Technical textiles
Machinery for technical textiles: sewing and heat sealing of protective clothing
Flame-retardant clothing, technical rainwear, PPE and cleanroom garments. Sewing on laminates and membranes, and seam heat sealing so that the garment meets the standard it is bought for.
A protective garment is bought for what it withstands, and what it withstands is decided at the seam. The fabric comes certified from the factory; the seam is up to you. Every stitch is a hole in the barrier that the laminate had intact, and that is where tests fail. That is why in this sector the sewing machine doesn't work alone: it is followed by a sealing machine.
What is made and with which materials
Not all technical garments need the same thing. These are the four families we see most, and what changes in each.
| Family | Typical garments | What makes it difficult |
|---|---|---|
| Fire protection | Firefighter jackets, welder overalls, heavy industry clothing | Aramid fabric, mandatory flame-retardant thread, several layers sewn at once |
| Technical rainwear | Rain jackets, mountain clothing, marine, outdoor work | Laminates and membranes: the needle hole lets water through if it isn't sealed |
| High visibility and technical workwear | Vests, overalls, garments with reflective strips | Reflective tape that can't take high temperature in the wrong place |
| Cleanroom and healthcare | Coveralls, gowns, sterile and disposable garments | It mustn't shed particles: closed seams with no loose threads |
Materials that go through the machine: two and three-layer laminated fabrics, breathable membranes, non-wovens, aramids, PU and PVC coated fabrics, and heat sealing tape in the width each seam requires.
The needle hole: why sewing is not enough
The laminate arrives from the supplier with its barrier intact and its certificate behind it. As soon as the needle passes through, every stitch opens a passage, and a one-metre seam means several hundred. Water gets in under pressure, so do chemical vapours, and in a cleanroom those holes let particles out from inside.
That is what the hydrostatic head test on the seam measures, and it is where the garment fails when the fabric on its own would have passed easily.
Heat sealing closes it
A heat tape is applied over the sewn seam with hot air and roller pressure: the tape melts its adhesive layer, bonds to the laminate and covers the stitch line. The seam keeps its mechanical strength and recovers the barrier.
It is not the same as welding
Welding joins two materials without thread, by heat or high frequency, and that works on canvas and PVC. On technical garments you almost always sew first and seal afterwards, because the seam provides strength that welding alone doesn't.
Three operations, three machines
A technical garment line is built with three workstations. This is the order and what each one does.
Cutting
Laminate doesn't forgive cutting with scissors or a badly spread lay: if the ply shifts, the piece comes out of square and the seam doesn't fall where it should. Automated cutting, with a spreader if production justifies it.
See industrial cutting
Sewing
Foot and feed that don't mark the laminate, fine tension so as not to perforate more than necessary, and the ability to work with flame-retardant thread, which is more abrasive than normal thread. Depending on the garment you need a lockstitch flatbed, coverstitch, overlock and free cylinder arm to close sleeves and cuffs that are already assembled.
Sewing · Coverstitch · Overlock
Heat sealing
This is the workstation that defines the sector. Hot air, pressure rollers and control of temperature and speed, because each laminate needs its own settings and overdoing it burns the membrane.
See heat sealing machines
A useful warning: the bottleneck is almost always sealing, not sewing. One sealer can't keep up with three or four sewing machines, so the right question when sizing isn't which sealer to buy, but how many metres of seam have to be sealed per day.
Tubular pieces: sleeves, trouser legs and cuffs
A technical garment closes into tubes. Once the sleeve is sewn, neither the needle nor the sealing nozzle can get in where they could with the piece open, and that is where the free cylinder arm stops being an option and decides whether you can make the garment or not.
Sewing in the tube
The cylinder arm lets you put the closed piece in and sew from the inside with the same stitch quality as on the flat. Without it, the sleeve and cuff force you to redo the assembly order, and the result shows.
Sealing in the tube
The seam of a sleeve has to be sealed on the inside. When choosing the sealer, the arm configuration decides how far you can reach: if it doesn't fit in the sleeve, that seam stays unsealed and the garment doesn't comply.
It is the first question to ask before looking at prices: which closed pieces you have to sew and seal, and with what diameter. That gives you the arm you need, on the sewing machine and on the sealer.
Heat sealing: tape and machine
The tape is chosen by the garment material, and the machine by the metres to be sealed per day.
Two or three-layer tape. Two-layer tape has a backing and adhesive: it is the usual choice on two-layer laminates and garments where the inside isn't visible. Three-layer tape adds a further reinforcement layer and stands up better to washing, abrasion and chemical demands, which is what PPE with many industrial wash cycles requires.
| If your case is | Family | Data sheets |
|---|---|---|
| You are starting to seal, short runs or sample workshop | PFAFF 8303i Baseline | 8303i-340/001 |
| Continuous production, with several arm and nozzle configurations depending on the garment | PFAFF 8303ix | 140/011 · 243/011 · 245/011 · 341/011 · 342/011 |
| Large series and sustained demanding work | PFAFF 8330 | 8330-040 · 8330-041 · 8330-042 · 8330-043 |
Frequently asked questions
Can I seal on any fabric?
No. The tape needs to grip a compatible surface, usually a laminate or a coating. It won't stick to uncoated fabric. Before deciding on a machine you have to test with your material.
Do I need to sew if I am going to seal?
On garments, yes. The seam provides mechanical strength and the sealing provides the barrier. Stitch-free welding is used on canvas and technical articles, not on clothing.
Will the sealer I already have for another garment do?
It depends on the arm and the nozzle. A long straight seam and a closed cuff aren't sealed with the same configuration; that is why there are several variants within the same machine family.
How long does it take to pay for itself?
It depends on the metres of seam per day and on what is thrown away today due to failed tests. We do that calculation with you using your figures.
Do you also sell the tape?
Yes, as a consumable. You can see it under spare parts and consumables.
Do you provide training when the machine is installed?
Yes. We support you through installation, commissioning, training and maintenance. In heat sealing it is essential: the machine has to be set up for each material, and that setting is taught.
Tell us about your garment
Tell us what you make, with which laminate and how many metres of seam you seal per day. With that we will tell you which machine you need and, if necessary, we test with your material first.
Is your garment workwear without a standard requirement? Then you will be more interested in garment manufacturing machinery. Do you work with canvas, covers or textile structures rather than garments? See awnings or sun protection.
Related advice
- Do you make PVC or PU canvas for awnings, marquees and trucks?: high frequency, hot wedge or hot air, and the PFAFF 8320, 8362 and 8390 welders.
- Which machine do you need to make pool covers?: bubble covers and PVC covers with the PFAFF 8362-126 hot wedge welder, and compound feed for the binding.