PFAFF, a legendary company servicing the sewing machine industry for over 140 years, is a symbol of quality, assurance and reliability. Its PFAFF 3741/3745/3721 Docu-seam is a quality assurance system designed for use on safety relevant seams in car upholstery sewing, giving extra safety in driving.
The system monitors and guarantees perfect execution of the nominal breakage point on the reference seam from where the side airbag unfolds in the event of a serious incident.
The seam must meet precisely stipulated parameters, i.e. on the one hand, it shouldn’t be too secure as this will prevent the side airbag from expanding and unfolding, while on the other the seam must have a minimum strength so that it does not tear open unexpectedly during the normal use.
With this machine, PFAFF has developed a solution which uses measuring technology online to detect, analyse and document process parameters “stitch by stitch” during the stitching process. A sensor measures the thread force in cN, and the corresponding thread tension is then adjusted within a closed control circuit using a stepper motor. The seam strength is assessed as good/bad and the data stored automatically in a database where all important process parameters are saved. This database can also be used for internal statistical purposes to evaluate both the good and bad docu-seams. At the same time a label is printed with clear text and barcode which details process parameters. The label can be sewn into the seat seam for later inspection of each side airbag seat seam. If a docu-seam is faulty the sewing machine automatically stops and can only be released for the next sewing process by a person with access authorisation rights for the docu-sewing system.
This function prevents a faulty docu-seam from being delivered to the customer, which significantly increases process safety and reliability. An essential benefit of this system is that it guarantees consistent sewing quality by identifying and sorting out unusable seams in good time. This is important for product liability to counter and effectively refute any potential claims of recourse. PFAFF Docu-seam systems can be connected to the customer’s ERP system – an important precondition especially in the automobile industry.
The system is equipped with the following components:
- POWERLINE sewing machine head with triple feed
- Stepper motors for stitch length and thread tension
- Multi-position cylinder for 4 programmable foot strokes
- Sensor system for measuring thread force
- Integrated electrical winder
- New electronic edge guide
- Touchscreen control panel
- Stationary scanners, manual scanners and label printer
PFAFF Docu-seam systems are another important tool for quality assurance within the overall automobile production chain, even if it “just” deals with one simple element – an approximately 40 cm long seam section. Other possible uses of this machine include the production of parachutes, seatbelts, sails, awnings, tarpaulins – anything involving the production of safety related seams.