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Putting the ‘Specialty’ in Finishing Tools

(May 2012) posted on Tue May 22, 2012

These 17 tools can help keep the production floor humming.

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Customizable RF Welds
A portable RF welder with an integrated press, computer, and frequency-inverted motor, Forsstrom’s TD 200-800 is designed for the manufacturing of large products with straight welds such as billboards, tents, tarps, truck covers, and sunshades. The smallest of the company’s travelling machines (with emitted power of 5 to 20 kW), the TD 200-800 can have its table customized to the size of the products that will be produced; it can also be plain or equipped with one or two small troughs for material storage. Various options are available.

One-Stroke Eyelets
Munro’s 16FEI automatic pneumatic eyelet and washer setting machine is capable of cutting a hole in a variety of materials – including aluminum sign board and Kevlar, reports the company – and then feeding and setting the eyelet and washer in a single stroke. Setting time: less than 1 second; no adjustment is necessary when setting through thin or thick material, reports Munro. The 16FEI can be set up for either plain eyelets with tooth or neck washers, or rolled rim eyelets and washers. Comes complete with workbench, tool kit, and spare die.

The Tech of Joining
While you may be familiar with industrial sewing machines used to join printed graphics, you may not be quite as familiar the other joining technologies. Here are some basics on each:

Sewing: Joining panels with a sewing machine offers several advantages, including that the seam can be removed (welded seams generally cannot be removed without destroying the material). Sewing provides a very strong seam, particularly with industrial sewing machines and over-lock sergers, which typically sew and finish a seam and trim off the excess fabric all in one step. Then there’s the speed factor: Some offer speeds of more than 11 ft/min with 40 stitches/in. Some industrial machines have a walking foot to produce consistent stitches, and double-needle chainstitch machines use multiple spools of thread for large-volume production. On the downside, however, since sewing makes holes in the material, the resulting seam is generally not watertight and the holes may weaken the fabric. Plus, depending on the project, shops may have to deal with matching thread color and threads that fade under constant sunlight.

RF or HF Welding: Radio or High Frequency (RF or HF) welders use radio-frequency energy to generate heat, and then pressure is applied. The energy is generated between two metal bars; this is important because the weld is only applied on the material that touches the bars-limiting the area that can be welded at one time. The speed of RF welding is typically slower than that of heated welding, and RF welders can generally only be used on PVC, PET, and polyurethane (other materials can be RF welded, but only under special conditions). The material also must be very clean for a secure RF weld; dirt is not such a problem, but if a fabric has any salts or iron shavings on it, or is wet, the fabric may burn or arc. Manufacturers of RF welders, report that RF is easier to use than heat welding (see below) on projects that involve many tiny pieces or complicated angles because it’s difficult to start and stop with heated rotary welding techniques.

Heated Welding: Hot-air or wedge rotary welders utilize hot air or a heated metal wedge to heat the fabric. The material is typically pulled through rollers (or the heated head travels along a track) where heat is applied, with the rollers applying the required welding pressure. Heat-based welders can weld PVC, polyurethane, PP, PE, and acrylics (with welding tape). Continuous feeding of materials (with rollers) adds to the speed, and rollers make it easy to weld long, straight seams. OEMs in the hot-air welder camp note that heated welding doesn’t affect solvent-based inks. In addition, hot-air welder OEMs report that, compared to RF: hot-air’s speed is roughly double, it takes less people to operate, and it requires a smaller initial capital expenditure.

Ultrasonic Welding: Another welding option is ultrasonic welding. Like RF welding, ultrasonic creates heat through friction, but the heat is created between the layers, rather than in the materials themselves; the vibrating tool (die) creates the heat. Ultrasonic can join most plastic materials such as PE, PP, PVC, and PU. This welding technology is fast (up to 65 ft/min), but it can prove more costly to weld large surface areas.