2014

njector nozzles for injection systems basically con-

sist of a nozzle tip, the needle with a spring seat, a

spring, sleeve and a type of cover that encloses the

entire unit. Mounting them is a complex process since

components of each individual injector nozzle are all

separate parts. This makes each injector unique. The

needle or spring of one nozzle cannot simply be refit-

ted on another nozzle without a loss in quality. Many

nozzle components, from the spring seat to the spring,

right through to the individual ground needle, have to

be measured precisely and matched with each other.

The assembly of these unique nozzle products is fully

automated on the conveyor belt.

This type of assembly is made possible by special

machine builders such as Sonplas GmbH from Straub-

ing. The company specializes in assembly and test-

ing equipment for car parts suppliers. Based in Lower

Bavaria they have made a name for themselves in the

sector, with machines that assemble or test supplied

parts through which fuel later flows in the vehicle. Many

international car parts suppliers appreciate this exper-

tise with almost 200 employees with this know-how.

At the end of 2012 Sonplas won the order to

design and build two machines for assembling injec-

tor nozzles. “The special feature of these machines was

the fact that measuring was carried out in front of each

assembly station and then the workpiece machined

according to this measurement,” Sonplas sales man-

ager Hermann Pankofer explains. This is a special chal-

lenge for the machine construction. This meant that

the spring of the injector was not simply fitted on the

needle. The machine firstly measures the force of the

spring at a station and then presses the spring seat

according to the measuring results. The spring is then

placed on the needle and another machine checks the

height of the spring at a defined counter force. The

height must be measured with a tolerance less than

Unique Products on

the Conveyor Belt

Sonplas uses Turck's BL ident RFID system and uprox+ sensors in an assembly plant

for injector nozzles

1 micrometer, since the strength and the seat of the

spring later influence the injection action of the injector

nozzle in the engine.

Assembly process requires traceability

The complex coordination of measurements and

assembly processes requires the relevant measuring

data to be tracked and assigned uniquely. “Each com-

ponent is tracked, not only the injector nozzle in its

entirety, but also each individual part itself,” says project

manager Manuel Lehner. In order to assign the compo-

nents to a nozzle, they move on the workpiece carrier

of the nozzle. The workpiece carrier specially optimized

for the plant provides a separate place for each required

injector component. RFID readers read the tags that are

fitted on each individual workpiece carrier.

For the assembly machines Sonplas looked for an

RFID system that can be mounted compactly in the

machine. “The problem was not so much the large

read/write distances involved but the fact that the

tag had to be fitted directly on the aluminum of

the workpiece carrier,” Lehner describes. The ideal

tag could be found in the extensive portfolio of

the Turck RFID system: Turck's TW-Q25L12,5-M-

B128 tag – not much larger than a thumb

nail – meets all the requirements.

Eleven TN-M18-H1147 read/write

heads in an M18 threaded

barrel are fitted in each of

the two machines in order

to identify the workpiece

carriers.

Long switching dis-

tance on aluminum

Sonplas looked for inductive sensors as

initiators in order to detect the material car-

riers on the belt and to check the correct posi-

tion of the workpiece carriers for the tags to be read.

This required a compact switch with a long switching

distance on aluminum. Only an uprox+ sensor from

Turck was ultimately able to meet this set of require-

ments. Other proximity switches do not manage to

guarantee such a large switching on aluminum with

the same level of reliability. The four millimeter switch-

ing distance of the NI4U-EG08-AP6X used is consider-

able for a sensor in the M8 housing – and is the same

for all metals. Sonplas fitted 56 sensors in each of the

“

The fact that the

Turck sensor detects

aluminum so well was

a major benefit for us.

This saved us having to

implement any labor-

intensive alternative

solutions.

”

Manuel Lehner,

Sonplas

Special machine builders Sonplas developed and built

two machines for assembling high-precision injector

nozzles. To meet customer requirements in terms of

precision and repetition accuracy, the individual nozzles

and their components must be identified accurately in

the process. For this Sonplas uses Turck's BL ident RFID

system and uprox+ proximity switches which detect

aluminum workpiece carriers on the conveyor belt.





Quick read

The tag is

fitted directly

in the aluminum

workpiece carrier