Liquid Leak Test

Fuel injector quality is a decisive factor in the efficiency of motor vehicle engines. Sonplas has considerable experience in the design and construction of test benches for the leak testing of fuel injection valves.

The manually loaded test bench has been designed for different gasoline injectors. It offers high flexibility in testing injectors with different geometries due to a simple change of the injector fixtures and a single changeover dialogue in the software. The fully automated control software allows easy handling and high flexibility. Results and current values are displayed in the main window to guarantee an easy overview of the process.


Production Equipment for GDI Injectors

This production equipment is an automatic system for calibration and test of high-pressure solenoid fuel injectors.
The operation starts with loading the injector by means of a robot into a rotary dial. After reading the serial code (DMC), the injector enters the calibration unit. In the module the injectors are driven for about 150000 cycles in order to run-in and therefore stabilize the part.
The injector will be calibrated to a target flow, two additional flows can be rechecked at different test conditions. The next work process verifies the spray geometry of the injector by analyzing a shadowgraph taken image. Within the last performed work step the seat leakage will be tested with the patented liquid leak test.
Before unloading, the injector will be flushed out with air, so that the part will exit the production equipment in dry condition.
Finally, good parts will be placed into pallets, scraps will be sorted into the dedicated scrap rails.

GDI Sample Lab Equipment

Bench for GDI injectors with 2 independent stations:
Spray test: Optical measurement of spray geometry
Liquid leak test: Leakage measurement of closed injectors

Realization as laboratory bench with high flexibility e.g. during product development processes.

[Translate to englisch:] Kalibrier- und Prüfanlage für GDI Injektoren

[Translate to englisch:] Diese Produktionslinie prüft und montiert Hochdruck-Spuleninjektoren.
Sie ist konzipiert als vollautomatisierte Anlage, in der folgende Arbeitsschritte ausgeführt werden:

    - Einlaufen der Prüflinge mit Funktionsprüfung
    - Kalibrieren des dynamischen Durchflusses
    - Messung weiterer statischer und dynamischer Flüsse
    - Messung der Strahlgeometrie
    - hydraulische Dichtheitsprüfung
    - Ausblasen
    - Filtermontage
    - “Combustion seal”- Montage
    - optischer Pincheck

Ein zentraler Roboter belädt die Prüflinge aus einer Palette in Werkstückträger. Diese werden über ein Bandsystem an die Module verteilt. Zum Produktionsstart wurde die Anlage mit zwei baugleichen Prüfmodulen und einem Montagemodul ausgestattet. Bei Bedarf können noch weitere Prüfmodule in die Linie integriert werden, um die Ausbringung zu erhöhen.

HEXELL – spray pattern test bench

The HEXELL spray pattern test bench tests the spray pattern of a fuel injector on the basis of the distance of the injector from the measuring cell. The test bench is used to test production test pieces but can also be used to test the nozzle behaviour of fuel injectors. The spray pattern of an injector depends on the medium temperature and pressure. Calibrated sensors measure these two values and transmit the test readings to the analyser cabinet for processing. The bench is designed for testing various injector types at different distances from the measuring cell. In order to keep extraction times to the minimum, the measuring cell is cleaned by a high pressure air flow. This air flow is generated by a vacuum pump and the flow can be increased by means of compressed air where necessary.

Endurance test bench for high-pressure gasoline injections

The 12-station endurance test bench is designed for the life testing of highpressure petrol injection valves of various sizes. The bench has exchangeable adapters for the various types of test parts. The bench is supplied with fuel from a mobile tank trolley. This is equipped with a centrifugal pump and a large, stainless steel drip pan. The fuel supply is connected to the test bench with drip-proof, quick-release connectors. The fuel tank temperature and level are monitored continuously. The number of test stations can be selected when the test plan data are being entered. During the test, the fuel pressure and the electrical control signal are timecontrolled to enable measurement of flow and temperature. The high pressure required for the test cycle is produced by a radial piston pump.

