The right machine is decided by your bag material, your daily volume and how the line runs – not by the brand on it. The six headings below are based on the data sheets of the machines in our own catalogue.
Portable or pedestal?
This first split decides everything else. Portable machines weigh 3–5 kg, are carried by the operator and – in the shared wording of the catalogue records – close a bag in 5–8 seconds. They suit plants where the filling point moves and daily volume is moderate.
Pedestal systems are part of the line. The DS9C runs at 2,700 rpm; the complete SMPFC-101 system adds a 180 cm column, a 3 m conveyor and a feeding unit running at 7–18 m/min. Here the conveyor brings the bag to the machine. With a continuously running filling line, a portable machine becomes the bottleneck.
Single or double thread chain stitch?
Single thread chain stitch is standard on most portables in the catalogue (NP-7A, NP-7H, N600). Thread consumption is low and the seam unravels in one pull from the end thread – flour and feed plants prefer this seam because bags must open fast.
Double thread chain stitch appears on the NP-8 and on the SMPFC-101 system. The NP-8 record states its purpose directly: “closing heavy bags”. The heavier the bag and the more the seam is stressed in handling, the more double thread is the safe side.
Power source: mains, battery, air
The standard option is 220 V mains; most portables in the catalogue run on 60 W, 220 V, 50 Hz.
Where the cable is the problem, a battery model earns its place: per its record the GK9-36 sews about 500 bags on a 2-hour charge.
The third option concerns few plants, but where it applies there is no substitute: the NP-7R runs on compressed air and its record gives the application as “Ex-proof environments – gunpowder and explosives plants”. Where an electrical spark is unacceptable, the pneumatic model is the choice.
Bag material and thickness
The data sheets give almost the same list throughout: woven polypropylene and polyethylene, jute, hemp, burlap, cotton and kraft paper. Material alone therefore rarely decides; thickness does. The DS9C states a material thickness of 8 mm – the value to check on multi-layer or gusseted heavy bags.
Lubrication
The catalogue shows three approaches. Self-lubricating models keep daily maintenance to a minimum. Oil-pump systems (NP-7H, NP-8, N600 AK) distribute oil to the moving parts automatically; the Newlong sheet asks for Tellus #32 or a 22–32 cSt mineral oil at 40 °C. For the GK9-500 the record specifies SAE 20 machine oil. The pedestal DS9C runs in an oil bath.
The detail looks trivial at purchase and explains half of the service calls six months later.
Needles and spare parts
Nearly every portable machine in the catalogue takes the same needle: DN×1 size 25. For plants running several brands side by side that is good news – one needle item covers them all. The complete SMPFC-101 system uses a DR-26 needle and calls for PE/PP 12/4-5 thread.