completion or flow testing. In addition, lines built by ELPLC are equipped with ELPLC’s proprietary TOMAI Factory System. One of its functionalities is that the full production history of each piece is available and can be analyzed. This can be done with respect to various criteria and selected filters, such as efficiency analysis by station or operator. Data export is also available.

Footnotes

[1] GWP – Global Warming Potential – a coefficient of the potential to create a greenhouse effect, determined by comparing the amount of heat absorbed by a specific mass of gas to the amount of heat retained by a similar mass of carbon dioxide. GWP for CO2 is 1. The coefficient is recalculated for a specific time interval – usually 100 years

ELPLC SA machines and lines

We specialize in designing and building machines, complete robotic assembly lines and developing software for industry. We offer our expertise to many industries. We provide Industry 4.0 / Smart Factory solutions.

The lighting installed in automobiles has changed with the development of automobiles. The initial Ford T models still used carbide lamps, but by the 1920s dynamos and electric bulbs began to be widely used. The power medium in the form of electricity remained, but new types of light sources such as halogen bulbs, xenon headlamps and finally light-emitting diodes (LEDs) appeared one after another. LED headlights have quite a list of advantages, especially if we talk about energy efficiency, life span and quality of light, which can be easily tested by automated quality inspection.

How are LED car lamps built?

The different models of lamps differ, of course, depending on the make of the car, the purpose or the manufacturer of the lamp itself. In the housing of the headlight, there is a support frame, an electronic control module, LED modules and a cooling system. The headlights can contain up to dozens of LEDs. The control module can offer different lighting sequences for each component. All this is housed in a diffuser with appropriate lenses and bezel.

What processes are involved in the production of LED lights?

The primary issue is to have assembly lines adapted to the types of lamps produced. The designed workstations must ensure that all components are delivered in the right way, that the processes are carried out in the right sequence, and that ESD protection [1] is provided where necessary. Several main groups of processes can be distinguished in the production of LED lights:

• locating, assembling and bolting
• cleaning and surface preparation, e.g. by plasma [2], blowing with air ionization
• heating in an oven
• heating, including by ultrasonic and infrared
• gluing and sealing
• printing and application of labels
• testing for leakage, presence of all components, geometry, checking gaps between housing and lens
• vision testing of lamp functionality, electrical absorption of finished lamp, luminescence

Robotization

Some of the assembly operations are performed at manual workstations, but equipped with automated screwdrivers in torque converter and reaction arm versions. Components are fed by gravity descenders or vibratory feeders, and screws are fed by a dispenser. Many of these processes are worth automating and robotizing. Multi-purpose robots are used to transfer product between stations or outlets, for example, to retrieve lamps from a furnace. Robots also work well in the bonding process, e.g. for surface preparation by plasma or precise application of glue. An ultrasonic welding unit with a sonotrode [3] can be attached to a robotic arm to position it precisely. A good example of the robotization of lamp assembly, where 3 robots of different brands are integrated, can be found in the lens application, plasma and glue station designed and built by ELPLC.

Lamp assembly lines from ELPLC

For several years, ELPLC has had in its portfolio the realization of complete assembly lines for automotive lights of various types. These include manual assembly stations, robotic stations with rotary tables, handling robots and specialized EOL testers. Dedicated software supporting multiple testing methods was also developed for the testers. It is a hardware-independent tool for managing the testing process centrally from a workstation or remotely.

Full traceability with TOMAI Factory System

Lines built by ELPLC are equipped with the proprietary TOMAI Factory System. One of its functionalities is that the full production history of each piece is available and can be analyzed. This can be done against various criteria and selected filters, such as efficiency analysis by station or operator. Data export is also available.

Footnotes

1. ESD (Electro-Static Discharge) protection is a system for protecting electronic components sensitive to electrostatic discharge.
2. plasma treatment – acting on a surface with ionized gas, changing the chemical reactivity of surface atoms. A method of cleaning components before the bonding process.
3. sonotrode – the final device of an ultrasonic welding machine, its function is the final amplification of the amplitude and transfer of vibration energy. The sonotrode is mechanically connected to the electrical signal to vibration converter and amplitude amplifier. Typical operating frequencies are 20, 30 or 35 kHz.

ELPLC S.A. machines and lines

We specialize in designing and building machines, complete robotic assembly lines and developing software for industry. We offer our expertise to many industries. We provide Industry 4.0 / Smart Factory solutions.

According to estimates by the Energy Market Agency, the installed capacity of photovoltaics in Poland at the end of November 2022 was 11.92 GW, accounting for 54% of the installed capacity of RES. Each installation is a corresponding number of photovoltaic modules and inverters. An inverter consists of a number of electronic components depending on the sophistication of the design and additional functions. One such component is the choke, which, being part of the output circuit, reduces current ripple. The choke is a structure containing cores, coils and additional mounting components.

Choke assembly line

ELPLC S.A. is building a choke assembly line for one of Europe’s leading manufacturers. The line features a high degree of automation, robotization and autonomy, and supports multiple product references. The operator’s role will be limited only to replenishing semi-finished products in the feeders. Assembly slots have been designed to handle all the references required by the customer without retooling.

Stages of choke production

The first stage of production is to unwind and cut the wire to size. Then its ends are milled and the coil is formed. The next stage of production is the soldering of the ends under a nitrogen shield and vision quality control. Loading of the finished coils onto the main assembly line and internal reloading from pallet buffers is performed by OMRON’s high-speed SCARA robots.

The main assembly line is 12 stations connected by a pallet conveyor. An RFID system ensures product tracking in the process. Vibratory feeders deliver semi-finished products to the assembly process:

• resilient sheets
• core
• segments
• decks and casing
• coils in the quantity resulting from the models of the selected packages

After bundling, the robot moves the product to a rotary welding nest that provides double-sided welding. Vision inspection, electrical tests of initial inductance and voltage strength are used to check product quality. A laser marking machine engraves an alphanumeric symbol on the carcass and a SCARA robot unloads the finished parts into bulk packaging.

Control system and ELPLC Smart Factory

The control system is based on a Mitsubishi Melsec iQ-R series PLC with additional distributed I/O and servo modules communicating via CC-Link network. The ELPLC Smart Factory system is responsible for production data acquisition. It is a production management and monitoring system that collects data from machines, analyzes it online and presents the results in reports that are easy to read for operators. It consists of two modular applications: Monitoring and Web. It allows OEE indicators and defined KPIs to be determined by analyzing production flow and micro-downtime. It provides information to UR services enabling early machine diagnostics – Predictive Maintenance. In addition, data exchange with the customer’s internal MES system is provided.

Large project

The construction of an automatic choke production line is one of ELPLC S.A.’s largest projects in 2023, right alongside the successful implementation of an advanced e-bike battery line. It will provide the customer with the production of an important inverter component at an appropriate level of quality and efficiency.

ELPLC S.A.’s machines and lines

We specialize in designing and building machines, complete robotic assembly lines—including specialized lamp assembly lines—and developing software for industry. We offer our expertise to many industries. We provide Industry 4.0 / Smart Factory solutions.