Sachet Packaging Machine

Overview

A sachet packaging machine takes a single web of flexible laminate film and turns it into a stream of small flat sealed packets, each holding one measured dose of product. It is the workhorse behind single-serve ketchup, shampoo samples, oral rehydration salts, spice blends, instant coffee and countless pharmaceutical powders. The machine runs vertically: film comes off a reel at the top, folds into shape, gets a back seal and side seals, receives its fill, and is then cross-sealed and cut off at the bottom as a finished sachet.

The work flows through fixed stations in order. The Film Feed unwinds the reel and tracks the print, the Forming Station station folds the web, the Vertical Seal closes the back seam, the Dosing System system drops in the product, and the Cross Seal and Cut seals the top and bottom and cuts the sachet free. A Date Coder marks the lot and date, and the whole sequence is run from the Control Cabinet cabinet. The Machine Frame holds every station rigid and washes down clean.

Film handling and registration

The film is a thin laminate, often paper backed with polyethylene, or polyester laminated to aluminium foil and a heat-seal layer. Foil laminates give a moisture and oxygen barrier that protects powders and pharmaceuticals; plain PE laminates are cheaper and used for less sensitive products. The reel sits on an Reel Shaft that pays film out under tension held by a Dancer Arm. Without steady tension the seals wrinkle and the cut wanders.

Printed film carries an eye-mark, a small black rectangle in the gutter between artwork repeats. The Registration Eye reads each mark and the control corrects the film draw so the cut always lands between two designs rather than through the printing. An Edge Guide keeps the web tracking straight so the seams stay parallel.

Forming and sealing

The flat web is folded by the Forming Plow into either a single tube, for a back-seam sachet, or two facing layers, for a four-side-seal sachet from two webs. Sealing is entirely thermal: heated bars press the film layers together long enough to melt the inner seal layer, which then fuses as it cools under pressure. The Vertical Seal Bar closes the back seam while the film runs, and the Cross Seal Jaw closes the top and bottom across the web.

Each bar holds a Heating Element and a Thermocouple feeding a PID loop, so the seal temperature stays within a few degrees of setpoint. Too cool and the seal leaks; too hot and the film burns through or the layers delaminate. The Cut Knife mounted between the cross-jaw faces severs the finished sachet as the next one is sealed above it.

Dosing the product

Filling is matched to the product. Powders such as coffee or drink mix use an Auger Filler driven by a Servo Motor that meters by counted turns; the Hopper Agitator keeps the powder flowing so each shot weighs the same. Free-flowing granules use a volumetric cup that fills by gravity and dumps a fixed cup volume. Liquids such as sauce or shampoo use a piston pump that draws and discharges a set stroke. Whatever the method, the fill drops through the Fill Tube into the open sachet during the brief window after the side seal and before the top seal.

Fill accuracy depends on product consistency. A powder that varies in bulk density will shift the auger weight, so high-value lines add a checkweigher downstream and feed corrections back to the dosing servo.

Coding, control and discharge

Every sachet gets a lot number and expiry date from the Date Coder, whose Print Head burns the code through a Coding Ribbon onto the film. This satisfies traceability rules for food and pharma.

The Control Cabinet cabinet holds the PLC that times the film draw, fill and jaw motion, the Servo Drive units, and the Temperature Controller modules. The operator works through the HMI Touchscreen, which stores recipes for each product: sachet size, fill weight, seal temperatures and dwell. Finished sachets fall through the Discharge Chute onto a take-away Drive Belt that feeds a counter, cartoner or collection tray.

Variants and use

The single-lane machine described here runs 40 to 120 sachets a minute. For high volume the same forming and sealing principle is multiplied across many lanes: an eight-lane multilane machine forms eight webs side by side from one wide film and seals all eight cross seams in one stroke, reaching several hundred sachets a minute. Stick-pack machines are a narrow variant that makes long thin tubes for sugar, salt and instant drinks. Continuous-motion machines replace the stop-and-seal cycle with rotating seal drums for the highest speeds.

The machine suits any product that ships as a single dose: condiments, cosmetic samples, pharmaceutical powders, agrochemicals and pet food. Its appeal is low film cost per pack and a small footprint, and its limits are the modest fill weight and the leak risk inherent in heat seals, which is why pharma lines pair it with seal-integrity testing.