Documented quality - stitch by stitch

Kaiserslautern, (PresseBox) - PFAFF Docu-seam-systems are a quality assurance systems designed for use on safety relevant seams. PFAFF docu-sewing systems make an important contribution to extra driving safety. They monitor and guarantee 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: on the one hand, it shouldn't be too secure as this will prevent the side airbag from expanding and unfolding; on the other hand the seam must have a minimum strength so that it does not tear open unexpectedly during normal use.

With this machines, PFAFF has developed solutions 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 doc-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-sewing systems are another important tool for quality assurance within the overall automobile production chain, even if it "just" deals with one simple element - an approx. 40 cm long seam section. Other possible uses for this machines include the production of parachutes, seatbelts, sails, awnings, tarpaulins - anything involving the production of safety related seams.

World premiere
PFAFF 3721 docu seam system with driven feed wheel and roller presser

With the new 3721, PFAFF has developed a system for delicate materials made from leather and artificial leather for the first time. The new PFAFF 3721 is the first docu-seam machine with separately driven feed wheel and roller presser. This allows a more differentiated sewing operation. The machine can provide edge trimming up to 1.5 mm.

A typical application is the cover for the passenger airbag on the dashboard - an operation involving tight curves alternating with straight seam sections. Thanks to the possibility of programmed differentiation for the curves, reproducible quality is guaranteed. And the edge is trimmed at the same time to produce a midget seam. This does away with the need for finishing.The 3721 is the answer to the trend for ever more refined and sophisticated materials for fitting out car interiors, while also catering for safety-relevant seams.

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