Multi-head weigher stands: choosing for the line
How to choose a stand for a multi-head weigher: dimensions, load, height adjustment. Standard and custom solutions.
A multi-head weigher is precise and expensive equipment, the heart of a packaging line. But it works exactly as well as it stands stably. A multi-head weigher stand is not just a “table” but a load-bearing structure that holds the geometry, damps vibration and sets the product drop height. Let us look at how to choose it correctly.
Why a special stand is needed
A multi-head weigher weighs portions accurate to the gram — for a 200–500 g pack the error typically stays within ±0.5–1 g. Such accuracy requires a stable support: any oscillation of the structure distorts the load-cell readings, because the cells respond to acceleration just as they do to the useful weight of the product. A random “table” of thin-walled profile tube does not suit here — it has a natural frequency in the 8–15 Hz range, dangerously close to the discharge frequency of the heads.
The second task of the stand is to raise the weigher to the required height. Product from the multi-head falls into the packaging machine by gravity, so the drop must be exactly above the receiving funnel. The stand’s height and geometry are calculated for the specific “weigher — packer” pair, accounting for the film travel and the position of the sealing jaws. An error of even 30–40 mm skews the product’s fall trajectory and leads to jamming in the seam or contamination of the sealing zone.
Design requirements
A proper multi-head weigher stand meets several requirements:
- Rigidity — the frame must not vibrate in resonance with the weigher’s operation; we set the structure’s natural frequency above 25 Hz.
- AISI 304 stainless steel — contact with the food zone, regular washing; a 40×40 or 50×50 mm profile with a 2–3 mm wall.
- Adjustable feet — to compensate for floor unevenness, precise levelling to within 0.5 mm/m.
- Open structure — access to service the weigher from below and the side, to replace load cells and clean the funnels.
- A platform or stairs — safe operator access to loading the weigher, with a railing from 1100 mm.
Separately we calculate the unit fixing the weigher to the top frame. A multi-head weigher usually rests on three or four support points, and these points must coincide with the frame’s stiffening nodes, not the middle of a beam span. Otherwise even a structure that looks rigid will “play” under the dynamic load of the heads.
Standard stand parameters
| Parameter | Value |
|---|---|
| Material | AISI 304 stainless steel |
| Frame profile | 40×40–50×50 mm, 2–3 mm wall |
| Height (adjustable) | 1500–3500 mm |
| Foot adjustment range | ±50 mm |
| Load | up to 800 kg |
| Number of support legs | 4–6 |
| Structure’s natural frequency | above 25 Hz |
| Levelling accuracy | 0.5 mm/m |
| Operator platform | as needed, with a railing from 1100 mm |
Height is the main variable parameter. It is determined by the packaging machine’s height plus the space needed for funnels and finished-product transporters. For a line with weight control and a metal detector, we allow another 250–400 mm under the stand for the discharge conveyor.
How vibration is damped
Vibration is the main enemy of weighing accuracy. The heads open cyclically, and each portion discharge is an impulse transmitted into the frame. If the stand resonates, the load cells “see” this oscillation and over-report the weight of the next portion. There are three ways to fight this: raise the frame’s rigidity with braces, shifting the natural frequency upward; set the weigher on damping feet; anchor the stand to the concrete floor. In practice we combine the first and third approaches — a rigid welded frame plus anchors give the most stable result.
Standard or custom
Most multi-head weighers are placed on typical stands for a standard packer height. But a real line often requires an individual solution:
- Non-standard height — when a transporter runs under the weigher or a non-typical packer stands there.
- Integration with the line — the stand carries not just the weigher but also the feed conveyor, bunker.
- Limited space — in a cramped workshop the structure is designed compact, with an offset platform.
- Elevated hygiene requirements — a fully welded structure with no bolt cavities.
Engineer’s tip. The most common mistake is ordering the stand separately from the weigher and packer “by approximate dimensions”. The product drop height must match the packer’s receiving funnel to within centimetres. We always take the exact mounting dimensions of both machines and calculate the stand to them. Otherwise the finished structure has to be cut to fit on site.
Common ordering mistakes
Over years of making such structures we have compiled a list of mistakes that cost the customer most:
- Ordering “from a photo” with no mounting dimensions. Two weighers of the same class from different makers differ in the position of the feet and the height of the funnels.
- Skimping on the profile section. A thin-walled 25×25 mm tube gives a frame twice as cheap that loses weighing accuracy already at medium line speeds.
- Bolted assembly in the food zone. Bolted joints form cavities where product and water accumulate — a continuous welded seam is more hygienic.
- No operator platform. Loading the weigher “from a ladder” is dangerous and slows down the raw-material change.
- Ignoring the discharge conveyor. If space under it is not allowed for in advance, the finished stand has to be extended.
The stand as part of the line
A multi-head weigher stand is custom equipment that makes sense to design together with the rest of the packaging unit. On our projects the stand, feed conveyor and operator platform go as a single drawing set. Product feed to the weigher is provided by conveyors and transporters matched to the stand’s height. This approach removes on-site fitting and speeds up installation. More material on laying out packaging units under the tag equipment.
Conclusion
A multi-head weigher stand is a load-bearing structure that determines both weighing accuracy and the correctness of product drop. The key requirements are rigidity, stainless steel, adjustable feet and the precise height for the packer. It is worth ordering it together with the weigher and packer by exact dimensions. If you are designing a packaging unit with a multi-head weigher, get in touch — we will calculate and make a stand for your line.
