Pet food looks like a snack line from a distance. In practice it is one of the harder categories to package well, because the product is abrasive, dusty, heavy, and often packed in bags that have to survive being dragged across a warehouse floor.
A machine that handles 200 g of potato chips beautifully will not necessarily survive a 10 kg bag of kibble running three shifts.
Kibble is abrasive
Every piece has sharp edges and a hard, dry surface. Run it through a standard film and it will abrade the print, scuff the seal area, and wear the inside of your forming tube over months.
Specify a film with an abrasion-resistant outer layer, and expect to pay for it. On heavy bags, a PET or nylon-reinforced structure is normal, and a paper outer layer is popular for the matte look but needs a good barrier underneath to survive handling.
Bag formats for pet food
- Side gusset bag, 2 to 15 kg – the workhorse. Needs a gusset former, a strong seal, and often a handle
- Flat bottom bag – best shelf presence, usually premade, good for premium retail
- Stand-up pouch with zipper – treats, 200 g to 1 kg
- Woven or laminated sack – bulk 15 to 25 kg, usually a separate bagging line
- Tray and carton – wet food, a completely different machine set
A 10 kg gusset bag has a real weight problem: the seal has to hold 10 kg under acceleration, and the bag has to survive being lifted by one corner. Seal width and film structure matter more here than on any snack bag.
Weighing kibble
A multihead weigher is the normal choice, and for good reason: kibble piece weight varies, and the combination principle averages it out. Look for dimpled or textured hoppers, because smooth stainless lets kibble slide too fast and settle badly.
For large bags, a two-stage system works well: weigh a bulk portion and a fine portion, so a 10 kg bag is not being weighed to the gram in one dump. And add a checkweigher, because a 10 kg bag that is 100 g heavy costs real money over a year.
Dust is the enemy of every load cell and every photoelectric sensor on the line. Specify dust protection on the weighing frame, and plan a vacuum point at the fill station.
Seal contamination
Kibble dust and fat residue sit exactly where the jaws close. On a heavy bag, a contaminated seal does not just leak, it fails completely in the pallet.
Use a product guard, a short air purge, and a jaw cleaning routine every break. For fatty products, a jaw coating that resists build-up is worth the extra cost. And check seal strength on the finished bag, not on a sample pulled straight off the machine, because a heavy bag stresses the seal for hours after it is made.
Wet food is a different plant
Cans, trays, and retort pouches are a separate discipline: filling by volume, seaming or retort-grade sealing, and a whole different set of validation requirements. If you are doing both dry and wet, treat them as two projects, not one line with an attachment.
Treats and chews
Irregular shapes are the problem. A long chew stick will not drop through a standard hopper, and a soft treat deforms under load. Look at a flow wrapper with a product conveyor rather than a VFFS, or a counting and collating system feeding a pouch machine.
For sticks and dental chews, a horizontal flow wrapper with an infeed conveyor and a photo-eye registration is usually the right machine, because the product is placed rather than dropped.
Speeds and layout
| Product | Typical output | Machine |
|---|---|---|
| Retail kibble, 2 to 4 kg | 25 to 40 bags/min | VFFS with 14-head weigher |
| Bulk kibble, 10 to 15 kg | 8 to 15 bags/min | VFFS heavy duty, or linear weigher |
| Treats, 100 to 300 g | 40 to 60 bags/min | VFFS or premade pouch machine |
| Chews and sticks | 40 to 80 packs/min | Flow wrapper |
| Wet food pouches | 30 to 60 pouches/min | Premade pouch machine with spout or retort sealing |
One layout note: heavy bags need a powered outfeed and a bag flattener, not a gravity chute. A 10 kg bag dropped onto a conveyor from height will split, and the operator will be lifting it all day.
Labelling and compliance
Pet food labels carry guaranteed analysis, feeding guidelines, and lot codes, and many markets require specific wording. Build the labeller into the line rather than adding it later, and make sure the print position is fixed by the machine, not by the operator’s eye.
If you are weighing the whole line, our guide to choosing between a multihead and a linear weigher covers the accuracy math, and the VFFS range covers the heavy-duty bagging side.
Frequently asked questions
Can one machine do 200 g treats and 10 kg kibble?
Technically with enough change parts, practically no. The film path, the former, the sealing pressure, and the outfeed all want different things. Two machines are usually cheaper than one machine compromised in both directions.
How thick should the film be for a 10 kg bag?
Usually 120 to 160 micron total, with a nylon or PET layer for puncture resistance. Ask the film supplier to test a filled bag by dropping it from pallet height before you commit to a structure.
Why do my seals fail on heavy bags but pass inspection?
Because the stress arrives after packing. A seal can pass a peel test and still fail when 10 kg pulls on it in a pallet for a week. Test after 24 hours, and test a bag from the bottom of the stack.
Is a checkweigher worth it for pet food?
Yes, especially on large bags. Giveaway at 10 kg scale is expensive, and a checkweigher also catches a weigher that has drifted before you ship a pallet.