Test bench for flow measurement at extreme temperature conditions

The climatic test bench is used for testing the flow of Piezo injectors at extreme temperatures that prevail in combustion engines. Exxsol or n-Heptan can be used as test fluid. The possible temperature range is between -40°C and +150°C whereas a temperature difference of 150°C between the chamber and the fluid is possible. The chamber includes 4 injector banks. Each bank can hold up to 6 Piezo injectors. The flow can be measured with a Coriolis flow meter or/and a high -precision balance. The injectors are supplied via a high pressure pump with a maximum flow of 30l/min at 250bar. In order to ensure the explosion protection the chamber is rinsed with nitrogen and afterwards pressurised to generate an inert environment in the chamber before the test is started.

Calibration & test system for gasoline injectors

This production line is an automatic system for calibration, test
and final assembly of low-pressure fuel injectors. The machine is a fully automatic production line for performing the following process steps:

  • Check for damaged o-rings
  • Run-in with check of the solenoid by special driver cards
  • Static flow measurement
  • Calibration of the dynamic flow
  • Measurement of the dynamic flow
  • Blow out
  • Measurement of the tip-leak
  • Assembly of a top cap

The machine is automatically loaded by a robot. The injectors are placed into calibration fixtures and transported to the processing modules by means of a conveyor belt. The line comprises two calibration modules with the same functions. If one module needs
to be stopped (e.g. for maintenance), the line will continue producing with less efficiency.

Calibration and test line for Deka VII fuel injectors based on “Lean Concept”

This automatic production line with manual on- and offload is used for calibration, test and assembly of low pressure fuel injectors.
The following work steps are carried out:

  • regulated filter prepress to reduce cycle time
  • run-in of injectors with coil check supported by intelligent driver boards
  • static flow measurement
  • calibration of dynamic flow
  • dynamic flow measurement
  • seat leakage check with patented system
  • assembly of identification clip

μHammering Calibration Process

Conventional calibration processes with wedge adjustment or by spindle cannot meet the requirements of many applications with regard to higher positioning accuracy anymore. This results in an increased reject rate and rising production costs. Microhammering has been developed in order to meet these demands, to eliminate known disadvantages of the established technologies and to open up new possibilities in the field of assembly and calibration technology:

  • Significantly increased positioning accuracy
  • Elimination of the stick-slip effect during the press-in operation by micro-impuls feed rate
  • Reduced component stress by minimized static load
  • Intelligent process control with high robustness against batch influences and variations of the press fit tolerances
  • Reduced influence of the elastic component deformation on the positioning result

Microhammering obtains a feed rate, contrary to conventional processes, not with high static loads but with dosed force impulses in the microsecond range. This technology reduces the elastic deformation of the component as well as the consequent obstruction and increase of the press-in force. As a result, the components are exposed significantly lower effective forces and prevented from unsolicited material deformations.

More informations here...

GDI injector function test

The test bench has been designed for testing important characteristics of high-pressure piezo and solenoid injectors. It is equipped with explosion-proof components. The tests are performed with N-heptane.

The following test functions are available:

  • Dynamic flow tests (for determination of characteristic curves) in mg / inj depending on fuel pressure, injection frequency or drive pulse form.
  • Determination of opening and closing characteristics by laser vibrometer tests.
  • Determination of the injection process by shot to shot measurements.
  • Optical injection spray tests by radial and axial camera systems.
  • Injector seat leakage measurement by non-dispersive infrared (NDIR) technology

Calibration & test system for Piezo GDI injectors

This production line is an automatic system for calibration, test and final assembly of high-pressure fuel injectors. The operation starts with loading the injector by a robot into pallets that are transported through the line by a conveyor system. After reading the serial number (DMC) and an electrical R-C-L check of the Piezo stack, the injector enters one of 5 equal calibration modules. In the calibration module the injector is driven for about 10 minutes in order to run-in and stabilize the part. The injector is now calibrated to the target flow and the flow is tested at several targets. Afterwards, the Sonplas patented wet leak test is performed.
15 % of the injectors are retested in an audit station by three different physical flow measurement methods. In case the audit detects deviations from the targets, the audit is able to regulate the calibration modules or even to stop them if the difference is too big. In the next station the spray of the injector is detected by 3 camera systems. The spray angles are calculated and the spray is tested for gaps. After some final assembly processes the injector is lasermarked with production data. An optical check by an image processing system closes the operations in the production line.

GDI Quality Test Bench

The quality flow test bench is designed for the entire analysis of all important parameters of GDI-fuel injectors. The test bench is equipped with explosion protected components. N-heptane or Exxsol is used as test fluid.

