Miller Weldmaster PS300 Back-Seam Bag Sealing Machine

What the PS300 does

The Miller Weldmaster PS300 is a back-seam bag sealing machine. It folds flat material around and welds the longitudinal overlap seam by hot air, forming the material into a continuous tube, which is the body of the bag. It runs at up to 100 m/min, lays a seam 25 to 38 mm wide at up to 788°C, and is servo controlled so it synchronises with the line. Unlike a top closer, which seals a filled bag at the end of the line, the PS300 forms the bag tube upstream.

The terminology shifts from one buyer to the next. A back seam sealing machine or a bag back seam welding machine is the PS300, and so is a bag tube forming machine, an overlap seam welding machine or a bag making machine. Whichever name you know it by, this is the machine that forms the tube.

Built for bag makers and forming lines

The PS300 is for operations that form the bag body rather than just close a filled one: woven sack and FIBC bag makers, form-fill-seal packaging lines, tube and sleeve bag converters, and valve and open-mouth bag producers. It folds flat material and welds the back seam continuously, so the bag tube comes off the machine ready for the next step, cutting, bottoming or filling. Optional add-ons include a grommet machine and an ultrasonic cutter, and the machine can be custom-designed to suit your material and layout.

It is digitally and servo controlled, so start-up is quick and it keeps pace with the line. A precision folding system gives clean, straight folds, a quick-change folding system handles different fold sizes and types, and recipe management makes changing between products straightforward.

Welded back seam vs glued or stitched, and vs the top closers

Forming a bag tube with glue or hot melt adds a consumable, a curing step and a mess, and a stitched seam leaves holes. A welded overlap back seam fuses the material into one piece with no consumable and no holes, which makes a cleaner, stronger tube at speed. Within the range, the PS300 forms the bag body via the back seam, while the PS150 and PS400 close the top of a filled bag. Many lines use a forming machine like the PS300 upstream and a top closer downstream, and our team will help you place the right machine where it belongs.

• No consumable: the seam is welded, so there is no glue or hot melt to buy or cure.
• Strong tube: a fused overlap seam has no stitch holes to leak or weaken.
• Fast: continuous back-seam welding at up to 100 m/min for high-volume bag making.
• Configurable: quick-change folds, plus optional grommet and ultrasonic cutter.
• Where it sits: the PS300 forms the bag tube; the PS150 and PS400 close filled tops.

Industries that use the PS300

Any operation that forms a bag body or sleeve is a fit. Miller Weldmaster builds the PS300 for packaging and bag-making lines across:

• Woven sacks and FIBC: woven PP sack bodies and FIBC bag liners.
• Form-fill-seal: lines that form a tube around the product before filling.
• Tube and sleeve bags: continuous tube and sleeve converting.
• Valve and open-mouth bags: bag bodies for cement, food and chemical packing.
• Liners and covers: tubular liners and protective sleeves.
• Contract bag making: third-party and co-manufacturing operations.

Why source the PS300 through Magnum Resources

Magnum Resources is the authorised India partner for Miller Weldmaster, the US fabric and packaging welding specialist. A back-seam former has to match your material and line, so we work the fold, seam and any options like the grommet head or ultrasonic cutter out with the factory before you commit. We bring it in, clear customs, fit it to your line and train your team. Folding and seal parts then come back to us, not an overseas desk.

If you are assessing a back seam sealing machine or a bag tube former for a woven sack, FIBC or form-fill-seal line in India, talk to our engineers about your material, bag size and line speed. We will give you straight specs, a lead time you can plan around, and a quotation configured to the line.