Verbesserung einer Fadenschneidemaschine zur Produktion von medizinischen Fäden

Success Story

Improve­ment of a thread cut­ting machine for the pro­duc­tion of med­ical suture

A new mechanical design and the use of servo drives allow the production of different profiles with one machine.
Thread cut­ting machine, heart of the machine: the yarn infeed and cutting

Long aux­il­iary process times and man­u­al inter­ven­tion with pre­vi­ous pro­duc­tion lines

The processed prod­ucts are monofil­a­ment threads with a diam­e­ter of 0.25 to 1.0 mm, which are pro­vid­ed with a spe­cif­ic pro­file in the form of inden­ta­tions. These sutures are used, for exam­ple, for cos­met­ic cor­rec­tions such as facelifts, but also for wound clo­sure. The pro­files dif­fer in the num­ber, depth, shape and ori­en­ta­tion of the inden­ta­tions. The machines pre­vi­ous­ly used for pro­duc­tion could only be used for one or a few prod­uct types and had only lim­it­ed adjust­ment pos­si­bil­i­ties. There was a sep­a­rate machine for each new type of thread. The blanks had to be insert­ed man­u­al­ly before each process, which was very time-con­sum­ing and prone to errors.

New con­cept enables adjustable pro­files and full automation

Thanks to a new mechan­i­cal design and the use of ser­vo dri­ves, the func­tion of the machine has been com­plete­ly revised. The arrange­ment of the cuts, which was pre­vi­ous­ly deter­mined by the fixed mechan­i­cal guides, now only depends on the para­me­ter set of the ser­vo dri­ves. Only the knife angle must be adjust­ed man­u­al­ly. But also, for this adjust­ment an auto­mat­ic pro­ce­dure has already been devel­oped and test­ed for the next update of the machine.

To change the pro­files, the appro­pri­ate recipe must now be select­ed on the machine’s con­trol pan­el. In addi­tion, the pro­files can be new­ly cre­at­ed and edit­ed. In order to be able to check the set­tings eas­i­ly, the pro­file is dis­played graph­i­cal­ly on the pan­el. If a para­me­ter is adjust­ed, the image is dynam­i­cal­ly adapted.

After each cut, the thread, which pre­vi­ous­ly always had to be re-insert­ed, is pulled off a bob­bin by an auto­mat­ed infeed and fed into the machine and the cut­ting process starts again. The thread cut accord­ing to the selec­tion is deposit­ed in a box. This way, pro­duc­tion is ful­ly auto­mat­ed and employ­ee inter­ven­tion is only nec­es­sary to change the bob­bin. Due to the adap­ta­tion, the set-up times could be reduced con­sid­er­ably, and the prod­uct vari­ance of the indi­vid­ual machines could be increased.

Selec­tion of the pro­file via con­trol pan­el, micro­scope images of the products

Soft encoders guar­an­tee max­i­mum cus­tomiza­tion possibilities

The soft­ware is based on a rotary trans­fer machine, each with a soft encoder for the main process, the posi­tion­ing and ten­sion­ing of the thread, and the sec­ondary process through which the pro­file cuts are car­ried out. This means that not only the speed of the machine is freely adjustable, but also the cut­ting pro­files can be set by the para­me­ter sets as described above. This flex­i­bil­i­ty makes it pos­si­ble to use the machine also for the devel­op­ment of new prod­ucts, which pre­vi­ous­ly had to be cre­at­ed by hand in the lab­o­ra­to­ry. The machine con­cept can be trans­ferred to many oth­er appli­ca­tions where simul­ta­ne­ous pro­cess­ing and pull-through move­ment of the mate­r­i­al is required.

Contact Person
QA Mitarbeiter Dany Reinartz
Dany Reinartz
Software Engineer
Specializations: Control Engineering, Profibus and Profinet analysis.

Polymedtex GmbH
Salacherstraße 90
73054 Eislingen

Producer of medical suture and sutural material for surgery.