The bench provides the following test functions:

  • dynamic flow test in mg/inj (volumetric/gravimetric) in order to calculate injector linearity and offset
  • static flow test in g/s (volumetric/gravimetric)
  • ascertainment of opening and closing times
  • coil resistance
  • coil inductance
  • isolation test
  • proof pressure test
  • seat leak test
  • injector spray characteristic (spray density, axial & radial spray geometry)

Robot loader for EDM machines

The loader has been designed for fully automatic on- and offloading of 2 EDM machines as well as for conservation and flow measurement of eroded nozzle elements for gasoline direct injection. The unmachined parts are transported to the robot cell by means of a line feeder. A robot distributes the parts between the external EDM machines, the conservation station, the hole control and the measuring station. The eroded and tested parts are put into 9 classified boxes.

Flow and spray test bench for gasoline injectors

Important characteristics of low pressure gasoline injectors can be
ascertained by means of this test bench. N-heptane or Exxsol D40 can
be used as test fluid. Therefore explosion proof components ensure
safe test operations.

Following test runs can be performed:

  • Dynamic flow test in g/1000inj (gravimetric method with high precision balance)
  • Static flow test in g/s (gravimetric method with high precision balance)
  • Verification of the injector's characteristics of linearity
  • Investigation of the minimal opening and closing voltage
  • Investigation regarding spray proportions by means of discrete gravimetrical measurement of the geometric distribution of the injected test fluid.

HPDI calibration rotary table

This system has been developed for a leading supplier of the automotive industry. It has been designed for calibration of the dynamic flow and for final testing of gasoline high-pressure direct injectors (HPDI). The machine consists of an automatic rotary table loaded and off-loaded by an ADEPT ONE robot. A run in process is performed before calibration. The plant is equipped with low pressure and high pressure fuel supply systems.


Injector spray pattern test by laser optics

This plant is the result of a joint project between BMW, RWTH-Aachen Technical University, LaVision, TSI and Sonplas. The plant tests the spray pattern of injector nozzles. The plant reproduces engine operating conditions but without any of the fluctuations of real-life engines. There are two test procedures:



Laser Induced Fluorescence as rapid 2D test method for measuring the shape and density of the injector spray pattern.


Phase Doppler Analysis measures the size and speed of the ball-shaped fuel particles without interfering with the flow or the flow rate.


Flow and spray test of GDI injectors

The test bench is designed for the investigation of geometrical spray characteristics and flow measurements of injectors and nozzle elements. After the manual loading of the test parts the complete automatic test sequence starts including the analysis of spray characteristics and flow data. The spray test cavity is configured for radial backlight inspections and axial light sheet inspections. A motorized traversing system positions the axial light sheet optics. The nest rotation driven by means of a stepper motor allows a complete geometrical investigation of the spray characteristics.

Calibration Line for GDI Injectors

This production line is an automatic system for calibration, test and final assembly of high-pressure solenoid fuel injectors.
It is a fully automatic line and able to perform the following  process steps:

    • Run-in with a functional check of the injector
    • Calibration of the dynamic flow
    • Measurement of static and dynamic flows with different  driver parameters
    • Measurement of spray geometry
    • Liquid leak test
    • Blow out
    • Filter assembly
    • Combustion seal assembly
    • Optical connector-pin check
    • Washer and snap-ring assembly


The system is automatically loaded by a central robot combined with a conveyor system which connects the calibration modules. The line consists of several calibration modules with equal functionality and one assembly module. If one calibration module needs to be stopped (e.g. for maintenance), the line will continue producing with less efficiency.

Flow Test & EDM Loader for GDI Valve Seats

The machine has been designed for fully automatic on- and offloading of 2 EMD machines as well as for type recognition and flow measurement of EDM processed nozzle components for gasoline direct injection.
The blank parts are transported to the camera station (used for type recognition) by bowl feeder. The robot distributes the parts between the external EDM machines and a rotary table. The rotary table distributes the parts to the following stations:

  • Flow measurement station
  • Air purge station


The flow tested parts are put into several classified offload boxes.

Sonplas GmbH- Sachsenring 57 - D-94315 Straubing - Deutschland - Tel: +49 (0) 94 21 / 92 75 - 0 Fax: +49 (0) 94 21 / 92 75 199 - info(at)

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